overview of hydrological dispersion module - hdm of rodos · 3.1 general information 28 3.2...

Overview of Hydrological Dispersion Module- HDM of RODOS

R O D O SDECISION SUPPORT FOR NUCLEAR EMERGENCIES

R E P O R T

RODOS-WG4-TN(99)18

RODOS(WG4)-TN(99)18

1

Overview of Hydrological Dispersion Module - HDM of RODOSRODOS-WG4-TN(99)18

Heling R., Raskob W., Popov A., Zheleznyak M.

NRG-KEMA, FZK, TYPHOON, IMMSP

Email: [email protected]

06.1999

RODOS(WG4)-TN(99)18

2

Management Summary

The report presents an overview of the models and main features of theHydrological Dispersion Module –HDM of RODOS.

Within the RODOS system, HDM is the module for simulating thetransfer of radioactive material in aquatic environment – watersheds,rivers, lakes, reservoirs, estuaries and groundwater. HDM uses theoutput fallout from the Atmospheric Dispersion Module of RODOS(ADM) as the input source term. It also could simulate theconsequences of the direct radioactive material releases into surfacewater and ground water. The output of HDM is simulatedconcentration of radionuclides in water, sediment, fishes to be used bythe aquatic foodchain submodel of FDMA- the RODOS’ dose module .

The results of HDM are used with FDMA to estimate the effect ofshort and long term countermeasures in order to mitigate the radiationexposure of the public.

RODOS(WG4)-TN(99)18

3

Contents

1 Introduction 7

2 Hydrological dispersion of radionuclides – key processes and modellingapproaches 9

2.1 Characterisation of the key transport and exchange processes 9

2.1.1 Surface runoff 9

2.1.2 Transport in rivers 10

2.1.3 Behaviour in lakes and reservoirs 12

2.2 Overview of the modelling approaches 13

2.2.1 Generic equations 13

2.2.2 Models of radionuclide trasport in water bodies 16

2.2.3 Modelling of radinuclide exchanges in the system water-suspended sediment-bottomdeposition 23

2.2.4 Modelling of river hydrodynamics and sediment transport 25

3 Realisation of a hydrological model chain inside RODOS 28

3.1 General information 28

3.2 Objectives of the model development and integration 34

3.3 HDM Interface 36

4 Descriptions of the main models 44

4.1 RETRACE-2 Model 44

4.1.1 Introduction 44

4.1.2 A concept of wash-off modelling in the RODOS hydrological chain 45

4.1.3 General information on RETRACE wash-off models 47

4.1.4 Basic equations of the RETRACE-2 model 49

4.1.5 RETRACE-2 Input and Output Data 56

4.2 RIVTOX 57

4.2.1 Submodel of river hydraulics 57

4.2.2 Sediment transport submodel 60

4.2.3 Submodel of radinuclide transport 64

4.2.4 Boundary and initial conditions in river network 67

4.2.5 RIVTOX Input and Output Data 69

4.3 COASTOX 70

4.3.1 Submodels 70

4.3.2 Sediments transport submodel 73

4.3.3 Submodel of radinuclide transport 75

4.3.4 COASTOX input data 77

RODOS(WG4)-TN(99)18

4

4.4 THREETOX 79

4.5 Lake model LAKECO 80

4.5.1 Introduction 80

4.5.2 Hydrological processes 82

4.5.3 Biological uptake modelling 86

4.5.4 Modelling more nuclides 89

5 Test and application of the hydrological chain 90

5.1.1 Implementation and validation studies for the RETRACE-RIVTOX chain 90

5.1.2 RIVTOX and COASTOX implementation and testing in Slovakia 95

5.1.3 Implementation and testing of 3-D model THREETOX 99

5.1.4 LAKECO testing 105

5.1.5 Customisation on mountainous areas. 106

5.1.6 Testing of the models for the special applicatiosns 107

RODOS(WG4)-TN(99)18

5

List of FiguresFigure 1: Flow diagram of the key-processes of the radionuclide transport in rivers 11Figure 2: HDM Chain 1 (HC-1) : watershed-rivers&lakes under atmospheric fallout 29Figure 3: HC 2 - direct release to river.HC-2A simulation in small scale with COASTOX to zoom releasearea and to transfer than COASTOX output data to RIVTOX;HC-2B simulation in river basin scale only byRIVTOX 29Figure 4: HC 3 - atmospheric fallout on the river basin including large river reservoirs. River channels aresimulated by RIVTOX, reservoirs by COASTOX. 30Figure 5: HC 4: - direct release into the river net with large reservoirs. River channels are simulated byRIVTOX, reservoirs by COASTOX. 30Fig. 6. HC 5: - simulation of the radionuclide transport in deep stratified lakes, deep reservoirs or estuariesunder influence of river inflow and fallout on the water surface. 30Figure 7. HDM Interface structure (I) 37Figure 8. HDM Interface structure (II) 38Figure 9. HDM Interface structure (III) 39Figure 10. HDM Interface structure (IV) 39Figure 11. Data base of HDM 40Figure 12. RETRACE interface –watershed parameters 40Figure 13. RETRACE Interface –radioionuclides runoff 41Figure 14. RIVTOX interface 41Fig. 15. COASTOX interface 42Figure 16. THREETOX interface 43Figure 17: River stream parameters 59Figure 18: River stream scheme 67Figure 19: Water body parameters 70Figure 20: Ilya river basin 91Figure 21: Meteorological and hydrological data for the Ilya river basin 91Figure 22: Measured (2) and simualated (1) hydrograph in outlet of Ilya river. 92Figure 23: Cs-137 in surface runoff; daily averaged concentration in runoff from the Ilya River catchment(simulation by RETRACE) 93

Figure 24: RIVTOX Simulation of 137Cs concentration on suspended sediment at the outflow from the IlyaRiver 93Figure 25: Simulation results of the combined RIVTOX and RETRACE model for the flood event of the RiverRhine in 1993. Comparison of predicted and measured discharge data for Andemach and Maxau. 94Figure 26: Comparison of the simulated by RIVTOX and measured discharges for 4 sites at the River Rhinefor December 1993 flood. 95

Figure 27: Simulated Cs137 concentration (Bq/kg) in upper bottom layer of Kralova Reservoir - 40 daysafter the accidental release. 97Figure 28: Implementation of HDM COASTOX interface for Kralova Reservoir (Bathymetry) 98Figure 29: Implementation of HDM COASTOX interface for Kralova Reservoir (Bathymetry) 99Figure 30:. Measured bottom contamination in Bodensee Lake (decay corrected to April 1986); 100Figure 31: Simulated bottom contamination in Lake Bodensee Lake for March 1988. 100Figure 32: The 137Cs inventory in water (1), suspended sediments (2) and bottom (3) of the Bodensee Lakesimulated by THREETOX (two sets of the parameters) and compared with measurements(Kaminsky atal.1997) 101Figure . 33: Simulated bottom contamination of the Dnieper-Bug Estuary and the Black Sea (Bq kg-1) inApril 1988: (a) 137Cs (b) 90Sr. 102Figure 34: Computed vs. measured distribution of dissolved 90Sr in the surface layer of Dnieper-BugEstuary in March 1988. 103Figure 35: Simulated surface velocity in the Chernobyl Cooling Pond in 18.07.1983 104Figure 36: Simulated and measured surface temperature in the Chernobyl Cooling Pond in 18.07.1983 104Figure 37: Simulated and measured dynamics of the 137�s content of the Chernobyl Cooling Pond. Solidline: Kd = 3 m3/kg, dashed line is Kd=15 m3/�g. 105Figure 38: LAKECO results for the BIOMOVS-II Chernobyl NPP Cooling Pond scenario 106Figure 39. Example of a prediction of the downward transfer of Sr-90 under the Chernobyl shelter.Comparison of predicted and measured activity-depth profiles of 90Sr in the aqueous phase in 1995.

RODOS(WG4)-TN(99)18

6

Profiles were obtained for two sources in the shelter (—–) case 1 and (- - -) case 2. ∆ and Ο denote meanvalues of radionuclide activity detected in two different well depths. 108

RODOS(WG4)-TN(99)18

7

1 Introduction

The evaluation of the radiological consequences of accidental releasesof radionuclides from various sites demonstrated a significantcontribution from the contaminated waterbodies to the dose of thepopulation. This was clearly shown, e.g., for the Clinch River-Tennessee River basin - releases from Oak Ridge, for the Techa River /Ob River watershed - releases from “Mayak” , for the Dnieper riverbasin, and for the population in the vicinity of Scandinavian lakes -Chernobyl accident. The remobilisation of dry and wet depositedmaterial by long term floods and heavy rain events, and theresuspension of sediments during storm events resulted in themigration of radionuclides and affected also uncontaminatedagricultural areas together with drinking water supplies downstreamfrom the source of the initial contamination. Additionally, theremobilisation of radionuclides stored in the bottom sediments of lakesand reservoirs caused a delayed transfer of activity to the aquaticenvironment.

However, in contrast to their potential importance in case of nuclearaccidents, emergency systems which consider both the atmosphericand hydrological transport and exchange processes are lacking. Onereason for this situation might be due to the fact that the key-processeswhen dealing with the radiological consequences of accidental releasesof radionuclides to hydrological systems are complex and notcompletely understood. Following the Chernobyl accident, therealisation of such a Hydrological Dispersion Module (HDM) insidethe RODOS system (real-time on-line decision support) for nuclearemergency management in Europe has been started (Heling at al.1997,Raskob at at.1996, Zheleznyak at al. 1993, 1996).

HDM is developed at the NRG –KEMA, the Netherlands; FZKKarlsruhe, Germany; IMMSP, Kiev, Ukraine; TYPHOON, Obninsk,Russia; IPEP, Minsk, Belorussia, NTSC Democritos, Athens, Greece.Testing and customisation work was performed by NPPRI, Slovakia.The work on the module development and customisation is sponsoredby the Commission of the European Communities within its RadiationProtection Research Programme in the projects “Customisation andfurther development of RODOS for operational use” (RODOS-B) and“Enhancement of the EU Decision Support System RODOS and itsCustomisation for Use in Eastern Europe (INCO-Copernicus projectRODOS-E)” .

The HDM was developed within the RODOS project’s WorkingGroup 4 (Hydrological Modelling) chaired by Rudie Heling (NRG-KEMA). WG4 has provided its activities in collaboration with WG3(Countermeasures and Consequences), WG 5 (Data Assimilation andUncertainties), WG1 (System Development and Quality Assurance)

RODOS(WG4)-TN(99)18

8

under the overall management of RODOS Management Group. Thehardware and software framework of the whole RODOS system isbeing developed at the Institut für Kern- und Energietechnik of theForschungszentrum Karlsruhe (FZK/IKET), which acts as thecoordinator in the CEC research programme. Here the RODOSsoftware of all contributing institutes is implemented on a computersystem.

The detailed description of the work provided within the Project ispresented in the separate reports of the WG4 teams. The reference listof the reports is presented below.

This report provides the general overview of the HydrologicalDispersion Module of RODOS.

RODOS(WG4)-TN(99)18

9

2 Hydrological dispersion of radionuclides – key processes andmodelling approaches

2.1 Characterisation of the key transport and exchange processes

First of all, the most important transport and exchange processes,which should be considered in such a system, have to be identified. Inprinciple, they can be split up into the three areas: surface runoff,transport in rivers, and behaviour of radionuclides in lakes orreservoirs. Furtheron it is reasonable to subdivide the physicaldependencies into a pure hydrological part, e.g. water - and particulatetransport, and into a radio-chemical part (e.g. exchange processesbetween the individual phases such as radionuclides bound on particlesagainst radionuclides in solution). It is also necessary to weight theimportance of the processes with the effort to realise it in computermodels with respect to such boundary conditions as acceptablecomputing time and the availability of input data. The importance ofthe process however, is also related to the spatial and temporal range ofthe model application (e.g., subscale parametrisation).

2.1.1 Surface runoff

The most important processes affecting the amount of water andparticulate in horizontal and vertical directions are:

• infiltration into deeper soil,

• evapotranspiration from soil and vegetation,

• downhill surface washoff

• downhill subsurface runoff and

• erosion of particulate.

Only by the consideration of these key processes, a realistic assessmentof the runoff of water and particulate seems to be possible. Howevernot only the present status but also the history of the catchment playsan important role. Dependent on the past rain events, the water contentin the surface soil may prevent (dry soil) or may initiate (saturated soil)surface runoff. Each of the processes mentioned above can be dividedinto several sub-processes. An illustrative example is the hillslopewashoff which can be divided into an aerial runoff part and runoff inrills. Runoff in rills may occur for example when the hillslope is notcovered by vegetation. A heavy rain event will lead to a high surfacewater flux with soil erosion which is channelled in rills. The creation ofrills however increases the transport velocity downhill and decreasesthe infiltration rate of the running water. As the modelling of such aprocess in catchment sizes of several hundred-thousand square

RODOS(WG4)-TN(99)18

10

kilometres exceeds by far the capability of our present computertechnology- even if the necessary input data would be available- itcannot be described as an individual process. But as it affects theresults a compromise mathematical approach is to introduce so-calledeffective parameters which include not only the aerial part of thehillslope washoff but also the part of the rills. This method of usingeffective parameters is one of the procedures to include sub-scaleprocesses into a macroscopic modelling approach.

The radio-chemical characterisation of the radionuclides in soil isbased on their division into several groups depending on their ability toexchange with the water phase (dissolved, reversibly sorbed,irreversibly sorbed and fixed forms). Sorption of radionuclides occurboth on the organic matter and on the mineral components of the soil.Moreover, characteristic sorption and desorption rates can differsignificantly depending on the sorbent. Mainly three groups ofinteractions with the soil solution and the soil matrix can bedistinguished: alkaline and earth-alkaline metals (e.g. K, Sr, Cs),transition metals (e.g. Co, Ru, plutonium and uranium isotopes) andnon-metals (e.g. iodine and sulphur). As these processes are complexand not completely understood at present, simple but physically basedapproaches can be applied for their mathematical description . Theseapproaches are mainly based on available geo-chemical data e.g. pHvalues and the content of important ions such as potassium andcalcium.

2.1.2 Transport in rivers

Any pollutant in a river is transported by the water flow (advectionprocesses) and its concentration is altered by the simultaneousinfluence of turbulent diffusion processes. The radionuclides can alsointeract with suspended sediments and bottom depositions. Thepollutant transfer between the river water and suspended sediments canbe described as an adsorption-desorption process. The transfer betweenriver water and the upper layer of the bottom deposition is determinedby adsorption-desorption and diffusion processes. The sedimentationof contaminated suspended sediments and the bottom erosion are alsoimportant pathways of the “water column-bottom” exchange ofradionuclides (Figure 1).

As mentioned also for the surface runoff, two different types ofprocesses can be identified. These are the hydrological ones, whichdescribe water, suspended sediment and bottom dynamics, and theradio-chemical processes, which govern the fate of radionuclides inthose different phases driven by the hydraulic forces.

Key processes which might be part of any hydraulic submodels are:

RODOS(WG4)-TN(99)18

11

• advective-diffusive transport of water flow,

• suspended sediment transport, and

• sedimentation, resuspension and erosion.

The fate of radionuclides is in general driven by:

• dissolved contaminant transport by the river/reservoir flow,

• particulate contaminant (pollution absorbed by sediment)transport by the river/reservoir flow (this includes a separatedescription of the contaminant transported by clay, silt, mudand sand with different grain size), and

• contamination dynamics in the upper active layer of bottomsediments.

Concentrationin

Biota

Concentration ofsediment S

Uptake

Advection

Diffusion

Concentrationin

solute C

Concentration onsuspended sediment

Cs

Adsorption

Desorption

Concentration Cb in upper bottom layer

Concentration in deep bottom deposition

Adsorption Desorption Sedimentation Resuspension

Figure 1: Flow diagram of the key-processes of the radionuclide transport in rivers

The main physical exchange mechanisms are the sedimentation ofcontaminated suspended matter into the river bed and resuspension ofthe sediments into water. They are controlled by hydraulic factors (e.g.river flow, sediment transport), and depend strongly on the sedimentsize fractionation (e.g. clay, silt, sand and gravel). Radionuclidediffusion through interstitial water is a process which accounts for

RODOS(WG4)-TN(99)18

12

migration phenomena not related to sediment transport. Adsorption anddesorption of radionuclides by the surface bed sediment are the mainchemical exchange processes. These processes are not alwayscompletely reversible and are controlled by geochemical reactions ofthe dissolved radionuclides with the sediment. Uptake and subsequentexcretion of radionuclides by aquatic biota and, in general, perturbationof sediments due to the action of living organisms represent biologicalprocesses which are responsible for the exchange of radionuclidesbetween water and the bed sediment.

2.1.3 Behaviour in lakes and reservoirs

In many lakes wind-induced waves, turbulence, stratification, andseiches are the most important reasons for the mixing, and thus dilutionof the contaminant in the lake water. Stratification for example iscaused by solar insolation on the lake surface. Stratification restrictsthe transfer of radionuclides and limits the dilution only within theupper part (epilimnion) when deposition of radionuclides occurs on thelake surface. Lateron, when mixing occurs, the concentration candecrease dramatically especially when the depth of the epilimnion isrelatively small in comparison with the total depth of the lake.Stratification also affects the residence time of the lake water which isin general one of the most important factors for affecting the activityconcentration within many lakes, in particular, for those with low in-and out-flow rates.

Process Importance

Aquatic processes

Residence time of water in lake High

Turbulent mixing includingstratification

High

Sedimentation / resuspension Moderate

Adsorption and desorption Moderate

Sediment processes

Bioturbation Low

Resuspension High

Diffusion Low

Burial Low

Biological Processes

(dynamical modelling)

Biological half-life High

Foodweb composition Moderate

Consumption rate organisms High

Table 1: Key processes with respect to the radionuclide behaviour in lakes and reservoirs

RODOS(WG4)-TN(99)18

13

Apart from the hydrological transport and the mixing processes,sedimentation and resuspension of particles affect significantly theconcentration distribution of the total pollutant in the lake. Thesedimentation itself is governed by the adsorption to particles and thesedimentation rate in the lake. High adsorption and a high amount ofparticulate matter cause rapid removal of the activity from the watercolumn by the scavenging process.

Besides drinking water, uptake of radionuclides by aquaticorganisms might be one of the dominating pathways in aquaticassessment models designed for lakes or reservoirs. Therefore, it isimportant to know the transfer of the radionuclides through the aquaticfoodchains. An important role in this uptake is the trophic status of thelake, and the fraction of nuclides dissolved in the water. The bio-availability of the activity in the lake water controls the uptake bylower organisms such as phytoplankton. The concentration factorbetween water and lower organisms is of major importance, as itcontrols for almost 100 % the contamination of fish. In oligotrophiclakes the uptake by lower organisms is high, due to the high dissolvedfraction caused by low amounts of suspended matter and low ionconcentrations. The bioaccumulation in fish is governed by theretention time or biological half time of a nuclide in fish. Thebiological half-life is the time aquatic organisms need to loose 50% oftheir body burden of activity. The higher the biological half-life of anuclide in a specific organism, the later the concentration peak of thisradionuclide occurs in the aquatic organism. Furthermore, the targettissue plays an important role in the retention time in fish. Cs-137 forinstance remains in the flesh, while Sr-90 remains in the fish bones.Lanthanides and actinides are stored mostly in the organs, such askidney and liver. A summary of the above-mentioned processestogether with an attempt of carefully considering of their importancecan be found in Table 1.

2.2 Overview of the modelling approaches

2.2.1 Generic equations

The transport and behaviour of radionuclides can be predicted withvarious degrees of sophistication, ranging from a simple algebraicmass-balance approach to a multi-dimensional numerical solution ofthe problems. Basis of all the computer models is the law of massconservation of any contaminant. It can be expressed in terms of theadvection-diffusion equation in Cartesian coordinates

RODOS(WG4)-TN(99)18

14

∂∂

∂∂

∂∂

∂∂

∑ ∑Ct

+ x

(U C) = x

(C

x) + K C + S

ii

ii

ij=1m

j j=1n

jε (1)

where:

C= concentration of the contaminant

t= time

Ui= velocity term

xi= Cartesian coordinates

εi= diffusion/dispersion coefficient

Σkj= sum of decay rates for a contaminant

ΣSj= sum of sink and/or source terms

The above equation must be solved simultaneously for all phases ofthe contaminant (dissolved radionuclides, particulate radionuclidesabsorbed by sediment, biota etc.). It is not possible to solve the coupledequation analytically for a general case. Therefore, numericaltechniques must be used. For some simple cases, mostly handling onlydissolved radionuclides, analytical solutions are possible.

Analytical solutions can be used to solve the radionuclide transportin various waterbodies, e.g. within lakes and reservoirs. However, asmentioned before, they are only valid for the description of dissolvedradionuclides without including any adsorption/desorptionmechanisms. Radionuclides with small distribution coefficients (Kd),which are mostly transported in a dissolved form, can be adequatelydescribed with these analytical methods. These models are lessapplicable for radionuclides with large Kd values which can be easilyabsorbed by suspended and bottom sediments.

It is possible to derive several groups of models from the basicequation. Mainly six groups of models can be distinguished to describethe aquatic system.

Type I General advection-diffusion equations with (or without)decay and sink/source terms

∂∂

∂∂

∂∂

∂∂

∑ ∑Ct

+U x

C = x

(C

x) + K C + Si

i ii

ij=1m

j j=1n

jε (2)

RODOS(WG4)-TN(99)18

15

This equation includes the basic transport mechanisms of advectionand diffusion for both conservative and non-conservative substances,and is the most complete form of a water quality model. The model is,however, in principle only valid for dissolved radionuclides with decayand source (sink) terms representing radionuclide decay and reductionof dissolved concentrations by non-moveable sediment of biota. Thistype of model cannot handle dissolved radionuclide transport coupledwith particulate radionuclide transport, e.g. adsorption and/ordesorption of radionuclides by sediments and biota, transport,deposition, and resuspension of contaminated sediments. This Type I isgenerally applicable for aquatic systems.

In the equations of type II to V (Type VI is not based on thediffusion/dispersion equation) some parts of the basic formula areomitted when the code is applied to a specific aquatic system.

Type II General advection-diffusion equations with (or without)decay and sink/source terms

In this type, the dispersion term is omitted, and the equationtherefore can only be applied to predict the behaviour of radionuclidesin fast-moving rivers.

∂∂

∂∂

∑ ∑Ct

+U x

C = K C + Sii

j=1m

j j=1n

j (3)

Type III. Langrangian routing models with decay and source/sinkterm

In this type the dispersion and the advection term is omitted, and theequation therefore can only be applied to predict the behaviour ofradionuclides in uniform, non-tidal rivers.

dCdt

= K C + Sj=1m

j j=1n

j∑ ∑ (4)

This type calculates the concentration in a Langrangian system, i.e.the longitudinal coordinate is moving with the flow velocity. Althoughthe governing equation seems not to have spatial coordinates, thesolution is unsteady, one-dimensional, with decay, and sink/sourceoccurring during the travel time throughout the system. The advantage

RODOS(WG4)-TN(99)18

16

of the Type III is that the equation is simpler to handle than type II. Adisadvantage is the one-dimensional character of the equation. Type IIIis valid to calculate the transport of dissolved nuclides with decay andadsorption and of other substances with constant adsorption rates,however, the particulate nuclide concentrations need to beprecalculated.

Type IV. Complete mix-model

In this type, like in Type III, the dispersion and the advection termis omitted, but the equation can only be applied to predict thebehaviour of radionuclides in uniform, well-mixed lakes, since it hasno spatial coordinates. Interactions with non-moveable bed sedimentcan be modelled as well. This approach, the so-called box-model, canbe applied on relatively shallow lakes without stratification. However,for the short-term and near field categories these models are notsufficient to predict the mixing and dispersion of the nuclidessufficiently correct. Therefore, 2D/3D models should be applied inthese cases (Type I).

∂∂

∑ ∑Ct

= K C + Sj=1m

j j=1n

j (5)

Type V. Diffusion equations with (or without) decay andsink/source terms

This type is only applicable for quiescent water bodies. Theapplication is therefore very limited.

∂∂

∂∂

∂∂

∑ ∑Ct

= x

(C

x) + K C + S

ii

ij=1

mj j=1

njε (6)

Type VI. Monte Carlo Model, particle tracking model

This type of model is not based on the solution of the mathematicalequation but, rather describes the movement of particles step by step.Each particle, representing a pollutant in its various forms, is followedwhen discharged from a certain source. The random movement iscalculated by means of the model. There is no numerical dispersionproblem in this approach, and is therefore an attractive alternative fromthe advection-dispersion method.

2.2.2 Models of radionuclide trasport in water bodies

Some of these modelling methods have been reviewed in the earlyeighties (see e.g. IAEA Safety Series No.50-SG-S6, 1985; Codell etal., 1982; Onishi et al., 1981, Santschi and Honeyman 1989). The

RODOS(WG4)-TN(99)18

17

further development of the computer technology during the last decadeand the urgent need to increase the predictability of models in order toprovide adequate information for making decision concerning theremedial measures in the most contaminated water bodies after theChernobyl accident has led to the intensive development of rivermodelling.

Mathematical models describing the radionuclide transport anddispersion in rivers and reservoirs can be classified according to twodifferent approaches - (1) spatial averaging of the variables and (2) theindividual treatment of variables describing radionuclides in differentphysical-chemical forms.

Variables averaged over compartments represent the highest level ofaveraging and, as a result, are used in models of the lowest spatialdimension. These box-type (zero dimension) models treat the entirebody of water (including the sediment layer, etc.) or a part of the entirebody (e.g. one box for water and one for sediments) as a homogeneouscompartment.

Cross-sectionally averaged variables are often used in the channelmodels and in the models for narrow reservoirs. This 1-D approach isused to simulate pollutant transport from the distances larger thantenths of river width downstream the point-source term ( i.e. after fullmixing o contaminant over crossection) up to the hundreds ofkilometres. The time scale for river 1-D models is from minutes up totens of years (e.g. for long term sedimentation studies).

The two dimensional (2-D) vertical models operate with widthaveraged variables. These models are used to describe a current, asuspended sediment and a radionuclide transport in case of asignificant variability with respect to the channel depth.

Depth averaged variables are used in the lateral-longitudinal 2-Dmodels which describe flow pattern and radionuclide dispersion inshallow reservoirs, parts of the river channels and flood plains.

The lowest level of averaging takes place in the 3-D models solvingprimitive or basic governing equations. The real spatial averaging scaleof these models is based on the width of the computational grid butnot on the a certain parameterization or averaging procedure.

The pollutants in rivers are transported by the water flow (advectionprocesses) with the simultaneous influence of the turbulent diffusionprocesses. The radionuclides can interact with the suspended sedimentsand bottom depositions. A pollutant transfer between the river waterand the suspended sediment is described by the adsorption-desorptionprocesses. The transfer between the river water and the upper layer ofthe bottom deposition is under the influence of adsorption-desorptionand diffusion processes. The sedimentation of contaminated suspendedsediments and the bottom erosion are also important pathway of the

RODOS(WG4)-TN(99)18

18

“water column-bottom” radionuclides exchange. Different types ofriver models describe these processes at different levels ofparametrisation.

River models, independently of their spatial resolution, include twomain submodels: hydraulic ones, describing water, suspended sedimentand bottom dynamics and submodels concerning the fate ofradionuclides in the ifferent phases driven by these hydraulicprocesses.

Modelling the fate of the radionuclides in all three different phases -radionuclides in solution, in suspension and deposited on sediments isvery important. Such an approach of the simulation of radionuclidedispersion has been considered by Onishi et al. (1977, 1979, 1981,1982) and Zheleznyak et al. (1990-1999) for one-, two- and three-dimensional models and by Booth (1975), Schückler et al. (1976 ),Monte (1992), Benes and Cernic (1990), and Hofer and Bayer (1993)for full-mixed box models.

The simplified approach of radiounuclides-sediments interaction wasused in models of White and Gloyna (1969), Shih and Gloyna (1970),CHNSED (Fields, 1976), HOTSED (Fields, 1977).

For the simulation of radionuclide transport in several United Statesrivers, the one-dimensional channel model TODAM has been used(Onishi et al., 1982 The model describes radionuclide transportattached on three typical fracture of the suspended sediments - sand,silt and clay with the specific Kd values for each of them. TheRadionuclide transport module is supported by the comprehensivesuspended sediment transport module, that describes the transport ofcohesive and non-cohesive sediments. TODAM does not include theriver hydodynamic module. It was used on the base of riverhydrodynamics calculated by specific codes (DKWAV or HEC-2 orCHARIMA). TODAM was used to simulate PU-239 transport duringflush-flood events in the Mortandad Canyon, New Mexico, USA(Whelan and Onishi, 1983), to reconstruct bottom contamination of theClinch-River- Tennessee River System due to releases from the OakRidge Natioonal Laboratory (Onishi, private communication), tosimulate Sr-90 and Cs-1237 transport in Dnieper Reservoir after theChernobyl accident (Zheleznyak, Blaylock and al., 1995).

