groundwater surface water interaction in gde

Groundwater surface water interaction in GDE Deliverable D4.2

Partner: University of Oulu

B. Kløve, P. Ala-aho, G. Bertrand, A. Erturk, A. Gemitzi, E. Gönec A. Moszczynska, M.

Mileusnic H. Kupfersberger, J. Kværner, , A. Lundberg, S. Peña Haro, P. Rossi, D. Siergieiev,

P. Wachniew, A. Wolak

Deliverable summary

Project title

Acronym GENESIS

Contract number

226536

Date due Month 28 in GENESIS

Final version submitted to EC Month 32 in GENESIS

Complete references

Groundwater surface water interaction in GDE: GENSIS project deliverable 4.2

Contact person Björn Klöve

Contact information [email protected]

Authors and their affiliation University of Oulu (UOULU)

Project homepage www.thegenesisproject.eu

Confidentiality

Key words Groundwater, ecosystems, hydrology, groundwater-surface-water interaction, conceptual and numerical models.

Summary (publishable) for policy uptake

This report reviews and discussed the interaction of groundwater in GDEs. The report presents and integrates past and new results. Different methods used to measure groundwater interaction with ecosystems are presented. Various GENESIS case studies across Europe to demonstrate the variable and complex role of groundwater in GDEs. The basis for developing conceptual for GDEs is presented. Various methods to model GDEs are discussed.

mailto:[email protected]

http://www.thegenesisproject.eu/

List of GENESIS partners

Norwegian Institute for Agricultural and Environmental Research (CO)

Bioforsk Norway

University of Oulu UOULU Finland

Joanneum Research Forschungsgesellschaft mbH JR Austria

Swiss Federal Institute of Technology Zurich ETH Switzerland

Luleå University of Technology LUT Sweden

University of Bucharest UB Romania

GIS-Geoindustry, s.r.o. GIS Czech Republic

French National institute for Agricultural research INRA France

Alterra - Wageningen University and Research Centre Alterra The Netherlands

Helmholtz München Gesundheit Umwelt HMGU Germany

Swiss Federal Institute of Aquatic Science and Technology EAWAG Switzerland

University of Science and Technology AGH Poland

Università Cattolica del Sacro Cuore UCSC Italy

Integrated Global Ecosystem Management Research and Consulting Co.

IGEM Turkey

Technical University of Valencia UPVLC Spain

Democritus University of Thrace DUTh Greece

Cracow University of Technology CUT Poland

University of Neuchâtel UNINE Switzerland

Athens University of Economics and Business- Research Centre AUEB-RC Greece

University of Dundee UNIVDUN United Kingdom

University of Zagreb - Faculty of Mining, Geology and Petroleum Engineering

UNIZG-RGNF Croatia

Helmholtz Centre for Environmental Research UFZ Germany

Swedish Meteorological and Hydrological Institute SMHI Sweden

University of Bologna UBOLOGNA Italy

University of Kiel UKIEL Germany

Table of contents

1. Introduction ......................................................................................................................................... 7

1.1 Groundwater in aquatic and terrestrial ecosystems ..................................................................... 7

1.2 Water Framework and Groundwater Directive ............................................................................ 9

1.3 Presentation of GENESIS studies ................................................................................................... 9

2. Measurement approaches to detect groundwater in GDE ............................................................... 12

2.1 Hydrogeological measurements in GDEs .................................................................................... 12

2.2 Temperature and EC as indicators of groundwater .................................................................... 14

2.3 Geochemistry as indicator of groundwater ................................................................................ 16

2.4 Isotopes as indicators of groundwater ........................................................................................ 18

2.5 Tracer tests .................................................................................................................................. 21

2.6 Mapping of recharge and discharge points ................................................................................. 22

3. Results from GENESIS main GDE study sites ..................................................................................... 23

3.1 Esker aquifer lake interaction, Rokua Finland ............................................................................. 23

3.1.1 Hydrogeology, site description and methods ...................................................................... 23

3.1.2 Major outcome from the study ............................................................................................ 25

3.1.3 Conceptual models for surface water – groundwater interaction ....................................... 26

3.2 Lule river hyporheic zone interaction, Sweden ........................................................................... 29



3.3 Riperian zone interaction, Switzerland ....................................................................................... 34




3.4 Dalyan Mediterranean Lagoon, Turkey ....................................................................................... 42

3.4.1 Site Description and Hydrology ............................................................................................ 42

3.4.2 Methods ............................................................................................................................... 45



3.5 River lake lagoon interaction, Greece ......................................................................................... 53




3.6 Bogucice Sands - Niepolomice Forest, Poland ............................................................................ 59

3.6.1. Site description, hydrogeology and water use .................................................................... 59

3.7 Częstochowa aquifer interaction, Poland ................................................................................... 64




3.8 The Grue site, Norway (Bioforsk) ................................................................................................ 71

3.8.1 Site description, hydrogeolgy and methods ........................................................................ 71



3.9 Sava river, interaction with groundwater ................................................................................... 75

3.9.1 Hydrodynamic pattern of the Sava River – groundwater interaction .................................. 76

3.9.2 Hydrogeochemical evidence of the Sava River –groundwater interaction .......................... 79

3.10 Fontanili springs, Italy, Hydrogeology, site description and methods ...................................... 80

3.10.1 Introduction ........................................................................................................................ 80

3.10.2 Groundwater – Surface Water interactions: Fontanili of the Lombardy Region ............... 86

3.10.3 Major outcome from studies on selected fontanili ............................................................ 90

3.10.4 Conceptual model for surface water – groundwater interaction ...................................... 91

4. Modelling of surface-groundwater interaction in aquifers ............................................................... 92

4.1 Groundwater interaction with ecosystems ................................................................................. 92

4.2 Conceptual models ...................................................................................................................... 93

4.3 Numerical modelling needs and approaches .............................................................................. 94

4.3.1 Numerical modelling needs .................................................................................................. 94

4.3.2 Water balance calculation in GDEs....................................................................................... 96

4.3.3 Surface water groundwater interaction models .................................................................. 97

4.3.4 Stream-aquifer interaction models ...................................................................................... 98

4.3.5 Leakage coefficient approach ............................................................................................... 98

4.3.6 Future modeling needs....................................................................................................... 100

References ........................................................................................................................................... 102

Appendix 1 ........................................................................................................................................... 113

Appendix 2 ........................................................................................................................................... 118

1. Introduction

1.1 Groundwater in aquatic and terrestrial ecosystems

Groundwater dependent ecosystems (GDEs) may be defined as ecosystems for which current

composition, structure and function are reliant on a supply of groundwater. GDEs are a vital

but as yet not fully understood component of the natural environment. In many cases

groundwater makes an important but poorly documented contribution to various aquatic and

terrestrial ecosystems such as: I) rivers and lakes including aquatic, hyporheic, hypolenthic

and riparian habitats, II) subterranean aquifers and caves, III) wetlands and springs, and IV)

estuarine and nearshore marine ecosystems (adapted from Boulton, 2005). The aquifer itself

is also an important ecosystem (Danielopol and Pospisil, 2001).

The ecosystem reliance on groundwater may be continuous, seasonal or occasional. The

reliance becomes apparent when the supply of groundwater is removed for a sufficient

length of time that changes in plant function (typically rates of water use decline first) can be

observed. Groundwater is often the main source of water for vegetation in dry climates.

Some systems, such as springs, are completely fed by groundwater and would not otherwise

exist. This is also reflected in flora and fauna, with springs harbouring many species adapted

to these special conditions. In general, groundwater provides water, nutrients, buoyancy, and

stable water temperature, but the effects of this on GDEs are not thoroughly documented.

Fig 1.1-1 Flow lines and groundwater levels in a cross-section of soil/rock with

homogeneous and isotropic hydraulic conductivity, with possible locations of GDEs (Klöve

et al 2011a).

Groundwater moves along flow paths from recharge areas to discharge areas within GDEs

(Fig. 1.1-1). Infiltration occurs when meteoric water (including retarded fractions such as

snow and glaciers) enters the ground. Water then usually moves through the unsaturated

zone and reaches the saturated part of the aquifer contributing to groundwater recharge.

Some surface waters both receive and recharge groundwater. Groundwater recharge may

include contribution from adjacent aquifers. Discharge from the aquifer occurs at springs,

streams, lakes, wetlands, transpiration by plants with roots that extend to near the water table

and by direct soil water and groundwater evaporation. Groundwater can also discharge to

adjacent aquifers (e.g. downward leakage from an aquifer to a deeper one). Groundwater

typically discharges to surface water bodies where the slope of the water table changes

suddenly (e.g. Winter et al., 1998). In many cases springs are found where geological layer

and/or hydraulic conductivity of the aquifer change. The actual conceptual model for a given

aquifer will vary locally depending on geology, climate, water use, slope and topography.

This should also include the unsaturated zone which plays an important role both for

groundwater quantitative and quality aspects. Local groundwater flow often occurs near the

surface and over short distances, i.e. from a higher elevation recharge area to an adjacent

discharge area such as small springs. Intermediate and regional flows usually occur at a

greater depth and over greater distance. Steeper and undulating landscapes have the most

local flow points. Groundwater flow is always three-dimensional, but can often be analysed

in two-dimensional cross sections (Fig. 1.1-1). Analysis of these flow paths is important

when studying GDEs because it can provide valuable information about potential threats to

the quantity and quality of groundwater.

Different ecosystems depend on groundwater in complex ways. Some springs, such as

karstic systems, show very high variations of discharge or often run dry occasionally

(intermittent springs). Peatlands fed by surface flow, rain and groundwater are adapted to

stable water tables fluctuating near the soil surface. Fens receive a continuous supply of

groundwater and bogs receive only precipitation on the surface but groundwater pressure

provides buoyancy and prevents drainage. The hydrogeology and multi-scale flow patterns

influence both the timing and duration of groundwater discharge (hydroperiod). From a

hydro-ecological point of view, the concept of hydroperiod provides an interesting starting

point for the classification of GDEs because it integrates several abiotic parameters (drivers),

e.g. climate, extent of flow paths, aquifer type (i.e. porous or discontinuous) and land use of

the catchment, which eventually constrain ecological uses of groundwater. Four types of

hydroperiods can be distinguished (adapted from Alfaro and Wallace, 1994):

- Periodic: Usually a clear seasonal pattern, average discharge climatically controlled

precipitation/evapotranspiration changes).

- Intermittent: Great variability in flow.

- Episodic: Completely irregular flow, occurring only when there are very high water

levels in the aquifer.

- Perennial: Continuous source year round.

As a function of these features, the importance of groundwater supply relative to other

potential water sources varies. A constant supply of groundwater normally maintains

dependent ecosystems such as wetlands and springs typically located in landscape

depressions. Here, groundwater is most likely the sole or dominating source of water. The

high contribution of groundwater compared with other water sources can be seen if i) the

water quality directly reflects that of groundwater, or in dry climates ii) if the transpirative

water losses from vegetation are maintained by groundwater. As these systems exhibit a

rather constant temperature that differs from that of adjacent surface waters, temperature can

also be used as a tracer to evaluate the degree of groundwater-surface water interaction

(Anibas et al. 2011). In addition, the vegetation composition of GDEs will often reflect

groundwater composition.

Biological processes in GDEs can have an influence on hydrology which is not well known.

Microbial activity forms biofilms that cover stream beds potentially affecting the

permeability of the stream bed. Succession of vegetation in ecosystems changees

hydrological processes such as interception and evapotranspiration. Vegetation also

influences flow resistance, and flow influences the vegetation composition (e.g. emergent

vegetation is not present if flow is above 1 m/s, see e.g. Bertrand et al. 2011). Discharge

dynamics also affect the substrate composition, which influences the diversity and nature of

macrozoobenthic communities (ecologic, phenotypic and genotypic adaptations, Bertrand et

al. 2011).

A spatially and temporally integrated view of relations between the GDEs and the local and

regional groundwater flow systems can be provided by environmental tracers such as stable

isotopes of water, tritium, noble gases, CFCs or SF6 (e.g. Kværner and Kløve, 2006).

Besides their significance in developing conceptual and numerical models of flow and

transport in groundwater systems, the environmental tracers allow identification and

quantification of sources of discharge to GDEs as well as dating of groundwater. Knowledge

of groundwater age distribution is a key factor in the assessment of GDE vulnerability to

climate and land-use changes, groundwater exploitation and pollution. Dominant time scales

of water flow and solute transport to the ecosystem determine time lags associated with its

responses to both commencement and cessation of such disturbances.

1.2 Water Framework and Groundwater Directive

GDEs and associated aquatic ecosystems are important to protect as they provide many

ecosystem services. A few GDEs, such as some wetlands, are important for migratory birds

or rare species and are protected by international and local agreements and legislation.

Wetlands have been protected by the international Ramsar convention on wetlands since

1971. In Europe legal actions with strong commitments for environmental protection include

the Habitat Directive (EC, 1992) with the Natura 2000 network of protected sites and strict

system for species protection. In Europe groundwater is threatened by land-use, pollution

and extensive water use for irrigation. The Water Framework Directive (EC, 2000) aims to

achieve good quality of surface and ground water by 2015. Therefore, groundwater threshold

values must be set to protect associated aquatic ecosystems and human health (Hinsby et al

2008). Protection of surface waters is also need for economical and recreational point of

view. The Groundwater Directive (EC, 2006) lists several pollutants that should be assessed

and provides regulation to limit pollution, reverse upward trends, and protect groundwater

resources. Also it requires that nearby ecosystems relying on groundwater must not be

damaged due by changes in groundwater quality or quantity. For assessment of vulnerability

of these ecosystems more information is needed about the role of groundwater in ecosystems

(Hinsby et al. 2008).

1.3 Presentation of GENESIS studies

In GENESIS groundwater interaction with lakes, rivers, springs, peatlands, forests and costal

lagoons are studied for different regions, climate and land-use pressures (Table 1.3-1, Fig.

1.3-1). Both aquatic and terrestrial systems are studied. Measurements on the sites started as

the GENESIS project started in 2010 and still continues. This report gives an overview of

measurements carried out and first results with focus on groundwater-surface interaction.

Table 1.3-1 List of main sites studied in GENESIS.