The 1-D model of SPA "TYPHOON" State HydrometeorologicalCommittee of USSR (Borzilov et al., 1989 ) used empirical data on thesediment transport rate and flow. The model includes more detaileddescriptions of the transfer between different forms of radionuclides.Model parameters have been identified on the basis of experimentaldata of the Pripyat River spring floods.

The 1-D model by Smitz and Everbecq (1986,) considers kinetics ofradionuclide interaction with two size fractions of suspended solids.The model was verified for migration of radionuclides in the Meuse

RODOS(WG4)-TN(99)18

19

River, and subsequently was extensively applied elsewhere (Smitz,private communication).

Several 1-D numerical models have been developed to simulate non-radioactive pollutant transport in the rivers. These models do not takeinto consideration the specification of the radionuclide transport andradionuclide interaction with sediments, however some of them couldbe, in principal, modified for such purposes. One of the most wellknown European 1-D modelling system of the pollutant transport in theriver net is MIKE11, developed by the Danish Hydraulic Institute(Havno et al., 1995). MIKE-11 is a modelling system for thesimulation of flows, sediment transport and water quality in estuaries,rivers, irrigation systems and other water bodies. MIKE11 has beendesigned for n integrated modular structure with basic computationalmodules for hydrology, hydrodynamics, advection -dispersion, waterquality and cohesive and non-cohesive sediment transport. It alsoincludes modules for the surface runoff. MIKE-11 has a well-developed graphical user interface integrated with the pre- and post-processors that support the system interaction with the GIS (Sorensenet al., 1996a).

One-dimensional model RIVTOX was developed to simulate theradionuclide transport inthe solute, on the suspended sediments and inthe bottom depositions. After the Chernobyl accident it has beenapplied for the prediction of the radionuclide transport in the riversystems(Zheleznyak et al., 1992, Tkalich et al., 1993, Slavik,Zheleznyak et al. 1997) . The model includes a submodel of theradionuclide transport and two submodels of the “driving forces” – ahydrodynamic (hydraulics) submodel and a sediment transportsubmodel.

Vertically averaged, the two-dimensional models are widely used inmodelling (simulation) the hydrodynamics and water quality ofrelatively shallow estuaries, reservoirs, floodplains and coastal areas(e.g. Orlob, 1983) and wind-driven lakes. The assumption of thesemodels is the vertically well-mixed layer that allows for verticalintegration of the continuity, momentum, and mass-transportequations. Averaging the primitive 3-D equations over the depth mayderive the model equations. From the early eighties the 2-D lateral-longitudinal models are widely used as the efficient tools to simulatepollution of water bodies (e.g., Taylor and Pagenkopf, 1981; Di Toroand Connoly 1980, Di Toro and Matystik, 1980).

The well known nowaday commercial computational hydraulicsoftware systems of the DHI - MIKE-21 (Sorensen et al., 1996, Vestedet al., 1996), of the Delft Hydraulics - Delft3D in 2-D mode, of HRWallingford/EdF- (TELMAC), and BOSS-SMS include the 2-Dhydrodynamic codes and the water quality-models.

RODOS(WG4)-TN(99)18

20

As for the radionuclide transport the first comprehensive modelsimulating the radionuclide transport in the solute and on thesuspended sediments and taking into account the pollutant exchangewith the bottom sediments has been developed by Yasuo Onishi,PNNL

The FETRA code (Onishi, 1981) is based on the unsteady two-dimensional equations which simulate the transport, the deposition andthe resuspension of sediments and contaminants together with theirinteractions. The model describes the transport of cohesive and non-cohesive sediments by using the Du Boy formula. FETRA wasvalidated on the base of experimental data for the James River estuary,Virginia ,USA. Recently, FETRA was applied to simulate Sr-90 wash-out from the Pripyat River floodplain (Onishi, 1995, personalinformation).

The COASTOX model was developed at the Cybernetics Center, Kiev(Zheleznyak, 1990, Zheleznyak et al., 1991-1996 ) to simulate thetransport and the dispersion of pollutants in the Dnieper reservoirs andin the Pripyat River. It contains the radionuclide transport submodelssimilar to those used in FETRA. The model includes the edimenttransport, the transport by the advection-diffusion, and the radionuclide- sediment interactions. It considers the dynamics of the bottomdepositions and describes the rate of the sedimentation and theresuspension as a function of the difference between the actual andequilibrium concentration of the suspended matter depending on thetransport capacity of the flow. The latter is calculated on the basis ofthe semi-empirical relationships. The Kd approach has been used fordescribing the adsorption/desorption and the diffusion transfer of theradionuclides in the systems "solution - suspended sediments" and"solution - bottom deposition". The exchange rates between thesolution and the particles are taken into account to obtain the morerealistic simulation of the kinetics of the processes. The adsorption anddesorption rates are assumed to be not equal. The Finite-differenmethods are used to solve the equations. The two main differencesbetween FETRA and COASTOX are that the latter has the possibilityto calculate non-reversible adsorption processes and that it contains thehydrodynamic submodel. In contrast, FETRA can be used onlycoupled with some other hydrodynamical computer codes. COASTOXwas applied and validated for the Kiev Reservoir, the Pripyat Riverfloodplain, the Kralova Reservoir, and the Vakh River.

It is reasonable to provide three-dimensional modelling of the transportof radionuclides in rivers and reservoirs in conditions of large verticaland lateral gradients of the hydrodynamical fields. Such conditionsmay occur close to the point of the release of radioactive material intowater bodies, in the vicinity of heavy contaminated bottom areas, andin stratified water bodies.

RODOS(WG4)-TN(99)18

21

The FLESCOT model (Onishi and Trent 1982) is an unsteady,three-dimensional, finite difference model. It consists of submodels ofhydrodynamics, turbulence, water temperature, salinity, sediments(both cohesive and noncohesive) and contaminants (both dissolved andsorbed on sediment). The FLESCOT model also simulates thebehaviour of sediments and contaminants in the river bed, affected byerosion/deposition, direct adsorption/desorption between water andbottom sediments, and bioturbation. It can calculate wind-induced flowand wave-induced sediment transport, thus affecting radionuclidetransport in shallow water. The model has been applied to the HudsonRiver estuary in New York for CS-137 migration and accumulation, toBuzzards Bay/New Bedford Harbor in Massachusetts for PCBs andheavy metals assessing their transport and potential remediationactivities, and to a hypothetical 3000m deep ocean for low-levelradioactive waste disposal assessment. FLESCOT, also as othermodels of Onishi of lower dimensions presented below (TODAM,FETRA, SERATRA), uses multiple bed layers. The first layer (usuallytaken as a few cm thick) implicitly includes a very thin top layer(assigned as twice the bed sediment grown size) characterised by thechemical equilibrium between the attached and interstitial dissolvedform of the radionuclide. Onishi's models also calculate sedimentationand erosion rates for different sediment size fractions taking intoaccount the water flow and sediment characteristics.

The three dimensional model THREETOX (Zheleznyak,Margvelashvili 1997, Margvelashvili et al 19997-1999) that wasincluded into the HDM will be described. The important specific ofthe code is coupling of hydrodynamic and radionuclide transportmodels.

Box models (other names - compartment models or 0-D models) arewide spread tools for ecological modelling in aquatic systems (see e.g.Orlob, 1983). Some of the models which were developed to simulatedifferent kinds of pollutants can be also applied for the simulation ofthe transport of radionuclides in rivers - e.g. EXAMS (Burnas andCline, 1982; Felmy et al, 1983), WASP4 (Ambrose et al. 1988). Earlyradionuclide transport models were constructed as box models (seeoverviews of Onishi et al., 1981, Codell et al., 1982, Santchi andHoneyman, 1989) and were applied mainly for lakes. The applicationof box-type models for rivers is constrained by the assumption ofcomplete mixing in the compartment. On the other hand, box modelscan be considered as the finite-difference approximation of 1-D rivermodels, however mostly only applied on a coarse computational grid.

The two-phase box model (radionuclides in bottom sediments andradionuclides in water) developed by the United States NuclearRegulatory Commission (USNRC, 1978) is a simplification of thefive-phase model proposed by Booth (1975). The model has been used

RODOS(WG4)-TN(99)18

22

for Clinch and Tennessee Rivers case studies (USNRC, 1978; IAEA,1985).

The SMC model (Benes and Cernik, 1990) describes the transportof radionuclides in suspended and dissolved forms in river channels. Itconsists of hydrodynamic, sediment transport and radionuclidetransport submodels. Distribution of the radionuclide between thewater and the suspended solids is described by a kinetic equation for atwo-step reversible reaction. The deposition of radionuclide in thebottom sediments depends on the exchange between suspended solidsand bottom sediments characterised by an exchange coefficient. Themodel was used for modelling of migration of Cs-137 accidentallyreleased into the Dudvakh River (Benes et al., 1994). Thesedimentation rate is a parameter of the model and can be tuned duringthe calculations.

Monte's box-model (Monte, 1993) is based on the subdivision of thewater body in a set of sub-systems corresponding to the set ofreservoirs. In each sub-system the following processes are considered:radionuclide transport due to the horizontal movement of water andsuspended matter; radionuclide interaction with suspended matter andwith the top sediment layer; migration of radionuclides through thesediment; sedimentation and resuspension. The model accounts forthree layers: a first thin top layer in which radionuclides are inchemical equilibrium with the overlying water; a second layer (justbelow the first) exchanging radionuclides with the overlying waterthrough the top layer and/or with the deeper layer which acts as anultimate radionuclide sink. The suspended sediment transport andsedimentation rate is not calculated in the model. These values aretaken from measured data.

The equations are solved by using a set of first order differentialequations. The model demonstrated reasonable good results in avalidation study for the Dnieper reservoir cascade within the VAMPprogram.

The WATOX model (Zheleznyak, 1990, Zheleznyak et al.,1991,1994 ) is a box-type model based on a set of first orderdifferential equations describing water, sediment and radionuclidetransport. Dissolved contamination, contamination on suspendedsediment and the contamination of the bottom sediment are consideredwith a special treatment of the contamination-sediment interaction. Theparametrisation of these processes is similar to those used by Schückleret al. (1976), however, some further processes are included.Additionally, a supplementary submodel to simulate the temporalvariations of sedimentation-resuspension rates during flood events inreservoirs is included. As described for RIVTOX, COASTOX andTHREETOX, also WATOX takes into account different Kd values forsuspended and bottom sediments, together with different exchange ratecoefficients for adsorption and desorption. Model verification shows

RODOS(WG4)-TN(99)18

23

the high significance of this mechanism for the fate of Cs-137 inreservoirs. The model was tested and calibrated on the basis of post-Chernobyl data for the Dnieper reservoir cascade.

The Hofer and Bayer model (1993) is a dynamic extension of theabove mentioned steady state (static) model developed by Schükler etal. The dynamics of radionuclide concentrations in filtrated water, onsuspended sediments and bottom sediments is described by the set ofordinary differential equations on the basis of two different Kd valuesfor adsorption and desorption and exchange rate coefficients. Themodel coefficients were not calibrated on the basis of measurements.

In the box model of Mundschenk (1988), the processes of directadsorption and diffusion exchange between water and bottomdepositions is omitted. It is assumed that the radionuclides interactdirectly only with suspended matter.

The analytical models describe the radionuclide fate in rivers onthe basis of analytical solution of the equations of box-model or 1-Dmodels with respect to several simplifying assumption (e.g. flowparameters are constant within the river branch, water-bottomradionuclide exchange processes could be described only by oneparameter and so on). Examples of this approach are presented byCoppa (1992); IAEA (1985); and USNRC (1975). Theoversimplification in these approaches ends up in the fact, that theparameters of an analytical model calibrated for one water body cannot be used for other one without significant recalibration. The furtherdevelopment of the computer technique permits nowadays to usenumerical models which describe the main significant processes inmore detail based on physical characteristics of the site. Analyticalmodel can be used only as a first estimation of the situation - asexample as a conservative upper estimation of the radionuclideconcentration after accidental releases. Therefore, they will not beconsidered in the further discussion.

2.2.3 Modelling of radinuclide exchanges in the system water-suspended sediment-bottom deposition

Mathematical models describing sorption of metals onhomogeneous solid surfaces, which are primarily metal hydroxides andreference clay minerals, are based on surface complexation and ion-exchange theories. However, the traditional approach in describing andpredicting the fate of radionuclides on heterogeneous solids such assoil, suspended and bottom sediments is mainly empirical and is stillbased on the use of the parametrisation of the simplified adsorption-sorption kinetics and use of the equilibrium distribution coefficientsKd.

RODOS(WG4)-TN(99)18

24

Kd = Cs/C, (7)

where

Cs = amount of contaminant sorbed by sediment in equilibrium

C = amount of contaminant left in solution in equilibrium

The popularity of Kd-models can be also explained by the ease ofdetermination of the distribution coefficient from simple laboratoryexperiments and field data. Although this approach has some practicalbenefit, the data are usually site dependent and seldom have predictivevalue for other places. The distribution coefficient Kd, which isdependent on liquid and solid phase characteristics, is the integratedresult of various physical-chemical processes controlling the retentionof the radionuclides. This approach assumes complete sorptionequilibrium, which is seldom the case in natural condition. Morecomplex models, based on the analysis

Literature data from laboratory experiments and field measurementsindicate that sorption of radionuclides by clay minerals, soil andsediments depends on the nature of the clay minerals and is akinetically controlled process which may continue over time scales upto several years. A kinetic approach of the sorption phenomena istherefore necessary for various reasons. Thus for realistic modelling ofthe vertical transport of radionuclides and heavy metals in soil and theaquatic environment, knowledge is needed not only about the sorptionequilibrium, but also about the sorption kinetics.

Konoplev et al. (1990 - 1999) have investigated the role of thephysical-chemical forms of radionuclides and their transformationprocesses. The dissolved fraction of a radionuclide can exist either ascations, as neutrally or as negatively charged complex with dissolvedorganic substances, or as mineral component of the soil moisture. Thecation form of a radionuclide in solution is in equilibrium with thefraction of the radionuclide absorbed onto the solid particles. In thesolid phase, radionuclides can be in exchangeable and non-exchangeable form. In their exchangeable form the radionuclide issorbed by an ion exchange mechanism. The non-exchangeable formconsists of radionuclides originate from nuclear fuel particles or areradionuclides absorbed by a mechanism of irreversible sorption (i.e.incorporation into a mineral crystal lattice, formation of radionuclide-organic in soluble compounds etc.)

Benes et al. (1992) describe the sorption of the radionuclides bymeans of two parallel or consecutive reaction for ion exchange withtwo elements bounds at two different sites on the solid phase. Theequation and parameters for all kinetic models were derived for generalion-exchange reactions.

RODOS(WG4)-TN(99)18

25

Comans (1990) studied the caesium sorption on potassium andcalcium saturated illite. Applying the linearisation method developedby Jannasch et al. (1988) to determine the number of processes, threeconsecutive reactions can be distinguished: one fast, instantaneousreaction and two distinct slow processes. For investigating the sorptionof caesium on time scales of days to weeks which is most relevant fornatural systems, two-box and three- box models were suggested andthe isotherm of Freundlich was assumed to describe the equilibrium.Intercomparison with experimental data for periods longer than twoweeks showed, that reversible reaction on calcium-illite was too slow,whereas the second process (irreversible reaction) was too fast.Therefore, a more complicated three- box model was used. This modelassumed the existence of the easily accessible sorption sites andsorption sites, where the kinetically controlled process are followed byirreversible sorption.

There is no unified mathematical description of the sorption processgoverning the behaviour of metals and particulate radionuclides .Further detailed study of the sorption kinetics of radionuclides willallow to examine existing concepts in terms of a more fundamentaldescription of the underlying processes.

In general, models of radionuclide transport in the rivers/reservoirsdo not include the above presented kinetics in their complete details.However, a reasonable level of model complexity which may reflectthe main features of the exchange processes (radionuclides transfer inthe system “water - suspended sediments - bottom depositions” -transition from a non-equilibrium to an equilibrium state, different Kdvalue for bottom deposition and suspended sediments, different rates ofsorption and desorption) seems to be represented by a “Kd - exchangerate” approach which is used in practically all contemporary models(Onishi et al., Smitz, Zheleznyak et al. ). RIVTOX model used as thisapproach as more complicated two-step kinetic model, describing 137Cstransfer between exchangeable and non- exchangeable forms (Slavik,Zheleznyak et al., 1997).

2.2.4 Modelling of river hydrodynamics and sediment transport

To simulate the radionuclide transport in rivers, it is necessary toestimate beforehand the river flow and the suspended sedimenttransport driven by the river hydrodynamic processes. There are a lotof models to simulate river hydraulics and hydrodynamics. TheOverviews of the methods are presented in M. Abott, 1979; Cunge J.,Holly F. and Verwey A., 1986; Orlob, 1983 and others. Thecontemporary “state-of-the-art” in the field is presented by Rutherford,1994 and demonstrated by Jobson, 1989, Zheleznyak and Marinets,1993.

RODOS(WG4)-TN(99)18

26

The one-dimensional models based on cross-sectionally averagedvariables seem to be the most important for the determination of theriver flow. Well known are computer codes such as HEC-6 and HEC-2SR (Hydrological Engineering Center, 1977, 1982), REDSED (Chen,1988), FLUVIAL 11 (Chang, 1988), IALLUVIAL (Karim et al., 1981,1987) and CHARIMA (Holly et al., 1990) which expands theIALLUVIAL approaches, as well as MIKE-11 (Danish HydraulicsInstitute), and TELMAC (Laboratory of Hydraulics, EDF, France).The two last ones are commercially distributed modelling systemswhich include models of different dimensions. HEC-2SR, FLUVIAL11, CHARIMA, MIKE-11, and TELMAC contain river hydraulicmodules based on a numerical solution of the Saint-Venant equation.The possibility of an efficient estimation of river hydraulics on the baseof the numerical solution of the “diffusive wave” equation and thesimplified version of the Saint-Venant equation were

Suspended sediments act as a carrier of radionuclides in theriver/reservoir flow. The amount of radionuclides transported by thesediments depends on the suspended sediment concentration in theriver flow and the Kd value. After the Chernobyl accident, forexample, up to the half of CS-137 transported by the Pripyat Riverfrom the vicinity of the Chernobyl NPP was bound on suspendedsediments (Voitsekhovitch et al., 1992). The sedimentation and bottomerosion processes play a key role in the flow self-purification and inthe secondary contamination.

The mathematical modelling of the sediment and the transport is alarge branch of hydraulics where overviews could be found in Ackersand White (1973), Grishanin (1976), Cunge, Holly and Verwey (1986),Engelund and Fredsoe (1976), Holly et al. (1990), Karim et al.(1981,1987), Mehta et al. (1989), Onishi (1993), Raudkivi (1967), vanRijn (1984). For the steady state conditions, the sediment dischargesare calculated by the empirical and semi-empirical formulae whichconnect the sediment discharge with the sediment parameters, the flowvelocities and the river cross-section characteristics or shear stressacting on the bed. In case of the cohesive sediments (finest silt andclay) and hesive bonds between the particles it has to be taken intoaccount (Mehta et al. 1989). The variability of the streams andsediment parameters lead to the situation that up to nowadays severaldifferent formulae are used for the practical applications. It wasdemonstrated within validation studies (Onishi, 1993) that theapproaches of Ackers -White, Engelund-Hansen, Rijn and Toffaletishow the most acceptable results for non-cohesive sediments over awide range of flow and sediment conditions. However, for anindividual river, the best result can be also obtained by the empiricalformulae especially tuned for this river.

The sediment transport models are based on the suspendedsediment-mass conservation equation (advection-diffusion equation

RODOS(WG4)-TN(99)18

27

with the sink-source term describing sedimentation resuspension rate)and the equation of bottom deformation (Exner equation). The mostimportant problem for modelling is the parametrisation of thesedimentation and resuspension rates. A physically based approachcalculates these rates as a function of the difference between the actualand the equilibrium concentration of the suspended sediments. This isoften titled “suspended sediment capacity” and can be derived on thebase of the above mentioned formulae.

The suspended sediments models include different formulae forcalculating the equilibrium sediment concentration. The mostcomprehensive models (e.g. CHARIMA) contain modules of the riverhydraulic computation and methods to simulate the bottom erosiondependent on the sediment grain distribution in the upper bottom layer(bottom armouring calculation) and to calculate the bottom frictiondependent on the simulated dynamics of the bottom forms.

The sediment transport models are also a part of the radionuclidetransport models described in Onishi et al. (TODAM, SERATRA,FETRA, FLESQOT) and RIVTOX, COASTOX and THREETOXmodels included into the RODOS –HDM. .

RODOS(WG4)-TN(99)18

28

3 Realisation of a hydrological model chain inside RODOS

3.1 General information

A hydrological model chain of RODOS (HDM) was outlined initiallycovering the processes, such as runoff of radionuclides from watershedsfollowing deposition from the atmosphere (RETRACE-1 for smallwatersheds and RETRACE-2 for large watersheds), transport ofradionuclides in river systems (1-D model RIVTOX) and the radionuclidebehavior in lakes and reservoirs (radioecological box model LAKECO and2-D model COASTOX). The near range transport and dispersion ofradionuclides following direct releases into the river are described by theCOASTOX model. The output from the hydrological model chain istransferred into the food chain model FDMA which is part of both theterrestrial and hydrological modules of RODOS to calculate the mainexposure pathways, such as the doses from the consumption of drinkingwater, fish, irrigated foodstuffs, and from external irradiation.

The model chain was extended during the last period of HDM developmentto cover needs for radionuclide transport modeling for different kind of waterbodies in different temporal and spatial scales of resolution. The HDMmodels and aims of their application in emergency and non- emergencyphase are presented . in Table 2.

The main HDM application in emergency phase is to predict exposure dosefor the population on the basis of the simulated radionuclide concentration inwater and water stuff. The HDM chains of the models should be constructedduring the RODOS implementation phase taking into account the specific ofhydrological network in the area of RODOS implementation (rivers, lakes,reservoirs, estuaries, coastal areas of seas).

RODOS is developed as “a comprehensive decision support system fornuclear emergencies in Europe following an accidental release toatmosphere", and therefore the main results of HDM is simulatedconcentrations of radionuclides in the water following the atmosphericfallout. HDM gives also the supplementary possibility to simulateradionuclides transport in aquatic systems after a direct release of radioactivematerials into the water. This second function could be useful for RODOSusers as for simulation of the consequences of this specific kind of possibleNPP accident, as for model calibration and tuning on the basis of thepreviously recorded accidents.

The HDM chains are presented at Figures 2-6.

RODOS(WG4)-TN(99)18

29

LAKECO

Fallout from Atmospheric.Dispersion Module (ADM) of RODOS

RETRACE-2

RIVTOX

RODOS FDMA model input

Figure 2: HDM Chain 1 (HC-1) : watershed-rivers&lakes under atmospheric fallout

Direct release to

COASTOX RIVTOX

RODOS FDMA input

A

A

B A

Figure 3: HC 2 - direct release to river.HC-2A simulation in small scale with COASTOX to zoom releasearea and to transfer than COASTOX output data to RIVTOX;HC-2B simulation in river basin scale only

by RIVTOX

RODOS(WG4)-TN(99)18

30

RETRACE - 2 COASTOX RIVTOX Input to

Fallout RIVTOX

Figure 4: HC 3 - atmospheric fallout on the river basin including large river reservoirs. River channels aresimulated by RIVTOX, reservoirs by COASTOX.

COASTOX RIVTOX Input

to FDMA

RIVTOX

Direct release

Figure 5: HC 4: - direct release into the river net with large reservoirs. River channels are simulated byRIVTOX, reservoirs by COASTOX.

THREETOX RIVTOX RIVTOX

Fallout

Fig. 6. HC 5: - simulation of the radionuclide transport in deep stratified lakes, deep reservoirs or estuariesunder influence of river inflow and fallout on the water surface.

HDM in the version prepared for integration into RODOS includeschain HC-1 as “Automatic mode” . This chain could be started fromthe main RODOS interface, automatically taking file of theradionuclide fallout on watershed and preparing the input files foraquatic submodel of FDMA as the result of the calculations.

RODOS(WG4)-TN(99)18

31

Each from described above chains HC-1 – HC-5 and theircombinations, as also each models of the chains could be executedunder the upper HDM interface.

Besides the models of the main package, presented in the HC-1 – HC-5: RETRACE2, RIVTOX, COASTOX, LAKECO, THREETOXadditional modules are being developed for those aquaticcompartments and temporal scales which require special modelapproaches. These are short-term small scale watershed modelRETRACE-1, subsurface flow models SUSTOX, GROWTOX andWADZONE, longterm watershed and river models RETRACE-3 andWATOX, layered model for stratified lakes LATOX, 2-D vertical-longitudinal model for special countermeasures RIVMORPH. (seeTable 2).

RODOS(WG4)-TN(99)18

32

Table 2: Hydrological Models and their application within the RODOS system.

Emergency Phase

(input actual data)

Non–Emergency Phase

(statistical input data)

Model application:

HYDRO–A, HYDRO–D

Model application:

HYDRO–A, HYDRO–D, HYDRO–S, HYDRO–C

Temporal scale Temporal scale

Short term

(Time span up to 2 – 7 days)

Middle term

(Time span from 2 days)

Long term

(Time span longer than one season)

Spatial scale Spatial scale Spatial scale

Target Area Small scale Middle scale Small scale

(countermeasure analysis)

Middle–large scale

(forecast and c/measures)

Small scale Middle–large scale

Watershed RETRACE–1 b

RETRACE–2 a

RETRACE–2 a RETRACE–1 b RETRACE–2 a ZRETRACE–3 b

Rivers COASTOX (2D) a RIVTOX (1D) a COASTOX a, THREETOX b

and RIVMORPHRIVTOX a WATOX b

Reservoirs COASTOX a

THREETOX (3D) b

RIVTOX a

(set of reservoirs)

COASTOX a

THREETOX b

RIVTOX a WATOX b

Lakes COASTOX a, THREETOX b andLAKECO (+biota) a

COASTOX a

THREETOX b

LAKECO a

LATOX

LAKECO a

LATOX

Groundwater SUSTOX

VADZONE

SUSTOX

GROWTOX

SUSTOX GROWTOX

Abbreviations:

HYDRO–A(tmospherical Release), HYDRO–D(irect Release), HYDRO–S(pecial Studies), HYDRO–C(ountermeasures)

RODOS(WG4)-TN(99)18

33

RODOS(WG4)-TN(99)18

34

3.2 Objectives of the model development and integration

The main objectives of the HDM is to simulate radionuclideconcentration in compartments of hydrosphere after the accidentalreleases from nuclear installation to prepare necessary input datafor the simulation of the exposure dose for population via aquaticpathway.

The hydrological model chain is a part of the analyzingsubsystem of RODOS to predict activity concentrations inwaterbodies. These models will also operate in the consequencesubsystem of RODOS - CSY, for identifying strategies of possiblecountermeasures. Starting points for the early phase can be a directrelease into a river or lake and/or the predicted contamination of aland area following an atmospheric release of radionuclides. Tofacilitate and enhance the quality of emergency actions, themathematical description of the processes involved is required.RODOS will therefore contain a chain of models, which cover allthe relevant processes such as the direct inflow into rivers, themigration and the run-off of radionuclides from watersheds, thetransport of radionuclides in large river systems includingexchange with sediments and the behaviour of radionuclides inlakes and reservoirs. On later stages after the accident, theestimated deposition data will be corrected by monitoring data. AsRODOS is designed to predict the short-term and long-termconsequences of the accidental releases, the HDM contains modelsof different temporal and spatial scales that are used to achievegeneral objectives of HDM use by the each model specificobjectives fulfillment. .

Watershed models RETRACE –1,2,3 as results produce therates of water, sediment and radionuclide inflow into river channelnetwork, lakes and reservoirs within watershed on the basis ofradionuclide fallout information and meteorological data(precipitation rate, temperature) transferred from the atmosphericmodule of RODOS. The temporaly distributed data on lateralwater inflow and radionuclide concentration are produced in thenodes of grids created on the grafs of the river network, coastlinesof the large lakes and reservoirs or in the separate nodesrepresenting the small lakes.

The main results of the RIVTOX in HDM are crossectionallyavaraged radionuclide concentrations in water, suspendedsediments and bottom deposition in the nodes of river channelnetwork. RIVTOX uses output results of RETRACE to simulateriver transport of radionuclides after wash-off from the watershedsor the scenarios of the direct releases to the water could be usedfor the simulation of radionuclide transport from the point sources.The special procedure is used for the interpolation of the RIVTOX

RODOS(WG4)-TN(99)18

35

results on the river grids to the input grid of the RODOS dosemodule FDMA.

The main results of the radioecological box model for lakesLAKECO in HDM are radionuclide concentration in the biotic andabiotic compartments of the wate body. Temporal dynamic of thelake-averaged concentrations of radionuclide in waters, suspendedsediment, phytoplankton, fishes and other components of theaquatic foodchain is simulated and data are transferred into thenearest node of the grid of dose module FDMA.

Two-dimensional model COASTOX produce the depthavaraged concentration of radionuclides in the nodes of therectangular grid that covers water bodies – parts of the rivers in thevicinity of the point sources of radionuclide, large shallow lakes,reservoirs. Simulated by COASTOX time-depending arrays of theconcentrations could be interpolated into nodes of dose grid or usedafter cros-sectional integration as input files for RIVTOX, if thismodel is used for modeling downstream river flow.

THREETOX results in HDM are files of radionuclideconcentrations in the nodes of 3-D grid constructed for deep lakesand other stratified water bodies – estuaries, cooling ponds ofnuclear power plants, marine coastal areas. These time-depending3-D arrays are used for the interpolation to the grids of the dosemodule FDMA, as also in the case of the river outflow fromlake/reservoir could be used to obtain construct the boundarycondition for RIVTOX model.

The one-and-a-half dimension model LATOX results in HDMare 1-D temporally variable grid of radfionuclide concentrationaveraged over vertical crossections of the deep stratified lakes. Thespecial module of LATOX parametrising the hydrodynamicalprocesses in the lake gives possibility to provide simulation of thestratified lakes only on the basis of the standard meteorologicalinformation without involvement of the special input data on lakehydrotermodynamics.

SUSTOX code that includes 1D-, 2D-, and 3D-models is usedin HDM to produce arrays of radionuclide concentration in thevariably saturated subsurface environment from unsaturated zoneto groundwater. Taking into account low dose significance ofgroundwater pathways the model results could be useful forestimation of the efficiency of the special post-accidentalgroundwater protective countermeasures and for simulation of thegroundwater radionuclide fluxes into the river net.

GROWTOX model results in HDM in are 1-D or 2-D fields ofthe crossectionally- or layer- avaraged concentratioins ofradionuclides in groundwater. The GROWTOX is useful forestimation of groundwater radionuclides transport on much largerspatial scales than SUSTOX.

RODOS(WG4)-TN(99)18

36

To allow a detailed view on the sedimentation and remobilisationprocesses within a smaller part of a river or reservoir, IPEP, Bela-Russia, had developed the RIVMORPH 2-D river model. Thiscode can be also used for example to assess the efficency of bottomtraps in rivers.

The infiltration model VADZONE, to describe the fast transferof radionuclides in the initial phase after the accident from soilsurface to the shallow groundwater, is uder development by SPATyphoon. This allows a first assessment if the shallow groundwatermight be contaminated via transport through macropores (e.g. deadroots or rain worm wholes) - a process which is much faster thanthe flux through the ordinary soil matrix.

A runoff model for urban areas RETURB will extend theRETRACE family to describe the runoff in larger cities in a moreappropriate manor. It will be operated as a submodule ofRETRACE-2 and called if grid elements are indicated as urbanterrain.

The hydrological processes have site specific nature and tocustomize HDM in the specific areas a lot of data should be used.Therefore one of the key direction of the HDM development ispreparation of the special tools to be used for more flexible moduleadaptation for the specific watershed, river network, water bodydata. Some of the tools connected with GIS are developed andpresented in the RODOS, however the development of others asalso hydrological data base development are in process.

The data assimilation procedures are used in the RIVTOXmodule of HDM to use measured date to increase predictive powerof the system for the case of radionuclide propagation in largeriver. The result of developed “sliding -down source method isimprovement of the predictions for down-stream sites by the usingof the measured data sets as the boundary conditions for thesimulation.

3.3 HDM Interface

As the hydrological chain will operate as an individual part ofthe RODOS System, a user friendly graphical interface has beendeveloped to operate the individual models inside the hydrologicalmodule. The interface provides the possibility of easily accessingall the information necessary to run the individual models as wellas displaying the results in a way decision makers can handle themThe interface allows:

§ to input and to edit data and parameters through a system ofuser configured dialogues and input windows;

§ to run models separately or simultaneously with thepossibility of exchanging data between individual modelsvia shared memory;

§ to manage the data base and to create predefined scenarios;

RODOS(WG4)-TN(99)18

37

§ to present data base information and on-line results of thesimulations in graphs and maps (e.g. contamination);

§ to receive data from and transfer data to other RODOSmodules (e.g. read results of atmospheric dispersion,forward concentrations to the foodchain module); and

§ to support different modes with different user services: twointeractive modes for the decision maker - first: “wholechain” (complete model chain starting with the arealcontamination), and ”direct release” (COASTOX,RIVTOX, LAKECO); and second: run individual models (also possible with loading of predefined scenarios) andfinally the “scenario maker” model for creating scenariosand manipulating data bases

The general structure of the interface is presented on the Figures.7-16. More detailed description is presented in the User Guide report.

WG4 - RODOS Rhodes meeting

Model’s driver

Model

Input file(s) of special format

Integration with RODOS Integration with RODOS (Automatic Mode)(Automatic Mode)

HDM Interface StructureHDM Interface Structure

Output file(s) of special format

Start calculation

Supervision of execution

RODOS

Data exchange through Shared Memory

Figure 7. HDM Interface structure (I)

RODOS(WG4)-TN(99)18

38


Model’s driver

Model


Integration with RODOS Integration with RODOS (Automatic Mode)(Automatic Mode)



Start calculation


RODOS

Data exchange through Shared Memory

Figure 8. HDM Interface structure (II)

RODOS(WG4)-TN(99)18

39

WG4 - RODOS Rhodes mee t ing

DB

Driver of Threetox

Driver of Coastox

Data Navigator

Structure of Top-level Interface Structure of Top-level Interface (Interactive Mode)(Interactive Mode)


RODOS

Data exchange through Shared MemoryData access through RoNetClientAccess to the model’s meta -data

Driver of Retrace

Driver of Rivtox

GUI of Retrace

GUI of Rivtox

RtGraph

Driver of Lakeco

Figure 9. HDM Interface structure (III)


Model’s driver

Model


DB

Integration of Models Integration of Models (Interactive Mode)(Interactive Mode)



Model’s GUI

Extract input data from Data Base

Store results into Data Base

Access to the model’s meta-data

Start calculation


Figure 10. HDM Interface structure (IV)

RODOS(WG4)-TN(99)18

40


Data Base of HDMData Base of HDMExample of Data Exchange Between RIVTOX and COASTOXExample of Data Exchange Between RIVTOX and COASTOX

DB

Workspace 1:RIVTOX

Workspace 2:RIVTOX

Workspace 4:RIVTOX

Workspace 3:COASTOX

Figure 11. Data base of HDM


Figure 12. RETRACE interface –watershed parameters

RODOS(WG4)-TN(99)18

41


Figure 13. RETRACE Interface –radioionuclides runoff

WG

Figure 14. RIVTOX interface

RODOS(WG4)-TN(99)18

42


COASTOX interfaceCOASTOX interface

*

Fig. 15. COASTOX interface

RODOS(WG4)-TN(99)18

43


THREETOX interfaceTHREETOX interface

Figure 16. THREETOX interface

RODOS(WG4)-TN(99)18

44

4 Descriptions of the main models

All models are described in all detailes in the separate reports. Herethere are presented only the descriptions of the models of the mainRODOS hydrological chain – RETRACE-2 –RIVTOX-COASTOX-LAKECO.

4.1 RETRACE-2 Model

4.1.1 Introduction

Since the surface of rivers and lakes is just a little portion of theland surface (for example, for Finland it is approximately 9 percent(Warner, F. and Harrison, R.M. 1993)), it should be expected thatfor the severe radiation accident, most of the radionuclide activityafter atmospheric fallout will be concentrated in the soil ofwatersheds. A further migration of radionuclides in theenvironment is to a considerable extent connected with the waterand suspended sediment movement. After radionuclides enter therivers and lakes with the runoff, they can be included in the foodchains leading finally to a human. That is why particular attentionwas given to surface radionuclide wash-off after the Chernobylfallout over the extensive areas of Europe.

Although the surface radionuclide wash-off is a secondary, and soa weaker, source of river and lake contamination as compared todirect effluents, this process is, however, capable of transporting anoticeable fraction of activity, particularly at an early accidentphase. For example, the studies of nuclear weapons test showedthat the short term runoff of 137Cs led to a transfer of 0.1 (Linsley etal., 1993), 1.3 (Yamagata et al., 1963) and 1.9% (Carlsson, 1978)of the inventory of different watersheds to watercourses during thefirst year after fallout. In subsequent years loss rates were in therange 0.001-1% per year (Helton et al., 1985). Losses of 90Sr were0.5-10% in the first year and 0.1-3.3% per year in subsequent years(Helton et al., 1985). This difference in loss rate reflects the morespecific retention of radiocaesium by the watershed soils.

Moreover, studies of the Chernobyl fallout (Santchi et al., 1990)showed that the short-term wash-off declined with a half-life oforder one week. In the longer term (timescale years), wash-offoccur as a result of slow erosion of soil particles as well asdesorption of activity from soils to runoff waters.

It should be noted that a peculiar feature of the radionuclide wash-off consists in an extremely small mass of a pollutant, so that insolving this problem, we have to deal with surface watercontamination with micro quantities of an extremely dangerouspollutant introduced by a human into the environment. To put itotherwise, the radionuclide wash-off from the watershed surface incase of a nuclear accident will lead to the problems of water quality

RODOS(WG4)-TN(99)18

45

and quality of the products related in one way or another to the useof fresh water.

The problem of water quality is widely recognised. It becameparticularly acute in the 60s following a large-scale application ofpesticides and insecticides in agriculture. The necessity to obtain apre-contamination water quality forecast resulted in thedevelopment of a large number of wash-off model (HSPF,CREAMS, SWRRB, EPIC, SHE (Singh, ed., 1995)). It should benoted that majority of the models developed at that time wereapplicable to only small watersheds of size from several hectares toseveral thousand square kilometres. That is why there models couldnot be used to simulate wash-off under the conditions similar tothose following the Chernobyl accident.

Intensive experimental and theoretical research on radionuclidemigration in the soils and fresh water started earlier. They wereinspired both by nuclear weapon tests and by the nuclear fuel cycle.The investigations resulted in understanding of physico-chemicaland hydrological processes which determine the radionuclidebehaviour in the "soil-water" system (Warner and Harrison, 1993).

Thus by the time of the Chernobyl accident, the processes of theradionuclide surface wash-off had received sufficientunderstanding. The works on creating the RODOS system made itpossible to combine the available knowledge and experience toprognosticate the wash-off from large territories that may becontaminated in case of a major nuclear accident similar to theChernobyl disaster.

4.1.2 A concept of wash-off modelling in the RODOS hydrological chain

The decision-making in RODOS starts with a population doseprediction for the whole contaminated area, however large the areais. The dose prediction is known to be based on the prediction ofradionuclide concentration in the food chain links and in theenvironmental elements including water and bottom sediment inrivers, lakes and seas. Of interest are dose forecasts for the early(acute) accident stage, as well as for one year and seventy yearsfollowing the accident (ICRP-63, 1991, IAEA-115, 1996).Therefore it is exactly for these ranges the forecasts ofconcentrations in a hydrological chain of RODOS models must bedeveloped. It should be also taken into account that at a lateaccident phase, a short-term forecast of wash-off for individualheavy rainstorms from a small highly contaminated area ("spots")may be important to develop.

It is evident that in developing these predictions, the models shouldconsider characteristic time of radionuclide transport processes.The surface radionuclide wash-off is known to be determined bothby hydrological processes of runoff formation and by physico-chemical processes in the "radionuclide-soil-water" system(Warner and Harrison, 1993, WMO, 1992).

RODOS(WG4)-TN(99)18

46

The surface runoff and erosion on hill slopes usually occur duringrelatively short intervals, i.e. from several minutes to several hoursduring heavy rains and from several hours to several days duringsnow-melt. An important time scale is watershed concentrationtime that depends both on the watershed size and on many otherwatershed characteristics (climate, orography, type and structure ofsoil, presence and type of vegetation, land-use). Variety of factorsdetermining the runoff formation and a random character ofprecipitation, as well as insufficient observations of the surfacerunoff formation present considerable difficulties in developing themodels applicable to obtain operative runoff prognoses (Singh,1995).

A special case should also be mentioned - the radionuclide wash-off from flood plains of rivers that can occur during a long periodof time (from several days to several months). This case isespecially important because rivers flood plains are usually placesof active economic activity and rest of the population.

Additional time scales of the problem are determined by both adecay of radioactive nuclides and physico-chemical processes inwatersheds that lead to a gradual decrease in a fraction of mobileforms (Santchi, et al., 1990, Monte, 1996).

In addition to the time scales indicated it should be taken intoaccount that the lead time of the sufficiently accuratemeteorological forecast is now no more than 48 hours, with a spaceresolution of these forecasts being not better than one degree.

The analysis of the problem formulation within the RODOSsystem, along with the analysis of regularities of the radionuclidesurface wash-off, yielded the following conclusions. First, it seemspossible to limit the quantity of radionuclides considered in ahydrological chain of the RODOS models.

Second, it was recognised necessary for the RODOS hydrologicalchain to have three wash-off models that are able to provideprognoses of radionuclide concentrations with a different leadtimes. The area of application of each of the three models is shownin Table 3.

Table 3: Lead Times and Spatial Scales of Applicability for RETRACE Models

Prognosis Type Lead Time Space Scale of Wash-OffPrognosis

Model Name

Short-term (acute andearly accident phase) 2 days

the whole contaminated area(large watershed) RETRACE-2

Mid-term (early andlate accident phase)

2-30 days the whole contaminated area(large watershed)

RETRACE-2

Short-term(late accident phase) 2 days

territory with individualhighly contaminated "spot"(small watershed))

RETRACE-1

RODOS(WG4)-TN(99)18

47

Prognosis Type Lead Time Space Scale of Wash-OffPrognosis

Model Name

Long-term(late accident phase)

1 year,70 years

the whole contaminated area(large watershed)

RETRACE-3

It should be emphasised that although the models bear the samename, they are fundamentally different in the way of describing thewash-off processes. Besides, it is the short-range forecast alone thatmay have a deterministic meaning given the necessary inputinformation, while medium- and long-term prognoses have aprobabilistic meaning. It is seen from the Table that theRETRACE-2 model is most important for decision-making at anearly accident stage. That is why this model is included in the maincomposition of the RODOS hydrological chain of the models. TheRETRACE-1 and RETRACE-3 models can also be used to solve anumber of important problems, for example, to evaluate a peakradionuclide concentration in the runoff from local "contaminationspots" (RETRACE-1 model) or to estimate the efficiency ofhydrological countermeasures (RETRACE-3 model). Due to itsparticular significance, the RETRACE-2 model received primaryemphasis in this paper.

4.1.3 General information on RETRACE wash-off models

Historically, RETRACE wash-off models were developed andvalidated in the SPA "Typhoon" within the frames of JSP-1,BIOMOVS II, RODOS-E and RODOS-B projects. Wash-offmodels are largely based on the developments of the StateHydrological Institute (SHI) and SPA "Typhoon" which aresubordinates to the Roshydromet that is responsible forhydrometeorological and radiation monitoring in Russia. Table 4lists principal stages of the model development which give someinsight into the composition, capabilities and validation of themodels.

Table 4: Development history of RETRACE models

Year The development steps

1993• development of RETRACE-1, first description of the model as an interim

RODOS report;• development of the RETRACE Monitor, Version 1;

1994• validation of RETRACE-1 with the BIOMOVS II Scenario W;• preparation of a data set for the Ilia River (1988 rain flood event) to

validate chain of RIVTOX and RETRACE;• start of RETRACE-2 model development;

1995

• finish of RETRACE-2 model Version 1 development;• validation of RETRACE-2 (Version 1) and RIVTOX with the Ilia River

scenario (1988 rain flood event);• start of data preparation to validate RETRACE-2 (Version 1) and

RODOS(WG4)-TN(99)18

48

Year The development steps

RIVTOX with a River Rhine scenario (1993-1994 rain flood event);• development of the RETRACE Monitor, Version 2;

1996• continuation of RETRACE-2 (Version 1) and RIVTOX validation with a

River Rhine scenario (1993-1994 rain flood event);• development of RETRACE Monitor, Version 2• description RETRACE models in Technical Documentation of JSP-1

Project

1997• development of the snow melt submodel of RETRACE-2;• end of RETRACE-2 (Version 1) and RIVTOX validation with River

Rhine scenario (1993-94 flood event)

1998

• development of RETRACE-2 radionuclide wash-off submodel for urbanterritories;

• development of programming tools to customise wash-off models andimplementation of these tools in RETRACE Monitor, Version 3;

• integration of RETRACE-2 (Version 1) and RETRACE Monitor, Version3 into the RODOS PRTY 3.1 and 3.2

The model for the short-term forecast of radionuclide wash-offfrom small watersheds was the first to be developed in 1993(Popov and Borodin, 1993); that is why it was referred to asRETRACE-1.To describe the runoff of water and transportedmatter (sediments, radionuclides) in the RETRACE-1 physico-mathematical model, a numerical solution of non-linear two-dimensional partial equations was applied (2D kinematic waveapproach). This model in its hydrological part is similar tonumerous and widely used runoff models, such SHE, SWRRB, etc.(Singh, 1995).

Coincident with RETRACE-1, the first version of the RETRACEMonitor (referred to as RMonitor in Table 4) interface wasdeveloped that controls the calculation and displays the results. Inlater version the RMonitor was provided with a set of softwaretools to prepare watershed input data to be used by models.

The RETRACE-1 model was validated against the BIOMOVS IIproject Scenario W data and showed good results as compared tothe other models proposed (Konoplev et al., 1997). In 1994 theRETRACE-1 model was supplemented with modules to calculatewash-off during snow melt and with a module to calculate avertical migration of the radionuclide (Popov, 1995). Thesemodules were also validated from Scenario W data of the BIOMOSII project.

Being physico-mathematical the RETRACE-1 model shares alladvantages and disadvantages of this class of models. The majorproblem of this kind of models consists in heavy demands on theamount of input information which are often difficult to meet(WMO, 1975). A special studies initiated WMO (WMO, 1975)have showed, that conceptual models allow one to avoid this

RODOS(WG4)-TN(99)18

49

difficulty. Based on this experience, second runoff model whichwere developed for large-scale watersheds was the distributedconceptual model. This model was named RETRACE-2 (Popov,1995, Popov et al., 1997).

The RETRACE-2 model, along with the RIVTOX model ofradionuclide transport in rivers, was validated against the data ofthe specially developed scenario for the Ilia River (Zheleznyak etal., 1996, Heling et al., 1997, Popov et al., 1997). Moreover, thehydrological submodel RETRACE-2 was validated against the dataof the extreme flood observed in December 1993 on the RhineRiver (Popov and Heling, 1996). Joint validation requiredconsiderable time since a large amount of data was necessary to beprepared for both of the models. Besides, to have a possibility tosimulate extreme conditions in river channels, the algorithms of theRIVTOX model were modified.

To customise the RETRACE-2 model to different areas, severalsoftware tools were developed in 1997-98 within the frames ofRODOS-B and RODOS-E projects. Besides, the submodel ofradionuclide wash-off from the urban territory was beingdeveloped at the same time to be incorporated into RETRACE-2 asan additional module.

To provide a wash-off predictions of third type (see Table 1), thelong-term radionuclide wash-off model is being developed in 1997-98 within the RODOS-E project.

4.1.4 Basic equations of the RETRACE-2 model

4.1.4.1 Hydrological submodel

The most complicated problem of the runoff formation modellingis to consider in an adequate manner of space variability ofhydrophysical watersheds parameters. To solve this problem, theRETRACE-2 model employs a method developed by Vinogradov(Vinogradov, 1967, Vinogradov, 1988) that incorporates theadvantages inherent for distributed physico-mathematical modelsand for lumped models. The following principles form the basic ofthe method applied:

1. the variety of the conditions of natural complexes may begeneralised to several types of runoff-forming complexes(RFC) which are characterised by unique sets of the modelparameters; the number of RFC types is not large anddetermined by a knowledge of a hydrological regime of theterritory; the conditions of the runoff formation over theentire territory relating to the same RFC type are type areassumed identical;

2. the watershed surface may be broken up by a rectangulargeographical grid so that each grid cell may be assigned justto one type of RFC; grid cells represent calculation points(CP);

RODOS(WG4)-TN(99)18

50

3. a set of CPUs of one type makes up RFC which may notconsist of adjacent CPUs; configurations are possible whenRFC form a "spotty" structure on the watershed surface;

4. a size of the grid cell is large enough to incorporate a portionof the water course (either temporal or constant); a directionof the water course determines a direction of the withdrawalof a prevailing portion of the surface runoff, as well assediment and radionuclides; given several constant watercourses, the direction of the outflow of water and washed-ofmatter is assumed to coincide with the direction of thelargest water course.

The conclusion made from points 1 to 3 consists in capability ofusing expertise of a hydrological regime in selected parts ofwatersheds, which is particularly important for the modelling oflarge watersheds. It follows from assumption 4 that lineardimensions of CPUs are limited from below by a water-courselength of the first order which is 0.2-1 km for different territories(Strahler, 1952, Maidment, 1992). These assumptions also suggestthat the RETRACE-2 model employs an artificial channel net workcalculated from relief data and partially coincided with the actualriver network.

In the RETRACE-2 model, like in prototype Vinogradov's models,operates on daily basis that makes it easy to provide themeteorological input data. In according with Vinogradov'sconception, the formation of the runoff from a watershed is dividedinto two phases:

• pre-channel transformation, which means considering thedynamics of losses and soil infiltration for each CP and

• channel transformation, which means considering the lateralre-distribution of the runoff water between CPs and thenetwork of ephemeral and perennial channels.

As a result of the fulfilment of the two transformation phases, wecan answer the questions "How much water of the surface runoffwill reach a specified portion of the river?" and "When will ithappen?". To put it otherwise, it becomes possible to construct ahydrograph of the lateral inflow to a specified channel branch.

A pre-channel runoff transformation for each CP is supposed totake place as a composition of up to nine different types of surfaceand subsurface flows. Each type of flow is represented by storagehaving mostly logical than physical meaning (Table 5). In shouldbe mentioned that there is no general classification of runoff typessince such a classification is only the manner to think about or themodel of complex "runoff from watershed" phenomena takingplace in nature. So the Table 5 represents the classification used bySHI hydrologists in their models and also in RETRACE-2 model,that is why Russian terminology is used in the Table 5.

RODOS(WG4)-TN(99)18

51

Note also, that in the Table 5 the Horton indexes (Strahler, 1952,Maidment, 1992) were used and it was supposed that flows withindices 1 to 4 corresponding to ephemeral channels exist in eachCP.

Table 5:

Storagenumber

Runoff type Residence time forstorage, τi

Index ofchannel

draining runoff1 Overland flow 16.7 min 12 Upper soil and swampy flow 52.7 min 13 Lower soil flow 2.8 hr 14 Fast groundwater flow -1 2.8 hr 15 Fast groundwater flow -2 1.2 days 26 Groundwater flow -1 12 days 47 Groundwater flow -2 3.8 months 68 Deep groundwater flow -1 3.2 yr. 89 Deep groundwater flow -2 31.7 yr. 10

An important modification of the RETRACE-2 hydrologicalsubmodel, as compared to its prototype models, consists in the factthat the number of runoff types and storage was decreased to three,namely:

• quickflow, including saturated overland plus rapid subsurfaceflow through pipes, macropores, etc.; corresponds 1st to 4th

types in Table 5;

• fast groundwater flow; corresponds to 5th third plus runoff typesin Table 5;

• slow subsurface flow; corresponds to 6th runoff types in Table 5.

This can be done due to the fact that the lead time of RETRACE-2prognosis (Table 1) does not exceed 30 days, therefore the waterfrom the storage 7-9 will not reach drainage channels for the timeinterval considered.

It is important that each storage in the model is described in aunified approximation based on the analysis of empirical data. Inthis approximation the water balance in a storage is written asfollows:

RStd

Wd−= , (8)

where W - water volume in a storage, m3; S - effective inflow to astorage, m3/s, which may be either from outside soil (precipitationand melting snow water) or from upper storage; R - discharge(outflow rate) from a storage, m3/s.

Water discharge for all types of storage is approximated by theanalytical dependence (Vinogradov, 1967):

RODOS(WG4)-TN(99)18

52

[ ]1WabR −⋅⋅= )(exp , (9)

where a (m-3) and b (m3/s) are the first and second hydraulicparameters dependent on RFC type.

The advantage of this approximation of the R(W) used is in the factthat it provides an analytical expressions for searched dependenciesW(t) and R(t). The using of analytical solution instead numericalprovides significant acceleration of simulation process which isnecessary to consider runoff from large watersheds.

Equations (8), (9), when sequentially applied to each storage inaccordance with a vertical water movement, allow water dischargefor a time step and new values of storage volume to be obtained. Inthis case the infiltration from surface to soil depth provides theinflow into reservoirs 1 and 2 which are appropriate to surfacerunoff types. The remaining reservoirs (3-9) receive the water thatbecame accessible to the runoff after the soil moisture deficit wascompensated for, i.e. the excess water relative to normal fieldmoisture capacity of the soil.

The model assumes that the part of discharge from storage i (i≥3)arrives at the river network, whereas the other part enters storagei+1, i.e. it becomes the discharge of the inflow into storage i+1

S k Ri i i i+ += ⋅1 1, , (10)

where ki,i+1 - coefficients of water exchange between storage,representing the model parameters (for RETRACE-2 realisationthere are only two such parameters for each RFC type).

Runoff losses are determined in the model by using empiricaldependencies for soil evaporation and soil infiltration. It issignificant that in this case a probability distribution of rainintensity is taken into account, i.e. an exponential distribution isassumed. By using this distribution, the model calculates dailymean values of the runoff formation intensity, i.e. the dischargevalues Ri.

A horizontal transformation of runoff water (i.e. a movement ofwater from the precipitation site to the receiving watercourse) takesplace both over the slope surface (via ephemeral streams, cricks,etc.) and under the soil surface. With regard to the classification ofrunoff types (Table 5) and the evaluation of the channel flow index,the RETRACE-2 model calculates for each CP the distancetravelled by the runoff water to the drainage channel along theartificial channel system. A velocity of the slowest runoff isassumed to be equal to the filtration coefficient in the saturatedsoil. The value of this coefficient for each type of REC is an inputparameter and its default value could be estimated by using thedata for the soil type prevailing in the RFC. Based on these data,for each CP, the concentration time for the slowest runoff type iscalculated.

RODOS(WG4)-TN(99)18

53

To determine the concentration time for other (quicker) runofftypes, the model employs two assumptions. First, for each CP, theway along which the water moves to the drainage channel isassumed to be the same for all runoff types. Second, the water

movement velocity for the ith runoff type is assumed to be iτ

τ9

times as high as the filtration rate, with τi being determined inTable 5. This velocity estimates are used in the model as a defaultvalues. In the customisation of the model the concentration timesfor each runoff type should be calibrated.

4.1.4.2 Soil Erosion Submodel

The modelling of soil water erosion in watershed scales representsan extremely complicated problem (Hadley et al., 1985). Thereforeall the models of the watershed runoff formation employ empiricalrelationships that require calibration being applied for new territory(Singh, 1995).

The soil erosion is described by the RETRACE-2 model in thesame level of complexity as it is used by the hydrologicalsubmodel. Sediments are assumed to move with the overland flowalone. Since all runoff water and sediment form the given CP isassumed to concentrate in the output channel then there is nolateral mass exchange with adjacent CPs but only between CP anddrainage network. The rate of the soil mass losses for the given CP

or erosion rate dt

dM is described by the equation

1RStd

Mdtr ⋅= , (11)

where Str is turbidity of overland flow, kg/m3, and R1 is theoverland flow discharge, m3/s.

To calculate turbidity Str, the following three assumptions wereused in the RETRACE-2 model. First, the storage of sediments atthe soil surface was assumed to be unlimited. Second, the turbidityof slope flows assumed to have a maximum value equal to theflow's transport capacity. Third, to take into account re-sedimentation processes over a relatively large area of the CP, itwas assumed that only the sediments of the finest fraction (with aparticle size of d≤ 0.005 mm), would reach the channel network,whereas particles of larger fractions are retained at the slopesurface. The last assumption leads to a decrease in the effectivevalue of the erosion rate and, to some extent, compensates for theerrors caused by the use of the first assumption.

For the transport capacity of flows, a large number of empiricalrelationship are known. For the transport capacity of the waterflow, the following empirical dependence is used (Kuznetzov,1992):

RODOS(WG4)-TN(99)18

54

17.05.1

5.2

hw

nv11Str ⋅

⋅⋅= , (12)

where n is the Manning roughness coefficient, m-1/3s,characterising the RFC; v is the effective velocity of surface waterflows specified by the Chezy-Manning relationship, m/s, h is thedepth of surface water flows, m, calculated from the waterdischarge value R1 and the flow width L, m, which is equal to theside length of the rectangular restricting a CP and directed alongthe flow in the cell,

L

Rh 1= , (13)

w is the fall velocity of sediments, m/s, representing a calibrationparameter of the model; the default value for the fall velocity ofsediments with size d=0.005 mm is (used (Kuznetzov, 1992))

5−=10w m/s. (14)

4.1.4.3 Radionuclide Transport Submodel

Radionuclide Forms in Soil

A distinguishing feature of radioactive contamination due to anuclear accident is the variety of radionuclide forms present in bothatmospheric fallout and soil. When a major nuclear accidentoccurs, nuclear fuel debris, incorporating decay products, arereleased into the environment. Some of the radionuclides are alsodeposited on the ground as aerosol particles which have beenformed in the atmosphere due to condensation.