Site and

location

Aquifer

description GDE types Climate

Socio-

economic

use of GDE

and aquifer

Anthropogenic

threat

Rokua, Finland

Esker,

shallow

unconfined

sand deposit

Lakes, springs,

streams,

peatlands

Cold

temperate

Recreation,

Natura 2002

protection,

forestry

Forestry

Lule river

Sweden No aquifer

River hyporheic

zone

Cold

temperate

Recreation,

hydropower Hydropower

Rhone river

floodplain,

Switzerland

Bogucice

Sands -

Niepolomice

Forest, Poland

Confined

layered

aquifer with

uphill

recharge

areas

Fen interaction

with deep

groundwater

Temperate

Natura 2002,

Potable

water

extraction

Potable water

extraction

Dalyan lagoon

Lagoon

interaction with

surface,

groundwater

and sea water

Mediterranean

Agriculture,

tourism,

fisheries,

Ramsar site

Irrigation

Vosvoziz river,

Greece

Semi

confined

alluvial plain

River lake

lagoon

interaction,

Greece

Mediterranean

Agriculture,

fisheries,

Natura 2000

Irrigation

Sava river,

Croatia

Grue, Glomma

river, Norway No aqui

River cultivated

field interaction

Cold

temperate Agriculture

Cultivation and

pesticide

application

Czestochowa

aquifer, Poland

Fig. 1.3-1 Map of GENESIS study sites.

2. Measurement approaches to detect groundwater in GDE

2.1 Hydrogeological measurements in GDEs

Hydrological measurements form the first tool to water resources such as groundwater.

These measurements give information on quantity of water at a given time and space.

Sometimes this can directly indicate groundwater exfiltration. For example if base flow is

high the input of groundwater to the ecosystem is usually high. Hydrological data on water

quantity is also needed to establish water balances that are needed to understand many

systems. Water levels and pressure head in groundwater and GDEs can directly indicate the

direction of flow and show interactions. Other methods can be powerful to show flow

pathways and flow lines. Here we will review some hydrogeological methods used in

GENESIS that are not part of standard hydrological measurements such seepage meters (Lee

1977), and potentiometric measurements (Rosenberry and LaBaugh 2008) and present our

experiments with these measurements.

Lake, groundwater or river water level measurements should be carried out with fixed points

to ensure no movement of the base level and for later comparison of data. Lake stage can be

monitored with a method often used in steam stage monitoring. Water level is recorded from

a stilling well which is hydraulically connected to the stream. For lake or river level

measurements in cold conditions, the monitoring should be done from shore undergrounds to

ensure also monitoring during frost (Fig. 2.1-1). It is advisable to place loggers hidden from

public.

Fig. 2.1-1 Lake level measurement with logging pressure sensor.

Seepage meters are useful to measure the inflow of groundwater to and from lakes (Fig. 2.1-

2).

Fig. 2.1-2 Seepage measurement.

Potentiomanometer can be used to determine the direction of hydraulic gradient between

surface water and groundwater. Method can be applied to small streams in the groundwater

discharge area where seepage meter is not applicable.

Fig. 2.1-3 Use of potentiomanometer in a small streams located at peat production area (left)

and groundwater discharge area (right) to determine the direction of water seepage.

In many cases also geophysical measurements provide important information in GDE.

Ground penetrating radar can be used on the lake ice to give the layering of sediments as

shown in Fig. 2.1-4.

Fig. 2.1-4 Lake bed profile from ground penetrating radar measurement.

2.2 Temperature and EC as indicators of groundwater

Temperature

In natural systems where no significant phase change (e.g. evaporation) occurs, temperature

can be used as a heat flow tracer. The interest in temperature monitoring of GDEs is based on

the principle that groundwater temperature is relatively stable throughout the year whereas

surface water temperature heavily depends on daily and seasonal air temperature variations.

Where these two systems are hydraulically connected, heat (energy) in the subsurface is

transported by flowing water (advection), as well as by heat conduction via the fluid and solid

parts of the soil matrix (e.g. Stallman 1965). The advective flow strongly influences the

temperature distribution in the mixing zone between groundwater and surface water, called

hyporheic or hypolentic zones (HZ) respectively for flowing and lentic systems. Hence water

movement between groundwater and surface water can be traced by measuring temperature

distributions between the two systems (Constantz and Stonestrom, 2003; Anderson, 2005).

Thus, temperature is intensively used as qualitative and/or quantitative indicator of flow in

most of GDE investigations. At first, spatio-temporal thermal variability in the HZ permits to

allocate zones of groundwater recharge or discharge. Schematically, gaining river reaches or

lake shores are characterized by relatively stable temperatures, whereas losing reaches

demonstrate vastly variable heat balance behavior (Fig 2.2-1; Shimada et al., 1993). Secondly,

quantitative variables can also be estimated. Thermal patterns of the HZ can be used to derive

hydraulic conductivities (Su et al., 2004) if water fluxes are known. Flux estimates are

possible by fitting solutions of the heat flow equation to observed temperature distributions in

the soil. This approach implies to use heat capacities and conductivities of water and rocks

and to identify the hydrological state of the system that is steady-state or transient. In this later

case, boundary conditions should be controlled with care, what increase the input data

requirement (Anibas et al., 2009).

Fig 2.2-1 Conceptual scheme of temperature use to assess SW-GW exchanges in a gaining

(left) and losing (right) reach.

From a technical point of view, most of the temperature sensors are portative, simple to set

up, robust, accurate (accuracy ±0,1°C)and inexpensive in comparison to other environmental

measurements devices. Expanded memory permits long working time. Recently, significant

progress were made in the understanding of HZ processes, through high frequency monitoring

(Hoehn and Cirpka, 2006; Vogt et al., 2010). This tool was also revealed to be highly useful

to understand disturbed system such as hydropower regulated environment (Gerechtet al.,

2011). Apart from direct measurements of temperature using deployed sensor techniques an

airborne IR technology can be applied where large scale spatial distribution of

recharge/discharge zones should be defined. An example of IR measurements form a stream

is shown in Fig. 2.2-2.

Fig. 2.2-2 Image of temperature photography from a stream with groundwater intrusion

(black color, photo Pöyry Ltd).

Thus, in several Genesis case studies, temperature monitoring at various spatio-temporal

scales is actively employed. For example, the evaluation of lake-groundwater interactions

(localizations, fluxes) was carried out within a large esker body in Finland (UOULU); and

river-groundwater interaction downstream to a dam in Sweden (LTU) in order to provide

basis for flow modeling.

Due to retardant behavior of temperature (especially where conduction is important in

comparison to advection), this tracer cannot be easily used to evaluate water transit times over

long distances. Combination with another tracer technique is often necessary.

Electrical conductivity

Electrical Conductivity (EC) is an indicator of ionic content of water. Usually, there is a large

difference in EC between surface water and groundwater. This difference is due to

heterogeneity of transit times (generally longer within aquifer, allowing longer water-rocks

interactions) and of weathering degree (alteration power is higher in sub terrain systems due

to higher pCO2) (Appelo and Postma, 2005). This gradient is even greater in coastal areas

where GDEs are influenced by seawater intrusions. Fluctuations of EC results from variation

of total dissolved solids. Electrical conductivity propagation has the advantage to be mainly

dependent on Darcian velocity through the porous media concurrently showing less smooth

trend (Cirpkaet al., 2007) which is not the case for the temperature. In aquatic ecosystems, EC

variability may be caused by biological carbon turnover on seasonal scale, and such factors as

photosynthesis and respiration on diurnal basis (Odum, 1956). More stable signal from EC

varies on a diurnal basis due to variations in bicarbonate and hardness (affect inorganic

carbon cycle equilibrium, provoking phase changes – either precipitation or dissolution of

calcium and magnesium carbonates), on several days basis as a result of extended

precipitation, and on seasonal basis reflecting winter base flow conditions dominated by the

groundwater flow (in majority of the cases).

Similarly to temperature monitoring, different infiltration regimes can be registered by

analyzing diurnal and seasonal EC patterns. As it has been observed by Hatch et al. (2006)

daily EC variations are predominantly distinct at low river water level and high temperatures.

Diurnal photosynthetical processes responsible for pCO2 fluctuations keep EC highest in the

early morning, and lowest in the afternoon. Seasonal variations usually introduce

discrepancies between the river and groundwater data sets and can be mathematically

removed. Assuming a constant EC in the subsurface waters SW-GW interactions may be

evaluated through deconvolutions of the temporal EC signal on the SW-GW interface. This

technique also assumes that EC is a conservative tracer, what is not the case in reality.

Consequently, to allow the direct evaluation of water transit time, EC modifications due to

weathering or precipitation processes should have significantly slower kinetics than water

velocity.

There is a variety of conductivity measuring cells available on the market. Many of them

incorporate logger, some require an external logger connection. Due to the temperature

dependency of measured EC, these devices are often combined with temperature sensors. The

instruments obtained high measuring accuracy however they require periodical calibration

due to foiling and drift.

In the Luleå case study (LTU) EC is used in conjunction with temperature and water level

measurements. Higher EC values are observed at the day start when CO2 concentrations are

highest and during winter when the base flow is dominant (relevant for the pristine Kalix

River). High river water stages in the hydropower regulated Lule River provoke decreased EC

plume in the HZ.

2.3 Geochemistry as indicator of groundwater

Geochemistry of groundwater is usually characterized by the bedrock and porous media

where it flows. This leaves a signal to the groundwater that can be distinctly different from

surface water. Precipitation is usually free from or low in most weathering products. The

potential use of geochemistry as indicator depends on i) the stability or conservative nature

of the chemical compound, ii) differences in end-members (e.g groundwater and

precipitation). In theory chemical composition of water can be used to determine age and

hydrograph separation to estimate the portion of groundwater. Age determination is

qualitative (old or new etc).

In many cases groundwater composition is stable whereas surface water responds more

rapidly to precipitation events and biological in-stream retention and release of substances.

Also the rate of erosion and decomposition rates of vegetation influence stream water

composition. Typically streams have highest suspended matter and humic compounds seen

as elevated color, dissolved organic matter, TOC, DOC and BOD

In groundwater the chemical composition can vary spatially from point to point. This is

normally due to changes in sediment and bedrock properties, water residence time in soils

and rock and pH. Changes in pH directly influence composition and concentration of many

elements such as Al. Redox potential and oxygen content will also influence the

composition. Recently percolated water or unsaturated soil layer (vadoze) water is normally

different from groundwater.

Geochemical compounds that have been used in hydrological studies include SiO2, electrical

conductivity (EC). SiO2 is a weathering product and it seems to increase with groundwater

age. Similarly EC increases with age and is higher in groundwater than in rainwater. As EC

is easily measured automatically, it can give information on events as shown in fig 2.3-1

where inflow and outflow hydrographs are shown for a Fen in Norway (Kværner and Kløve

2008).

Fig 2.3-1 Hourly stream water electric conductivity (lS m_1) and runoff at fen inlet and

outlet during episodic events (Kværner and Kløve 2008).

Chloride (Cl) in precipitation is a useful tracer. Its mean concentration in rainwater depends

on distance from the sea. It is a conservative compound with no or little reaction and it

increases only due to evaporation. It is also commonly linked to pollution such as application

of road salt, municipal waste and sewage. It can indicate sea water intrusion or relict sea

water or salt deposits in the ground. Following Cl as a tracer can be valuable with other

tracer measurements as it is conservative and therefore indicate external input from

contaminated sites or different waters. It is also useful for mass balance studies in case of

evaporation being a major component. Cl normally correlated well with EC which is easily

and affordably measured in the environment, at least when the Cl concentration is high.

There are some difficulties in using geochemistry however. The compounds can be

influenced by pH-Eh environment. Also the concentration can be time dependent so different

end members are difficult to define for hydrograph separation. Also, they are not as widely

used as isotopes.

2.4 Isotopes as indicators of groundwater

A spatially and temporally integrated view of relations between the GDEs and the local and

regional groundwater flow systems can be provided by environmental tracers such as stable

isotopes of water, tritium, noble gases, CFCs or SF6 (e.g. Kværner and Kløve, 2006;

Ronkanen and Kløve, 2010). Besides their significance in developing conceptual and

numerical models of flow and transport in groundwater systems the environmental tracers

allow identification and quantification of sources of discharge to GDEs as well as dating of

groundwater.

Fig 2.4-1 Distribution of measured 18

O and artificial tracer addition in a peatland that received

peat harvesting runoff water (treatment wetland). The main flow field is shown with a thick

line. (Ronkanen and Kløve, 2008)

Water isotope measurement within a GDE show areas where flow occur and this can be

related to flow fields in GDE which is useful for calibration of models. In systems with small

amount of inflow with constant properties, areas of elevated18

O would indicate stagnant zones

with no flow if system is sampled after a dry period. Evaporation of surface water bodies (E)

leads to enrichment of the liquid phase in heavy isotopes 2H and

18O. Consequently, stagnant

zones within the wetlands will have a high evaporation/inflow (E/Q) ratio and should be

characterized by elevated 2H and

18O content compared to the inflow of wetlands when E/Q is

low. Therefore, properly designed survey of stable isotope composition of water within the

given wetland system should yield important information concerning spatial heterogeneity of

isotopic composition of water in this system. Isotopic composition can be linked to the water

flow patterns, residence time and preferential flow. Stabile isotopes are useful also when the

residence time in GDEs is very long and tracer additions cannot be used due to (i) unsteady

flow caused by changing hydraulic load and weather, (ii) density currents (Schmid et al.,

2004) and (iii) high costs or intensive time requirement. The principle of this method is

highlighted in figure 2.4-1 (Ronkanen and Klöve, 2008) that shows measured 18

O and

artificial tracer addition in a peatland wetland that received runoff water (treatment wetland).

Areas of groundwater upwelling would be seen as different isotopic signatures than areas that

receive surface water only. Studies of isotope can show areas where groundwater interacts

with the GDEs.

In surface water - groundwater interaction isotopes can be used to verify this contact. A

classical example is the study of stream water influence on groundwater in a pumping well

along the stream bank (Fig 2.4-2, after Stichler et al. 1986). Applying mathematical flow

models to environmental tracer data it is possible to obtain the following practical

information in bank filtration research problems: (1) calculating the portion of river water

infiltrating to the groundwater; (2) determining flow parameters: mean transit time of water,

T, and dispersion parameter, D/vx; and (3) predicting possible contamination of the

groundwater by pollution of the river water.