Radionuclides are present in the soil in three main forms: watersoluble, exchangeable and non-exchangeable. The maindistinguishing feature of the exchangeable form is the presence atthe same time in both sorbed on soil grains form and dissolved inthe pore water form. Since the water soluble and dissolvedexchangeable form of radionuclide are transported with runoffwater it is commonly used the term mobile form for them. Further,non-exchangeable and sorbed exchangeable form of radionuclideare transported with sediments and the term particulated form isused for this composition. To use the radionuclide activity balanceit is necessary to provide RETRACE-2 model with the initialcomposition of fallout via definition of activity portion for eachform.

The equilibrium state of exchangeable radionuclide in dissolvedand sorbed states is described by distribution coefficient Kd. Aswas shown experimentally (Ahuja, 1986, Sansone andVoitsekhovitch, 1996) that in the thin top level of soil theequilibrium of exchangeable form with runoff water is reached forrather short time interval 1-10 minutes. This thin top layer isusually referred as interaction layer and for the Chernobyl zonehad the depth about 1-4 mm (Sansone and Voitsekhovitch, 1996).

RODOS(WG4)-TN(99)18

55

Basing on these experiments it was supposed in RETRACE-2model that the concentration of exchangeable radionuclide for inrunoff water is equal to the concentration in pore solution ofinteraction layer under the saturation conditions. Therefore the Kd

value becomes one of the parameters of the radionuclide transportsubmodel of RETRACE-2.

Although there are wide literature devoted to distributioncoefficient measurements (Onishi et al., 1981, Coughtrey ndThorne, 1983, Sansone and Voitsekhovitch, 1996) the problem ofits proper selecting for given soil-radionuclide pair is still existing.This problem becomes much more complicated for wash-offmodelling since the soil properties could widely range. It should bementioned that sophisticated methods of value calculation(Konoplev et al., 1992, Sansone and Voitsekhovitch, 1996) couldbe applied at least for 90Sr in RETRACE-2 model but they needadditional data on soil properties. As default the expert proved Kd

values from literature are used in RETRACE-2 model.

Vertical Migration of Radionuclides in Soil

It should be noted that for the early accident stage, the verticalmigration impact for easily-sorbed radionuclides (137Cs, 90Sr) isinsignificant. But for late phase it could be necessary to considerthe radionuclide activity reduction in the interaction layer. Thisreduction could take place due to natural processes, e.g. wash-off,vertical migration into the deep soil, root uptake, wind re-suspension, and due to countermeasures, e.g. by ploughing.

Vertical radionuclide migration is calculated in RETRACE-2model with using of a diffusion Prokhorov model (Prokhorov1981) which is applied to a mobile form of radionuclides. As forthe particulated form of radionuclides, a vertical migration wasassumed to be insignificant.

Radionuclide Transport Equations

Taking into account the aforementioned radionuclide compositionin soil, the following activity balance equations are used in theRETRACE-2 at early accident phase:

for a dissolved fraction of the exchangeable sorbed form,

αθθ

λα s

ext

m

mex1d

sex

FdZR +

L

q

FR + - =

dtd

⋅

⋅⋅⋅

⋅, , (15)

for a sorbed fraction of the exchangeable sorbed form,

αρ

λα p

ex1

m

trd

pex

F

RS + - =

dt

d⋅

⋅ , (16)

and for non-exchangeable form of the radionuclide,

RODOS(WG4)-TN(99)18

56

αρ

λα p

un1

m

trd

pun

FRS + - =

dtd

⋅

⋅ , (17)

where the lower index ex is related to the values describing theexchangeable radionuclide form, the index un is related to the non-exchangeable radionuclide form, the upper index s refers to thevalues describing a dissolved fraction of the exchangeableradionuclide form, the upper index p refers to a particulated forms;α is the surface radionuclide density, Bq/m2; λd is the radioactivedecay rate, s-1; dZ is the thickness of the soil unsaturated zone, m;F is the area of the CP surface, m2; θ is the field moisture capacity;R1 is the overland flow discharge, m3/s; Rt is the total subsurfaceflow discharge, m3/s; Lm is the depth of the interaction layer andqex,m is a portion of radionuclide in exchangeable form comprisedin the interaction layer that was calculated by the Prokhorov model.

Wash-out of the radionuclide soluble form is modelled by thefollowing scheme. If the first after radioactive fallout rain provideoverland runoff, then the portion of soluble form reaching thedrainage net is supposed to be proportional to the runoff excess.Otherwise it is supposed, that the total soluble form of radionuclidewill completely migrate deeper than a interaction layer and sofurther it becomes not available for wash-off.

Equations (15), (17) can be easily integrated for each CP using thedata on water discharge and sediments have been obtained in thehydrological and erosion submodels. It should be noted that theradionuclide transport by the underground flow (equation (15)) istaken into account only for those CPs which includes perennialrivers.

4.1.5 RETRACE-2 Input and Output Data

Taking into account a well-known difficulty in collecting fhydrophysical and meteorological data for large watersheds, theRETRACE-2 model was designed to use only data of the standardhydrological and meteorological observations. All data used in themodel may be subdivided into three major types:

• static input data on a watershed and radionuclide properties in the“soil-water” system;

• dynamic input data concerning the data on the specificemergency situation;

• files of “scenarios” describing implementations of calculations.

Static input data are prepared during the customisation of RODOShydrological chain of models for the specified area. By and largehydrophysical data on the area are similar to those normally used inthe other well-known models (HSPF, SHE) (Singh, 1995). Theprevailing part of these data can be obtained from differentmanuals and maps. In should be emphasised that the as the mostreasonable size of CP is 1-2 km as RETRACE-2 requirements to a

RODOS(WG4)-TN(99)18

57

space resolution of these data are substantially lower than those ofphysico-mathematical models (such as SHE). A number ofparameters that have a physical meaning, but are not measured in adirect way (such as infiltration rate for RFC, radionuclidedistribution coefficients for RFC, fall velocity of sedimentstransporting the particulated radionuclides) require a calibration.With no calibrated data, the indicated parameters may be estimatedby expertise, but this could lead to a substantial increase inuncertainty of the modelling results.

Dynamic input data, unlike static input data, come to light right atthe moment of the emergency situation. The data on the surfacedensity of radionuclide contamination of the territory and themeteorological forecast on precipitation and air humidity arerelated to this type of data. With no meteorological forecast (forexample, when producing prognosis for more than two days), themodel’s software allows for their generation by using climatic dataon precipitation frequency and depths. The algorithm of generatingmeteorological parameters is similar to that suggested in theWGEN model (Richardson and Wright, 1984).

The files of scenarios make it possible to speed up considerably thelaunching and calibration of the model. In fact, these data are onlyintended to control the calculation and presentation of the results.

4.2 RIVTOX

The one-dimensional model RIVTOX was developed at IPMMS,Cybernetics Centre, Kiev, Ukraine to solve watercontamination/use problems of Ukrainian rivers after theChernobyl accident (Zheleznyk at al., 1992, Tkalich et al. 1994).The radionuclide transport part of the model is similar to theTODAM model (Onishi, 1982), however simplifications have bedone to receive practically applicable model with not too much setof the input data. On the other hand, nowadays RIVTOX includesthe more detailed description of the adsorption-desorptionprocesses (e.g. non equal rates of the desorption and adsorption,different Kd for bottom sediments and suspended sediments) thatwas included into the model on the basis of validation onChernobyl data. RIVTOX was validated for the Clinch River theTennessee river in the frame of IAEA VAMP program(Zheleznyak et al. 1995) and for the Dudvah River-the Vah Riverthat is the Danube tributary (Slavik et al., 1997). During last studythe possibility of the use in the RIVTOX two-step kinetics has beenanalysed.

4.2.1 Submodel of river hydraulics

RIVTOX includes two submodles for simulation crossectionalaveraged flow velocity and water elevation in a network of rivercanals. The First one is based on the full set of the Saint- Venantequations. The Second one is “diffusive wave” simplified form ofthe Saint-Venant equations. The latter one as it was demonstrated

RODOS(WG4)-TN(99)18

58

(e.g. Jobson, 1989; Marinets, Zheleznyak 1993) could give a goodaccuracy in the results for the flood routing in the river net thatdoes not include structures ( dams, gates) which could havesignificant upstream influence on the flow parameters. Full Saint-Venant equations should be used in the situation with significantupstream influence of the river structure, including e.g. pumping tothe water intakes of the irrigation channels and so on.

The hydraulic parameters of a stream (depth, sectional area,velocity) could be calculated using the full dynamic model or thediffusive wave model. TheFull dynamic model is used for riverswith dams other obstacles in the channel and for accelerated flows.The Diffusive wave approximation of full dynamic model could beused in case of the insignificant upstream influence of peculiaritiesin a channel.

The next assumptions should be valid to use the Saint-Venantequations for water flow modelling:

− flow is mainly one-dimensional (velocity is constant in thecross section), fluid which is incompressible andhomogeneous;

− curvature of current-flow lines is small, and verticalacceleration is insignificant;

− bottom slope is small, and parameters change slightly along astream;

− turbulence and friction influence could be taken into accountin accordance with resistance laws for constant flows;

The system of Saint-Venant equations include continuityequation (mass conservation law) (18) and momentum equation(19)

l

A Qq

t x∂ ∂∂ ∂

+ = (18)

2

0f

Q Q hgA S

t x A x∂ ∂ ∂∂ ∂ ∂

+ + + =

(19)

The glossary of terms used in the models is presented at the end ofthe subsection.

The components of the equation (19) mean: local acceleration,hydrostatic gradient, gravity, and friction.

The total water depth and bed slope are defined as follows:

bh y y= − (20)

0by

S tgx

∂ α∂

= − = (21)

RODOS(WG4)-TN(99)18

59

α

Q Q

2by

1by

x

h

by

y

z

Figure 17: River stream parameters

The momentum equation (19) could be rewritten on the basis ofabove notation as follows

2

0 0fQ Q y

gA S St x A x

∂ ∂ ∂∂ ∂ ∂

+ + + − = (22)

The friction slope fS is calculated using one of the empirical

resistance laws, such as Chezy’s or Manning’s, for example:

2f

Q QS

K= (23)

here K is a stream metering characteristics.

The usual approach in river hydraulics is to use empirical Chezy’sfriction coefficient CzC .

CzK C A R= (24)

The hydraulic radius of the flow R is defined as AP , where P is

“wetted perimeter” of the stream. For a wide river channel P valueis close to a river width b ( P b≈ ) and then R h≈ .

On the basis of the Mannings’s empirical “friction parameter” n

(average value is 0,02 0,03−&& for the plain rivers) CzC is determinedas

16

1CzC R

n= (25)

In the kinematic wave approximation only two lass terms areconsidered in the equation (22), i.e. 0fS S= ., that leads to formula

0

QK

S= (26)

In this approximation using (23) -(25), could be obtained Chezy’sformula for steady state flow

0/ CzQ A C RS= . (27)

The substitution of (28) into the mass balance equation (1) usingthe assumptions ,A bR R h= ≈ and Manning’s formula (25) will leadto kinematic wave equation

RODOS(WG4)-TN(99)18

60

( ) 106

12 10

( )l

bh bhS n q

t x

∂ ∂∂ ∂

−+ = (29)

The diffusive wave approximation of Saint-Venant equations (18),(22) could be derived by the neglecting the first two terms in themomentum equation (22). In this case after differentiation (18) onx and (22) on t and assuming

1 1l

K dK h dK Qq

t dh t dh b x b∂ ∂ ∂ = = − − ∂ ∂ ∂

(30)

we obtain:

2

2 0w wd w l

Q Q QV E V q

t x x∂ ∂ ∂

+ − − =∂ ∂ ∂

(31)

here wV is the wave propagation velocity (wave celerity), and wdE

is the diffusion coefficient

w

Q KV

bK h∂

=∂

, 2

2wdK

EbQ

= (32)

As a result it is received one parabolic equation instead of thesystem of two hyperbolic equations.

The formulas (32) could be simplified on the basis of assumption(26) that leads to

1w

dQV

b dh= ,

02wd

QE

bS= (33)

On the basis of formula (27) and approximations ,A bR R h= ≈ theformula for the wave propagation velocity could be furthersimplified :

3

2w

QV

bh= ,

02wd

QE

bS= (34)

The functional relation between water discharge and waterelevation (depth) is established on the basis of Chezy formulae.

The numerical solver for diffusive wave equation (31), (34) isincluded into the main hydraulic module of the RIVTOX –HDM.The module of the numerical solution of the full Saint-Venantequations is included only as the option for rivers with dams andgates (without support via GUI).

4.2.2 Sediment transport submodel

The suspended sediment transport in river channels is described bythe 1-D advection -diffusion equation that includes a sink-sourceterm describing sedimentation and resuspension rates and lateraldistributed inflow of sediments

RODOS(WG4)-TN(99)18

61

( ) ( ) ( )S b l

AS QS ASE

t x x x

∂ ∂ ∂ ∂+ − = Φ + Φ

∂ ∂ ∂ ∂ , (35)

where bΦ is a vertical sediment flux at the bottom, describingsedimentation or resuspension processes in the dependence on theflow dynamical parameters and size of bottom sediments.

( )b res sed

Aq q

hΦ = ⋅ − . (36)

The fluxes are calculated as a difference between actual andequilibrium suspended sediment concentration multiplied on fallvelocity of sediment grains:

( )( )

0

0

res

sed

q w F S S

q w F S S

β ∗

∗

= ⋅ −

= ⋅ −, (37)

where F(x) is a function defined as

( ) , 0

0, 02

x xx xF x

x

>+ = ≡ <

(38)

The coefficient of the erodibility β characterizes the bottomprotection from erosion due to cohesion and natural armoring ofthe upper layer of river bed, vegetation. This empirical coefficientas usually has values of magnitude 0.1-0.01.

The equilibrium suspended sediment concentration (flow capacity)S∗ * can be calculated by different approaches. The first empiricalformula used in RIVTOX ( Zheleznyak et al.1993) was taken fromBijker’s method ( Bijker, 1998).

The equilibrium discharge of the suspended sediments *p=QS iscalculated as a function of the bed load bp :

)ln(83.1 20

1 Izh

Ipp b += (39)

where 1I and 2I are the functions of the undimensional fall

velocity )/( *0* kUww =

and bottom roughness hrr /* =

'1

'

'

*

1*

1

*

*

*

* 1

)1(216.0 dz

zz

rr

Iw

rw

w

∫

−−

=−

, (40)

RODOS(WG4)-TN(99)18

62

**

*

*

11 '' '*

2 '*

10.216 ln

(1 )

ww

wr

r zI z dz

r z

− −= −

∫ (41)

where

z’=z/h, r=30 0r - typical size of the bottom inhomogeneity, k - von

Karman parameter (k=0.4), *U - bottom shear stress velocity

* /c w fU T ghSρ= = (42)

The bottom sediment equilibrium flow is described as follows:

0.5

5 exp 0.27cb

cwcw

T Dp D

TT

µ ρρ

= −

rr

rr (43)

where

cTr

- current driven bottom shear stress,

cTr

- bottom shear stress driven by joint action of the currents andwaves,

D - averaged size of sediments,

µ - the parameter of the bottom ripples.

The formula (43) was proposed for coastal areas and for riversmainly used for the large reservoirs parts. In recent versions ofRIVTOX van Rijn’s methods of calculation of suspended sedimenttransport is included into the module library.

The lateral inflow of suspended sediments to the river net lΦ in theequation (35) could be presented as follows

l l lq SΦ = , (44)

The distributed runoff inflow to the river net lq and the suspendedsediment concentration in the runoff lS are simulated by the HDMRETRACE model.

Substitution of the (36) and (44) into (35) leads to the followingequation:

( ) ( ) ( ) ( )S res sed l l

AS QS AS AE q q q S

t x x x h

∂ ∂ ∂ ∂+ − = − +

∂ ∂ ∂ ∂ , (45)

which could be taken into account the water balance equation (1)presented in such a form

RODOS(WG4)-TN(99)18

63

( )1 1( )l

S res sed l

qS S SU AE q q S S

t x A x x h A∂ ∂ ∂ ∂ + − = − + − ∂ ∂ ∂ ∂

(46)

where /U Q A= -crossectionally averaged flow velocity, SE -dispersion coefficient for suspended sediments. It is assumed, thatfor suspended sediments could be used the same dispersioncoefficient as for a soluble tracer in water flow. The overview ofthe methods of the calculation of the dispersion coefficient for 1-Dchannel flow has been presented by F.Holly ( 1985 ) and recentlyby Won Seo (1998).

The widely used formulas are as follows:

Elder (1958):

*x EE U hα= (47)

The calibration constant αE has a constant value of 5.9.

Fischer (1973) (in presentation of van Majzik, 1992):

2 2

*x F

b UE

h Uα= (48)

The calibration constant αF , e.g. for the Rhine River has a value of0.011.

Won Seo (1998):

1.251.23

*x W

b UE

h Uα

= (49)

The calibration constant αW is given in the literature having a valueof 0.64.

The simplest approach based on the Elder formula (47) , shearstress velocity definition (42) and Chezy’s and Manning’s formula(3)-(6), is used in RIVTOX

56

*s x E EE E U h gnU hα α −= = = (50)

The values of the parameter Eα should be calibrated if traceexperiment data are available for the river of the modelimplementation.

The Other longitudinal dispersion formulas could be usedoptionally.

The fluxes of the sedimentation and the resuspension (37) controlthe dynamics of the upper most contaminated layer of the bottom

RODOS(WG4)-TN(99)18

64

sediments. The thickness of this layer *Z could be calculated fromthe mass balance equation

*

(1 )s sed er

dZq q

dtρ ε− = − (51)

After the simulation of stream hydrodynamics, the numericalsolution of the equations (21), (24) is used with the appropriateempirical formulas for the modelling of the suspended sedimenttransport in the river flow.

4.2.3 Submodel of radinuclide transport

This submodel of RIVTOX describes the advection diffusiontransport of the cross-sectionally averaged concentrations ofradionuclides in the solution C, the concentration of radionuclides

on the suspended sediments sC and the concentration bC in thetop layer of the bottom depositions. The adsorption/desorption andthe diffusive contamination transport in the systems "solution -suspended sediments" and "solution - bottom deposition" is treatedvia the Kd approach for the equilibrium state, additionally takinginto account the exchange rates ,i ja between solution and particles

for the more realistic simulation of the kinetic processes.

The present version of RIVTOX uses different values of thesorption and desorption rates a1,2 and a2,1 for the system "water-suspended sediment" and a1,3 and a3,1 for the system "water-bottomdeposits" because this fits better with the real physical-chemicalbehaviour of radionuclides in the water systems. Furthermore, theuse of the different exchange rates gives a better fit in thesimulations

( ) ( )

( ) ( )

( )

( )*

*

S S S*

b*

C C 1 C, , , , , ,

C C 1 C, , , , , , , ,

C, , , , ,

,

l

SS Sl

b b

b

CC S b CC l

CC S b C S SC l l

C S b C

*C Z

QAE f S C C C Z p f C C

t A x A x x

QAE f S C C C Z p f C C C C

t A x A x x

f S C C C Z pt

Zf S p

t

∂ ∂ ∂ ∂ + − = + ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂

+ − = + ∂ ∂ ∂ ∂ ∂

=∂

∂=

∂

r

r

r

r

, (52)

where

RODOS(WG4)-TN(99)18

65

( ) ( ) ( )

( )

( ) ( )

( )

( ) ( )( )

*

1,2 1,3

1,2

1,3 *

1

1

l

S

l

b

SC S bdS db

Cl

b SsedC S S

dS

S Sl lC

b SresC b b

dbS

Zf C a K SC C a K C C

hQ

f C CA

q C Cf C a K C C

hSQS C C

fAS

q C Cf a K C C C

Z

ρ ελ

λ

λρ ε

−= − − − − −

= −

−= − + − +

−=

−= − − −

−

, (53)

The numerical solver for the system of the equations (53) isincluded into the RIVTOX code.

RODOS(WG4)-TN(99)18

66

Glossary of terms used in the section 2.1

Q m3/sec water discharge

A m2 water sectional area

b M water width

h M water depth

y M depth, (calculated from reference level)

by M river-bed level, (calculated from reference level)

lq m/sec2 water discharge of lateral inflow, distributed along stream

g m2/sec gravitational acceleration

fS Stream friction slope

0S Stream bed slope

K m3/sec Metering characteristic

V m2/sec Water velocity

wdE m2/sec Water longitudinal diffusion coefficient

S kg/m3 Suspended sediment concentration

S∗kg/m3 Suspended sediment equilibrium concentration

bΦ kg/m·sec total vertical flux of sediments at water-river bed interface per unit ofriver branch length

resq kg/m2·sec Resuspension (erosion) rate per unit area of the bottom (upwarddirected flux)

sedq kg/m2·sec Sedimentation rate per unit area of the bottom (dawnward directedflux)

β Erodibility empirical coefficient

0w m2/sec Sediment fall velocity

lΦ kg/m·sec Suspended sediment flux from lateral inflow per unit of river branchlength

lS kg/m3 suspended sediment concentration in the lateral water inflow

SE m2/sec longitudinal dispersion coefficient for sediments

xE m2/sec longitudinal dispersion coefficient for soluble tracer

Eα parameter of the longitudinal dispersion for Elder’s formula

U m/sec crossectionally averaged flow velocity

*U m/sec bottom shear stress velocity

K von Karman parameter

cTr kg/(m

sec2)current driven bottom shear stress

D M averaged size of sediments,

*Z M thickness of the bottom sediment upper layer

Sρ Kg/m3 density of the suspended sediments ( default value 2600 )

Sρ Kg/m3 water density ( default value 1000 )

ε porosity of the bottom sediments

C Bq/m3 radionuclide concentration in solution

RODOS(WG4)-TN(99)18

67

SC Bq/kg radionuclide concentration on suspended sediments

bC Bq/kg radionuclide concentration in bottom depositions

lC Bq/m3 radionuclide concentration in solution of lateral inflow

SlC Bq/kg radionuclide concentration on suspended sediments in lateral inflow

CE m2/sec radionuclide longitudinal dispersion coefficient

λ sec-1 decay coefficient

1,2a sec-1 sorption rate in “water-suspended sediments” system

2,1a sec-1 desorption rate in “water-suspended sediments” system

1,3a sec-1 sorption rate in “water-bottom deposition” system

3,1a sec-1 desorption rate in “water-bottom deposition” system

dSK m3/kg distribution coefficient in “water-suspended sediments” system

dbK m3/kg distribution coefficient in “water-bottom deposition” system

4.2.4 Boundary and initial conditions in river network

River network

For a complex river net the above models are applied to the rivernetwork graph. Each equation is solved for the respective "simplechannel" (branch) with the relevant initial conditions on a branchand the appropriate boundary condition in a junction of the rivernet. Each branch is considered as a river channel name "simplechannel" means that inside this branch there are no junctions with 2or more inflows or outflows, sharp changes in depth or width of thestream or water discharge. These points are named "special" pointsand define a scheme of the river net for the simulation purposes.

crossections,calculation points

inflow boundary

outflow boundary

Figure 18: River stream scheme

RODOS(WG4)-TN(99)18

68

For the numerical solution of the model equations each branch iscovered by the set of the grid nodes (computational mesh) aspresented on Figure 18. The configuration of the graph and the sizeof the branches could be taken from the GIS (e.g. MapInfo map) ,The information about the river hydrographical characteristics (e.g.mean depth and width, typical discharge, the crossection data -A=A (h) or b=b(h) tables) is prepared for some river crossectionsto be interpolated into the computational nodes in the modellingsystem.

Boundary condition and initial conditions

a) In all models, for all influx points of the river net, the source termconditions should be set:

0

0

0

0

( ) ( )

( ) ( )

( ) ( )

( ) ( )

x

x

x

S S

x

Q t Q t

S t S t

C t C t

C t C t

=

=

=

=

=

=

=

=

%

%

%

%

, (54)

where ( )Q t% , ( )S t% , ( )C t% , ( )SC t% are the source functions

b) At the outflow nodes the condition of the free propagation:

S

Qx l

x l

Sx l

x l

Cx l

x l

S SC

x l

x l

Q Q Qf

t A x

S Q Sf

t A x

C Q Cf

t A x

C Q Cf

t A x

==

==

==

==

∂ ∂ + = ∂ ∂ ∂ ∂ + = ∂ ∂

∂ ∂ + = ∂ ∂

∂ ∂+ = ∂ ∂

, (55)

where l - a branch length.

c) The Conjunction node (inflow from more than one branch andoutflow through one branch) conditions of the free propagation areimposed at the inflow branch.

The mass balance conditions:

( ) ( )

( ) ( )

( ) ( )

( ) ( )

0

0

0

0

i

i

i

i

x x lout ii

x x lout ii

x x lout ii

x x lout ii

Q Q

QC QC

QS QS

QSC QSC

= =

= =

= =

= =

=

=

=

=

∑

∑

∑

∑

, (56)

RODOS(WG4)-TN(99)18

69

d) The fork nodes (inflow from one branch and outflow through twoor mode branches).

At the inflow branch the free propagation conditions (55) areimposed. At the outflow branches source term conditions (54) areimposed, where the source functions are equal to the output fromthe inflow branch.

The initial conditions should be also set for all parameters in allpoints of the numerical mesh at the start time.

4.2.5 RIVTOX Input and Output Data

The input data of the model are as follows:

• The Parameters of the river channel network such as the length of thebranches and the positions of the junctions, the dependence of the areaof crossection of the channel from the water surface elevation, thebottom roughness, typical scenarios of the river floods for thesimulation of direct releases of radionuclides into the water.

• The Typical distribution of the grain size of the suspended sedimentsand grain sizes of the bottom deposits.

• Time dependent information about the point sources for the simulationof the direct release and the output from RETRACE as the lateralinflow of the contamination for the modelling of the fate of pollutantswhich were washed out from the watershed.

The radionuclide transport parameters are defined in RIVTOX –HDM 4.0 for 7 radionuclides. The pesented values could beconsidered as the default values, that could be supplementarycalibrated on the basis of processing of measured data during thedirect implementation of the model.

Table 6: Radionuclide transport parameters

Nuclide Kdb

(m3/kg)

Kds

(m3/kg)

a12

(1/day)

a21

(1/day)

a13

(1/day)

a31

(1/day)

Cs-137 3 15 1 0.02 0.01 0.002778

Sr-90 0.25 0.8 1 0.02 0.04 0.002778

H-3 0 0 0 0 0 0

Co-60 5 20 1 0.02 0.01 0.002778

I-131 0.01 0.01 1 0.02 0.04 0.002778

Pu-239 200 800 1 0.02 0.01 0.002778

Ru-106 4 15 1 0.02 0.01 0.002778

The output data are as follows arrays that presents the value ofvariables in the nodes of the grid, constructed on river branches

RODOS(WG4)-TN(99)18

70

q time variable crossectionally averaged concentration ofradonuclides in the solute;

q time variable crossectionally averaged concentration ofradonuclides on the suspended sediments;

q time variable crossectionally averaged concentration ofradonuclides in the upper layer of the botttom sediments.

The output data of the RIVTOX module is used by the specialmodule “PREPARATION” to be transferred into the RODOS dosecalculation module FDMA.

4.3 COASTOX

4.3.1 Submodels

4.3.1.1 Submodel of stream hydraulics

The two-dimensional lateral longitudinal models could be derivedfrom the primitive 3-D equations by their averaging over the depth.The 2-D variables f(x,y,t) are linked with the primitive 3-Dvariables f'(x,y,z,t) by the formula

1( , , ) ( , , , )

H

f x y t f x y z tH

η

η −

′=+ ∫ (57)

where ( , ) ( ) ( , )j j jx t H x h x tη + = - the total water depth (see Fig.1)

0 η

z

V

U H

y

x

z

η

Figure 19: Water body parameters

The depth-averaged currents in a shallow lake or a water reservoirare determined by the balance between the wind shear stress ωτ ,

the bottom shear stress bτ , the vertically averaged tensor of thehorizontal turbulent exchange ijT , and by the force driven by the

surface elevation gradient kx∂η ∂ . The corresponding system of theequations for the vertically averaged horizontal flow velocities jU

(j=1 for x direction and j=2 for y directions) and the total water

RODOS(WG4)-TN(99)18

71

depth h could be written in the form of the equations of mass andmomentum conservation (O.Philips,1980):

( )0k

k

hU

t x

∂∂η∂ ∂

+ = (58)

( ) ( ) ( )1 1j j w bk kj j j

k k k

hU UhU gh T

t x x x

∂ ∂ ∂η ∂ τ τ∂ ∂ ∂ ρ ∂ ρ

+ + = + − (59)

where k = 1,2; j = 1,2,

jU − vertically averaged horizontal flow velocities in the x (j=1)

and y (j=2) directions.

The shear stresses at the free surface and at the bottom aredetermined by the quadratic friction laws respectively through thewind velocity Wand stream velocity U:

wj w w jc W Wτ ρ=

uur(60)

bj f jc U Uτ ρ=

r(61)

where k = 1,2; j = 1,2, The glossary of the terms used in the modelsis presented at the end of the subsection.

The substitution of the equations (58),(60), (61) into themomentum equation (59) leads to the equation in the form

k k

wb

j

j jk jhU Uh

U UU g W W

t x xλλ∂ ∂ ∂ η

∂ ∂ ∂+ + = − +r uur

(62)

The horizontal turbulent diffusion term is omitted in the equation(62)taking into account that in the numerical solutions of thisequation this term as usually has the lower magnitude then thenumerical diffusion of the finite-difference scheme.

The hyperbolic system of the equations (58),(62) is known as“shallow water equations”.

The bottom friction parameter b

λ in river hydraulics is often

calculated through the Chezy’s coefficient czC

bcz

gC

λ = (63)

This coefficient could be calculated on the basis of the Manningformula

1 / 61CzC h

n= (64)

For the empirical “friction factor” n there are a lot ofrecommendations on the definition of its value for different waterbodies.

RODOS(WG4)-TN(99)18

72

For steady flow conditions the efficient numerical methods tocalculate flow velocity distribution could be obtained in “diffusive”approximation of the shallow water equations. The advective

acceleration term k

x

UU

jk∂∂

,could be omitted in the equation (62)

for the water bodies without sharp velocity gradients. Then thesystem (58), (62) taking into account formulas (63), (64),.could bewritten

WWUUhgn

xg jwj

rr

3/4

2

j

λ∂

η∂+−= (65)

0 x

)(hU

k

k=

∂∂

.(66)

In correspondence with the continuity equations (66) the streamfunction is defined as follows

; .y xU h U hx y

∂ ∂∂ ∂Φ Φ= − = (67)

The equation (65) without wind stress could be rewritten

( ) ( )( )

( ) ( )( )

2 2

1 0 3 10 3

, ,0

, ,

n x y A n x y A

x x y yh x y h x y∂ ∂ ∂ ∂∂ ∂ ∂ ∂

Φ ΦΦ Φ+ =

(68)

where

( )22

,Ax y

∂ ∂∂ ∂

Φ Φ Φ = +

The omitted in (68) wind stress terms could not change a lot theprocedures of the numerical solution of this equation.

For the channel flow constrained by the boundaries B1 and B2 theboundary conditions for the stream function are

B1: 0Φ = :

B2: const QΦ = = , (69)

where Q - total water discharge in the flow.

The condition of normal flux though the open boundaries areapplied at the upstream and down-stream end of the consideredarea:

0.m

∂∂

Φ= , (70)

where m - the normal to the open boundary.

In the specific case of the straight channel of the permanent shape(the depth distribution is the same in any crossection) the equation(68) has the analytical solution. We would consider x-orientedchannel in the area 0 ,0xx L y b≤ ≤ ≤ ≤ . The depth of the flow isassumed to be constant in direction x , therefore

RODOS(WG4)-TN(99)18

73

( , ) ( )h x y H y= (71)

For such a stream, taking into account the boundary conditions(69) at B1=0 and B2=b the equation (68) has the solution

( )( )

( )5 3

05 3

0

y

y

L

Qy h y dy

h y dy

Φ = ∫∫

(72)

The analytical formulae could be received from (72) for thespecific shape of the channel cross-section. If the water depth isdescribed by the function

( )

2,0

2

2 1 ,2

H by y

bh y

y bH y b

b

≤ ≤= − ≤ ≤

(73)

From (72) we obtain

( )

8 35 3

8 3

5 3

2 ,0 ,2

1 2 1 , .2

y bQ y

by

b bQ y b

y

≤ ≤ Φ = − − ≤ ≤

(74)

This analytical solution was used to verify the numerical methodsdeveloped to solve the equation (69).

The glossary of terms used in the models is presented at the end ofthe subsection.

4.3.2 Sediments transport submodel

The suspended sediment transport in the river channels is describedby the 2-D advection -diffusion equation that includes a sink-source term describing the sedimentation of the suspendedsediments and their resuspension from the erodible bed.

The depth averaged advection-diffusion equation of the suspendedsediment transport is written

k ikk k i

hS S(hSU )= hE

t x x x res sedq q∂ ∂ ∂ ∂∂ ∂ ∂ ∂

+ + − (75)

where S and S* are the vertically averaged suspended sediment

concentration and the equilibrium suspended sedimentconcentration respectively. The vertical fluxes of the sediments –the sedimentation rate sedq and the resuspension rate resq arecalculated through the difference of the actual and equilibriumconcentration of the suspended sediments

( )( )

0

0

res ER

sed

q w F S S

q w F S S

ββ

β∗

∗

= ⋅ −

= ⋅ −, (76)

where F(x) is the function defined as

RODOS(WG4)-TN(99)18

74

( ) , 0

0, 02

x xx xF x

x

>+ = ≡ <

(77)

The coefficient of the erodibility ERβ characterizes the bottomprotection from erosion due to cohesion and natural armoring ofthe upper layer of the river bed, vegetation. This empiricalcoefficient as usually has values of the magnitude 0.1-0.01. β - isthe ratio of the near-bottom suspended sediment concentration tothe depth averaged concentration;

The ikE - coefficients of the horizontal dispersion for sediments isassumed the same as for the dispersion of the soluble pollutant.

There are calculated on the basis of the formula (Holly,1985)2 2

11 cos sine pE D Dθ θ= + ,

( )12 sin cose pE D D θ θ= −

2 222 sin cose pE D Dθ θ= + , (78)

where θ - angle between the local flow direction and the x-axis;.

eD and pD are the dispersion coefficients in the directions parallel

and perpendicular, respectively, to the local velocity vector. Thesecoefficients are determined by the Elder formula

*

*

,

,e E

p p

D U h

D U h

αα

==

(79)

where U* -the bottom shear stress, Eα and pα - the empirical

parameters of the longitudinal and transverse diffusion.

The depth averaged equilibrium concentration of the suspendedsediments S* is calculated by the Bijker method (Bijker, 1968), and

includes the effects of the bottom shear stress, generated by waves,on the magnitude of S*.

The thickness of the upper contaminated layer of sediments canbe described by the equation of the bottom deformation:

s b*s

Z (1- ) q q

t∂ρ ε∂

= − (80)

where the sedimentation and the resuspension rates are calculatedthrough the difference of the actual and equilibrium concentrationof the suspended sediments (Zheleznyak et al., 1992).

After the simulation of a stream hydrodynamics the numericalsolution of the equations(75), (80) is used for the modelling of 2-Dsuspended sediment transport in streams.

RODOS(WG4)-TN(99)18

75

4.3.3 Submodel of radinuclide transport

This submodel of COASTOX describes the advection diffusiontransport of the cross-sectionally averaged concentrations ofradionuclides in the solution C, the concentration of radionuclideson the suspended sediments sC and the concentration bC in the toplayer of the bottom depositions. The adsorption/desorption and thediffusive contamination transport in the systems "solution -suspended sediments" and "solution - bottom deposition" aretreated via the Kd approach for the equilibrium state, additionallytaking into account the exchange rates ,i ja between the solution and

the particles for the more realistic simulation of the kinetics of theprocesses.

The depth averaged equation of the transport of the dilutedcontamination is written as:

( )

( ) ( ) ( )

kk

s bik 1-2 ds * 1-3 db

k i

hChCU =

t xC

hE - hC-hA S K C-C - 1- Z K C-Cx x s A

∂ ∂∂ ∂∂ ∂ λ ρ ε

∂ ∂

+

(81)

where:

The transport equation for Cs is defined as follows:

s ss

k ikk k i

hSC SC(hSC U)= hE -

t x x x

∂ ∂ ∂ ∂∂ ∂ ∂ ∂

+

s s b sds1-2

- hSC +hA S(K C-C )+C -Cres sedq qλ (82)

The contamination of the upper layer of bottom deposits can bedescribed by the equation

bb b s*

* 1-3 dbs

Z C 1=Z (K C-C ) - (C -C )

t (1- ) res sedA q q∂

∂ ρ ε(83)

The coefficients of the exchange rate between the compartment“solute” (subscript {}1), “suspended sediments” {}2 and “bottomdeposition” {}3 describe non-reversible kinetics, i.e.

1,2

1 2

2,1

,

,

sds

sds

a K C CA

a K C C−

>= <

(84)

1,3

1 3

3,1

,

,

bdb

bdb

a K C CA

a K C C−

>= <

(85)

where 1,2a and 1,3a are adsorption rate coefficients, respectively, for

the systems “suspended sediment”- “water” and “bottomsediment”- “water”; 2,1a and 3,1a - desorption rate coefficients for

the same systems.

RODOS(WG4)-TN(99)18

76

Glossary of terms used for COASTOX description

jU m/sec vertically averaged horizontal flow velocities in the x (j=1) and y(j=2) directions

jW m/sec Horizontal wind velocities

wρ Kg/ m3 air density

wc air friction coefficient

fc bottom friction coefficient

h M total water depth

η M water surface elevation ( deviation from the equilibrium water level)

H M water depth measured from the equilibrium water level r

b M width of a stream

Q m3/sec water discharge through crossection

Φ m3/sec stream function

CzC m/sec2 Chezy coefficient

n m5/6sec2 Manning friction factor

wjτ kg/(m sec2) shear stress driven by wind at water surface

bjτ kg/(m sec2) bottom shear stress driven by currents

S Kg/m3 concentration of suspended sediments averaged over a depth

S∗Kg/m3 equilibrium concentration of suspended sediments averaged over a

depth

resq Kg/m2·sec resuspension (erosion) rate per unit area of the bottom (upwarddirected flux)

sedq Kg/m2·sec sedimentation rate per unit area of the bottom (dawnward directedflux)

β ratio of the near-bottom suspended sediment concentration to1e depthaveraged concentration;;

ERβ coefficient of erodibility of bottom.

0w M2/sec Sediment fall velocity

ikE M2/sec Components of dispersion coefficient (i=1,2;k=1,2) in 2-D flow

eD M2/sec Dispersion coefficients in the direction parallel to the local velocityvector

pD M2/sec Dispersion coefficients in the direction perpendicular to the localvelocity vector

Eα empirical parameters of longitudinal diffusion

pα Empirical parameters of transverse diffusion.

*U M/sec bottom shear stress velocity

*Z M thickness of the bottom sediment upper layer

Sρ Kg/m3 density of the suspended sediments ( default value 2600 )

wρ Kg/m3 water density ( default value 1000 )

ε porosity of the bottom sediments

C Bq/m3 Radionuclide concentration in the solution

SC Bq/kg Radionuclide concentration on the suspended sediments

bC Bq/kg Radionuclide concentration in the bottom depositions

RODOS(WG4)-TN(99)18

77

lC Bq/m3 radionuclide concentration in the solution of the lateral inflow

SlC Bq/kg radionuclide concentration on the suspended sediments in the lateral

inflow

CE m2/sec Radionuclide longitudinal dispersion coefficient

λ sec-1 Decay coefficient

1,2a sec-1 Coefficient of the adsorption rate for “water-suspended sediments”system

2,1a sec-1 coefficient of the desorption rate for “water-suspended sediments”system

1,3a sec-1 coefficient of the adsorption rate for “water-bottom sediment” system

3,1a sec-1 coefficient of the desorption rate of “water-bottom sediment ” system

dSK m3/kg distribution coefficient in “water-suspended sediments” system

dbK m3/kg distribution coefficient in “water-bottom deposition” system

4.3.4 COASTOX input data

The program “COASTOX” was developed for the simulation ofbehaviour of radionuclides in the aquatic environment. Theprogram consists of two main modules. One considers thecomputation of the two-dimensional tidal currents and the other isused for the simulation of the spatial distributions of theconcentration of radionuclides in three different phases: in thesolution, in the suspended sediments and in the bottom deposits. Atpresent the following list of nuclides ise considered in COASTOX:H-3, Co-60, Sr-90, Ru-106, I-131, Cs-137, Pu-239.

The main input file for the program ”COASTOX” contains thebathimetric information about the water body. This file has theextension of “ . grdb” and includes the following data:

• The code of the format (DSAA);• The dimension of the grid;• The length of the grid;• The width of the grid;• minimum and maximum values of the reservoir depth;• the two-dimensional dot matrix of the reservoir depth values

,unit - m;• the flag of the flow direction ( “-1.” - from left to right, “ 1.”

- from right to left);• the number of the islands;• the level of the land (the minimum value of the reservoir

depth).• hydrodynamic calculations of the depth-averaged current

velocities requires the setting of the following parameters:• Q - total water discharge, unit - m3/s;• dt - time-step (usually equal “2.”);• itmax - maximum number of calculation steps .

Output files from the hydrodynamic calculations are files withthe name “uvs. ” where the extension name defines the information

RODOS(WG4)-TN(99)18

78

included. This are either the individual components of the depth-averaged current velocities as well as the input file againcontaining the bathimetric map which was described above. Allthese output files are input files for the computation of theradionuclide distribution in the water body. Moreover, if thereexists information about an initial or previous contamination of thewater body, the procedure of the sediment transport calculationrequires three following input files for each radionuclide:

• the file of the concentration in the solute, unit - pci/m3;• the file of the concentration in the suspended sediments, unit

- pci/kg;• the file of the concentration in the bottom deposits, unit -

pci/kg.

This procedure additionally requires , for the entire set ofradionuclides, the input file which contains the sedimentconcentration, unit - pci/kg. This input file of the concentration canhave a name with the extension “ .grdr ” and beneath the dotmatrix of the concentration, the following information ise included:

• the number of the radionuclides and the radionuclide name(elements of radionuclides, list starts with the number zero);

• the number and name of the phase;• date, namely month, day, time (h: m: s), year.

The Output files of the concentrations in the sediments, in thesolute , in the suspended sediments, and in the bottom deposits arewritten by the same format as the input files and have names withthe extension of “.grdr “. If there is no information about initialconcentrations or background values, zero values for these arraysmust be set. Additionally, an initial value of the thickness of thecontaminated upper active bottom deposits layer, unit - kg/m3, hasto be assigned. The parameters which have to be set for thecalculation of the radionuclide concentration are shown in thefollowing tables:

• dsz - particle size of the bottom deposits, unit - cm;• beta - ratio of the concentration of the near-bottom

suspended sediments to the depth-averaged concentration;• ros - particle density of the bottom deposits, unit - kg/ m3;• epr - particle porosity of the bottom deposits, unit - kg/m3;• dt - time-step for the pollution simulation, unit - s.

The exchange rates between water, sediments and bottomdeposits are based on the distribution coefficients:

• bk. - ratio between particles in the bottom deposits and thesolution under steady state conditions;

RODOS(WG4)-TN(99)18

79

• skd - ratio between particles in the suspended sediments andthe solution under steady state condition.

Another group of coefficients are the transfer rates which aredetermined by the characteristic time of the transfer,

• a12 - from the solution to the suspended sediments;• a13 - from the solution to the bottom;• a31 - from the bottom to the solution .

The setting of the parameters for the source points the of inflowcontamination is highly important for the process of the simulation.The source can be defined by the input from a user and one via thelateral boundaries, delivered, for example, by the runoff modelRETRACE. The values of the concentrations in the solute and inthe suspended sediments have to be determined for eachradionuclide in each source point. The sediment concentration hasto be specified in each source point and for all radionuclides. Whensources are defined by input it is necessary to set, additionally, thedischarge for this source. If a source contains several gridpoints itis necessary to set the complete discharge for all of them.

4.4 THREETOX

The THREETOX code was developed (Margvelashvili et al.1996-1999) to simulate 3-D hydrodynamics, suspended sedimenttransport and radionuclide dispersion in deep lakes and reservoirs,coastal areas and estuaries. The THREETOX code includes a set ofsubmodels: hydrodynamics, ice thermo-hydrodynamics, sedimenttransport and radionuclide transport.

Hydrodynamics submodel The hydrodynamics is simulated on thebase of three-dimensional, time-dependent, free surface, primitiveequation model The model equations are written in Cartesian co-ordinates. The prognostic variables of the hydrodynamics code arethe three components of the velocity fields, temperature, salinityand surface elevation. The water body is assumed hydrostatic andincompressible. The concept of eddy viscosity/diffusivity andPrandtl’s hypothesis with the variable turbulence length scale areused to define the turbulence stresses. At the free surface all fluxes(momentum, heat, etc.) are prescribed. At the bottom and at theland boundaries the conditions of no diffusive fluxes of anyproperty are used. .

Suspended sediment transport submodel. Suspended sedimenttransport is described by the advection- diffusion equations, takinginto account fall velocity of the sediment grains. The bottomboundary condition describes sediment resuspension or settlingdown in dependence on the ratio between equilibrium and actualnear bottom suspended sediment concentration.

RODOS(WG4)-TN(99)18

80

Radionuclide transport submodel. The equations of radionuclidestransport describe the radionuclides concentration in solute, in thesuspended sediments and in the bottom deposition. The exchangesbetween these variables are described as adsorption-desorption andsedimentation-resuspension processes. The boundary conditionsare no flux of the radionuclides concentration in solute, in thesuspended sediments through the water surface and its flux equal tothe difference of amount of eroded and deposited radionuclides atthe bottom boundary. The thickness of the upper layer of thecontaminated bottom deposition is governed by the equation of thebottom deformation

Sigma system of co-ordinates is used to avoid difficulties innumerical solution of problem for realistic bottom topography.Splitting of the barotropic and baroclinic modes are imposed in thecode. The governing equations together with the boundaryconditions are solved by finite difference techniques. Ahorizontally and vertically staggered mesh is used forcomputations. The model is running under UNIX on workstationHP-9000/735 and under WINDOWS 95/NT on PC.

4.5 Lake model LAKECO

4.5.1 Introduction

The box-type model LAKECO, developed at KEMA, Arnhem(Heling, 1992-1999) is used for predicting the behaviour ofradionuclides in lakes and reservoirs. It calculates the concentrationof the activity in the water column, in sediments and in the biotadynamically. It is divided into an abiotic part, describing thechange of the activity concentrations in the water/soil column bymeans of linear differential equations of the first order, and a bioticpart predicting the transfer throughout the aquatic food chain.

The processes which are taken into account are: particlescavenging/sedimentation, molecular diffusion, enhancedmigration of radionuclides in solution due to physical andbiological mixing processes, particle reworking - also by physicaland biological means - and the downward transfer of radionuclidesinside the sea bed as a result of sedimentation. To describe thebehaviour of radionuclides in sediments, both fractions of solvedand dissolved chemical phases are considered. A complex dynamicmodel, taking into account the position of the different species inthe food web, has been developed for predicting the transferthroughout the aquatic food chains. This dynamic uptake-model isbased upon studies on mercury in fish .

Sensitivity analysis showed that the distribution coefficient water -suspended matter, and the concentration factor water -phytoplankton are the most sensitive parameters. Less sensitive arethe reworking rate and the biological half-life of the aquaticorganisms. To improve the predictive power and the flexibility of

RODOS(WG4)-TN(99)18

81

LAKECO, new submodels for assessing these sensitive parameterswere implemented. As a result, the modified model LAKECO-Bhas more environmental parameters, like the potassiumconcentration in the lake water, as input, but less model specificparameters. Thus, LAKECO-B has become an aquatic modelwhich needs no fine-tuning as environmental input parameterscontrol the model.

The aim of the LAKECO-B release was to develop a tool that couldbe applied generally on a wide range of ecosystems, without theneed of experts to calibrate and adapt the model. A large number ofsubmodels, mostly physically based, some empirically based,improved the predictive power, and reduced the amount ofparameters to be supplied by the user significantly. The originalmodels on which LAKECO were based were lacking this flexibility,or were complex in such a way, that intensive site studies andanalysis were required to apply.

LAKECO-B has various degrees of application based on theinformation the user supplies. When e.g. data on the aquaticfoodweb are lacking, average and generic levels are supplied forbiological half lives. In the case lake temperature and mean bodyweight are known, a submodel supplies information on the expectedbiological half live of fish. These submodels are extensivelydescribed in the report of the validation study VAMP (IAEA, inpress).

New submodels in LAKECO-B are used to predict the followingparameters beforehand:

• concentration factor water phytoplankton,

• the distribution coefficient of radiocaesium on the basis ofpotassium and ammonium concentrations,

• the size of the sediment accumulation area based on the lakebathymetry,

• the biological half life of fish based on lake temperature andbody weight,

• the reworking rate, the transfer of radionuclides from thesediments to the lake, and

• the distribution coefficient in the sediment layers, when thecation concentration in the sediments is not known, and when thenuclide to be modelled is not caesium.

And the following processes were taken into account (optional):

• the leaching of fuel particles or insoluble particles, and

• the delay of the transfer of nuclides due to ice cover.

RODOS(WG4)-TN(99)18

82

The model is physically reasonable since most of the new processesof LAKECO-B are physically and not empirically based. Thetransfer to phytoplankton for instance is based on laboratory studieson uptake behaviour in plant cells in various conditions, and not onstatistical analysis of field measurements. LAKECO however is notdesigned for deep lakes and a more sophisticated submodel shouldbe introduced to cover this. It should be noted, that deep lake modelsare in most cases rather complex and detailed information on mixingperiods, temperature regimes over the years, and on verticalmigration or turbulent diffusion in the vertical direction of the watercolumn is required as input.

The aim of the LAKECO developers has been to form a lake modelas applicable as possible which can be easily coupled to othermodels or data. LAKECO was enhanced to be flexible and to beimplemented into the decision support system RODOS, andtherefore little attention was paid to an extension with a catchmentmodel. Simple equations were added, but they are absolutely notrequired when LAKECO is linked with other aquatic models. This istherefore not a selection criterion or an aspect in the furtherdiscussions.

4.5.2 Hydrological processes

It is of great importance to know the discharge from and to the lake.This value determines the lake or hydrological residence time. Thelake residence time in LAKECO-B is calculated in a generic way, bydividing the lake volume (V) by the mean discharge (Q). Wheninformation on the time dependent flow is available or river modelsprovide this figure, the time dependent resident residence time canbe calculated by the following equation T=Q(t)/V, where T is thehydrological residence time in days, V the lake volume, and Q(t) thedischarge rate in m3/day. The retention rate is calculated on the basisof this equation simply by the reciproke of the residence time (i.e.Lake Water Retention = 1/T(t)). This approach is rather straightforward, but is convenient enough when the discharge is known. Themodelling of the transfer of the secondary load from the catchmentto the lake is not present in the standard release of LAKECO-B. In aspecial release however, it was modelled and appeared not to be ofgreat importance for the prediction of the peak levels in fish. Thelevels in the water in the long term tend to be somewhatunderestimated when this submodel is not applied. This is alsodemonstrated in publications on the behaviour of radiocaesium inlakes in Cumbria (McDougall, 1991). In this optional submodel it isassumed that about one percent of the mobile nuclide inventory ofthe nuclides in a bog area, and 0.1 % of the nuclides from the dryarea is transferred to the lake each year. The amount of mobilenuclides decreasing by fixation is simply described by a default rate.

RODOS(WG4)-TN(99)18

83

4.5.2.1 Sedimentation processes

The LAKECO-B model is excelling in its description of thesediment-water interaction. A large number of processes ofimportance in the transfer are taken into account: scavenging, burial,porewater exchange, particle reworking, diffusion, and bioturbation.

These processes describe the transfer from and to the sediments inboth the dissolved and the particulate phase. Considering thedissolved phase might be of minor importance for radiocaesium -almost 99 % percent is adsorbed in the sediments - but it might be ofgreat importance for nuclides with a higher fraction in the dissolvedphase such as Tc-99 or I-129.

The sediment consists of three layers, an active layer, a passivelayer, and a deep layer which acts as a sink. The consideredinteraction processes between the dissolved phase and the lake waterare porewater exchange and diffusion, which also take place intoboth directions between the active and the passive layer. Burialtransports particles from the active sediment layer to the passivelayer, and particles are transferred by particle reworking from and tothe sediments. Note that there is one type of transport from thesecond, passive, sediment layer to the upper layer: diffusion. Theparticle reworking and porewater exchange are caused by physicaland biological effects, wind induced waves, and bioturbation. Thiscomplex sediment model is suitable for nuclides with differentadsorbing properties.

The most important parameter for radiocaesium is the lake water Kd.It is assessed by a submodel governed by the competitive cationspotassium and ammonium, and by the fraction of the FES, the socalled "frayed edge absorption sites", determining radiocaesiumadsorption (Comans et al, 1989). For the bottom sediments in theLAKECO model, there are two methods to calculate the sedimentKd. The sediment Kd can be estimated by the same submodel as forthe lake water Kd or can be based on a model considering twodifferent types of particles in the sediments, coarse sandy particleswith low adsorbing capacity, and fine nuclide carrier particles, whichare settled down from the lake water and with the lake Kd.

1. Both in the sediment and in the water column compartmentthe Kd is assessed by the Kd submodel governed by thepotassium and ammonium concentration.

2. In the water column the Kd is assessed; in the sediment, theoverall Kd is a result from the Kd of the deposited particlesand sandy particles with a lower Kd.

In case 1, the following equation is applied based on studies of theadsorption of radiocaesium on illite (Cremers et al; 1988; Comans &Hockley, 1992), and on personal communication with Comans(Comans, 1994) about default values for the parameters. Here, thespecific adsorption sites are taking into account by assessing the

RODOS(WG4)-TN(99)18

84

specific adsorption sites from a measurable parameter, the cationexchange capacity (CEC).

The following equation is derived on measurements of the Kd:

Where Kd is the distribution coefficient (m3 kg-1), CEC is the cationexchange capacity (meq g-1), FrFES is the fraction of the "frayed edgesites", MK the molarity of potassium ions (mM), and MNH4 themolarity of ammonium ions (mM).

If no information on the CEC is available, a default value of 0.1 meqg-1 was selected from a spectrum of CEC ranges of various sedimenttypes (De Preter, 1990). The potassium concentration in the lake ismostly known, the CEC is not always available. If not measured, theammonium concentration in the lake water is generally set to zerodue the oxic conditions of the active layer of the water column. Incase of stratification, a value of 0.4 mg/l is assumed for ammoniumin the lake water. For the sediments, a default value of 4 mg/l istaken. A standard fraction of 1.5 % of the CEC is defined as default(Comans, 1994). The above mentioned equation changes then into afunction where the Kd is inversely proportional to the potassiumconcentration.

In case 2, the same procedure with the similar generic ammoniumconcentration will be followed as in case 1 for assessing the lakewater Kd, but for the sediments the following method to calculate theKd value has been applied, derived under the assumption that the Kd

for sandy particles is one order of magnitude smaller than the Kd forsmall particles:

Kd sediment = Kd lake water (0.9 * α + 0.1),

where α is the fraction of small particles in the sediment layer,usually set at 0.1 (10%).

Due to these submodel(s) the user of the code has to provide thepotassium concentration as the only parameter. If this is notavailable, the trophic status can be an indication. High potassiumlevels often occur, where the pH is high, the hardness is high, andthe conductivity is high. In hardwater lakes with a high trophic statusas eutrophic lakes, the potassium levels are often above 3 - 4 mg/lcausing relatively low Kd values. Lower concentrations of potassiumcan be expected in oligotrophic lakes, with low pH (Håkanson &Jansson, 1988).

For other nuclides there are no special submodels available topredict the Kd. For the lake water Kd, generic literature values have

d FESK NH

K = Fr * CEC*1000

M +5 M 4

86

RODOS(WG4)-TN(99)18

85

to be applied, while for the sediment Kd subsequently the dilution bycoarse particles can be applied to calculate the Kd.

4.5.2.2 Remobilisation

The remobilisation of particulate and dissolved nuclides from thesediment layers depends on the bioturbation and physical effects ofwind induced waves. This effect is determined by the ratio betweenthe surface and the mean depth. Large shallow lakes are generallyresuspension lakes, while deep mountain lakes are sedimentaccumulators. In LAKECO the morphology influences theremobilisation of nuclides from the sediments to the extent windeffects and bioturbation disturb the sediment. This moderator iscalled the Dynamic Ratio (dimensionless), as proposed by Håkanson& Jansson (1983).