Fig 2.4-2 Schematic model of streamwater mixing into a groundwater pumping well along a

stream groundwater area of the Danube river (Stichler et al 1986).

Lake–groundwater interactions isotope studies have focused on i) modelling of the water flow

in the surrounding lakes (e.g. Winter, 1978, 1983; Cheng and Anderson, 1994; Kacimov,

2000, 2007; Abbo et al., 2003) and ii) application of environmental tracer data to calculate

water balance in lakes (e.g. Zuber, 1983; Gonfiantini, 1986; Herczeg and Imboden, 1988;

Yehdegho et al., 1997; Katz et al., 1997 or Kumar et al., 2001). A recent study below (Fig

2.4-3) shows how a groundwater well capture zone can be estimated and the portion of lake

water in the groundwater can be estimated with environmental isotopes (Stichler et al 2008).

Fig 2.4-3 Simulated contour lines of hydraulic head (m. a.s.l.), lake water proportion (%) in

down gradient aquifer and final contour of the capture zone (grey shade) found as a best fit for

observed and simulated hydraulic heads and lake water proportion distribution (Stichler et al

2008).

2.5 Tracer tests

Artificial tracers (isotopes, salt, fluorescent dyes and color) can be added to groundwater or

surface water to study flow processes in aquifers and related ecosystems. Typical additions

points are groundwater wells or stream points with good mixing conditions. The benefit of

using salt such as NaCl is that it can be easily measured with electrical conductivity after

calibration of conductivity probes. The use of salt pose a risk of density currents and the flow

velocity (Reynolds number) of the system must be sufficient. If used in groundwater

piezometers, these must be properly mixed after salt addition.

Tracers show flow pathways and give information about aquifer structure including hydraulic

conductivity. Tracer tests in streams can give information on hyporheic exchange. Sometimes

conservative tracers are used in combination with reactive tracers if retention of substances is

studied. Typically also several tracers are used in parallel. Sometimes simple tracers can be

used first before a more detailed analysis with e.g. radioactive 3H. The use of radioactive

tracers normally requires a permit from authorities where risk of use is estimated. Tracer test

require detailed plans for monitoring design. Normally, they give important new information

about the groundwater system (Fig. 2.5-1).

Fig. 2.5-1 Injection well and detection wells. This tracer experiment showed groundwater

flow from injection well towards wells 1-3 (photo UNIZG-RGNF, Croatia).

2.6 Mapping of recharge and discharge points

In many cases mapping of recharge and flow patterns in space can be valuable. This can be

done using maps e.g. to detect fracture zones that potentially carry groundwater (Fig. 2.6-1).

Fig 2.6-1 Groundwater exfiltration from fractured rock along faults and fracture zones

(www.ngu.no).

In shallow small groundwater systems the recharge-discharge patterns can be complex. In

many cases a detailed survey of discharge patterns is crucial to understand the overall flow

system. A result from such a analysis is shown in Fig. 2.6-2 for the Rokua sand aquifer in

Finland.

Fig. 2.6-2 Discharge measurement points (blue dots) from the Rokua recharge area (white

area). Relative size of blue dot shows the amount of baseflow run-off.

3. Results from GENESIS main GDE study sites

3.1 Esker aquifer lake interaction, Rokua Finland

3.1.1 Hydrogeology, site description and methods

Esker aquifers were formed during the last deglaciation some 9000-12 000 years ago

(Tikkanen 2002). Long and narrow formations of sand and gravel are associated with the

retreat of the ice (Svendsen et al. 2004), which in Fenno-Scandinavia had its centre just north

of the Bay of Bothnia. Eskers form important aquifers in the Fenno-Scandinavian shield and

are also common in other regions covered by the last glaciation.

The Rokua esker area forms part of a long esker ridge stretching inland from the North

Ostrobothnian coast (Aartolahti 1974; Ala-aho 2010). It is situated 100 km inland from the

coast, has an area of 90 km2 and rises at its highest point about 80 m above the surrounding

peatlands. It is clearly visible in an otherwise flat landscape. The esker material consists

mainly of sand with layers varying in thickness from 30 m to more than 100 m above the

bedrock. A deposit of gravel has also been found. Rokua has a rolling terrain because of

kettle hole, wave action and aolian dunes (Aartolahti 1974). In contrast, the surrounding

peatlands started to form some 8000 years ago between the sand deposits and in some kettle

holes (Pajunen 1995). These peat layers have grown to be in some locations more than 5 m

thick and have a low permeability (Fig. 3.1-1). Groundwater recharges on the esker sand

areas and discharges to surrounding peatlands and nearby water bodies.

Fig 3.1-1 Cross-section of Rokua esker with location of groundwater table, potentiometric

surfaces and indication of water level variation and flow patterns in ecosystems (arrows).

Eskers are often connected to rivers, lakes and wetlands, and such groundwater-dependent

systems are of high ecological value (Kløve et al. 2011a; 2011b). Ecosystems protected by

NATURA2000 in Rokua area include rare lake types, old forests in natural state and lichen

coverings supporting endangered vegetation and insect species.

As lakes on the Rokua esker are embedded in the aquifer, both lake water levels and water

quality are highly dependent on the aquifer system. The highly dynamic relationship

between lake systems and aquifers is largely determined by geology, climate and topology of

the area. Interactions between lakes and groundwater can be divided into three basic types.

The lake can have: 1) groundwater inflow from the entire lake bed (groundwater discharge);

2) groundwater outflow from the entire lake bed (groundwater recharge); or 3) both

situations occurring at the same time in different parts of the lake (Winter et al. 1998, Ala-

aho 2010). Groundwater exchange not only affects lake water levels and water chemistry,

but also lake ecosystems by providing nutrients, inorganic ions and stable water temperature

(Hayashi and Rosenberry 2002).

Groundwater-fed kettle lakes of Rokua consist of two different types. Lakes without outlet

are clear and oligotrophic. Lakes with outlet on the other hand are more humic and

eutrophic. Both lake types are in a natural state and have a high recreational value though

groundwater level decline has caused changes in lake vegetation (Metsähallitus 2008).

Another groundwater dependent ecosystem in Rokua area are the springs in the surrounding

peatlands. Many of these springs have dried due to peatland drainage which has changed the

groundwater flow systems (Rossi et al. submitted). Spring ecosystems in Rokua discharge

area are mostly not included in natural conservation programs as they are too heavily altered.

Groundwater-surface water interaction in the kettle lakes were studied with seepage meters

(Lee 1977), chemical analysis and potentiometric measurements (Rosenberry and LaBaugh

2008). Seepage meters were used to measure temporal variation of groundwater discharge

and recharge rates in a pilot lake Ahveroinen. Measurements were made during two

sequential years. First year (2009) focus was more on the spatial variation, where the second

year (2010) measurements focused on the temporal changes in seepage. Chemical analyses

were used as natural tracers to define groundwater and rainwater ratios of lake inflow.

Potentiomanometer was used to identify groundwater exfiltration areas in peatlands.

Manometers will also be used in lakes for seepage definition and water sampling.

3.1.2 Major outcome from the study

Seepage measurements during years 2009-2010 revealed high spatial variation in seepage

velocities around the lake (fig. 3.1-2), with values ranging from -0.95 – 56 µm/s.

Fig 3.1-2 Interpolated seepage velocity around the lake during two consecutive years. For

both years inseepage is concentrated in the southern part of the lake, but outseepage shows

variation between years.

Results for year 2009 show inseepage areas in the southern part of the lake, and only obvious

outseepage measurements are found in north-east. During year 2010 inseepage was again

measured in the southern part, but outseepage was more concentrated in the western shore.

Interpolation and spatial distribution for 2010 is not as accurate as for 2009 because of only

six measurement locations (2009 16 locations). Reasons for differences in measurements

between 2009 and 2010 need further investigation, but are most likely related to

measurement errors (more probable in 2009 measurements) and differences in hydrological

conditions between years.

To reveal temporal variability in seepage velocity in lake Ahveroinen, eight seepage meter

measurements were made from six locations (fig 3.1-3) during 1.6.2010 – 4.11.2010 (in total

64 measurements).

Fig 3.1-3 Temporal variability for each measurement point 1-6 during year 2010.

According to seepage meter measurements seepage velocities remained quite constant during

measurement period, with no dramatic changes in e.g. direction of seepage from inseepage to

outseepage. Nevertheless seepage shows similar behaviour especially in points where

outseepage was constantly measured (points 1,2,4 and 6). This suggests that temporal

variation in seepage was not entirely caused by random variability and measurement errors,

but was to some extent related to changes in hydrological conditions (groundwater and lake

levels) during study period.

Spatial and to some extent also temporal variability of groundwater-lake interaction in pilot

lake Ahveroinen gives valuable insight of hydrology of all the lakes in Rokua esker area.

Lakes in the area are situated in different parts of the esker with unique hydrogeolological

settings surrounding each lake. Thus contribution of groundwater in lake hydrology can vary

significantly between individual lakes. This can lead to different behavior of lakes water

levels and also possibly trophy status in changing hydrogeological conditions, such as

extreme droughts.

3.1.3 Conceptual models for surface water – groundwater interaction

Lakes in the aquifer can roughly be divided to two categories with following attributes:

Table 3.1-1 Attributes characterizing lake types.

Attribute Type 1 Type 2

Lake level variability high/moderate low

trophic status oligotrophic eutrophic

nutrient/ion concentration low high

connection to streamflow closed basin lake inlets and outlets

elevation on the esker lower higher

Many of the differences between two lake types can be explained by the conceptual idea of

local and regional groundwater flow systems (Fig 3.1-4):

Fig 3.1-4 Conceptual model of regional and local groundwater-lake interactions.

Water levels in type 1 lakes depend on groundwater inflow from local flow system. There

GW inflow and outflow are mainly determined by GW-levels adjacent to lake. Therefore

changes in GW-table (resulting from changes in recharge) can have a significant impact in

GW-SW interaction. Residence time of GW discharging to lake is relatively short, possibly

leading to less leaching and chemically poor water (Fig 3.1-4).

In type 2 lakes, water level is affected by regional GW flow system, in addition to local flow

systems. Inflow is less sensitive for GW-table fluctuation/decline, as regional flow system

sustains steady inflow and local inflow can be replaced by regional inflow during season of

low recharge. Also inlets and outlets connecting the lakes favor steady water table.

Residence time of regional GW-flow is longer, leading possibly to more leaching from soil

to groundwater (Fig 3.1.-5).

Fig 3.1-5 Silica content with respect to lake altitude and lake type. More silica can be

explained by leaching and longer residence time.

3.2 Lule river hyporheic zone interaction, Sweden


Introduction

River regulation is extensive; about two thirds of fresh water flow into the sea is today

delayed by dams higher than 15m (Nilsson & Berggren, 2000). Malm Renöfält et al. (2010)

summarize the resultant pressure on freshwater ecosystems as:”Freshwater ecosystems now

belong among the world’s most threatened ecosystems”. Further stress on rivers can be

expected with pressure to increase hydropower production when phasing out of fossil fuels

and increasing the use of alternative power.

The pristine northern rivers are gaining (fed by the groundwater aquifers), even if shorter

stretches might be losing (e.g. Johansson et al. 2001) and the water stages in the ground and

the river are synchronized so high river water and groundwater stages typically coincide.

However, in regulated rivers this pattern is disturbed since high river water stages will occur

when the groundwater levels are low and vice versa. When short time regulation is practiced

rivers might change from gaining to loosing and back again within a day resulting in a

disturbed hyporheic zone and a perturbed ecosystem (Andersson et al. 2000; Nilsson &

Berggren 2000; Jansson et al. 2000; Jansson 2006).

In northern regulated boreal rivers the water is released fairly evenly throughout the year in

contrast to the normal seasonal runoff pattern with a clear snowmelt runoff peak (Fig 3.2-1).

Parts of the river stretches have minimum runoff while most of the water for these stretches

is diverted through tunnels to a turbine and then returned to the river (Figure 1). In many

rivers short time regulation is also applied in order to adjust the energy production to the

energy demand (large fluxes during days and small during nights). All these river and lake

alterations have impact on the groundwater in the river basin. In this study we focus on the

effects of altered seasonal pattern and short time regulation on the hyporheic zone, which is

the area just under and close to the river, where groundwater and river water mix.

During the last decade processes in natural hyporheic zones have been studied extensively

(Johansson et al. 2001; Jonsson & Wörman 2001; Landon et al. 2001; Cardenas & Wilson

2007; Claret & Boulton 2008). However, the knowledge regarding the hydrogeochemical

processes in the hyporheic zone for regulated rivers seems limited. Most studies seem to

focus on the water and heat fluxes (Sawyer et al. 2009; Arntzen et al. 2010; Gerecht et al.

2011) while studies of river regulation and resulting alterations of geochemical processes

seem rare (Nyberg et al. 2008).

Aim and scope

In order to increase our understanding of hyporheic zone processes when rivers are exposed

to seasonal regulation and short term stage fluctuations a test site has been installed at the

heavily regulated Lule River. The aim with the monitoring program was to register major

changes in groundwater fluxes, temperature patterns and geochemistry of the hyporheic

zone.

Fig 3.2-1 Conceptual representation of a pristine river (top) and the same river obstructed by

hydropower dam (base). Seasonal pattern of river discharge, groundwater stages and

groundwater flowpaths in response to river level fluctuations are shown.

River basin description

The Lule River is located in Northern Sweden; the river originates in the Caledonide

mountains with tundra type vegetation and flows south east through coniferous forests. The

upstream parts of the river include quartzite, mica schist, and amphibolite with a little

dolomite and limestone. Volcanic and plutonic rocks with till and podzol soils are prevalent

downstream (Fromm, 1965). The climate is sub-arctic with monthly average temperatures

ranging from –15ºC to +14ºC. Annual precipitation decreases from 1,000-1,500 mm in the

mountains to 400-700 mm at the coast and about 45% of it falls as snow. Annual

evapotranspiration is 100 mm in the upstream areas and 300 mm at the coast. The Lule

River is typically ice covered 5 months. The river is around 440 km long with the drainage

area 25110 km2 and average annual runoff 506 m

3/s (SMHI, Svenskt Vattenarkiv).