4.5.2.3 Fuel particles

One of the major characteristics of the Chernobyl accident is thedominating presence of fuel particles in the vicinity of the Chernobylreactor. This is highly associated with the reactor type and lessexpectable for other reactors in Europe. This special accident causesthat the dissolved fraction in the initial phase is relatively low, whilein a later stage the dissolved fraction increases due to leaching ofradionuclides from the fuel particles. Insoluble particles or fuelparticles, diminish both the bioavailability of caesium in the watercolumn, and reduce the retention time of radiocaesium in the lakewater. However, also on long distances from Chernobyl, theseparticles were a significant part of the fall out. For instance, forFinnish lakes a fraction of 50% of insoluble particles has beenassumed in model studies presented by Korhonen (Korhonen, 1990)to explain the levels of radiocaesium in the lake water and in thebiota. In the BIOMOVS II study (BIOMOVS, 1991) for the Swedishlake Hillesjön, a fraction of 75% was selected. One of the reasons inKorhonen's study to introduce this insoluble fraction, was thediscrepancy between measurements and predicted values. In thework of Salbu (Salbu, 1988), it was suggested, that in the Norwegianarea about 75% of the caesium deposited was bound to colloids orparticles in insoluble form. The phenomena of hot particles and theirbehaviour near the reactor site is described by several other authors(Al Rayyes et al, 1993; Tcherkezian 1994).

When LAKECO is applied on the - unique- Chernobyl type ofreactor accident, the problem of fuel particles is solved by means ofa simple fuel particle submodel. In order to simulate the leaching ofradiocaesium from fuel particles, a leaching rate of 10-2 per year isassumed. Again, the necessity is strongly dependent on the type ofreactor accident, and the distance between the source and the lake.However the presence of fuel particles should not be excludedbeforehand. So a special release of LAKECO can handle this fuelparticle problem.

RODOS(WG4)-TN(99)18

86

4.5.3 Biological uptake modelling

4.5.3.1 The foodweb model

LAKECO was originally developed to model the transfer ofradiocaesium in the aquatic foodchains. However, the description ofthe foodweb is based on the pharmokinetic equation, in which allprocesses are based on nuclide independent ecological andphysiological parameters. In LAKECO, this equation is adapted alsoto other nuclides (see below), or can be adapted to any toxic element(micropollutants such as heavy metals, and organic compounds suchas PCB's).

In ecological modelling often the pharmokinetical equation is used(see equation 87), while in most of the models in radioecologygeneric equations with generic rates from literature are applied.These rates often have no physical meaning, which limits theapplication range. In equation 87 elimination rate, and theextractability a and b are substance specific.

Md C

d t+ C

d M

d t= ( r + r ) * C * a + r * C * b - k M r e s p i r a t i o n g r o w t h f o o d u p t a k e ,w a t e r w a t e r e x c r e t i o n

(87)

Where the coefficients r are describing the uptake rates for growth,for respiration, and for water (passing via the gills) in kg d-1, and kthe elimination rate due to excretion at zero growth in d-1, and a andb are extraction coefficients from food and water, respectively. Afterrearranging equation 87, the following differential equation for the

description of the concentration C in an organism can be obtained:

where Kresp and Kgrowth are the food uptake rate for respiration (main-tenance) and growth, respectively in d-1, Kwater is the uptake ratedirect from lake water (via the gills) in l d-1, and a and b are thedimensionless extraction coefficients from food in the guts, and fromwater passing the gills, respectively.

The application of the above described equation in LAKECOimplies, that each organism is modelled on an individual basis andnot as simple compartment as it is common in radioecology. The useof different, when necessary standard, physiological parametervalues for the various groups of organisms - detritus feeders

organismresp growth food water water half life organism

dcdt

= a*( K + K )* C +b* K * C - Cλ (88)

RODOS(WG4)-TN(99)18

87

(benthos), zooplankton, phytoplankton, filterfeeders (molluscs),predator and prey fish, - allows to apply LAKECO under variousconditions (De Vries & Pieters, 1989; Jørgenson et al, 1991).

4.5.3.2 Parametrisation and submodels

The LAKECO foodweb model is very enhanced and complex, andfor the proper application foodweb information and nuclide specificparameters should be collected. In validation studies, radiologicaldata bases have been regarded as a unique chance to obtaininformation on the transfer of radiocaesium in aquatic foodchains. Areliable set of parameters is based on validation tests withradiocaesium measurements from various European lakes. On thebasis of these validation tests and of literature values, standardvalues for radiocaesium specific parameters such as extractioncoefficients were derived for radiocaesium. A set of standard physio-logical parameters for the different organisms was derived fromliterature and from data sets on growth curves of fish in variouslakes (Willemsen, 1977; De Vries & Pieters, 1989; Jørgenson et al,1991; Cazemier, 1986).

To make the application of LAKECO easier in different lakeecosystems, two submodels for the transfer from radiocaesium inlake water to phytoplankton, and a submodel to assess the biologicalhalf life in fish on the basis of the mean body weight and the lakewater temperature were added. For small fish types, the biologicalhalf life submodel differs from the submodel for large fish types inits parametrisation.

As the phytoplankton uptake is a very dominant parameter, at leastin the case of radiocaesium, two special submodels have beenimplemented in LAKECO to predict the uptake as a function of thepotassium concentration in the lake water. For concentrations below4 mg/l the Michaelis-Mente equation is applied, and above thisconcentration the Nernst equation. Both are process based equationsof which the parameters are determined in laboratory studies(Fernandez, personal com., 1994). For the uptake of radiostrontium,a submodel is present to calculate the effect of the lake waterhardness on the uptake in phytoplankton. The uptake is reducedsignificantly when the calcium concentration is high. Significantstrontium uptake in plankton can be expected in acid lakes such asthe Scandinavian forest lakes. The Concentration Factor forphytoplankton is an empirical linear power equation of the form CF= a * (Ca2+)-b, where b varies between 0.8 and 1.35.

Further, the differential equation for biouptake is principally meantto describe the behaviour of nuclides in the accumulation (target)tissue; each nuclide has its own preference organ or tissue foraccumulation. For calculating the dose effect of fish consumption forlarge fish, the nuclide concentration in the flesh is of importance,while for small fish types the total body concentration is ofimportance when consumed as a whole. Therefore, a procedure is

RODOS(WG4)-TN(99)18

88

introduced to modify the above mentioned equation for this targettissue effect.

The following aspects are considered in the calculation of theconcentration in fish:

1. Only the tissue where the radionuclide is accumulated istransferred from prey fish to predator fish, assuming zeroconcentration in the non-accumulating fish organs. This meansthat the concentration in the food of the predator fish is loweredby the weight fraction of the target tissue.

2. The above mentioned concentration in the food is applied tocalculate the concentration in the target tissue. The varioustissues have a nuclide independent biological half life. Theorgan type determines the half life of the nuclide in fish.

3. To calculate finally the total body concentration from theconcentration in the target tissue, the target tissue concentrationis multiplied with the weight fraction of the target tissue. Thefollowing equation is applied: C(total) = C(tissue, predicted) *weight fraction of target tissue.

4. When the concentration in fish flesh must be calculated, atarget tissue dependent modifier is applied, based onmeasurements reported in literature on the observed differencein nuclide concentration in flesh and target tissue of fish. Withthis modifier the nuclide concentration in the flesh is calculatedfrom the concentration in the target tissue.

This modification, not described here in detail, is improvingLAKECO-B significantly since the range of nuclides on whichcalculations can be performed is in fact limitless. This approach onlyrequires the knowledge which organ is the 'target' tissue of a specificnuclide.

Thus, the foodweb description is extremely generic. Any nuclide orany foodweb type can be modelled. In its standard release,LAKECO contains a simple foodweb: one toppredator (defined aspiscivorous fish), one type of prey fish, zooplankton and phyto-plankton. Depending on the foodweb composition in a particularlake, this chain can be modified for any given lake ecosystem. In thecase there is no specific food web information available the defaultfood chain is applied. In the standard case a predator fish isrepresenting fish like perch, pikeperch, and pike, and standard preyis representing small fish such as smelt, minnow, and roach, underthe assumption that prey fish consumes zooplankton.

The retention or biological half life is related to the mean weight ofthe fish and the lake temperature, based on literature (Reichle, 1970;Ugedal, 1992; IAEA, 1996). As in the VAMP model the uptakerates for prey and predator fish are not modified on lake temperatureor body weight, since the predictive power of the model will belowered when introducing this feature.

RODOS(WG4)-TN(99)18

89

There is no uptake to benthos assumed as this pathway seems to beof minor importance since radioceasium is hardly transferred fromparticles (Kolemainen, 1972) to benthos. In the LAKECO model.benthic uptake is associated with the consumption of phytoplanktonand zooplankton.

For organisms both the direct uptake of nuclides from water andfood is taken into account. The direct uptake from water might playa minor role, however, it plays a role in specific conditions, such asin the initial phase after the accident (Morgan, 1994; Hinton & Scott,1990). In LAKECO, the uptake rate directly from the water isorganism dependent and not nuclide dependent.

4.5.4 Modelling more nuclides

LAKECO is able to predict the behaviour of radionuclides in thelake water, the sediments, and in the biota for any nuclide. Althoughthe highest reliability can be expected for predicting theradiocaesium dispersion, other radionuclides can be modelled due tothe process based model description. At present, LAKECO as builtin the decision support system RODOS, is able to performpredictions for CS-137, Sr-90, I-131, Pu-239, Co-60, Ru-106, andH-3.

RODOS(WG4)-TN(99)18

90

5 Test and application of the hydrological chain

To prove the reliability of the various aquatic models, validationand intercomparison studies were performed for HDM models,among others, within the frame of the IAEA/CEC VAMP(Validation of Environmental Model Predictions) and theBIOMOVS II (Biological Model Validation Study phase II)programs, as well as within other special validation studies Themodels were tested also during their applications in Ukraine allperiod after the Chernobyl accident.. The knowledge gained hereinhas led to further model improvements (see e.g. the reports forseparate models.

Overview only of the specialised RODOS modelling studies ispresented in this chapter.

5.1.1 Implementation and validation studies for the RETRACE-RIVTOX chain

Most important is the test and validation of the whole modelchain. To this purpose RETRACE and RIVTOX were applied tothe catchment of the Ilya River, a tributary of the Uzh River,flowing into the Kiev Reservoir.

The Ilya river watershed is the first object for a validation of thewhole chain of the hydrological modelling starting from theprecipitation – the infiltration the surface runoff the sub-surfacerunoff - and finally the channel flow. This exercise will alsoinclude the toxicological part with the surface runoff and wash-offand the migration in the river net. The catchment of the Ilya River,which is the tributary to the Uzh River (flowing into the KievReservoir), is situated mainly in the 30-km Chernobyl zone (Figure20) and has a sizes of about 20 km in longitudinal direction and ofabout 15 km in the lateral direction. The data measured in 1988 bythe SPA Typhoon (Obninsk, Russia) and the UkrainianHydrometeorological Institute (Kiev, Ukraine) were used in thisvalidation study (Figure 21). The following set of the data is takeninto account:

• the map of soil contamination;

• the meteorological scenario (daily precipitation);

• the water discharge at the outlet;

• the concentration of soluble and sorbed forms of 90Sr and 137Cs atthe outlet;

• the contamination of bottom sediments.

RODOS(WG4)-TN(99)18

91

Figure 20: Ilya river basin

Figure 21: Meteorological and hydrological data for the Ilya river basin

The lateral inflow into the river net is simulated by the RETRACE(Figure 22) and was than used by RIVTOX to simulate thetransport in the river channels taking into account the interactionbetween radionuclides in the solution and on the suspendedsediments (Figure 23). The limited measured data are notcoincident with the exact moments of the short rainstorm floods atthe river. Therefore, the comparison of the measured and calculatedradionuclide concentrations should be done for averaged rather

RODOS(WG4)-TN(99)18

92

than for peak values. The uncertainties of the RIVTOX modellingwere evaluated using the Monte-Carlo techniques for water-sediment exchange parameter variations. The measured data arewithin 90% confidence intervals of simulated 137Cs concentrationon the sediments (Figure 24).

Figure 22: Measured (2) and simualated (1) hydrograph in outlet of Ilya river.

RODOS(WG4)-TN(99)18

93

Figure 23: Cs-137 in surface runoff; daily averaged concentration in runoff from the Ilya Rivercatchment (simulation by RETRACE)

Figure 24: RIVTOX Simulation of 137Cs concentration on suspended sediment at the outflow from theIlya River

RIVTOX was tested coupled with RETRACE to simulate theextremely high flood event took place in the Rhine River for aperiod of December 1993 - January 1994..

The main objective of the validation study was to compare themodel chain results with the daily averaged measured discharges infour outlets of the Rhine river. It should be mentioned thatelevation data for the Rhine watershed channel net (orographical)data used in validation have been obtained from the maps with thedifferent spatial resolution. This discrepancy in data resolutionresulted in problems with the definition of runoff directions based

RODOS(WG4)-TN(99)18

94

on relief. Therefore, due to input data resolution discrepancy ofsome misplacements of the lateral inflow has been inserted into thesimulation. Unfortunately, it is impossible now to estimate themagnitude of the errors dealt with input data problem.

Another problem concerned the input meteorological data.Precipitation data were provided by the German MeteorologicalService for about 70 meteorological stations but the air moisturedata was not available for this validation. To correct this absence ofdata it was supposed that for the whole period of the validationwhen the intensive rains took place, the air temperature was 5° Cand the relative air humidity was 90% which gives the air moisturedeficit 0.873 hPa. (Popov,1997).

Figure 25: Simulation results of the combined RIVTOX and RETRACE model for the flood event of theRiver Rhine in 1993. Comparison of predicted and measured discharge data for Andemach and Maxau.

RODOS(WG4)-TN(99)18

95

0

2000

4000

6000

8000

10000

12000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

Andernach meas.Kaub meas.

Mainz meas.

Maxau meas.

Andernach comp.Kaub comp.

Mainz comp.

Maxau comp.

Discharge (cub.m/sek)

Time (days)

Rhine River flood Dec. 1993

Figure 26: Comparison of the simulated by RIVTOX and measured discharges for 4 sites at the RiverRhine for December 1993 flood.

In Figure 25 and Figure 26, the simulation results are comparedwith the measurements for four crossections of the River Rhine.For two of them – upper site the Andemach and the lower one theMaxau. On figure 7 here are presented . the input precipitation dataand the result of the runoff simulation by RETRACE. The modelagreement with the measured data for this extreme flood situationwas reasonable. The Reasons for the disagreement are associatedwith the more diffusive character of the discharge hydrographsimulated by RIVTOX. More precisely, RIVTOX’s hydrographsdemonstrate less steepness of the fronts, and less magnitudes thanmeasured. This behaviour might be a result of the not enoughdetailed data about the river crossections, used during thesimulations.

5.1.2 RIVTOX and COASTOX implementation and testing in Slovakia

RIVTOX was implemented in collaboration with VUJE, Trnava,Slovakia to simulate the radionuclide transport in the river systemof the Dudvakh River- the Vakh River and the Bohunice NPP.

The waste water from the NPP “Bohunice” at JaskovskeBohunice, Slovakia is released through the technological 15 kmlong pipeline into the Vah River. Another pathway forradionuclides released from the NPPs during the accident (orregularly during switch off the technological pipeline) is the 5.2 kmlong Manivier canal with the concrete paved bed that transportswater from the NPP units cooling towers to the Dudvah River,that is right tributary of the Vah River. The last accidental releaseof 137Cs from the Unit A-1 occurred by this way in January 1989

RODOS(WG4)-TN(99)18

96

that highly contaminated the bottom sediments of the canal and ofthe Dudvah River.

The data collected in VUJE for this accident provides a uniquepossibility to test the model of the direct release of radionuclideinto the river system and its propagation in the river net from firsthours after the accident. The implementation of the RIVTOX forthis situation (Slavik et al., 1997) has demonstrated the needs touse two –step tradionuclide exchange kinetic submodels tosimulate radionuclide dynamics in the first post-accidental hours.

The detailed description of these results are presented in thepublication of Slavik et al., 1997 and RODOS WG4 report.

The Kralova Reservoir, Vakh River is the first reservoirdownstream Bohunice NPP that could be contaminated afteraccidental releases from the plant. The accidental release of 1989(Slavik et.al 1997) was used to validate the COASTOX model inclose cooperation with the Research Institute of Nuclear PowerPlants (VUJE), Trnava, Slovakia. The detailed description of thecase study is presented in the relevant RODOS WG4 report. Hereis presented only the brief overview of the main results of thisvalidation study.

The COASTOX was adopted for the Kralova Reservoir with the

following set of parameter values: Kds = 14 m3 /kg, a1,2 =30 day -1,

Kd = 2 m3 /kg, a1,3 =0.025 day -1, a3,1 =0.015, Z* =5 cm.

The model was coupled with the HDM-RODOS model RIVTOXthat provides the simulation of the radionuclide transport from theBohunice NPP to inflow crossection to the Kralova Reservoir(Slavek et al., 1999).

The simulation of 137

Cs dispersion in the Kralova Reservoirdemonstrates that the dominant process in contamination of thereservoir bottom isasettling of the contaminated sediments. Thesimulations of dispersion of June 1989 release reveal that the

highest concentration of 137Cs should be in the central part of thereservoir, in the place where the intensive sedimentationdownstream the steep bottom slope takes place (Fig.3). Suchpreliminary prediction that has been done in 1994 was confirmedlater by the field monitoring exercise that was carried out bycommon effort of the VUJE and Ukrainian HydrometeorologicalInstitute, Kiev, in 1995. During the monitoring exercises themaximum 137Cs concentrations in the reservoir - about 35-45Bq/kg in the top sediment layer and about 60 - 80 Bq/kg in thedeeper sediment layer were found in the same location of thecontaminated spot that has been predicted during thesimulation.(Fig.3), at the isoline 76 Bq/kg).

The HDM-COASTOX is implemented for the Kralova Reservoirand relevant data set of input information is presented with thissoftware (Fig.28).

RODOS(WG4)-TN(99)18

97

0 1000 2000 3000 4000 5000 6000 70000

1000

2000

3000

4000

Figure 27: Simulated Cs-137 concentration (Bq/kg) in upper bottom layer of Kralova Reservoir - 40days after the accidental release.

RODOS(WG4)-TN(99)18

98

Figure 28: Implementation of HDM COASTOX interface for Kralova Reservoir (Bathymetry)

RODOS(WG4)-TN(99)18

99

Figure 29: Implementation of HDM COASTOX interface for Kralova Reservoir (Bathymetry)

COASTOX was applied to describe the lake IJsselmeer which is apart of the Rhine River Basin. A release of radionuclide from aNuclear Power Plant located at the River Ijssel, the tributary of theRiver Rhine (q=100 m3/s, c=200 Bq/ m3 =const.) was assumed.The COASTOX was widely used to simulate radionuclide washingout from the Pripyat River floodplain at Chernobyl NPP and inseveral other case studies (Zheleznyak et al. 1993-1999).

5.1.3 Implementation and testing of 3-D model THREETOX

THREETOX, the three-dimensional finite DIFFERENCE elementmodel for radionuclide transport in inland waters and coastal areas,has been tested and validated against data for the dispersion ofradionuclides in the Bodensee (Lake Constance, Germany), in theDnieperBug Estuary (Dnieper River, Ukraine), and in the coolingponds of the NPPs of Zaporozhe and Chernobyl (Ukraine)[Margvelashvili et al.1997-1999, the specialised report of WG4).

The results revealed that the model is capable of simulatinghydrodynamics, sediment transport, and radionuclide behaviourwith a reasonable accuracy, considering the uncertainties in theinput parameters. The model is sufficient flexible, and can beimplemented to different water bodies. It can be used as a

RODOS(WG4)-TN(99)18

100

predictive tool for the assessment of radionuclide transport in lakes,reservoirs, and estuaries.. Some examples of the modelling resultsare presented on Figures.

--------

Figure 30:. Measured bottom contamination in Bodensee Lake (decay corrected to April 1986);

Figure 31: Simulated bottom contamination in Lake Bodensee Lake for March 1988.

RODOS(WG4)-TN(99)18

101

Figure 32: The 137Cs inventory in water (1), suspended sediments (2) and bottom (3) of the BodenseeLake simulated by THREETOX (two sets of the parameters) and compared with

measurements(Kaminsky at al.1997)

RODOS(WG4)-TN(99)18

102

b)

Figure . 33: Simulated bottom contamination of the Dnieper-Bug Estuary and the Black Sea (Bq kg-1)in April 1988: (a) 137Cs (b) 90Sr.

RODOS(WG4)-TN(99)18

103

b)

Figure 34: Computed vs. measured distribution of dissolved 90Sr in the surface layer of Dnieper-BugEstuary in March 1988.

Circles are data of Katrich, , filled circle – data of Policarpov(a)Sensitivity to Kd. Curve 1: Kdb = 0; Curve 2: Kdb = 3.0 m3/kg; Curve3: Kdb = 5.0 m3/kg; (b) Sensitivity to the 90Sr concentration in theDnieper mouth Cm. Curve 1: Cm = 1.25C0; Curve 2: Cm = C0; Curve3: Cm = 0.75 C0, where C0 is the measured concentration ;

RODOS(WG4)-TN(99)18

104

Figure 35: Simulated surface velocity in the Chernobyl Cooling Pond in 18.07.1983

Figure 36: Simulated and measured surface temperature in the Chernobyl Cooling Pond in 18.07.1983

RODOS(WG4)-TN(99)18

105

120 150 180 210 240 270 300 330 360

DAY

0.00E+0

4.00E+10

8.00E+10

1.20E+11

1.60E+11

2.00E+11

kBq

Figure 37: Simulated and measured dynamics of the 137�s content of the Chernobyl Cooling Pond.Solid line: Kd = 3 m3/kg, dashed line is Kd=15 m3/�g.

5.1.4 LAKECO testing

LAKECO was tested and validated within various internationalworking groups. Within the IAEA/CEC VAMP-project the lakemodel was successfully applied to a wide range of lake ecosystemsin Europe, different in terms of trophic status, climatology,deposition of radionuclides, and morphology. LAKECOparticipated in a blind test within BIOMOVS II, where a CoolingPond Scenario was outlined. As tuning of the model wasimpossible, this study could be considered as a quality test. Itshowed that the original LAKECO model, with a relatively greatnumber of parameters, most of them assessed on the basis of expertjudgement, was not able to predict the concentration in the aquaticsystem with the required accuracy. The enhanced modelLAKECO-B showed better results, which proved the increase ofpredictive power after the implementation of the new submodels.

RODOS(WG4)-TN(99)18

106

Figure 38: LAKECO results for the BIOMOVS-II Chernobyl NPP Cooling Pond scenario

The Figure above. shows in the left part the concentration inwater, averaged over the entire cooling pond (Bq/l), and presents inthe right part the activity in predatory fish (Bq/kg wet weight) forboth model variants. Furthermore a fuel leaching submodel wasadded to the code to govern the fact, that in the vicinity of a reactora high fraction of undissolvable particles can be expected.

5.1.5 Customisation on mountainous areas.

Demokritos, Greece, developed the DELTA/HYDRO model aimedto be a physically based distributed model, describing most of thehydrological processes taking place in natural watersheds inmountainous areas. This model is in the development phase, andwill be applied to evaluate the transfer of nuclides in mountainousareas in the case radionuclide contamination in these areas is to beexpected a contamination source to the river catchment.

The model incorporates the physical characteristics of thewatershed through a subdivision of the area of interest intotriangular areal unit elements, created by the DELTA/GAIA model,on the basis of digital elevation maps. All significant hydrologicalparameters such as ground slope, hydraulic conductivity, roughnesscoefficient, initial soil moisture content etc, are assumed to beuniform within each triangular ground surface element but theymay vary from one surface element to another.

The model automatically computes the geometrical characteristicsof the topography under treatment, whereas the hydrologicalparameters are set by the user as single values in each delimitedhomogeneous area of the watershed.

RODOS(WG4)-TN(99)18

107

The primary accomplishment of DELTA/HYDRO lies in itsaccurate description of the overland flow trajectories. This keyfeature of the model has been extensively reported by Catsaros(Catsaros et al, 1997). They include the automatic determination ofoverland flow trajectories towards the deepest slope direction,ending at the domain outer boundaries, local minima of altitude orfeeding channels.

Furthermore, the simulated network of channels is automaticallyredistributed, to create independent river systems. The criterioncharacterising an independent river system is an ending pointcommon to all its individual channel flows. Each river system isthen formed by one main river having numerous tributaries and ineach tributary junction, the river network is formed in such a waythat a given river gains water from at most one tributary. Thenumbering of the various tributaries follows the logic of gravity,from upstream to the downstream of the principal river of thesystem. Each river of the system is formed by a succession ofreaches; each reach is gaining water from its upstream reach and bya succession of runoff overland flow cascades contributing to thelateral inflow.

The various physical processes are modelled with efficient methodsable to handle the complexity of the physical phenomena; moreprecisely: The overland flow routing is performed using the well-known kinematic approximation where the flux and the velocityare functions of the flow depth. During rainfall episodes, theponding time is computed for each ground surface element;ponding may occur in different surfaces during different time steps,leading to a variable runoff source area which is time- andlocation-dependent. The various modules of the DELTA/HYDROmodel are currently under testing.

5.1.6 Testing of the models for the special applicatiosns

For modelling subsurface contamination stand- alone versionSUSTOX code for UNIX environment has been developed (Kivva,1998). 1-D (vertical), 2-D (vertical-longitudinal), and 3-D transientmodels of moisture movement through unsaturated-saturatedporous media and pollutant transport in soil and groundwater. Thedescription of the contaminated subsurface environment formulatedin these models is founded on governing equations for conservationof water mass and species mass. Liquid transport through soiloccurs in response to pressure gradients and gravitational bodyforces followed Darcy's flow equations. Species transport throughthe subsurface environment occurs by diffusion, dispersion,advection and radioactive decay. Adsorption or exchange reactionsbetween the solute and the soil matrix are considered asinstantaneous, and are described by a linear equilibrium isotherm.Successful tests are performed on modelling by means of SUSTOXthe downward transport of Sr-90 under the shelter of the Chernobyl

RODOS(WG4)-TN(99)18

108

Powerplant. In Figure 6 an example of this prediction is shown(Kivva, S., 1997).

1E-5 1E-4 1E-3 1E-2 0.1 1 1E+11E+21E+3 1E+41E+5 1E+61E+7

Aqueous activity (Bq/l) of Sr-90

0

2

4

6

8

10

12

14

16

18

Dep

th (

m)

Figure 39. Example of a prediction of the downward transfer of Sr-90 under the Chernobyl shelter.Comparison of predicted and measured activity-depth profiles of 90Sr in the aqueous phase in 1995.Profiles were obtained for two sources in the shelter (—–) case 1 and (- - -) case 2. ∆∆ and ΟΟ denote

mean values of radionuclide activity detected in two different well depths.

For certain areas, the classical dispersion and convection modelsunderestimate the transport time due to the assumption ofhomogeneous. The literature study performed on this remarkableeffect (Karasev, 1988; Freeze, 1993), showed that particular inclayey soil types, in areas with shallow groundwater (lower than2.5 m depth), were biological macropores are present, and wherethe rainfall intensity is sufficient to saturate the soil, this rapidtransfer of radionuclides throughout these channels can occur. Astudy on this effect on chemicals indicated that this quick transferis only of importance in the first period after the deposition. Duethese specific conditions, the model VADZONE will be applied inthe hydrological module of RODOS only in the first phase.

To develop and test this model, Typhoon collected relevant data forthe contamination of ground water in a selected territory (data onmeteorological, hydrological, pedological, geological conditions,contamination data for both catchments of the rivers Iput andRhine). Subsequent the model VADZONE will be developed andtested on the collected data.

The concept of fast filtration model based on the concept of soilmoisture in the vadose zone is implemented in the VADZONEprogram. The model relies on numerical solution of the one-dimensional Richards equation. The processes of filtration andevapotranspiration are taken into account. To acceleratecalculations in the vadose zone (near surface in case of strongrainfall and near groundwater) a version of the model has beendeveloped using the Green-Ampte method. In case of strongrainfall, along with soil moisture, the part of precipitation whichcan not be filtered by soil is also calculated. This part can betransported by macropores to groundwater at rather highconductivity of macropores and high soil moisture in the vadose

RODOS(WG4)-TN(99)18

109

zone. The conductivity of macropore is calculated from theirconcentration and size using empirical relations from (Smettem,1985). The part of precipitation which is not absorbed by soilmatrix and is not transported by macropores is the supply for thesurface runoff. Therefore, VADZONE can be used to refine thehydrological models included in RODOS.

The input parameters of the VADZONE model are texture,porosity and saturated hydraulic conductivity of soil, and leaf areaindex to calculate transpiration. The used meteo-parameters are 6-hour data on temperature and air humidity near surface and amountof rainfall. So far, rain duration is specified arbitrarily, but infuture; a weather generator is planned to be used for this purpose.

Calculations of soil moisture in the vadose zone using the archiveof meteorological data permit the reconstructing a moisture profile,given information about radionuclide deposition, without anyadditional measurements and, hence, make a fast conclusion abouta possibility of fast radionuclide runoff to groundwater. If theconditions providing for the macropore flux are met, according tofield data, several percent of the sorbed radionuclides can get intothe groundwater during the first 2 weeks after a deposition ofradionuclides. In the subsequent period, the radionuclidesconcentration in macropore flow will decrease and can beestimated by standard methods used in the runoff models of thehydro-chain as RETRACE- 1 and -2.