Site description

The Lule River case study site is located 100 km upstream from the river mouth (Fig. 3.2-2)

and a couple of km below a dam. The regulation pattern implies relatively low spring peaks

and high winter base flow, which favors collimation of the river bed and formation of a

clogging layer. Daily water release from the dam makes the river water stage typically vary

within about ±0.5 m. Fluvio-glacial and alluvial sediments dominate at the site interlaid by

sand and silt in hyporheic zone, while coarse sand is seen at the deeper horizons. The

average thickness of the alluvial pack is around 10m, with maximum 60-70m (SGU map

service). Existence of the clogging layer that is mostly composed of silt particles complicates

the exchange between the river and the hyporheic zone. Hydraulic conductivity of the

hyporheic sediments and the clogging layer differ two orders of magnitude on average. We

expect the clogging layer on the river-aquifer interface to increase residence time of the

water in the shallow hyporheic area. The river at the test site is around 300 m wide and 10m

deep.

Fig 3.2-2 Case study map with location of the study sites in the Lule and Kalix River.

Hypothesis

According to Boutt and Fleming, (2009) an advection-dispersion wave enters the hyporheic

zoned during high river water stages, with a dispersion front advancing ahead of the

advected water front (Figure 3). However, when the river stages fall below the groundwater

stages, only the advected water is returned back into the river (Fig 3.2-3). The dispersion

front may remain in the hyporheic zone for longer time thus affecting the groundwater

quality.

The findings of Boutt and Fleming (2009) were used as hypothesis for this study of

exchange processes on the surface water-groundwater interface in the regulated

environment. It was used to design the field monitoring and the modeling.

Fig 3.2-3 Groundwater movement in the hyporheic zone with advection and dispersion front

movements during raising water stage (left) and decreasing river water stage (right) for a

regulated river (modified from Boutt and Fleming, 2009).

Field site experiments and sampling

Four groundwater wells and one river station were installed in a profile orthogonal to the

river (Fig. 3.2-4) to collect continuous time series of water level, temperature, electrical

conductivity and pH. Logging equipment with transmission units was used to record and

transfer data. Water was sampled from the wells and the river for major chemical

compounds and nutrients on weekly or biweekly basis. The monitoring campaign was started

in July 2010 and continued for one year. A similar site was organized for monitoring the

hyporheic zone in the pristine Kalix River. Additional tests were conducted in the Luleå

River to determine the hydraulic conductivity of the clogging layer using constant pressure

head infiltration method (Cardenas and Zlotnik, 2003). Seepage measurement technique was

applied to collect information on spatial and temporal seepage distribution (Lee, 1977).

Plastic seepage devices were designed to collect samples for seepage water quality analyses.

A simple conservative tracer test was performed to monitor water movement in the

hyporheic zone and assess importance of the hyporheic zone flow parallel to the river flow

and water residence time in this zone.

Fig 3.2-4 General design of the monitoring site at the Lule and Kalix Rivers.


A set of geochemical and hydrological data including time series and bi-weekly taken water

samples were collected during one year monitoring period. Continuous observations

revealed tight connection between the river and the hyporheic zone. Preliminary analysis

showed frequent and high water stage variations in the river introducing an impulse wave

with an advection and dispersion front into the subsurface, confirming the above hypothesis.

Water level fluctuations in this area reached more than 1,5m at its maximum.

As a result of regulation the river water discharge was averaged throughout the year thus

decreasing the spring flood. River water temperature was slightly higher in winter and lower

in summer compared to the unregulated Kalix River. Altered Fe, Si, Mn, P and TOC

transport patterns were also observed in the regulated river where the seasonality of the river

transport was modified with a shift of spring and summer transport towards winter when the

river discharge was elevated due to increased electricity demand. We expect occurrence of

similar changes in water quality of the hyporheic zone.

Ground water stage response in the hyporheic zone to the varying river stages was almost

instant with water stage response decreasing inland. Preliminary assessment showed that,

during raising river water stages, river water with lower concentration of major dissolved

elements penetrates the hyporheic zone and introduces a diluted plume. The plume is

returned into the river once water stages were reverted. However, dispersion processes may

retain lower concentration in the hyporheic zone (Boutt and Fleming, 2009).

A tracer injection test showed a narrow plume (orthogonal to the river) of high electrical

conductivity groundwater flowing to the river suggesting absence of hyporheic flow parallel

to the river.

3.3 Riperian zone interaction, Switzerland


Description

The area of interest is located near the city of Sierre, in a Swiss alpine valley (46o17’35’’N;

7o31’59’’E; Fig 3.3-1A) The site mainly consists on the alluvial plain of the upper Rhône

river and occupies an area of approximatively 700 ha with an altitude varying from 500 to 700

m a.s.l. In this zone, the river flows from north-east to south-west (length ≈ 6 km) over about

50 m thick quaternary heterogenous fluvial deposits (width ≈ 1.5 km) which filled a valley

located at the contact between the Penninnic units (Carbonates, anhydrite, gypse) on south

and Helvetic units (Carbonates) on north. It constitutes one of the 100 most important

ecological zones at the European scale, and presents a spectacular biodiversity for both fauna

and flora (Bendel et al., 2006).

From a hydrological point of view, the mean annual local rainfall height is about 587 mm,

that leads the Pfyn forest to be the driest site in Switzerland (Schurch and Vuataz, 2000). The

upper Rhone watershed regime is of mainly of nival type: the snow and glaciers melting

provide a considerable amount of freshwater in the system during summer (Fette, 2005), and

low-level occurs during winters. From a spatial point of view, and on the basis of the dense

network or borehole located in the basin (CREALP), Schurch and Vuataz (2000) described

two main recharge areas of the aquifer (Fig 3.3-1A): the northeastern limit of the studied area

where surface water moves from the Rhone river bed on a front of about 700 m wide,

southward into the alluvium and the east-central part of the area where subsurface flow

supplies the Rhone alluvium. During low-level periods, the local subsurface flow coming

from the south part of the area (Penninnic units) remains the almost unique source of water

entering the alluvium. From an ecological point of view (Fig 3.3-1B), phytocoenosis vary

from dry environments associations (Pinus sylvestris, Stipa sp.) to active floodplain

associations (Alnus incana, Salix sp.) from upstream to downstream. Between these two end-

members, a mixed transition forest took place.

Method

For this study, 3 sites, S2, S4 and S5, were selected across the river plain (Fig 3.3-1B).

Studied sites were featured by various hydrological and pedological conditions which are

strongly related with the distance from the main river bed. To assess factors influencing water

uses patterns, oxygen-18 and deuterium signatures in the various water cycle compartments

(rainwater, soil water at various depths between 10 and 100 cm, plant water, groundwater,

river) were investigated in addition to the monitoring of hydrometerorological conditions. The

use of isotopic tools was described (e.g. Ehleringer and Dawson, 1992) and shown to be

useful in similar environment (e.g. Sanchez-Perez et al., 2008) because of the absence of

fractionation during plant water uptake. The field campaign was carried out between the

22/04 and the 31/08/2010 with a two weeks resolution and between the 31/08/2010 and

16/02/2011 once a month.


At the ecosystem scale, the direct consequence of recharge seasonality is an important

piezometric level variation (about 8 m) near the supplying river zone. In contrast, the

downstream part of Pfyn is characterized by a lower annual piezometric variability of about 1

or 2 m (Schurch and Vuataz, 2000). The hydrological continuum between the extreme

groundwater level variation zone and the buffered groundwater level variation zone could, at

least partially, explain the ecological continuum between dry ecosystems, upstream that might

not adapt to strong water access variability and the more typical groundwater-dependent

biocenoses, downstream.

In this area (S2, S4, S5), the comparison of isotopic signatures of rainwater, soil water and

groundwater indicate a variability of water uses that seems to be individual, species and time

dependant. As an example,

presents the statistics of the δ18

O and δ2H signatures for the different compartments analyzed

at the site S4. Rainwater has the most important variability (δ18

O= -9.9±3.6 ‰ vs VSMOW;

δ2H= -74±28 ‰ vs VSMOW) whereas groundwater is very stable (δ

18O= -14.9±0.7 ‰ vs

VSMOW; δ2H= -107±4 ‰ vs VSMOW). It appears that isotopic signatures variability

diminish from rainwater to groundwater through surface soil layers and deeper soil layers.

Plants show different trends according to the considered individual.

Through temporal correlation analyses (Table 3.3-1), it appears that soil signatures variability

depends on meteorological processes i.e. the rainfall input signature and an eventual

evaporation effect (but generally small according to Barnes and Turner, 1998) and on the

hydrodynamics of the soil layers (mixing, single of dual permeability) (e.g.; Brooks et al.,

2010). Surface layers (especially 10 and 30 cm layer) seem directly influenced by

meteorological processes. The deeper does not show relationships with rainwater, what

indicate that isotopic signatures should be more influenced hydrodynamic processes (e.g.

mixing). Plants and soils correlations are generally significant but vary between sites. In the

site S2, the poplar (Populus) signatures show correlation with 80 and 100 cm layers. The wild

cherry (Prunus avium) with 30 and 60 cm depths, and willow (Salix alba) with 80 cm layer.

In the site S4, the poplar does not show correlation in contrast to the willow, the pine (Pinus

sylvestris) shows consistency with 10 and 30 cm layers as well as the wild cherry (10 m)

interacting with soil 30 cm.

These correlations should be taken with care: Temporal variability of water uptake by plants

which can shift from a water source to another has been already pointed out by other studies

(Chimner and Cooper, 2004, Boujamlaoui et al., 2005; Li et al., 2006). In this context, the

accounting of the local specificities of each site (i.e. hydrometeorological conditions, soil

water patterns, and isotopic evolutions of each compartment) has to be taken into account. For

example, through Fig 3.3-2 illustrating soil and willow (showing no significant correlation

with any water compartment) patterns in S2, it can be seen that:

- Soils 10 cm present an obvious seasonal patterns that should be linked with rainfall

input (cf. Table 3.3-2). Soil 60 cm present a more complex pattern but variations are

generally buffered, always varying between 10 cm and groundwater signatures.

Sometimes (weeks of 15/07 and 29/07/2010), when piezometric level is the highest (-

3.2 m) soil 60 cm have a similar signature to groundwater (δ18

O # -14 ‰). This

observation suggests that groundwater might reach this zone, what would occur

through capillary rise. Such process has already been involved by Chimner and

Cooper (2004) and Sanchez-Perez et al. (2008) in a similar environment. Capillary rise

should also be favored by the increasing of the gradient or water potential between

saturated zone and root zone (Bertrand et al., in press, and references therein). As the

soil water content was at their lowest values during these weeks (# 18 % weight),

capillary rise could be favored.

- Willow signature varied mainly in two ways. During spring and summer, it ranged

between surface (10 cm) and deeper (60 cm) layers. This suggest water uptake from

both these layers. As willow presents signatures between soil 10 cm and soil 60 cm

during growing period and as soil 60 cm could be supplied by groundwater, these

results indicates that willow is potentially dependent on groundwater. During autumn

and winter, willow signature stabilized with a signature close to the signature of the

end of summer. This could indicate that the tree almost stopped to pump water, what

could be consistent with the end of the growing during cold period.


These results imply that surface water-groundwater interaction should ensure the equilibrium

the whole Pfyn forest ecosystem. At the alluvial plain scale, these interactions mainly occur at

the upstream site, implying a strong piezometric variation. In this area, dry ecosystem species

are favored because groundwater supply varies a lot. Downstream, this interaction seems to

play an important role from an ecological point of view. Capillary rises may favor

groundwater supply for plants. These results permit to propose a conceptual scheme of

surface water-groundwater-biocenoses interactions (Fig 3.3-3Fig). It highlights that these

interactions are dependent on hydrological condition (the nival regime implies that high flow

occur during growing period) and on pedological conditions because capillary rise is

generally favored by fine soil texture. These factors should be taken into account to

understand the importance of surface water-groundwater interactions for GDE functioning. It

would be also highly valuable for scenarios proposals on the future of these systems in the

context of global climate change (potentially changing river-aquifer relationships) and local

soil use changes (potentially changing alluvial forest groundwater supply).

Fig 3.3-1 Location and schematic geologic map of the Pfyn forest area, Canton Wallis,

Switzerland (modified from Schürch and Vuataz, 2000); (B) Ecological settings of the Pfyn

forest.

Fig 3.3-2 Meteorological, hydrological and isotopic data for site S2. Lines in

18O and water

content graphics represent trends through the 4 weeks mobile means.

Fig 3.3-3 Conceptual scheme of surface water-groundwater –biocenoses interaction (exemple

of willow at site 2) in the Pfyn alluvial forest.

Table 3.3-1 Examples of isotopic data statistics of isotopic data for plants, soil, rain, surface

waters and groundwater.

Variable

Nb of

Observations Mean

Std

deviation

δD (‰) Populus 15 m S4 16 -76 17

δ18

O (‰) Populus 15 m S4 16 -9.8 2.4

δD (‰) Prunus avium 10 m S4 15 -81 15

δ18

O (‰) Prunus avium 10 m S4 15 -10.2 2.4

δD (‰) Salix 2 m S4 16 -83 13

δ18

O (‰) Salix 2 m S4 16 -10.3 2.0

δD (‰) Alnus 10 m S4 14 -90 10

δ18

O (‰) Alnus 10 m S4 14 -11.6 1.4

δD (‰) Pinus Sylvestris 8 m S4 15 -70 20

δ18

O (‰) Pinus Sylvestris 8 m S4 15 -8.2 3.3

δD (‰) Soil 10 cm S4 15 -68 29

δ18

O (‰) Soil 10 cm S4 15 -8.8 4.2

δD (‰) Soil 30 cm S4 15 -74 28

δ18

O (‰) Soil 30 cm S4 15 -9.5 4.2

δD (‰) Soil 60 cm S4 14 -79 16

δ18

O (‰) Soil 60 cm S4 14 -10.9 2.4

δD (‰) Soil 80 cm S4 13 -76 13

δ18

O (‰) Soil 80 cm S4 13 -10.2 1.7

δD (‰) Soil 100 cm S4 6 -74 8

δ18

O (‰) Soil 100 cm S4 6 -10.0 1.5

δD (‰) Groundwater S4 16 -107 4

δ18

O (‰) Groundwater S4 16 -14.9 0.7

δD (‰) Rhône S5 15 -108 4

δ18

O (‰) Rhône S5 15 -15.1 1.0

δD (‰) Rainwater 13 -74 28

δ18

O (‰) Rainwater 13 -9.9 3.6

Table 3.3-2 Pearson correlations between soils layers, plant and rainwater for the 3 studied site.