Important issue is the validation of this complex river model and ofthe selection tools and its criteria. The validation of the reliabilityof the description of mass transfer processes in near bottom area oftransport flow by means of RIVMORPH model is executed usingthe laboratory data on dynamics of local changes bottom relief andcontamination data of Iput river. For the selection toolMORPHOLOGY the dominant river morphology characteristicsare identified. Description of the RIVMORPH model are publishedearlier (Andrijevski et , 1997)

RODOS(WG4)-TN(99)18

110

ConclusionsThe comprehensive set of the models of the hydrological

radionuclide dispersion of the different scale of the resolution havebeen improved and tested within the RODOS project. The softwareenvironment of the Hydrological Dispersion Module of RODOShas been developed. HDM is integrated in the Automatic Modewith ADM and FDMA. The further improvement of the HDMsoftware should be provided in parallel with the RODOSimplementation

RODOS(WG4)-TN(99)18

111

REFERENCES-WG4 REPORTSNumber Title Author Gen.CD Techn.CDWG4-TN(97)03 RIVMORPH Model Andrijievski et al. +WG4-TN(98)10 Extension of the existing hydrological model chain Andrijievski et al. +WG4-TN(99)13 Description of lakes and their catchments selected for model

development and validationSaxen et al. +

WG4-TN(99)10 User Guide for VADZONE Baranov et al. +WG4-TN(99)5 Description of VADZONE model Baranov et al. +WG4-TN(99)01 Radiological consequence model for regional lake environments

(REGLAKE)Suolanen +

WG4-TN(99)03 REGLAKE User Manual Rossi +WG4-TN(99)02 Validation of REGLAKE model Suolanen +WG4-TN(97)05 RIVTOX - one dimensional model for the simulation of the transport

of radionuclides in a network of river channelsM. Zheleznyak,G.Dontchits, N.DzjubaV.Giginyak, G.Lyashenko, A. Marinets,P. Tkalich

+

WG4-TN(97)07 COASTOX - two-dimensional model describing the lateral-longitudinal distribution of radionuclides in water bodies

M. Zheleznyak, T.Shepeleva, I. Mezhueva

+

WG4-RP(96)04 THREETOX-Computer Code to simulate three dimensionaldispersion of radionuclides in stratified water bodies

Marvelashvili, V.,Maderich, V.,Zheleznyak, M

+

WG4-TN(97)02 User Interface of the Hydrological Dispersion Module of RODOS Ya. Sorokin,G. Donchits, A. Popov,N. Slyakhtun, K.Kolomichuk, O.Levchuk, D. Gofman,M. Zheleznyak

+

WG4-TN(99)09 LATOX – Langrafian multilayered model to simulate radionuclidetransport in the deep stratified water bodies

V Maderich +

Please givenumberWG4-TN(99)14

Radionuclide concentrations in the water and top layer of bottomsediments of Bodensee: Hydrodynamical modelling based on theTHREETOX and LATOX codes

V Maderich, NMargvelashvili, MZheleznyak

+

RODOS(WG4)-TN(99)18

112

WG4-TN(99)6 SUSTOX – code to predict the vertical and vertical-longitudinal liquidand radionuclides movement at saturated-unsaturated porous media1997 (revised 1999)

S.Kivva +

WG4-TN(99)07 GROWTOX - A Numerical Simulator for Shallow Groundwater Flowand Species Transport in the Subsurface1998 (revised 1999)

S.Kivva +

WG5-TN(98)02 RIVTOX-River Transport Model: Analyses of Uncertainty ofModelling and Data Assimilation RODOS

M. Zheleznyak, V.Giginyak, T. Shepelva,G. Donchits, O.Levchuk

+

WG4-TN(99)15Simulation of the radionuclide transport in the Chernobyl CoolingPond on the basis of the THREETOX code

N.Margvelashvili,V.Maderich,S.Yuschenko,M.Zheleznyak

+

WG4-TN(99)16 Documentation of the RODOS External Program RETRACE toSimulate Radionuclide Wash-Off from Watersheds

A. Popov +

WG4)-TN(99)11

DELTA / HYDRO: A distributed runoff and channel routing code forwatersheds of complex topography. Code description and User’smanual.

Catsaros, N., Mita, C.,Varvayanni, M.

+

WG4-TN(99)17 LAKECO-B: model for radionuclide transfer in lakes and biota R. Heling +

WG4-TN(99)18 Overview of the HDM –Hydrological Dispersion Module of RODOS R.Heling at al. +

WG4)TN(99)05 Customisation of RODOS RIVTOX and COASTOX hydrologicalmodels to Slovak river reservoir net conditions

Slavik et al. +

WG4-TN(99)19 HDM User Guide Ya. Sorokin,G. Donchits, A. Popov

+

RODOS(WG4)-TN(99)18

113

GENERAL REFERENCES

Ackers P., White R. Sediment transport: new approach and analyses. J.Hydr.Div.ASCE, v99, No.11, 2041-2060 (1973).

Ahuja, L.R. 1986. "Characterization and Modelling of Chemical Transfer toRunoff". Advances in Soil Science , 4:149-188.

Ali M. H. M. Beaumont, L. M. C. Dutton, B. J. Handy, M. Hosty, A.F Parsons,S.P. Nielsen, Yu. Sivintsev, V. Lystsov, E.I. Yefimov, T. Sazukina, M.Zheleznyak, V. Maderich, N. Margvelashvili (1997). Evolution of theradiological situation around the nuclear reactors with spent fuel which havebeen scuttled in the Kara Sea, Final Report of CEC Study contract B-6340/95/000879 /MAR/C3, NNC Limited, UK, 1997

Al Rayyes, A.H., Ronneau, C., Stone, W.E.E., Genet, M.J., Ladrière, Cara, J.(1993) Radiocaesium in Hot Particles; Solubility vs Chemical Speciation. J.Envirnom. Radioactivity 21 pp 143-151

Ambrose R.B., Wool T.M., Connolly J.P., Schanz R.W. WASP4, aHydrodynamic and Water Quality Model - Model Theory, User Manual andProgrammer’s Guide. EPA/600/3-87/039, U.S. Environmental ProtectionAgency, Environmental Research Laboratory, Athens, Georgia. 1988. - 663p.

Andrijevskij, A., A.Loukashevich, A. Mikhalevich, A. Trifonov. RIVMORPHmodel. Radiation Protection Dosimetry. Vol. 73, Nos 1-4, pp 159 -172(1997).

ANONYMOUS, Methodology for evaluating the radiological consequences ofradioactive effluents released in normal operations, National RadiologicalProtection Board, Chilton, United Kingdom (1994).

ANONYMOUS, Guidelines for calculating derived release limits for radioactivematerial in airborne and liquid effluents for normal operation of nuclearfacilities, CAN/CSA-N288.1-M87, Canadian Standards Association Ed.,Toronto, Ontario, Canada, 69p (1987).

Ariathurai R., Krone R. B. (1976) Finite element model for cohesive sedimenttransport. J. Hydraul. Div. ASCE, 104, HY2, 323-328.

Batrakov G.F., Eremeev V.N., Chudinovskikh T.V., Zemlyanoy A.D.Radioactivity of the Black Sea. Ecosi-Hydrophysics, Sevastopol, 1994, 213pp., (in Russian).

Beck M.B., Water Quality Management: A Review of the Development andApplication of Mathematical Models. Lectures Notes inEngineering,IIASA,11(1985)108.

Benes P., Cernik M., Slavik, O., Modelling of Migration of 137Cs AccidentallyReleased into a Small River. J. Environ. Radioactivity 22, 279-293 (1994).

Benes P., Cernik, M., Model Calculations and Experimental Analysis ofTransport of Radiocesium in the System Wastewater Channel - Dudvah (inCzech Republic). Report of the Faculty of Nuclear Sciences and PhysicalEngineering, Czech Technical University, Prague 1990.

Benes P., Picat P., Cernik M., Quinalt J.M. Kinetics of radionuclide interactionwith suspended solids in modeling the migration of radionuclides in river.Parameters for two-step kinetics. J. Radioanalitical and Nuclear Chemistry,(1992)Vol. 159, N2, 175-186

Berkovski V., Voitsekhovitch O., Nasvit O, Zheleznyak M., Sansone U.Exposures from aquatic pathways. The radiological consequences ofChernobyl accident. Proceedings of the first international conference.Minsk, Belarus 18 - 22 March 1996. Editors A.Karaoglou, G.Desmet,

RODOS(WG4)-TN(99)18

114

G.N.Kelly and H.G.Menzel, European Commission. Luxembourg,1996, p.p.283-294.

Bicknell, B.R., J.C.Imhoff, J.L.Kittle Jr., A.S.Donigian, Jr. and R.C.Joahanson.1993. Hydrological Simulator Program - Fortran. User's Manual for Release10. U.S. EPA Environmental Research Laboratory, EPA/600/R-93/174,Athens, GA. 660 p.

Bijker E.W, Some considerations about scales for coastal models with movablebed, Delft Hydr. Lab., Publ. No 50, 1968.

Bijker E.W. Littoral drift as function of waves and currents. 11th CoastalEngineering Conference, London, 1968, p. 34-48.

Biomovs (1991) Dynamics within lake ecosystems. Technical report 12, scenarioA5.

BIOMOVS II. "Wash-Off of 90Sr and 137Cs from Two Experimental PlotsEstablished in the Vicinity of the Chernobyl Reactor", Description ofScenario W (Version 1.02), October 1993.

BIOMOVS-II, Technical Report N 1, Guidance for Uncertainty Analyses, July,1993, Publ. BIOMOVS II Steering Committee, Swedish RadiationProtection Institute,1993

Biomovs II (1996) Technical Report II No. 10. Assessment of the Consequences ofthe Radioactive Contamination of Aquatic Media and Biota.

Blumberg A.F. Numerical Model of Estuarine Circulation. (1977) J. of theHydraul. Div., V. 103, N HY3, p. 295-311.

Blumberg A.F., and L.H. Kantha, Open boundary condition for circulationmodels. J. Hydraul. Eng., 111, 1985, p.237-255.

Blumberg, A.F. and Mellor, G.L., (1987) A description of a three-dimensionalcoastal ocean circulation model, Three-Dimensional Coastal Ocean Models,N. Heaps (ed), Am. Geoph. Union, 208p.

Booth R.S, A system analysis model for calculating radionuclide transportbetween receiving water and bottom sediments, Oak Ridge National Lab.,ORNL-TM-4751, 1975, 37p.

Borzilov V.A., Konoplev A.V., Experimental investigation of radionuclideswashing out, falled out on earth after accident on Chernobyl NPP,Meteorologia and Gidrologia, 11(1988)(In Russian).

Borzilov, V.A., Sedunov, Yu.S., Novittsky, M.A., et al., Forecasting ofsecondary radioactive contamination of the rivers in 30-th kilometers zoneof the Chernobyl NPP, Meteorologia i Gidrologia, 2, 5-13 (1989) (InRussian).

Bulgakov A.A., Konoplev A.V., Popov V.E. 1992. "Prognosis of Sr-90 and Cs-137 behaviour in soil-water system after Chernobyl accident", In:Ecological and geophysical aspects of nuclear accidents (in Russian),Moscow, Hydrometeorological Publishing House, p.21-42

Burkov A., Gerasimenko A., Jobson H., Novitsky M., Voszhennikov O.,Zheleznyak M. Methods of calculating and forecasdting pollutant transportin water bodies. - Hydrological aspects of accidental pollution of waterbodies. Ch.6, Operational Hydrological Report No.37, WMO -No 754,Geneva, Switzerland, pp.65-92., 1992.

Burns L.A., Cline D.M. Exposure analysis modeling system - reference manualfor EXAMS II. EPA/600/3-85/038, U.S. Environmental Protection Agency,Environmental Research Laboratory, Athens, Georgia., 1985. - 402 p.

RODOS(WG4)-TN(99)18

115

Callendar E., Robbins J. Transport and acumulation of radionuclides and stableelements in a Missouri River Reservoir. - Water Resources Research, v. ,No. 1992

Carlsson, S. 1978. "A model for the Movement and Loss of 137Cs in a SmallWatershed", Health Physics, 34:33-37

Cazemier, W.G. (1986). Description of the population of pikeperch, bream, roach,and smelt in IJsselmeer. (In Dutch). RIVO report (Research Institute forFishery).

Catsaros, N., C. Mita, P. Deligiannis, M. Varvayanni, J.C. Statharas, J.G.Bartzis, Accurate Determination of Overland Flow Trajectories inSimulated Watersheds of Complex Topography, Radiation ProtectionDosimetry, Vol. 73, Nos 1-4, (1997) pp. 163-166.

Chang H.H. Fluvial processes in river engineering. - New York: Wilcy, 1988. -105 p.

Chapman B.M. Numerical simulation of the transport and speciation ofnonconservative chemical reactions in rivers. //Water Resources Research,Vol. 18, No.1, 1982, p. 155-167.

Chen, Y.H. Development of a quasi-nonequilibrium reservoir sedimentationmodel: REDSED. //In: Twelve Selected Computer Stream SedimentationModels Developed in the United States, edited by S-S. Fan, Federal EnergyRegulatory Commition, Washington, D.C., 1988, p. 491-510.

CHR/KHR (1978), “Das Rheingebiet, Hydrologische Monographie / Lebassin duRhin, Monographie hydrologique”, Staatsuitgeverij Den Haag, ISBN 90-12-775-0.

Codell R.B., Key K.T., Whelan G. Collection of mathematical models forradionuclide dispersion in surface water and ground water. //NUREG -0868, 1982. - 271 p.

Colon R., McMahon G.F. BRASS model: application to savannah river systemreserviors. J. Water Resour. Plann. Manage., 1987, vol. 113, no. 2, p. 177-190.

Comans, R.H.J., Haller, M., Van der Weijden, C.H., (1989) Reversibility ofcaesium interaction with clay minerals, suspended matter, and sediments ofDutch watercourses. Department of Geochemistry, Institute of Earth Sciences,University of Utrecht. (In Dutch)

Comans R.N.J, Haller M., DePreter P. Sorption of Cecium on iIlite;nonequilibrium behaviour and reversibility, Geochim.Cosmochim.Acta, 55,433-440 (1991)

Comans R.N.J. Sorption of cadmium and cesium at mineral/water interfaces.Ph.D. thesis, Rijksuniversiteit Utrecht. (1990 )

Comans, R.N.J., Hockley, D.E. (1992). Kinetics of caesium sorption on illite.Geochem. Cosmochim. Acta. 56. 1157-64.

Comans. (1994). Personal Communications.

Coppe, P., Estimated models of impact used by Electricité de France within theframework of the french and european regulations, Radioprotection, Specialissue, Proc. of the joint seminary from September 15th to 18th 1992,Fribourg, Switzerland, 185-189 (1993).

Coughtrey, P. and Thorne, M. 1983. "Radionuclide Distribution and Transport inTerrestrial Aquatic Ecosistems. A Critical Review Of Data", Vol.1. A.A.Balkema, Rotterdam

Cremers, A., Elsen, A., de Prater, P.M., Maes, A. (1988). Quantitative analysis ofradioceasium in soils. Nature, 335, 247-9.

RODOS(WG4)-TN(99)18

116

Cunge J.A., Holly F.M., Verwey A., Practical Aspects of Computational RiverHydraulics, Pitman Publ., London, 250p., 1986.

Demchenko R., Zheleznyak M., Koziy L. Modelling of Sedimentation andRadionuclides Deposition in a Bottom Trap. A. Peters et al.( eds.),Computational Methods. in: Water Resources X, vol. 2, Kluwer AcademicPublishers, Dordrecht, The Netherlands, 1994, pp. 1341-1348.

Demchenko R.I., Zheleznyak M.J, Numerical modelling of suspended sedimentsvertical distribution above uneven bottom In: System Analysis and Methodsof Mathematical Modelling in Ecology, V.Glushkov Institute of CyberneticsPubl., Kiev, 1990 ,66-72. (in Russian)

Deutsches Gewässerkundliches Jahrbuch des Rheingebiets, Teil 1, 2, 3. 1989.

De Vries D.J., De Vries M.B., (1988). Modelling the fate of HCB and PCB153 inthe lakes Ketelmeer and IJsselmeer. Report T250 Delft Hydraulics.

De Vries, M.B., Pieters, H., (1989) Accumulation of heavy metals in organisms.Bioaccumulation of mercury in pikeperch. Data analysis on IJsselmeer,Ketelmeer, and Markermeer. Delft Hydraulics. Report T 250

De Vries, D.J., Kroot, M.P. (1989) Modelling the behaviour and fate of heavymetals in aquatic systems with IMPAQT. Process descriptions and applicationto Ketelmeer and IJsselmeer. (In Dutch). Delft Hydraulics, report numberT0250.

Di Toro D. M. and Connolly J.P. Mathematical models for water quality inLarge Lakes. Part 2: Lakes Erie. U.S. Environmental Protection Agency,Duluth, Minnesota. EPA-600/3-3-80-065 (1980).

Di Toro D. M. and Matystik W. F. Jr. Mathematical models for water quality inLarge Lakes. Part 1: Lakes Huron and Siginaw Bay model development,verification and simulations. U.S. Environmental Protection Agency,Duluth, Minnesota. EPA-600/3-3-80-056 (1980).

Donigian A.S., Jr., J.C.Imhoff, B.R.Bicknell, J.L.Kittle. 1982. Guide to theApplication of the Hydrological Simulator Program - FORTRAN (HSPF)Contract No. 68-01-6207, US Environmental Protection Agency, Athens,GA.

Donigian, A.S.,Jr., B.R.Bicknell and J.C.Imhoff. 1995. Hydrological SimulationProgram - FORTRAN (HSPF). In: Computer Models of WatershedsHydrology. V.P.Singh, ed. Water Resource Publications, Highlands Ranch,Colorado. p.395-442

Dynamics of ocean. Ed. by Doronin Yu., L.: Hydrometeoizdat, 1980, 304 p. (inRussian)

Ehrhardt J., Shershakov V, Zheleznyak M., Mikhalevich A., RODOS: decisionsupport system for off-site emergency management in Europe. Theradiological consequences of Chernobyl accident. Proceedings of the firstinternational conference. Minsk, Belarus 18 - 22 March 1996. EditorsA.Karaoglou, G.Desmet, G.N.Kelly and H.G.Menzel. EuropeanCommission. Luxembourg, 1996, p. 1087-1096, EUR16544EN.

Ehrhardt, J. The RODOS system: decision support for off-site emergencymanagement in Europe. -Radiation Protection Dosimetry, 1997, v.73, No.1-4, pp.35-40

Elder J.W, 1958, The dispersion of marked fluid in turbulent shear flow,Cavendish laboratory, University of Cambridge, Fluid mechanics 5

Engelund F., Fredsoe J., A sediment transport model for straight alluvialchannels. -Nordic Hydrology, 7, (1976), pp.293-306

Eraslan A.H., Akin E.J., Barton J.M., Bledsoe J.L., Cross K.E., Diament H.,Fields D.E., Fisher S.K., Harris J.L., Hetrick D.M., Holdeman J.T., Kim

RODOS(WG4)-TN(99)18

117

K.K., Lietzke M.H., Park J.E., Pattersom M.R., Sharp R.D., Thomas B.Development of a unified transport approach for the assessment of power-plant impact. //ORNL/NUREG/TM-89, Oak Ridge National Laboratory,Oak Ridge, Tennessee, 1977. - 409 p.

Eraslan A.H., Lin W.L., Sharp R.D. FLOWER: a computer code for simulationthree-dimentional flow, temperature and salinity conditions in rivers,estuaries and ocean. NUREG/CR-3172, U.S. Nuclear RegulatoryCommision, Washington, D.C., 1983. - 231 p.

Felmy A.R., Brown S.M., Onishi Y., Argo R.S., Yabusaki S.B. MEXAMS - themetals exposure analysis modeling system. Prepared for the U.S.Environmental Protection Agency by Battelle, Pacific NorthwestLaboratories, Richland, Washington, 1983. - 295 p.

Fields D.E. CHNSED: simulation of sediment and trace contaminant transportwith sedimant/contaminant interaction. //ORNL/NSF/EATC-19, Oak RidgeNational Laboratory, Oak Ridge, Tennessee, 1976. - 170 p.

Fields D.E. HOTSET: a one dimentional, tidal-transient, discrete element modelfor simulating hydrodynamic conditions and absorbed and dissilvedradioisotope concentration in controlled rivers and estuaries. //ORNL/CSD-16, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 1977. - 227 p.

Fischer H.B, 1973, Longitudinal dispersion and turbulent mixing in open-channel flow, annual review fluid mechanics, University of California

Fletcher C.A.J.,1988, Computation Techniques for Fluid Dynamics:Fundamental and General Techniques, Springer-Verlag, Berlin-Heidelberg-London. Ch.1,2

Fread D.L. Flow routing. Handbook of hydrology /D.R. Maidment (ed.),McGraw-Hill, 1992, p. 10.1-10.36.

Fread D.L. The NWS DAMBRK model: theoretical background / userdocumentation. HRL-256, Hydrologica Research Laboratory, NationalWeather Service, Silver Spring, Md., 1988. - 189p.

Fread D.L., Lewis J.M. FLDWAV: a generalized flood routing model. Proc.National Conference on Hydraulic Engineering, ASCE, Colorado Springs,Colo., 1988. p. 688-673.

Freeze R.A. Integrated surface-groundwater transport of radionuclides and itsimpact on the site of nuclear power systems. UNESCO, IHP 4, Paris, SC-93/WS.51, 106-121, 1993.

Giginyak V., Shepeleva T., Zheleznyak M. 1998. Modelling of nearshoretransport of radionuclides and sediments under joint action of waves andcurrents. - Extended Synopses of International Symposium on MarinePollution, 5-9 October, Monaco, p.690-691.

Giginyak V., Shepeleva T., Zheleznyak M. 1998. Modelling of nearshoretransport of radionuclides and sediments under joint action of waves andcurrents. Extended Synopses of International Symposium on MarinePollution, 5-9 October, Monaco, p.690-691

Gofman D., Lyashenko G., Marinets A., Mezhueva I., Shepeleva T., Tkalich P.,Zheleznyak M. Implementation of the Aqatic Radionuclide TransportModels RIVTOX and COASTOX into the RODOS System. //Theradiological consequences of Chernobyl accident. Proceedings of the firstinternational conference. Minsk, Belarus 18 to 22 March 1996. EditorsA.Karaoglou, G.Desmet, G.N.Kelly and H.G.Menzel. EuropeanCommission. Luxembourg,1996, p.1181-1184.

Gofman D., LyashenkoG., Marinets A., Mezhueva I., Shepeleva T., Tkalich P.,Zheleznyak M.Implementation of the Aqatic Radionuclide TransportModels RIVTOX and COASTOX into the RODOS System. //The

RODOS(WG4)-TN(99)18

118

radiological consequences of Chernobyl accident. Proceedings of the firstinternational conference. Minsk, Belarus 18 to 22 March 1996. EditorsA.Karaoglou, G.Desmet, G.N.Kelly and H.G.Menzel. EuropeanCommission. Luxembourg,1996, p.1181-1184.

Hadley R.F., Lal R., Onstad C.A., Walling D.E., Yair A. 1985. "Recentdevelopments in erosion and sediment yield studies", UNESCO, TechnicalDocuments in Hydrology, IHP-II Project A.1.3.1, Paris 128 p.

Håkanson L, Jansson, M (1983) Principles of Lake Sedimentology. SpringerVerlag.

Hakanson, L., Ecometric and dynamic modelling. Springer Verlag, Berlin,Heidelberg, New York, London, Paris, Tokyo, 162p (1991)

Håkanson, L., Peters, H. (1996) Methods for predictive modelling. SPB AcademicPublishing.

Håkanson, L., Brittain, J.E., Monte, L., Heling, R., Bergström, U. (1996).Modelling of Radiocaesium in Lakes - the VAMP model. J. Environ.Radioactivity. Vol. 33 No. 3 pp 255-308.

Handbook of parameter values for the prediction of radionuclide transfer inenvironments. //IAEA Technical Report No. 364, Vienna, 1994. - 284 p.

Havno K., Madsen M.N., Dorge J. MIKE 11 -a generalized river modellingpackage.- Computer Models of Watershed Hydrology (Ed. V.P. Singh),Water Resources Publications, USA,1995.- p.p.733-782 .

Heling R., Zheleznyak M., Raskob W., Popov A., Borodin R., Gofman D.,Lyashenko G., Marinets A., Pokhil A., Shepeleva T., Tkalich P.Overview of modelling of hydrological pathways in RODOS. -Radiation Protection Dosimetry, 1997, v.73, No.1-4, pp.67-70

Heling R., Zheleznyak M., Raskob W., Popov A., Borodin R., Gofman D.,Lyashenko G., Marinets A., Pokhil A., Shepeleva T., Tkalich P. Overviewof modelling of hydrological pathways in RODOS. - Radiation ProtectionDosimetry, 1997, v.73, No.1-4, pp.67-70

Helton, J.C., Muller, A.B. and Bayer, A. 1985. "Contamination of Surface WaterBodies after Reactors Accidents by the Erosion of AtmosphericallyDeposited Radionuclides", Health Physics, 48(6): 757-771

Hofer H., Bayer A. Calculation of radionuclide dispersion in flowing waters witha dynamic model, Kerntechnik, v.58, No3, (1993) 164-169

Holly F.M, Dispersion in rivers and coastal waters. -1.Phisical principles anddispersion equations. Developments in Hydraulic Engineering., 3(1987)1-37.

Holly F.M., Yang J.C., Schwarz P., Schaefer J., Hsu S.H., Einhellig R.CHARIMA: numerical simulation on unsteady water and sedimentmovement in multiply connected networcs of mobile-bed channels. //IIHRReport No. 343, Iowa Institute of Hydraulic Research, University of Iowa,Iowa City, Iowa. 1990. - 327 p.

Hubel K., Erstellung eines dynamischen Modells zur Berechnung derStrahlenexposition uber den Wasserpfad bei stehenden und fliesendengewassern. Jahresbericht Bayersche Landesanstalt fur Wasserforcsung(St.Sch.1071), Munchen 1989

Hydrologic Engineering Center. HEC-2 water-surface profiles users manual.//U.S. Army Corps of Engineering, Davis, California. 1982. - 402p.

Hydrologic Engineering Center. HEC-6 scour and deposition in rivers andreservoirs. //U.S. Army Corps of Engineering, Davis, California. 1977. - 295p.

RODOS(WG4)-TN(99)18

119

IAEA, Safety Series N 100, Evaluation the Reability of Predictions Made UsingEnvironmental Transfer Models, IAEA, Vienna, 1989;

IAEA, Safety Series N50-SG-S6, Hydrological Dispersion of RadioactiveMaterial in Relation to Nuclear Power Plant Siting, Vienna, 116p (1985).

Institut fur Seenforschung. Langenargen am Bodensee. 1995.

INTERNATIONAL ATOMIC ENERGY AGENCY. 1996. "International BasicSafety Standards for Protection and for the Safety of Radiation Sources",Safety Series No. 115

INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION.1991. "Principles for Intervention for Protection of the Public in aRadiological Emergency", ICRP No 63.

Jannasch H.W., Honeyman B.D., Balistrieri L.S. and Murray J.W. (1988)Kinetics of trace element uptake by marine particles. Geochim. Cosmochim.Acta 52, 567-577.

Jobson H.E. Users manual for a flow model based on the diffusion analogi.U.S. Geological Survey, Resfton; Virginia, 1989. - 56 p.

Jørgenson, S.E., Nielsen, S.N., Jørgenson, L.E. (1991). Handbook of EcologicalParameters and Ecotoxicology. Elsevier Science Publishers B.V.

Kaminski S., Klenk Th., Lindner G.,Th. Richter, Schroeder G.,Schulz M.(1996)Cesium inventories from Chernobyl and nuclear weapons testingfallout in the sediments of lake Constance - a record of different transportprocesses. Proceedings of the International Symposium on IonisingRadiation, Stockholm, May 20-24.

Kanivets V.V., Voitsekhovich O.V., Simov Radioactive contamination of theBlack and Azov seas. In: Voitsekhovich O.V. ed. Radioecology of waterobjects of the Chernobyl NPP accident impact area. Chernobylinterinform,Kiev, 1997, pp. 127-151 (in Russian).

Karim M.F., Holley F.M., Yang J.C. IALLUVIAL numerical simulation ofmobile-bed rivers, part theoretical and numerical principles. //IIHR ReportNo. 309, Iowa Institute of Hydraulic Research, University of Iowa, IowaCity, Iowa, 1987. - 198 p.

Karim M.F., Kennedy J.F. Computer-based predictors for sediment dischargeand friction factor of alluvial streams. IIHR Report No. 242, Iowa Instituteof Hydraulic Research, University of Iowa, Iowa City, Iowa, 1981. - 273 p.