Groundwater does not show significant correlation with the other compartments.

Significant values of Pearson correlations

respectively for δD and δ18

O (α=0.1)

Site S2 Populus / soil 80 cm (0.585 0.737);

Populus / soil 100 cm (0.558-0.588)

Prunus avium / soil 30 cm (0.552-0.479 );

Prunus avium / soil 60 cm (0.559-0.502)

Salix : No significant correlation

Soil 10 cm /rainwater (0.641-0.618)

Soil 30 cm / rainwater (0.504-0.479)

Site S4 Salix / soil 10 cm (0.685-0.556 );

Salix / soil 30 cm (0.642-0.488 ) ;

Salix / rain (0.536-0.572)

Alnus : No significant correlation

Pinus sylvestris / soil 30 cm (0.780-0.728 );

Pinus sylvestris / soil 60 cm (0.642 -0.701)

Soil 10 cm /rainwater (0.820-0.759)

Soil 30 cm / rainwater (0.502-0.472)

Soil 60 /rainwater (0.530-0.622)

Site S5 Salix : No significant correlation

Alnus / Rainfall (0.765-0.685)

42

3.4 Dalyan Mediterranean Lagoon, Turkey

3.4.1 Site Description and Hydrology

The study area is in the Dalyan Lagoon watershed that is located in the south western

Mediterranean Sea coast of Republic of Turkey (Fig 3.4-1).

Da

lya

n L

ag

oo

n

Mediterranean

Sea

TURKEY

Mediterranean

Sea

Case Study Area

Fig 3.4-1 The Study area.

43

As illustrated in Figure 3.4-2; the study that is around 70 km2 large contains high elevations on

the upland up to more than 600 m above sea level, areas with high and low slopes, geological

heterogeneousness, an estuarine lagoon system and a complex land use structure containing

agriculture, forests

The estuarine lagoon (Dalyan Lagoon) was analyzed in previous studies and divided into

different regions with homogenous hydrographical and ecological properties as illustrated in

Fig 3.4-3. The details of those detailed analyses were reported by Gurel et. al. (2005).

(a) (b)

(c) (d)

Fig 3.4-2 (a) Slope map (b) Geological map (c) Soil map (d) Land use map.

44

Fig 3.4-3 Lagoon regions with homogenous hydrographical and ecological properties.

The case study area has a relatively heterogeneous geological structure and geomorphology. The

case study area consists of alluvial and karstic regions (Fig 3.4-4). There are hot and cold water

springs (Fig 3.4-5), springs that contain high amount of salinity and hydrogen sulphide. Several

of them have naturally occurring radioactivity.

(a) (b)

Fig 3.4-4 Geological formation (a) Alluvial formations (b) Karstic formations.

45

(a) (b)

Fig 3.4-5 Springs (a) Hot spring (b) Cold spring.

3.4.2 Methods

The complexity of the Dalyan case study area necessitated application of several tools and

methods; namely spatial technologies, monitoring and modelling.

Spatial technologies were utilized to create a database of all the land and aquatic ecosystems.

Data from different sources as well as monitoring data were compiled together to create several

map layers (such as the ones illustrated in Fig 3.5-2) that are used

- to generate the basic coverage for monitoring network design and inputs for simulation

models.

- to fill in the spatial gaps in data as far as possible

Monitoring was conducted in the lagoon and in terrestrial ecosystems (as shown in Figure x.1).

Groundwater monitoring was initiated utilizing a spatially high resolution monitoring network

illustrated in Fig 3.4-6.

46

Fig 3.4-6 Initial groundwater monitoring network.

The aim of the initial groundwater monitoring network was to observe the spatial variations of

groundwater quality in order to decide on the locations and structure of groundwater monitoring

wells and to understand the importance of saline water intrusion into the groundwater system.

The preliminary monitoring study was conducted using wells that were built for water supply.

Salinity and conductivity were used to locate the sites that are likely to receive saline water

because of possible seawater intrusion. Data collected from these wells indicated that there may

be a weak seawater intrusion into the groundwater system.

To investigate the seawater intrusion, a network of six new groundwater wells was designed

(Fig 3.4-7) where groundwater level, groundwater temperature, salinity and conductivity will be

monitored.

To be able to monitor the effects of other hydrological and coastal processes related to water

cycle in the case study area, surface water monitoring was conducted as well. The monitoring

network is illustrated in Fig 3.4-8. For the aim of investigating surface water-groundwater

interaction; temperature, salinity, pH and dissolved oxygen are monitored in surface water,

where the possible anomalies in the latter two parameters can be helpful to better understand the

effect of groundwater inflow into the lagoon system.

47

Fig 3.4-7 Groundwater monitoring wells.

To support the monitoring and modelling studies related to surface water-groundwater

interaction, a stable isotope tracer study is being conducted as well. Stable isotopes of hydrogen

(2H) and oxygen (

18O) are monitored together with chloride (not as isotope) to investigate the

origin and composition of water in different hydrological reservoirs. The related monitoring

network is illustrated in Fig 3.4-9, where the circled stations are used to take stable isotope

samples.

48

Fig 3.4-8 Surface water monitoring stations.

49

Fig 3.4-9 The monitoring network for stable isotope study.

A preliminary modelling study was conducted to estimate the groundwater inflow into the

lagoon system. The model is coupled with a surface water hydrodynamics model to simulate the

water budget components in the study area including the surface water-groundwater interaction.

Vertical hydrological forcing such as evapotranspiration, groundwater recharge and upwards

movement of groundwater to unsaturated soil are estimated using SWAT. More detailed

information related to these calculations is given by Gonenc et al (2011) and Ekdal et al.

(2011). The model formed a basis for the conceptual model for surface water-groundwater

interaction explained in Section 3.4.3. Preliminary results from this model are summarized in

Section 3.4.2.

50


The preliminary modelling and monitoring studies have shown that the surface water-

groundwater interaction is likely to be two directional. To better understand this interaction, an

optimized monitoring system was designed. One groundwater well has already been

constructed for preliminary testing and operation. Other wells will be constructed in the near

future. All the wells are designed to sample from multiple depths.

Conventional models were used to quantify to link the groundwater inflow to surface water.

The results from these models indicated that the groundwater inflow into the Dalyan Lagoon is

considerable if compared with the average inflows from other boundaries. The relative

importance increases especially in summer, when the inflows from the Koyceğiz Lake and

surface runoff decreases considerably. Fig 3.4-10 illustrates the preliminary calculations for

groundwater outflows to the Koycegiz Lake.

(a)

(b)

Fig 3.4-10 Estimated groundwater outflows into the Dalyan Lagoon.

51

The outflows from Koycegiz Lake to the Dalyan Lagoon for an average hydrological year

(From 1st of October unitl 30

th of September) are illustrated in Fig 3.4-11. Related details are

given by Ekdal et al (2003).

Fig 3.4-11 Outflow from Koycegiz Lake (Ekdal et al. 2003).

Outflow from Koycegiz Lake has a low salinity (around 2-4 ppt) hence important for the

estuarine ecosystem because it represents low salinity inflow. However according to the

monitoring results in this study groundwater inflow is even less saline (0.19 ppt – 1.35 ppt) and

may represent an important source of fresh water. Especially in the summer, (hydrological day

250 and later), groundwater inflow is an important freshwater source since outflows from

Koycegiz Lake decreased to approximately 6 m3/s on average and surface run-off can be

neglected. Considering model results given in Figure x.10a, groundwater outflow was almost

the same as the Koycegiz Lake outflow to Dalyan Lagoon.

The last outcome from the study is the conceptual model described in Section 3.4.3 that has a

bi-directional surface water-groundwater interaction.


A conceptual model is developed for the Dalyan case study area (Figure 3.4-12). The

conceptual model does not only consider hydrological interaction between groundwater and

surface water ecosystems but also the ecological interaction. The model is a fully coupled one

where all components of the entire case study ecosystem are bi-directionally linked.

52

Fig 3.4-12 The conceptual model.

53

3.5 River lake lagoon interaction, Greece


The study area is located in north eastern Greece and focuses on a semi confined aquifer known

as Neon Sidirochorion aquifer formed in the alluvial plain of Vosvozis river (Fig 3.5-1).It is

located approximately 5 km from the Thracian sea and covers an area of approximately 45 km2.

It is a plain area bounded to the north and east by low hills, to the west by Vosvozis River, and

to the south by Ismarida Lake. This part comprises a very important surface water ecosystem

formed by Ismarida lake and its surrounding wetland area and belongs to the Natura 2000

network (Greek Ministry of Environment, Physical Planning and Public Works 1986, 1996) and

should be protected according to the Greek law, EU conservation policies or international

treaties, such as the Ramsar Convention of 1971.

Fig 3.5-1 Location map of the study area aquifer.

54

The topography of the Ismarida plain may be classified as a part of the Vosvozis River delta.

Main surface water bodies in the study area include Vosvozis River and Ismarida Lake. The

overall length of Vosvozis River is roughly 40 km. Ismarida demonstrates great fluctuations in

water level, area, and volume and it currently occupies part of an area previously covered by a

much larger water body. Its surface area is about 3.4 km2[2]. For drainage reasons, the local

authorities, in the past, opened a canal connecting artificially Ismaridalake with the sea. The

initial goal, however, did not prove to work well, thus sea water entered the initially fresh water

ecosystem altering its natural fresh water character. Currently, Ismaridalake is a fresh water

ecosystem during rainy season (i.e. October to May) whereas during summertime it is

transformed to a mixed fresh water - salt water system, where complex interactions among

surface water, sea water and groundwater are taking place.[1]

The hydrogeological investigation of the study area and the conceptual model development was

based on data including:

- The 1: 50,000 scale geological map of Greece.

- Borehole stratigraphy data.

- Groundwater level data.

- Groundwater quality data.

- Isotopic analyses data.

- Previous studies data and results which were reassessed.

Hydrochemical data acquired during 2009 and 2010 showed that in the northern part of the

aquifer the Ca-HCO3 type of water is dominant, whereas in the central and southern part Na-Cl

waters prevail. An interesting aspect is the spatial and temporal distribution of Electrical

Conductivity (EC) values in the groundwater throughout two years i.e, 2009 and 2010. In the

southern aquifer part close to Ismarida lake groundwater demonstrates a great EC variability

which ranges from 850 (May) to 4500 μS/cm (September), which is in correlation with the

changes in the lake’s salinity. In the central part groundwater demonstrates much lower

seasonal EC variability, with EC values ranging from 2500 (May) to 3000 μS/cm (September).

The northern part has lower groundwater EC values up to 1025 μS/cm and very little seasonal

variability.[1]


Groundwater flow indicates the aquifer-river and aquifer-lake hydraulic interaction, as shown in

Fig 3.5-2. Generally, groundwater level follows a decreasing trend, as one move from Vosvozis

river to the east and flow vectors are mainly vertical to Vosvozis river, indicating aquifer-river

interaction. Also, at the south boundary of the study area flow vectors follow a West-Northwest

direction indicating possible aquifer-lake interaction. Groundwater levels in the aquifer show

great variability, both seasonal and spatial as illustrated in Fig 3.5-3. In the northern and central

part of the study area, the aquifer demonstrate seasonal variation that ranges from 10 to 30m

which is the cause of intense groundwater pumping for irrigation needs. The high groundwater

drawdown during summertime causes phreatic conditions to prevail to the initially semi

55

confined aquifer system. On the contrary, the southern part of the aquifer does not demonstrate

such seasonal groundwater level variability which can be attributed to the interaction, in this

part of the aquifer, with external sources of water, mainly Ismarida lake and Vosvozis river.

Fig 3.5- 2 (a) Location map of the study area with pumping boreholes and monitoring sites and

(b) geological map and hydrogeological cross section of the study aquifer.


In order to investigate the surface water – groundwater interaction in the study area, time series

analysis was performed. Using two types of seasonal ARIMA models (the first one simulates

groundwater abstraction time series and provides the input to the second type of ARIMA

models that simulates groundwater level time series in monitoring boreholes) it could be

mentioned that in the southern part of the aquifer, direct interaction with external water bodies

seems to take place, which in our case seem to be Ismarida lake and Vosvozis river. However, a

further clarification of the interaction of Ismarida lake with the aquifer was achieved with

isotopic analysis. [1]

Stable isotopes of the water molecule are indicators of conditions at the time and place of

groundwater recharge. They are influenced by processes affecting the water, rather than the

solutes, and can help identify waters that have undergone evaporation, recharge under different

climatic conditions, and help to resolve overall questions relating to mixing of waters from

different sources. The δ2H and δ

18O signatures of groundwaters are generally compared to those

of the precipitation represented by the Global Meteoric Water Line (GMWL) and the Local

Meteoric Water Line (LMWL)[3]. Stable isotope values that plot along the meteoric water lines

are compared to local precipitation to determine if groundwaters derive from recent local

recharge or originate from water that recharged the aquifer under different climatic conditions.

56

Deviations from the meteoric lines indicate modification of the groundwater by evaporation or

extensive water interactions[4].In our study area, water samples from surface waters,

groundwaters, sea water and rain water were analyzed by the UFZ – Helmholtz Centre for

Environmental Research, from February 2010 to December 2010. Results showed that the

isotopic composition ofδ2H and δ

18O of all ground waters in the study area ranges from -41.6‰

to -36.0‰ and from -6.6‰ to -5.3‰ respectively. In the conventionalδ18

O versus δ2H diagram,

these ground waters plot well below LMWL but on or slightly below the GMWL.

Fig 3.5-3 (a) Piezometric map for October 2010, (b) piezometric map for May 2010, (c)

groundwater level time series for the eight monitoring sites.