Katrich I.Yu., Nikitin A.I., Medinets V.I., Lepeshkin V.I., Kabanov A.I., Semko,N.N., Bazhanov V.N. Dynamics of the radioactive contamination caused byCNPP accident on observed data 1986-1990. In: Borzilov V.A., Kryshev I.I.Ecological and hydrophysical consequences of the nuclear accidents,Hydrometerological Publ., Moscow, 1992, p. 57-61 (in Russian)

Konoplev A.V., Bulgakov A.A., Popov V.E., Bobovnikova, Ts. I. Behaviour ofLong-lived Chernobyl Radionuclides in a Soil-Water System. Analyst 117,1041 (1992).

Konoplev A.V,.Bulgakov A.A and Shcuratova I.T., in: Migration in soil andsurface flow of the some radioactive products in the zone of ChernobylNPP, Meteorologia and Gidrologia,6(1990) 119-121(in Russian)

Konoplev A.V., Golubenkov A.V. Modelling of the vertical migration in soil asresult of a nuclear accident. Meteorologia i Gidrologia. v. 10, 62-68(1991)

Konoplev A.V., Forschner A., Kaminski S., Klenk T., Konopleva I.V., WalserM., Zibold G. (1996) Modelling of Cs-137 migration in sediments of twoprealpine lakes. Proceedings of the International Symposium on IonisingRadiation, Stockholm, May 20-24, 693-698.

RODOS(WG4)-TN(99)18

120

Konoplev, A.V., Bulgakov A.A., Popov V.E and Bobovnikova Ts. I. 1992."Behaviour of Long-lived Chernobyl Radionuclides in a Soil-WaterSystem", ANALYST 117:1041-1047.

Konoplev, A.V., Bulgakov, A.A., Hoffman, F.O., Kanyar, B., Lyashenko, G.,Nair, S.K., Popov, A.G., Raskob, W., Thissen, K.M., Watkins, B.,Zheleznyak, M. 1997. "Validation of Models of Radionuclide Wash-Outfrom Contaminated Watersheds Using Chernobyl Data", Healph Physics, inpress

Korhonen, R. (1990). Modelling the Transfer of 137Cs Fallout in a large FinnishWatercourse. Health Physics 59, 4, 1990 pp 443-454.

Koziy L., Maderich V., Margvelashvili N., Zheleznyak M. (1998) Three-dimensional model of radionuclide dispersion in the estuaries and shelf seas.J. Environmental Modeling and Software, 13 (5-6), 413-420.

Koziy L.,Margvelashvili N., Maderich V., Zheleznyak M. 1998. Three-dimensional simulation of dispersion of radionuclides in a stratifiedestuaries. Extended Synopses of International Symposium on MarinePollution, 5-9 October, Monaco.

Kraus E. Interaction of an atmosphere and ocean. L.: Hydrometeoizdat, 1976,295 p. (in Russian)

Kuznetzov, M.S., Glazunov, G.P., Zorina, E.F. 1992. "Physical Foundations ofSoil Erosion", (In Russian) Moscow State University Publishing House, 96p.

Limnologischer Zustand des Bodensees N22. 1996. Bearb. H. Muller.Internationale Gewassserschutzkommission fur den Bodensee.

Linsley, G.S., Haywood, S.M. and Dionian, J. 1993. "The Use of Fallout Data inthe Development of Models for the Transfer of Nuclides in Terrestrial andFreshwater Systems". In: Migration in the Terrestrial Environment of Long-Lived Radionuclides from the Nuclear Fuel Cycle, IAEA, Vienna, p.615-634

Liquid pathway generic study. Impact of accidental radioactivity releasesto hydrosphere from floating and land-based nuclearpower plants. //UnitedStates Nuclear Regulatory Commission. USNRC, NUREG-0440, 1978. -212 p.

Maderich V., Margvelashvily N., Zheleznyak M. (1998) Modelling ofradionuclide concentrations in the water and top layer of bottom sedimentsof Bodensee. In: Radioactivitat in Mensch und Umwelt, Karlsruhe, v.2, p.826-832.

Maidment, D. R., Editor in chief. 1992. Handbook of hydrology. ISBN 0-07-39732-5, McGraw-Hill, Inc.

Mangini A., Christian U., Stabel H.H. 1990. Pathways and residence times ofradiotracers in Lake Konstance. In Large Lakes: Ecological Structure andFunction (ed. M.M. Tilzer, C. Serruya) Brock/Springer Series inContemporary Bioscience, Springer-Verlag, p. 245-264.

Marchuk G., Kagan E. Dynamics of ocean tides. L.: Hydrometeoizdat, 1983, 359p. (in Russian)

Margvelashvili N., Maderich V., Zheleznyak M. (1997) THREETOX - computercode to simulate three-dimensional dispersion of radionuclides inhomogeneous and stratified water bodies. Radiation Protection Dosimetry,73, 177-180.

Margvelashvili N., Maderich V., Zheleznyak M. 1999. Simulation ofradionuclide flux from Dnieper-Bug Estuary into the Black sea. J.Environmental Radioactivity, v. 43, No. 2, pp. 157-171.

RODOS(WG4)-TN(99)18

121

Margvelashvili N., V.Maderich, and M.Zheleznyak (1997) THREETOX - acomputer code to simulate three-dimensional dispersion of radionuclides instratified water bodies. Radiation Protection Dosimetry, Vol. 73, Nos 1-4,pp. 177-180

Margvelashvili N.,Maderich V., Zheleznyak M. 1998. Simulation ofradionuclides fluxes from the Dnieper-Bug estuary into the Black Sea. - J.Environmental Radioactivity.1999, v.43, N 2, pp.157-172

Marinets A.,Gofman D., Zheleznyak M. Using GIS for modelling radionuclidetransport in complex river-reservoir network. - HydroGIS 96: Application ofGeographical Information Systems in Hydrology and Water ResourcesManagement (Proc.of Vienna Conf.1996) IAHS Publ.No.235, 1996, 325-330.

Mazijk van A. One dimensional approach of transport phenomena of dissolvedmatter in rivers. – Communication on Hydraulic and GeotechnicalEngineering. – Delft University of Technology, Faculty of CivilEngineering, Report No. 96-3, September 1996, -310 p.

McDougall S, Hilton J and Jenkins A (1991) A dynamic model of caesiumtransport in lakes and their catchments. Water Research 25 (4), 437-445.

Mehta J., Hayter P., Parker W., Krone R., Teeter A., Cohesive sedimenttransport. I:Process description. J.Hydraul.Eng.,115 (1989) 1076-1093

Modelling and study of the mechanisms of the transfer of radioactive materialfrom terrestrial ecosystems to water bodies, (1996) Final report ECP-3Project, CEC- Belarus, Russia, Ukraine Programme on the radiologicalconsequences of the Chernobyl accident.

Monte, L. - A predictive model for the behavior of radionucledes in lakessystem. Health Physics 65(3):288-294; 1993

Monte, L. 1996. Analysis of models assessing the radionuclide migration fromcatchments to water bodies. Health Physics, 70:227-237.

Morozov A., Zheleznyak M., Aliev K., Bilotkach U., Votsekhovitch O.Prediction of radionuclide migration in the Pripyat River and DnieperReservoirs and decision support of water protection measures on the basis ofmathematical modelling.-Book of Extennded Synopsesc. InternationalConference “One Decade after Chernobyl: Summing up the RadiologicalConsequences of the Accident”, Vienna, Austria 8-12 April 1996

Mundschenk ,H.,Tolksdprf W. Metodische Unterschungen zur Sedimentationmit Hilfe radioactiver Leitstoffe am Beispel eines Kleinhafens amMittelrhein. Deutsche Gewasserkundliche Mitteilungen 32 (1988) 110-119

Mundschenk H, W.J. Krause, G. Dersch and P. Wengler, “Überwachung derBundeswasserstrassen auf radioaktive Stoffe im Normal- und Ereignisfall.Konzept, Methoden und Ergebnisse.”, Bundesanstalt für Gewässerkunde,Koblenz, 1994, Bericht BfG-0783.

Mundschenk, H., Tolksdorf W., Methodische Unterschungen zur Sedimentationmit Hilfe radioaktiver Leitstoffe am Beispel eines Kleinhafens amMittelrhein. Deutsche Gew�sserkundliche Mitteilungen 32 (1988) 110-119

Onishi Y., Wheelan, G., Skaggs, R.L., Development of a Multi-mediaRadionuclide Exposure Assessment Methodology for Low-Level WasteManagement, PNL-3370, Pacific Northwest Laboratory, Richland,Washington D.C., (1982).

Onishi Y. Sediment transport models and their testing. - In NATO AdvancedStudies Institute Lecture Series, Pullman, WA, 1993

Onishi Y., Dummuller D.C., Trent D.S. (1989) Preliminary Testing ofTurbulence and Radionuclide Transport Modeling in Deep Ocean

RODOS(WG4)-TN(99)18

122

Environment. PNL-6853, Pacific Northwest Laboratory, Richland,Washington.

Onishi Y., Mathematical simulation of sediment and radionuclide transport in theColumbia River, Battelle Pacific Northwest Lab., Richland, WashingtonD.C., Rep. BNWL-2228, (August 1977).

Onishi Y., Serne J., Arnold E., Cowan C., Thompson F., Critical review:radionuclide transport, sediment transport, water quality, mathematicalmodeling and radionuclide adsorption/desorption mechanism,NUREG/CR-1322, Pacific Northwest Laboratory, Richland, 1981, 512p.

Onishi Y., Trent D., Mathematical Simulation of Sediment and RadionuclideTransport in Surface Waters, NUREG/CR-1034, Washington D.C., 1979 .

Onishi, Y., Sediment and Contaminant Transport Model, Journal of HydraulicDivision, American Society of Civil Engineers, 107 (HY9) 1089-1107(September 1981).

Orlob G.T(Ed.), Mathematical Modeling of Water Quality: Streams,Lakes,andReservoirs, International Series. on Applied Systems Analysis, IIASA,Pitman Press, 12 (1983) -518p..

Polikarpov G.G., Livingston H.D., Kulebakina L.G., Buesseler K.O., StokozovN.A., Casso S.A. Inflow of Chernobyl 90Sr to the Black Sea from the Dnieprriver. J. Estuarine, Coastal and Shelf Science, V. 34, 1992, 315-320.

Polikarpov G.G., Timoschuk V.I., Kulebakina L.G. Concentration of 90Sr in theaquatic environment of Lower Dnieper toward the Black Sea. Dopovidi(Proceedings) of National Academy of Sciences of Ukraine, ser. B, N3,1988 p.75-76 (in Russian).

Popov A., Borodin R. Pokhil M., Zheleznyak M.Heling R., Rascob W. et al.Overview of hydrological pathways in RODOS. - Proc. Sixth TopicalMeeting on Emergency Preparedness and Response. American NuclearSociaty, San-Francisco, 22-25 April 1997, Lawrence Livermore NationalLaboratory Publications Chairs, 1997, pp.419-422

Popov, A. and R. Heling. 1996. "Aquatic Transfer Models to Predict Wash-Offfrom Watersheds and the Migration of Radionuclides in Lakes forImplementation in RODOS", Proc. First Int. Conf. "The radiologicalconsequences of the Chernobyl accident", ISSN 1018-5593, p.1189-1192

Popov, A., Borodin R., PokhilA., Zheleznyak M., Gofman D., Ltashenko G.,Marinets., Shepeleva.., Tkalich P., Heling,R., Raskob, W. 1997. "Overview ofthe Modelling of Hydrological Pathways in RODOS", Proc. of the SixthTopical Meeting on Emergency Preparedness and Response, San-Francisco,California USA, 22-25 April 1997, p. 419-422.

Popov, A.G. 1995. "Brief description of the models SNOW, VERTICAL andRETRACE-2", RODOS(D) - TN(95)05 - Interim RODOS Report, January1995

Popov, A.G., Borodin, R.V. 1993. "Brief review of RETRACE model, version1", RODOS(D) - TN(93)03 - Interim RODOS Report, October 1993.

Popov, A.G., Borodin, R.V., Pokhil, A.Yu. 1997. "RODOS External ProgramRETRACE to Simulate Radionuclide Was-Off from Watersheds",RODOS(WG4) - TN(97)01 - Interim RODOS Report, Draft, October 10

Prokhorov, V.M. 1981. Radionuclide contaminant migration in soils. Physico-chemical mechanisms and modelling. (in Russian). M.: Energoatonizdat, 98pp.

Radioecology of the water bodies in the zone suffered from the Chernobylaccident. / Ed. by Vojtsekhovich O.B.- Kiev., Chernobylinform, 1999.- 308p.

RODOS(WG4)-TN(99)18

123

Raskob W., Popov A., Zheleznyak M. Heling R., Radioecological Models forInland Water Systems. –Forschungcentrum Karlsruhe, FZKA 6089, 1998 -225 pp

Raudkivi A. Loose boundary hydraulics, Pergamon Press, N.Y., (1967)

Richardson, C.W. and D.A. Wright. 1984. "WGEN: A Model for GeneratingDaily Weather Variables", U.S.Dept. Agric., Agric. Res. Ser., ARS-8, 83 p.

Rijn , van L.C., Model for sedimentation predictions In: XIX Congr.International Association for Hydraulic Research, Congress Proceedigs,New Delhi, India, 3(1981) 321-328.

Rijn van L.C., Sediment transport, Part I: Bed load transport. J.Hydraul.Engineering, 110(1984), pp 1431- 1456.

Rijn van L.C., Sediment transport, Part II: Suspended load transport. J.Hydraul.Engineering, 110(1984) 1613- 1641.

Rutherford, J.C., River mixing, John Wiley and Sons, England, 1994

Salbu, B. (1988) Radioinuclides associated with colloids and particles in theChernobyl fallout. In: Proceedings of an OECD(NEA)/CEC Workshop onrecent advances in reactor accident consequence assessment, 25-29 January1988. Rome. Paris: OECD Nuclear Energy Agency; 1988: p53-57

Sansone, U. and O.Voitsekhovitch, eds. 1996. "Modelling and study of themechanisms of the transfer of radioactive material from terrestrialecosystems to and in water bodies around Chernobyl. Experimentalcollaboration project No 3", Final report. EUR 16529 en, 184 pp.

Santchi, P.H., Bolhander, S., Zings, S., Luck, A., Farrenkothen, K. 1990. "Theself-cleaning capacity of surface waters after radioactive fallout. Evidencefrom European waters after Chernobyl, 1986-1988", Environ. Sci. Technol,24:519-527

Santschi P.H., Bollhader S., Zingg S., Luck A., Farbenkothen K. (1990) Theself-cleaning capacity of surface waters after radioactive fallout. Evidencefrom European waters after Chernobyl, 1986-1988. Environ. Sci. Tech. 24,519-527.

Santschi P.H., Honeyman B.D., Radionuclides in aquatic environments.Radiation Phys. and Chem., v.34, 2(1989) 213-240&

Saxen, R., Alatalo, M., Koskelainen, U. (1997) Description of lakes and theircatchments selected for model development and model validation. Technicalreport RODOS.

Schnoor J.L., D.J.Mossman, V.A.Borzilov, M.A.Novitsky, O.I.Voszhennikov,A.K.Gerasimenko. (1992) Mathematical model for chemical spills anddistributed source runoff to large rivers, In: Fate of Pesticides andChemicals in the Environment, J.L.Schnoor, (Ed.) John Wiley&Sons,Inc.

Schuckler M., Kalckbrenner R., Bayer A, Zuk�nftige radiologische Belastungdurch kerntechnische Anlagen im Einzugsgebiet des Oberrheins, T.2,Belastung uber den Wasserweg, Conference Dusseldorf, Proceedings,ZAED, Eggenstein-Leopoldshafen, 1976.

Shin C.S., Gloyna E.F. Mathematical model for the transport of radionuclides instream system. //Environmental surveillance in the vicinity of nuclearfacility. /Reinig W.C., Charles C. ed., Thomas Publishing Co., Springfield,Illinois, 1970, p. 518-532.

Shukla, B.S. 1993. Watershed, river and lake modeling through environmentalradioactivity ENVIRONMENTAL RESEARCH & PUBLICATIONS INC.,Hamilton, Ontario ISBN 0-9696383-0-2).

RODOS(WG4)-TN(99)18

124

Simonov A.I., Altman E.N. (Eds.) Hydrometeorology and hydrochemistry ofseas of USSR. v.IV, Black sea, 1, Hydrometeorological conditions.Hydrometeorological Publ., S.-Petersburg, 1991, 430 p. (in Russian).

Singh, V.P., ed., 1995. Computer Models of Watersheds Hydrology. WaterResource Publications, Highlands Ranch, Colorado, 1130 pp.

Singh, V.P., ed., 1995. Computer Models of Watersheds Hydrology. WaterResource Publications, Highlands Ranch, Colorado, 1130 pp

Slavik O., Zheleznyak M., Dzuba N., Marinets A., Lyashenko G., PapushL., Shepeleva T. , Mihaly B. Implementation of the decision supportsystem for the river-reservoir network affected by releases from theBohunice NPP, Slovakia - Radiation Protection Dosimetry, 1997, v.73,No.1-4, pp.171-175

Smettem K.R.J., Collis-George N. The influence of cylindrical macropores onsteady-state infiltration in a soil under pasture. J. Hydrol., v. 79, N1/2, p.107-114, 1985.

Smitz, Y., Everbecq, E., Modeling the Behaviour of Radionuclides in AquaticEcosystems, Paper presented at CEC Seminar on Cycling of Long-LivedRadionuclides in the Biosphere: Observations and Models, Madrid,September 1986.

Sørensen, H.R., Kjelds, J., Deckers, F., Waardenburg, F. (1996a): Application ofGIS in hydrological and hydraulic modelling: DLIS and MIKE11-GIS.HydroGIS 96: Application of Geographic Information Systems inHydrology and Water Resources Management. Proc. Vienna, April 1996,(IAHS Publ. no. 235, 1996).

Sørensen, H.R., Klucovska, J., Topolska, J., Clausen, T., Refsgaard, J.C. (1996b)An engineering case study - modelling the influences of GabcikovoHydropower Plant on the hydrology and ecology in the Slovakian part of theriver branch system of Zitny Ostrov. Distributed Hydrological Modelling.Ed. by Abbott, M.B. and J.C. Refsgaard, pp.233-253. Kluwer AcademicPublishers, 1996.

Stoffhaushalt des Bodensee. (1994) Bericht uber den Bewilligungszeitraum1992-93-94. 1994. Universitat Konstanz. 453p.

Stoffhaushalt des Bodensee.(1991) Bericht uber den Bewilligungszeitraum 1989-90-91. 1991.Universitat Konstanz. 465p.

Strahler, A.N. 1952. "Dynamic Basis of Geomorphology", Geol. Soc. Am. Bull.63:923-938

Taylor G. I. and Pagenkopf J. R., TRANQUAL- Two-dimensional modelling oftransport water quality processes. Proceedings, EPA storm water and waterquality management modelling group meeting, Niagara Falls, Canada(1981).

Tcherkezian, V. Shkinev, Khitrov L., Kolesov G., (1994) Experimental Approachto Chernobyl Hot particles. J. Environmental Radioactivity 22 pp127-139

Tkalich P., Zheleznyak M., Lyashenko G., Marinets A. RIVTOX - ComputerCode to Simulate Radionuclides Transport in Rivers,//A. Peters et al.( eds.) ,Computational Methods in Water Resources X, vol. 2, KluwerAcademic Publishers, Dordrecht, The Netherlands, 1994, pp. 11731180.

USNRC Liquid pathway generic study. Impact of accidental radioactivityreleases to hydrosphere from floating and land-based nuclearpower plants.United States Nuclear Regulatory Commission. USNRC, NUREG-0440,1978. - 212 p.

RODOS(WG4)-TN(99)18

125

Vested, H.J., Baretta, J.W., Ekebjærg, L.C., Labrosse, A.: Couplingofhydrodynamical transport and ecological models for 2D horizontal flow.Journal of Marine Systems, vol. 8, 1996, pp. 255-267

Vinogradov Yu. B. 1967. Rainstorm flood hydrological problems for smallcatchments of Middle Asia and South Kazakhstan. (In Russian). Leningrad,Hydrometeorological Publishing House, 263 pp.

Vinogradov Yu. B. 1988. Mathematical modelling of runoff formation. Criticalreview. (In Russian). Leningrad, Hydrometeorological Publishing House,312 pp.

Vinogradov Yu. B. 1988. Mathematical modelling of runoff formation. Criticalreview. (In Russian). Leningrad, Hydrometeorological Publishing House,312 pp.

Voitsekhovich O., Zheleznyak M. 1998. Aquatic countermeasures in theChernobyl zone: decision support based on field studies and mathematicalmodelling. Proc. USA EPA Conference on Post-AcidentalCountermeasures after Nuclear Accidents.Washington, DC, September1998, 6 pages

Voitsekhovitch O., Sansone U., Zheleznyak M., Bugai D. Water qualitymanagement of contaminated areas and its effect on doses from aquaticpathways . //The radiological consequences of Chernobyl accident.Proceedings of the first international conference. Minsk, Belarus 18 - 22March 1996. Editors A.Karaoglou, G.Desmet, G.N.Kelly and H.G.Menzel,European Commission. Luxembourg,1996, p.p. 401-410.

Voitsekhovitch O.V., Zheleznyak M.J., Onishi Y. Chernobyl nuclear accidenthydrological analyses and emergency evaluation of radionuclide distributionin the Dnieper River, Ukraine during the 1993 summer flood. - PacificNorthwest Laboratories, Battelle, PNL-9980, Richland, Washington, June1994, - 96 p.

Warner, F. and Harrison, R.M. (Eds.) 1993. SCOPE 50: Radioecology afterChernobyl. Biogeochemical Pathways of Artificial Radionuclides. JohnWiley & Sons, Ltd., Chichester, 368 pp.

Westall I.C., Zachary J.L., Morel F.M. MINEQL: a computer program for thecalculation of chemical equilibrium composition of aqueous systems.//Tech. Note 18, Dept. Civil Eng., Massachusetts Institute of Technology,Cambrige, Massachusetts, 1976. - 102 p.

White A., Gloyna E.F. Radioactivity transport in water-mathematical simulation.EHE-70-04, Technical report No. 19, prepared for the U.S. Atomic EnergyCommission by the University of Texas, Austin, Texas, 1969. - 231 p.

WMO. Technical report to the Commission for Hydrology No. 27 , 1989.Zhidikov A.P. and Romanov A.V. Models Used for Forecasting Snowmeltand Rainfall Runoff.

Won Seo I, Sung Cheong T, 1998, Predicting longitudinal dispersion coefficientin natural streams, J.Hydraulic Eng., Proc.ASCE. g

WORLD METEOROLOGICAL ORGANIZATION. 1975. "Intercomparison ofconceptual models used in operating hydrological forecasting", WMOOperational hydrological Report No.7 , 172p.

WORLD METEOROLOGICAL ORGANIZATION. 1992. "Hydrologicalaspects of accidental pollution of water bodies", WMO Operationalhydrological Report No.754, WMO, Geneva, 208p.

Yamagata, N., Matsuda, S. And Kodiara, K. 1963. "Runoff of 137Cs and 90Srfrom Rivers", Nature, 200:668-669

RODOS(WG4)-TN(99)18

126

Zheleznyak M. Mathematical models of radionuclide dispersion in a reservoir setIn: System Analysis and Methods of Mathematical Modelling in Ecology,V.Glushkov Institute of Cybernetics , Kiev, 1990 , 48-58 (in Russian).

Zheleznyak M. Multiple scale analyses of radioactive contamination for riversand reservoirs after the Chernobyl accident. - Multiple Scale Analyses andCoupled Physical Systems. Proc. Saint-Venant Symposium, August 28-29,1997, Presses de l’ecole nationale des ponts et chaussees, Paris, 1997, p.p.45-52.

Zheleznyak M. On the structure of near bottom oscillating turbulent boundarylayer. Hydromechanics, 58, Kiev, “Naukova Dumka”, 1998, p. 1-8 (inRussian)

Zheleznyak M. Prediction of hydrological radionuclide transport and modellingsupport of the aquatic countermeasures in the Chernobyl zone. - Proc. SixthTopical Meeting on Emergency Preparedness and Response. AmericanNuclear Sociaty, San-Francisco, 2225 April 1997, Lawrence LivermoreNational Laboratory Publications Chairs, 1997,pp.169-172.

Zheleznyak M. The mathematical modelling of radionuclide transport by surfacewater flow from the vicinity of the Chornobyl nuclear power plant.Condensed Matter Physics, 1997, No 12, p. 37-6

Zheleznyak M., Blaylock G., Gontier G., Konoplev A. et al. Modeling ofradionuclide transfer in rivers and reservoirs: validation study whithin theIAEA\CEC VAMP Programme. International Symposium on EnvironmentalImpact of Radioactive Releases, IAEA, Vienna, 8-12 May 1995, IAEA-SM-339, IAEA, 1995, p.330-331

Zheleznyak M., Demchenko R., Khursin S., Kuzmenko Yu., Tkalich P., VitjukN. Mathematical modeling of radionuclide dispersion in the Pripyat-Dnieperaquatic system after the Chernobyl accident. -The Science of the TotalEnvironment. 1992, v.112, p.89-114

Zheleznyak M., Demtchenko R., Kuzmenko Yu., Tkalich P., Dzuba N.,Mezhueva I. Mathe-matical modelling of radionuclide dispersion in thewater bodies of the Chernobyl NPP zone and in the Dnieper Reservoirs.-Hydrological Impact of Nuclear Power Plants. Proc. UNESCO Workshop-92, UNESCO Press, Paris,1993, pp.173-185

Zheleznyak M., Heling R., Raskob W., Popov A., Borodin R., Gofman D.,Lyashenko G., Marinets A., Pokhil A., Shepeleva T., Tkalich P. Modellingof Hydrological Pathways in RODOS. //The radiological consequences ofChernobyl accident. Proceedings of the first international conference.Minsk, Belarus 18 - 22 March 1996, Editors A.Karaoglou,G.Desmet,G.N.Kelly and H.G.Menzel. European Commission. Luxembourg, 1996,p.p.11391148.

Zheleznyak M., Kuzmenko Yu., Tkalich P., Dzuba N., Gofman D., GolovanovI., Marinets A. , Mezhueva I. Modelling of Radionuclides Transport inthe Set of River Reservoirs.//A. Peters et al.( eds.) , ComputationalMethods in Water Resources X, vol. 2, Kluwer Academic Publishers,Dordrecht, The Netherlands, 1994, pp. 1189 1196

Zheleznyak M., Margvelashvily N. Numerical modelling of three-dimensionalradionuclide fields in Kiev Reservoir. - Dopovidi (Proceedings) of NationalAcademy of Sciences of Ukraine, No.12, 1997 (in Russian)

Zheleznyak M., Marinets A. Modelling of long wave propagation in riverchannels on the base of “diffusion wave” equation, In book: CopmputationalTechnologies, v.2, N 6, 1993, Novosibirsk, Institute of ComputationalTechnologies of Russian Academy of Sciences, p.147-154 (In Russian)

Zheleznyak M., Shepeleva T., Sizonenko V., Mezhueva I. Simulation ofcountermeasures to diminish radionuclide fluxes from Chernobyl zone via

RODOS(WG4)-TN(99)18

127

aquatic pathways - Radiation Protection Dosimetry, 1997, v.73, No.1-4,pp.181-186

Zheleznyak M., Tkalich P.V., Lyashenko G.B., Marinets A.V. Radionuclideaquatic dispersion model-first approach to integration into the ÅÑ decisionsupport system on a basis of Post-Chernobyl experience. - RadiationProtection Dosimetry, N6, 1993, pp.37-43.

Zheleznyak M., Tkalich P.V., Lyashenko G.B., Marinets A.V. Radionuclideaquatic dispersion model-first approach to integration into the �� decisionsupport system on a basis of Post-Chernobyl experience. - RadiationProtection Dosimetry, N6, 1993, pp.37-43.

Zheleznyak M., Vojtcekhovich O., Demchenko R., Kuzmenko Yu., Tkalich P.,Khursin S., Simulating the effectiveness of measures to reduce the transportof radionuclides in the Pripyat-Dnieper - Proc. International Seminar onIntervention Levels and Countermeasures for Nuclear Accidents. Cadarashe,France, 7-11 October 1991.-Commission of the European Communities,Radiation Protection-54, EUR 14469, 1992, p.336-362.

RODOS(WG4)-TN(99)18

128

Document HistoryDocument Title: Overview of Hydrological Dispersion Module - HDM of

RODOS

RODOS number: RODOS-WG4-TN(99)18

Authors/Editors: Heling R., Raskob W., Popov A., Zheleznyak M.

Affiliation: NRG-KEMA, FZK, TYPHOON, IMMSP

Address:

E-Mail: [email protected]

Date of Issue: 06.1999

File Name: RODOS-WG4-TN(99)18 Overview of Hydrological DispersionModule - HDM of RODOS

Date of print: September 19, 2000