57

Fig 3.5-4 Plot of stable isotopes δ18

O / δ2H for all water samples.

Generally, the plots show some differences between the isotopic composition of samples taken

in winter and summer. (Fig 3.6-5 and Fig 3.6-6).


O / δ2H in the summer.

58


O / δ2H in the winter.

The isotopic signature of groundwater samples plot close to the GMWL during both seasons,

implying that precipitation is one of the water sources of the aquifer and that the infiltrated

water is completely mixed [5]. From the isotope values the water can be described as ‘young

water’.

Regarding seasonality, during summer, seawater enters Ismarida lake and the composition of

the isotopes in the lake differs from the composition of the isotopes in the winter. During

summer the isotopic composition ofδ2H and δ

18O in the lake ranges from -33.3‰ to -8.6‰ and

from -5.2‰ to -0.4‰ respectively. In the winter the isotopic composition of δ2H and δ

18O in

the lake ranges from –40.0‰ to -33.4‰ and from -6.7‰ to -5.2‰ respectively. This probably

indicates that during summer, seawater enters the lake and a river – aquifer interaction takes

place (same isotopic composition). On the contrary, in the winter, the lake is a ‘fresh water’

aquatic system, and an interaction of river – lake – aquifer takes place. This scenario is in

agreement with the findings of the time series analyses (Gemitzi and Stefanopoulos, 2011).

Further research will focus on the quantification of the interaction of the various water bodies in

the study area, analyzing data from the installed lysimeters, in combination with the isotopic

and hydrochemical data of the study area.

59

3.6 Bogucice Sands - Niepolomice Forest, Poland

3.6.1. Site description, hydrogeology and water use

The Bogucice Sands aquifer and the associated GDE (Niepolomice Forest) are located in the

south of Poland (Fig.3.6-1). The aquifer covers the area of ca. 200 km2 and belongs to the

category of medium groundwater basins in Poland. The system extends from ca. 49.99N-

19.97E to approximately 50.05N-20.33E. Urban areas and villages cover ca. 20% of the

surface. The remaining surface is occupied by agriculture (60%) and forestry (20%). In the

eastern part of the area forests and wetlands dominate (80% of area). The study area is located

in the transition region between oceanic and continental climatic zone. Average annual

precipitation in the area reaches 725 mm, with evapotranspiration fluctuating around 480 mm

and runoff of ca. 245 mm. Groundwater recharge takes between 8 and 28 percent of

precipitation. The annual average temperature is 8.2 degrees Celsius.

The Bogucice Sands aquifer is located on the border of the Carpathian Foredeep Basin and

belongs to the Upper Badenian. It is underlain by impermeable clays and claystones of the

Chodenice Beds. To the north, the aquifer is progressively covered by mudstones and

claystones with thin sandstone interbeds (Grabowiec Beds). Paleoflow directional indicators

suggest proximity to deltaic shoreline (Porębski and Oszczypko, 1999). The outcrops of

Bogucice Sands are located in the south, covered by thin Pleistocene-Holocene sediments

(sands, loesses and locally boulder clays). In the north, the aquifer is deeper and confined by

marine mudstones and claystones. Its total thickness is approximately 100 m, at the maximum

up to 310 m.

The hydrogeology of the aquifer can be considered in three areas: the recharge area related to

the outcrops of the Bogucice Sands in the south, the central confined area generally with

artesian water, and the northern discharge area in the Vistula river valley. Groundwater

movement takes place from outcrops in the south, in the direction of the Vistula river valley

where the aquifer is drained by upward seepage through semipermeable clayey formations of

the Tertiary Grabowiec Beds. In pre-exploitation era, artesian water existed almost on the whole

confined area. Intensive exploitation decreased the water table in some localities causing

downward seepage. The upper shallow aquifer located in Pleistocene-Holocene sediments is

related to drainage system of Vistula river and its tributaries. Unsaturated zone consists mainly

of sands and loess of variable depth, from zero in wetland areas to approximately 30 meters in

the recharge area of deeper aquifer layers.

The principal economic role of the deeper aquifer, consisting of two water-bearing strata

separated by Badenian clays, is to provide potable water for public and private users. Estimated

disposable resources are 40,000 m3/d with typical well capacities of 4 to 200 m

3/h (Witczak et

al., 2008). Hospitals and food processing plants also exploit some wells. The yield of the

aquifer is insufficient to meet all the needs and, as a consequence, licensing conflicts arise

between water supply companies and industry on the amount of water available for safe

exploitation.

60

The recharge area of the deeper aquifer and entire shallow phreatic aquifer is vulnerable to

diffuse sources of pollution from industrial emissions (big metallurgical plant in the north-west

and numerous local enterprises). Point sources of pollution may also exist due to disposal of

urban and rural wastes, including landfills and farm sources. There is also some evidence of

contamination from a linear source of pollution, a contaminated river draining large municipal

landfill located close to the southern border of the aquifer. Pollution from a newly constructed

highway should also be expected in the near future. Typical usage of fertilizers on the

agricultural areas of the upper aquifer amounts to ca. 70 kg N/ha year.

Fig 3.6-1 A – hydrogeological map of Bogucice case site. Groundwater Dependent Ecosystem

(Niepolomice Forest) is marked in red. B – cross-section of the aquifer (line A-B in Fig. 3.6-1)

with the position of wellfields Szarów and Wola Batorska. General direction of groundwater

flow is from south to north. Frame indicates approximate extent of the location of GDE shown

in Fig 3.6-2.

Eastern part of the shallow phreatic aquifer is occupied by Niepolomice Forest (cf. Fig 3.6-1).

The Niepolomice Forest is a lowland forest covering around 110 km2. This relict of once vast

61

forests covering the Sandomierz Basin is protected as a Natura 2000 Special Protection Area

“Puszcza Niepołomicka” (PLB120002) which supports bird populations of European

importance. Additionally a fen in the western part of the Forest comprises a separate Natura

2000 area “Torfowisko Wielkie Bloto” (PLH120080), a significant habitat of endangered

butterfly species associated with wet meadows. The Niepolomice Forest contains also several

nature reserves and the European bison breeding centre and has an important recreational value

as the largest forest complex in the vicinity of Krakow. Due to spatially variable lithologies and

groundwater levels, the Niepolomice Forest is a mosaic of various forest and non-forest

habitats, including wetlands, marsh forests, humid forests and fresh forests. Dependence of the

Niepolomice Forest stands on groundwater is enhanced by low available water capacity and low

capillary rise of soils (Kleczkowski, 1981, Suliński, 1981; Łajczak, 1997, Chelmicki et al,

2003). Groundwater conditions in the Niepolomice Forest, including Wielkie Bloto fen have

been affected by meliorations carried out mostly after the Second World War and by forest

management (Suliński, 1981; Łajczak, 1997; Lipka et al., 2006). Recently (September 2009) a

cluster of new pumping wells (Wola Batorska wellfield) has been set up close to the northern

border of Niepolomice Forest (Fig 3.6-1 – wells SW1-SW7). There is a growing concern that

exploitation of those wells may lead to lowering water table in the Niepolomice Forest area and,

as a consequence, trigger drastic changes of this unique groundwater dependent ecosystem.

3.4.2. Conceptual model of surface water - groundwater interaction

The conceptual hydrologic model of GDE Niepolomice Forest including Wielkie Bloto fen is

shown in Fig 3.6-2. Fig 3.6-2A depicts schematically presumable surface water/groundwater

interaction on the area under natural conditions, prior to major anthropogenic disturbance of the

system in the form of melioration works on Wielkie Bloto fen and management of the forest

(drainage trenches). Due to artesian conditions in the area and relatively thin clay layer

separating Badenian aquifer from shallow Quaternary aquifer, the upward leaching of deeper

groundwater may contribute in a significant way to the water balance of the investigated GDE.

In order to quantify dynamics of groundwater flow in the area of Niepolomice Forest and

Wielkie Bloto fen, concentrations of environmental tracers (stable isotopes water, tritium,

radiocarbon) were measured in wells existing in the recharge area of Bogucice Sands aquifer

(Szarów well field) and in the newly established wellfield Wola Batorska (cf. Fig.3.6-1). Also,

some surface water appearances in the area of Wielkie Bloto fen were investigated (Table 3.6-

1). These analyses are part of a larger, ongoing program aimed at characterization of spatial and

temporal distribution of environmental tracers in the Bogucice Sands aquifer and establishing

time scales of groundwater flow in this system (Zuber et al., 2005).

Tracer data reported in Table 3.6-1 indicate that in the recharge area, upstream of Wielkie Bloto

fen (Szarów well field) groundwater is relatively young. Presence of appreciable amounts of

tritium points to recharge in the past several decades. Radiocarbon content fluctuates between

48 and 65 pmc. In contrast, in the newly established well field Wola Batorska, tritium is absent

while radiocarbon content drops to a few pmc. Significant age of groundwater in this area is

confirmed by stable isotopes of water revealing characteristic shift towards more negative delta

values indicating glacial origin of water.

62

Fig 3.6-2B illustrates possible impact of recent changes in the area (establishment of a new well

field Wola Batorska, cf. Fig. 3.6-1) on groundwater flow regime. It is expected that intensive

pumping of deeper aquifer by newly established wells, planned in the near future, may modify

groundwater flow field in the area of GDE in such a way that hypothetical upward leakage will

be stopped or significantly reduced.

To prove potential discharge of deeper groundwater in the area of Wielkie Bloto fen it is

planned to drill an observation well and to perform sampling of groundwater at different depths.

Vertical profile of tritium concentration should provide direct evidence of possible interaction

between surface water and deeper groundwater in this area. In addition, appropriate modeling

runs of the existing 3D flow model of Bogucice Sands aquifer (Visual Modflow Pro, version

4.3) are planned in the near future in order to investigate possible impact of the newly establish

well field Wola Batorska on the groundwater flow in the Niepolomice Forest area.

Table 3.6-1 Environmental tracer data for groundwater in the area of Niepolomice Forest GDE.

Uncertainty of stable isotope data is equal 0.1 ‰ (18

O, 13

C) and 1‰ (2H). Tritium and

radiocarbon content is measured with the precision of 0.3 TU and 0.8 pmc, respectively.

Site description

Well No

18O

(‰)VSMO

W

2H

(‰)VSMO

W

Tritiu

m

content

(TU)

14C

(pmc)

13C

(‰)VPDB

Szarów well field:

Well No. 11

Well No. 12

Well No. 22

Well No. 23

Well No. 24

Well No. 42

-9.75

-9.93

-9.81

-9.84

-10.03

-9.68

-70.3

-70.1

-69.4

-68.5

-72.1

-69.2

9.0

1.1

16.1

0.7

15.2

0.3

64.6

63.6

n.m.

n.m.

n.m.

48.5

-14.1

-12.8

n.m.

n.m.

n.m.

-12.2

Wola Batorska well field:

Well SW-2

Well SW-3

Well SW-4

Well SW-5

Well SW-6

Well SW-7

-10.19

-10.67

-10.86

-10.89

-10.83

-10.71

-75.7

-78.3

-79.9

-79.2

-80.2

-78.2

0.3

0.4

0.1

0.0

0.1

0.1

2.9

n.m.

0.8

n.m.

n.m.

2.2

-10.2

n.m.

-10.5

n.m.

n.m.

-9.2

n.m. – not measured

63

It should be noted that a small spring occurring in the forest close to the Wielkie Bloto fen does

not contain tritium. This might point to direct impact of relatively old groundwater discharging

in this area. However, at this stage is not clear whether the spring is entirely of natural origin.

There is some possibility that it may originate from old, badly liquidated well which was

located in the vicinity of this spring. Further investigations will clarify that.

Fig 3.6-2 Conceptual model of surface water/groundwater interaction in the area of

Niepolomice Forest under natural conditions (A) and envisaged under new steady-state imposed

by heavy pumping by Wola Batorska well field (B). GDE – Groundwater Dependent

Ecosystems; GDTE – Groundwater Dependent Terrestrial Ecosystem; R – riparian and alluvial

forest; EWRs – Environmental Water Requirements; SY – Save Yield of aquifer.

64

3.7 Częstochowa aquifer interaction, Poland


The Case Study area (2365 km2) lays in the southern part of Poland, administratively belongs to

the Silesian Voivodeship. It is a part of the Cracow-Częstochowa Upland - the Częstochowa

Plateau which is the most impressive part of the Cracow Jurassic area. The Case Study borders

correspond to the borders of the Main Groundwater Basin No 326.

The MGWB 326 aquifer is naturally divided by the Warta river into two subasins (Fig 3.7-1):

MGWB 326 S and MGWB 326 N.

Average yearly precipitation varies between 600 - 800 mm/year. The climate is continental with

low humidity and considerably high amplitudes of temperature; the average yearly temperature is

70C. Such climate is conditioned among others by constant Icelandic depression and arctic high-

pressure whose activity can be felt mainly in winter. In summer, however, we can feel the

influence of high-pressure from the Azores and other fronts from the south, whose activity is

unfortunately strongly inhibited by the Carpatian massif.

In the geological structure of the Cracow-Częstochowa Upland two structural levels can be

distinguished: the krakovid level containing folding and partly metamorphisized pre-Cambrian

deposits up to upper Carboniferous and the level of the Mesozoic Cracow-Częstochowa

monoclinal fold, The oldest formations confirmed by drilling are metamorphic slates and phyllite

dating back to the pre-Cambrian. The Cambrian period is represented by argillaceous slates,

mudstone and sandstone whose thickness exceeds 1000 m. Those rocks eroded and became

folded, and then were covered with carbonate deposits of the Ordovician (limestone, marl,

dolomites). On top, there are partly metamorphisized Silurian slates whose layers blend with

course-grained sandstone and gravel. As a result of many tectonic movements taking place at the

turn of lower and upper Carboniferous, the character of sedimentation changed from the sea to

land type. Owing to the communicational activity of the rivers, the terrigenous material has been

carried and deposited along with accumulated flora material. That was the way the upper-

Carboniferous complex of sandstone, mudstone an slates came into being, including carbon

deposits and inserts. The Trias and Jurassic formations are sloping at a slight angle towards the

north-western direction. The Trias is represented by flat sea deposits which flooded the area at

that time. Those rocks (sandstone, marl, dolomites, limestone) are revealed only in the western

part of described region. Jurassic formations prevail in the whole area of the Kraków -

Częstochowa Jurassic (hence the name). The most dominant form of the Jurassic landscape is

rocky limestone occurring as isolated rocks called inselbergs and rocks in river valleys. Jurassic

limestone`s outstanding feature is strong karst formation which developed mainly in the Tertiary.

For the most part of the Tertiary described area was a land and there were various denudative

65

processes (erosion, weathering), which led to forming so-called palaeogene planation surface, i.e.

characteristic tops, particularly in the southern part of the Jurassic, scattered with numerous

limestone inselbergs. In the Miocene, as a result of sea transgression, limestone was formed at

the bottom of the reservoir, and first of all scales filling mainly tectonic trenches which came

into being in that period due to frequent orogenic movements. In the Quaternary, owing to

Scandinavian continental glacier present in that area, clay, sand and gravel accumulated there,

and at the end of the Ice Age, loess clay was wind-blown which currently covers the Cracow -

Częstochowa Upland making up very fertile soil.

Fig 3.7-1 The Częstochowa Case Study. Location. Geology.

Surface water – groundwater interaction was investigated for the part of the case study – the

Wiercica River catchment (349.8 km2), the tributary of the Warta River. The beginning of the

river is formed by several springs, the yield of which is affected by unsteady conditions of

groundwater recharge. Good water quality, as well as specific climatic conditions, is favourable

for existence of mosaic of biotopes: in dry and warm conditions some southern species are met

while in wet and cold - mountain and boreal ones. Average yearly precipitation in the period

2000-2004 was 670.2 mm for Częstochowa and 791.6 for Złoty Potok (Malina et al. 2007).

GDEs may be strongly dependant only on shallow waters, which means that they exist within

springs zones, where there is strong relation with precipitation, groundwater levels and with

humidity of aeration zone. Such conditions were found in the upper and middle parts of the

Wiercica catchment (Fig 3.7-2) and finally the investigation on surface water – groundwater

interaction was limited to this area. Shallow groundwater levels are observed only along river

valleys and around Mokrzeska Wola. Soil types ensure good contact with surface water, only

locally soil layers are semi-permeable.

66

Fig 3.7-2 The Wiercica watershed research area. Hydrography and land cover.

67


Transformation of flow through the aeration zone was simulated with the help of the piston

model of unsteady infiltration. Computer modeling consists of two sub-programs: i) PM – piston

model of infiltration, ii) hydrological model of net precipitation.

PM model.

PM model was applied to follow current states of GDEs in a sense of prediction of groundwater

recharge which is crucial for biotopes functioning. This might be made for short (seasonal) and

long term (climatic) changes of meteorological conditions as well as for various anthropogenic

pressures (land cover, position of groundwater table). PM model might be also applied to

simulate an unsteady recharge and then to model behavior of the whole groundwater basin in

models based on MES methods.

The model enables to determine increase or decrease of soil moisture as a result of precipitation

and evapotranspiration which than allows to estimate the dynamics of groundwater recharge. It is

a 1-D model and can be used for areas of uniform geotechnical, sozological and hydrological

nature.

Net precipitation.

Net precipitation is a separate module calculating this portion of precipitation which then

penetrates into soil cover. Here it was chosen a simplified model of evapotranspiration based on

the Turc’s equation (Pociask-Karteczka 2003) with the following input data: radiation, local

average temperature, precipitation height, plant cover in a sense of evapotranspiration capacity

and local depth of rizosfera. It is also possible to use the more detailed Penman-Monteith model

(Kowalik 2010) if only we are able to gather all the necessary input data.

So, the scheme of calculation of net precipitation consists of three steps: potential (total)

evapotranspiration determined on the basis of daily precipitation value biotope

evapotranspiration determined with respect to rizosfera depth, soil cover, vegetation season

real evapotranspiration.

68

Infiltration and effective precipitation

To simulate changes of water content the classical Green-Ampt (Green and Ampt 1911) model

for a sharp front is applied together with the piston model of unsaturated infiltration and the

Morel-Seytoux model of moisture redistribution (Morel-Seytoux 1984). It is assumed in the

model that moisture distribution in a soil after a wetting front is independent of process duration

and a front position (resembles movement of a piston). The process of moisture changes itself is

described by a couple of basic, commonly available parameters but this simplification does not

distort the phenomenon in a significant way.

Results

- For strongly permeable soils whole precipitation infiltrates into ground, directly recharging

groundwater. Along the profile low moisture is maintained, shortly after the precipitation

event (rain) soil gets dry. There may be no enough moisture left for more water consuming

plants.

- For medium permeable soils condition can be different. Although whole precipitation

infiltrates into ground, significant content remains for a few days after the rain, in approx. 2

cm subsurface layer. There is quite large seasonal moisture content remaining in deeper

layers, with good availability for plants.

- For low permeable soils slightly bigger precipitation event may form surface runoff.

Moisture content remains stable and quite significant. Higher moisture may stay for a few

days after rain, to depth of approx. 100m, however, high sucking head may prevent plants

from using that moisture.

Fig 3.7-3 Infiltration graph for sandy alluvial soil type in the Wiercica research area.

69

Fig.3.7-4 Infiltration graph for glacial till soil type in the Wiercica research area.

Fig 3.7-5 Infiltration graph for sandy clay (loess) soil type in the Wiercica research area


GDEs take water mainly from the aeration zone, hence moisture of this zone being dependant on

precipitation as well as on capillary fringe is highly important for the process. In this case it is

justified to apply the piston model of infiltration (PM – Piston Model). Moisture of the aeration

zone decides about availability of water for vegetation needs; this is possible only if moisture is

higher than moisture of fading. Up to the soil depth (about 0,5m), moisture is shaped by daily

precipitation but here evapotranspiration plays crucial role since it causes strong fluctuation of

70

moisture. In the deeper sub-soil level up to about 1 m the deeper infiltration is stabilized by a

between-layer runoff, which is than taken into account in a balance. All these mean that PM

model might be applied only for river valleys and marshes.

Transformation of flow through the aeration zone was simulated with the help of the piston

model of unsteady infiltration. For a single profile the model may be run as a simple calculation

sheet but the whole catchment it is necessary to build a computer program or at least to use one

of universal GIS application. The calculation scheme is presented below (Fig 3.7-6).

Fig 3.7-6 Scheme of modeling in the piston model of infiltration.

71

3.8 The Grue site, Norway (Bioforsk)

3.8.1 Site description, hydrogeology and methods

Site description – hydrogeology

The Grue study area is situated in the Glomma valley in south eastern Norway.

Whereas most of the areas in the valley bottom are used for agricultural purposes, the riparian

zone in the groundwater discharge zone adjacent to the river consists of forest ecosystems

dominated by broad-leaved trees, particularly Salix species.

The deep valley basin at Grue is filled up by lacustrine and marine deposits beneath a top layer

of fluvial sediments. Clay has been observed at a depth of 13-15 m at several locations (von der

Lippe 1998). Above this level the deposits consists mainly of sand. A top layer of flood plain

sediments of coarse silt and sand occurs in large parts of the river plains, however, but does not

exist in the riparian zone. The depth of the unsaturated zone in the riparian zone normally ranges

between 0 and several meters, and will vary during the year. Average groundwater recharge in

the area has been estimated to be at a size of 300 mm year-1

.

Methods

Monitoring wells has also established at several locations in this aquifer to uncover local and

regional flow patterns. In a selected transect through the riparian forest zone along Glomma,

water levels and temperature are monitored at hourly intervals in two monitoring wells. The

monitoring wells in the transect have been established in the middle of and close behind the

riparian zone, respectively (Fig 3.8-1). In the transect grain size distribution and layering of

sediments have also been characterized at several locations.


The soil in the riparian zone consist of point bar sediments of sand with low content of organic

material and low storage capacity for plant-available water. The periodically high groundwater

levels in the middle of the riparian forest zone (Fig 3.8-2) demonstrates that groundwater may

feed the root zone and /or the capillary rise zone and thus be important for vegetation in large

parts of the riparian zone. This also implicates that the riparian ecosystems may be susceptible to

groundwater contaminations and changes in groundwater hydrology.

72

$$

N

EW

S

Monitoring well$

Forest

Open area

Agricultural area

AB

200 Meters1000

Fig 3.8-1 Location of riparian zones and monitoring wells in a transect crossing the riparian zone

at the Grue site.

Higher groundwater table altitudes behind than in the riparian zone (Fig 3.8-3) indicate that

groundwater flow from the aquifer through the riparian zones towards the river Glomma most of

the year. Only in periods around flood peaks groundwater altitudes are higher in the in the

riparian zone than further from the river. The main pattern with flow of groundwater outflow

from the aquifer through the riparian zone is supported by the low and stable groundwater

temperature in the riparian zone (Fig 3.8-4).

The results in 2010 indicate relatively high groundwater tables in summer. Relatively high

groundwater (and river water) tables in the first parts of the summer might partly be due to snow

melting in the mountain parts of the water feeding catchments. This may counteract low

groundwater tables in critical periods when temperatures and potential evaporation from

vegetation are high and thus be important to ecosystems.

73

-7

-6

-5

-4

-3

-2

-1

0

01.0

7.2

010

15.0

7.2

010

29.0

7.2

010

12.0

8.2

010

25.0

8.2

010

08.0

9.2

010

22.0

9.2

010

06.1

0.2

010

20.1

0.2

010

03.1

1.2

010

17.1

1.2

010

01.1

2.2

010

15.1

2.2

010

29.1

2.2

010

m

Well A

Well B

Fig 3.8-2 Depth to groundwater table in monitoring wells in and behind the riparian forest zone

along the river Glomma at Grue.

148,0

148,5

149,0

149,5

150,0

150,5

151,0

01.0

7.2

010

16.0

7.2

010

31.0

7.2

010

15.0

8.2

010

30.0

8.2

010

13.0

9.2

010

28.0

9.2

010

13.1

0.2

010

28.1

0.2

010

12.1

1.2

010

26.1

1.2

010

11.1

2.2

010

26.1

2.2

010

Mete

r ab

ove s

ea l

evel

Well A

Well B

Fig 3.8-3 Groundwater table altitudes in and behind the riparian forest zone along the river

Glomma at Grue.

74

4,5

5,0

5,5

6,0

6,5

02.0

7.2

010

16.0

7.2

010

30.0

7.2

010

14.0

8.2

010

28.0

8.2

010

11.0

9.2

010

25.0

9.2

010

09.1

0.2

010

24.1

0.2

010

07.1

1.2

010

21.1

1.2

010

05.1

2.2

010

19.1

2.2

010

Deg

rees C

Well A

Well B

Fig 3.8-4 Groundwater temperatures in and behind the riparian forest zone along the river

Glomma.


The pattern of surface water – groundwater interaction in the riparian system is illustrated in Fig

3.8-5. The balance between and importance between different components is dynamic, and

varies both in space and time, e. g. in periods with elevated groundwater levels may groundwater

feed the root zone at higher altitudes than in periods with lover groundwater tables.

Fig 3.8-5 Hydrological processes and surface water – groundwater interactions in a forested

riparian system.

Infiltration of

precipitatian

Groundwater flow

Precipitation

Capillary rise

RIVER RIPARIAN ZONE AGRICULTURAL AREA

Evapotranspiration

Infiltration of river

water during floods

75

3.9 Sava river, interaction with groundwater

The Sava River is the largest river in Croatia and the second largest tributary to the Danube

River. It has outstanding biological and landscape diversity, hosting the largest complex of

alluvial floodplain wetlands in the Danube basin and the largest lowland forests. Due to its

importance at the European level, Sava river has been selected as a focal region in the Pan

European Biological and Landscape Diversity Strategy (PEBLDS) of the Council of Europe

(www.savariver.com). Along its course there are numerous protected areas at national and

international level. Several Natura 2000 sites are situated within the case study of Zagreb aquifer

The Sava River, with extremely asymmetric catchment area and 75% of the catchment situated

on the right bank of the river, divides the Zagreb aquifer system into two parts. The river, which

is the main source of groundwater recharge within aquifer system, is in direct hydraulic

connection with the shallow aquifer.

Head contour maps analysis (Posavec, 2006) showed that during high Sava river water levels the

river infiltrates ground water on all parts of the flow while during medium and low water levels

the river drains ground water on some parts of the flow (Fig 3.9-1).

Ground water levels are also strongly affected by the small river dam. An average drop of the

Sava river water level amounts 0.4 m/km while the drop of the water level downstream from the

river dam can be up to 6 m on a distance of only tens of meters. This strongly affects the aquifer

flow directions and ground water levels in close vicinity of the river dam.

76

Fig 3.9-1 River dam location and head contour maps showing impact on ground water flow

direction in near vicinity of the river dam.

3.9.1 Hydrodynamic pattern of the Sava River – groundwater interaction

The Sava River represents the main source of water for the Zagreb aquifer system. Although

recharge occurs also through precipitation, the changes in the Sava river water levels dominantly

influence the changes in the groundwater levels across the whole aquifer. The strong influence of

Sava River on groundwater recharge has been confirmed by multivariate statistical analysis -

principal component analysis (PCA), following the procedure by Winter et al. (2000) - of the

groundwater levels, which has been done in order to define groundwater table change rates and

fluctuation pattern in the vicinity of the Sava River. Data analysis procedure has been tested

which has allowed the use of 75 observation well locations and 10 years data series, i.e. total of

1025 measurements per location, in order to describe the groundwater dynamics.

77

Generally, PCA explains correlation between several variables concurrently, which helps finding

simpler relations that enable insight into the concealed structure of the data. These simpler

relations are expressed by a new group of variables referred to as principal components, which

retain maximum quantity of information and indicate the correlation of the variables. The main

objective of the PCA is to obtain certain number of principal components that will explain the

maximum possible part of the total variance (Brown, 1998).

The results of the PCA in Zagreb case study example revealed significant differences in

groundwater table fluctuation patterns in different parts of the aquifer system. It was shown that

most of the variance (70%) is explained by the first principal component, which revealed the

pattern of groundwater table changes in the vicinity of the Sava River (Fig 3.9-2).

Hydrographs of the observation wells near the Sava River follow the same pattern as the

hydrograph component scores for the first principal component. These observation wells are

installed in discharge area of the aquifer system. The fluctuation pattern is equal for the shallow

and deeper layers, and it reflects the impacts of the Sava River on groundwater.

Table 3.9-1 Eigenvalues from principal component analysis, the percentage of the total variance,

cumulative eigenvalues and cumulative percentage explained by principal components

Fig 3.9-2 Hydrographs for the observation wells near the Sava River compared with hydrograph

of principal component 1 factor scores.

Principal

Components Eigenvalues

Percentage of

total variance

Cumulative

Eigenvalues

Cumulative

percentage

1 49,28 70,41 49,29 70,41

2 8,18 11,68 57,46 82,09

3 3,96 5,66 61,43 87,75

78

Spatial zonation of areas with higher impact of the Sava river on ground water levels was

analyzed using recession curve models. The analysis of groundwater level time series using

recession curve models was performed with Master Recession Curve Tool (Posavec et al., 2006).

278 master recession curves were obtained for 278 analyzed observation wells. Processing was

performed on the computer configuration Pentium ® 4 CPU 3.40GHz with 2.0 GB of ECC

RAM, and it lasted 3 hours and 45 minutes.

Analysis of the spatial distribution of the selected regression model showed that the logarithmic

regression prevails in parts of the aquifer near the river Sava while polynomial regression

prevails in other parts of the aquifer (Fig 3.9-3). These results are logical and reasonable with

respect to changes in groundwater levels which occur faster in the vicinity of the Sava River. In

other parts of the aquifer where such strong boundaries do not exist, ground water level changes

occur less rapidly.

Fig 3.9-3 Regression models showing zones of higher impact of the Sava river.

79

3.9.2 Hydrogeochemical evidence of the Sava River –groundwater interaction

Direct evidence of the Sava River – groundwater interaction can also be revealed by the results

of geochemical investigation in Zagreb aquifer system. It was shown that using groundwater

modeling tool, PHREEQC (Parkhurst et all, 1980.) and multivariate statistical analysis, Cluster

analysis (Ward method of hierarchical tree clustering), hydrogeochemical homogenous areas can

be delineated within the Zagreb aquifer system, which are expected to react similarly or identically

to natural or man-caused events (Nakić et al, 2004). These analyses revealed very similar or

identical macro chemical composition of the groundwater in the area bordering with the river,

which support the evidence of intensive impacts of changes in the river water levels on the

groundwater tables within the belt by the river. Change in macro chemical composition on a

greater distance from the river confirmed weakening of the river impact on the aquifer

replenishment and domination of lasting seasonal replenishment conditions. Investigations of the

geochemical characteristics in the western part of the Zagreb aquifer systems have further

confirmed that direct exchange of water from the Sava River and groundwater occurs in the near

vicinity of the river (Vlahović et al, 2008). It was proved that this exchange weakens further

away, while the difference in hydrogeochemical characteristics between the Sava River water

and groundwater increases. Direct mixing of water from the Sava River and groundwater is

occurring in the near vicinity of the Sava River and it weakens further away while the differences

in hydrogeochemical characteristics grow.

In central part of the Zagreb aquifer system stable isotopes of oxygen and hydrogen are used to

identify groundwater recharge from Sava River (Horvatinčić et al., 2011). The difference in

stable – isotope signatures of river and precipitation are used to determine the relative

contribution of these two sources of groundwater recharge. Stable isotope analyses indicated

different infiltration times of surface water of the Sava River to different wells.

80

3.10 Fontanili springs, Italy, Hydrogeology, site description and methods

3.10.1 Introduction

Fontanili springs are semi-natural water emergences that create watercourses characteristic for

the Po Valley. With a surface of 46,000 km² the Po Valley is the largest flat area in Italy that

occupies 1/6th

of the Italian territory. Situated between the Alps and the Appenines the valley is

mostly located within the Italian borders apart from a small area located in Switzerland. River Po

that flows along the valley is 652 km long with a delta discharge of 1540 m3s

-1 and a catchment

area of 74145 km2. The climate of the Po Valley is mild continental characterized by relatively

cold winters and hot summers. The area has elevated air humidity and the average yearly

precipitation becomes higher moving from south east towards north-west. The Mantova plain has

the lowest rainfall with around 650-700 mm/year while the maximum values that exceed 2000

mm/year are noted in the vicinity of the alpine lakes. The atmospheric precipitation has two

yearly peaks – one during spring time and one in autumn. The variation in land cover of the Po

Valley influenced the formation of different miroclimates in the rural areas, in the urban areas

and a specific microclimate associated with the great lakes (Canepa, 2011).

Fig 3.10-1 Po Valley map (Wikimedia Commons media file depository).

81

The Po Valley has a complex surface water network with the great alpine lakes that give birth to

some of the main left-bank tributary rivers of the Po, rivers that originate from mountain springs

and a particular kind of rivulets that take their beginning in the fontanili springs. (Canepa, 2011).

Fontanili springs are specific watercourses that emerge along two lines of 5-50 km width located

between the upper and lower Po plains. These areas are called “linee delle risorgive" which

translated from Italian means simply “lines of springs’. In the north part of the Po Valley the line

of fontanili springs stretches below the Alps from the Cuneo Piemonte plain continuing east

towards the Veneto–Friuli plain. The other “line of springs” is more scattered and runs south

from the Po River below the Appenines along the area of Piacenza province continuing south-

east towards the area of Bologna.

Fig 3.10-2 Map of North Italy with marked “lines of springs” (modified from Minelli et al.,

2002)

82

Fig 3.10-3 Fontanili areas (modified from Ferrari and Lavezzi, 1995)

Water emergence along the “lines of springs” is caused by the difference in permeability of the

alluvial deposits in the area. The subsoil of the Po Valley consist mostly of late Miocene and

Quaternary deposits and sediments. The upper Po plain is built mostly of pebbles, gravel and

sand, as the terrain descends however, the granulometry of the building material reduces

gradually until it is no longer permeable. The lower Po plain consists mostly of silt and clay

characterized by low permeability (Minelli et al., 2002; De Luca et al., 2005). This fine material

creates a barrier in the flow of the shallow groundwater and causes the groundwater table to rise

and eventually intersect with the topographic surface which results in water seeping out to the

land. Historically these border areas between the upper and lower Po plain were covered with a

mosaic of wetlands, streams and small lakes (Minelli et al., 2002) that were formed by

groundwater emerging spontaneously.

83

Fig 3.10-4 A very general scheme illustrating the hydrogeological setting of the Po plain in

cross-section (modified from Boscolo and Mion, 2008).

Fontanili springs have characteristics much different than natural springs - they are described as

semi-natural springs because they were created by human interventions to facilitate and organize

the outflow of groundwater along the “lines of springs” where the water was naturally

conditioned to outcrop. These human interventions either modified the naturally emerging

streams, or created new water resurgences (De Luca et al., 2005; Conati, 2003). The fontanili are

sometimes called semi-artesian wells because their water comes from an unconfined aquifer

which is pressed by the overlying impermeable layers. Fontanili waters were directed to the

surface by excavation or tubular perforation of the terrain.

The first fontanili were created already in the XI-XII century by local religious congregations

that organized the outflow of groundwater by tubes and barrels inserted vertically 2-3 meters

deep into the earth. The resurgence of groundwater to the streams was in some cases also

facilitated by constructing drainage trenches. These installations together with an excavated

system of canals and ditches directed the outflow of groundwater and drained areas where

stagnant waters or frequent flooding did not allow land cultivation. This adjustment generated

more arable land. Additionally the network of canals allowed controlled and efficient crop

irrigation. Continuous access to relatively warm water generated very advantageous conditions

that favored higher crop yields and stimulated/boosted the development of agriculture in the

region. At that time water-meadows – an advantageous form of cropping that utilized the

fontanili waters, became a typical practice in the area (Minelli et al., 2002).

84

A typical fontanili begins with a “head” which is an excavation that forms a small circular pond

0,5 - 5 m deep. The water in such pond rarely exceeds the level of 2 m. The way the groundwater

is facilitated to emerge depends on the specific hydrogeologic setting of each fontanili. The

groundwater can flow out to the pool either through variously constructed drainage trenches or

through tubular installations inserted vertically into the ground. The historic wooden barrels and

tubes used initially in the medieval ages were not very durable and had to be replaced every 10-

15 years. Since XIX century the tubular wooden material has been substituted with more

resistant concrete and metal. Nowadays the vertical outflow of fontanili water is facilitated by

concrete rings of 1 – 2,5m depth or metal tubes that can be 3 – 10m deep. Still these installations

have to be regularly conserved and periodically replaced. A fontanili head can have one or

several tubular or drainage installations (Kløve et al., De Luca el at., 2005; Vitali and Moroni,

2010). In the Lombardy region the most common are small fontanili that form heads of 0,9 – 4 m

diameter. The big fontanili which are rather few, have ponds of up to 150m diameter (Kløve et

al., 2011).

The “throat” of the fontanili is a bottleneck which connects the fontanili head with an excavated

channel that allows further water flow.

Fig 3.10-5 Morphology of a fontanili spring with one tube (modified from Minelli et al., 2002).

85

Fig 3.10-6 Examples of various shapes of fontanili heads with multiple fontanili tubes (modified

from Ferrari and Lavezzi, 1995).

86

3.10.2 Groundwater – Surface Water interactions: Fontanili of the Lombardy Region

Fig 3.10-6 Map of the Lombardy region with marked locations of documented fontanili (data

from 2009).

The geomorphological structure in the Lombardy region conditioned the formation of 4 aquifers

that overly each other and are separated by impermeable layers of lime and clay.

Aquifer A represents the shallow groundwater that on average reaches 30 m below the ground

surface. This aquifer is mostly built of sand and gravel deposits and its waters recharge directly

from precipitation, irrigation of the cultivated land and infiltration from the surface water bodies.

87

This recharge is predominantly vertical as the aquifer resides in the phreatic zone. In the area of

the “line of springs” however this aquifer becomes semi-confined. Such situation is caused by

the specific multilayer structure of aquifer A - multiple stratums of silt and clay inserted between

the sand and gravel. Presence of these impermeable layers influence the formation of a high

hydraulic gradient in the aquifer. This gradient causes the groundwater lavel to rise form water

resurgences along the “lines of springs” (Carcano and Piccin, 2001; Malerba, 2009; Canepa,

2011).

The described aquifer supplies the fontanili springs in the Lombardy area. Because the

mentioned groundwater body resides in such a complex geomorphological structure and has a

large recharge area, it is relatively difficult to predict the spreading of contaminants within the

aquifer and their entering into the fontanili watercourses. (Canepa, 2011)

Another deeper aquifer - Aquifer B - resides below the described Aquifer A isolated from the

overlying waters by a continuous 5-15m thick layer of clay. This aquifer is only recharged by

precipitation in the northern margin of the groundwater basins, where the prevalent material is

permeable and the separation of the aquifers is less evident. The two deeper aquifers – C and D

are confined deep aquifers that do not have contact or direct influence on the fontanili waters

(Malerba, 2009).

As mentioned previously, the fontanili springs in the Lombardy region are supplied by water

from the semi-confined shallow groundwater. In such cases the water which is under a mild

pressure, is facilitated to outflow through metal tubes of various depth. These kinds of fontanili

springs are called semi-artesian and the outflow of water is mostly vertical. Water emerging from

the tubes is under a pressure that favors its springing out slightly above the fontanili water

surface (on average 10 to 20cm). Although the outflow of groundwater to the fontanili springs is

predominantly vertical, the input of the lateral flow from the phreatic zone can also be significant

depending on local hydrogeological conditions. Some fontanili pools are excavated much below

the phreatic zone level. In such cases the groundwater flows out not predominantly through the

vertical tubes, but additionally infiltrates from the banks of the excavated fontanili pool. In this

situation the lateral flow becomes a significant component of the groundwater discharge. The

water which moves laterally in the phreatic zone towards the fontanili head, washes out the finer

sediments, which with time makes the surrounding terrain, already built mostly of sand and

gravel, become even more permeable (Ferrari and Lavezzi, 1995).

The creation of fontanili springs significantly modified the landscape of the Po Valley reducing

the surface of naturally occurring humid areas by around 10%. The numerous fontanili in the

area formed a net of drainage canals which eventually united forming numerous rivulets. These

watercourses differ greatly from other rivers in the area that collect water from mountain springs.

Rivulets of fontanili origin have a very gentle slope of approximately 1 m/km, relatively low

medium flow values - 0,5 m3/s and a resulting reduced capacity of transport or erosion (Minelli

88

et al., 2002). The fontanili rivulets eventually discharge to the Po tributary rivers and to the Po

River itself.

Geochemical and physical properties of the fontanili waters differ from the surrounding surface

waters. pH of the fontanili water is usually neutral, oxygen levels do not reach saturation (Kløve

et al., 2011). Because the fontanili streams are supplied by groundwater, the water temperature in

these watercourses is relatively stable during the year. The mean water temperatures in the

fontanili oscillate around 10 – 16 C, they are the lowest during early spring, and the highest in

autumn. Other surface waters in the Po Valley are much more dependent on the atmospheric

conditions and their temperatures vary between 0 and 30 C throughout the year. Some fontanili

that are more depended on the phreatic zone for their water supply can have a more variable

temperature regime as they are more influenced by the atmospheric temperatures (Desio, 1973).

Water flow values in the fontanili springs change slightly throughout the year. Normally they are

the lowest from March until May, and the highest from August until December, however this

yearly tendency can be modified by some locally occurring influences such as temporary

droughts, intense rainfalls or crop irrigation (Ferrari and Lavezzi, 1995).

Fig 3.10-7 Conceptual model illustrating the groundwater – surface water interactions in a

fontanili spring.

89

Fontanili are watercourses that are totally dependent on groundwater for their water supply. The

specific conditions resulting from a continuous outflow of water with very minor temperature

oscillations throughout the year create habitats with a mild microclimate that sustain various

aquatic and terrestrial flora and fauna (D’Auria et al., 2006). Changes in the quantity of

groundwater or deterioration of its quality can significantly affect these water bodies and change

the ecosystem conditions.

Sensitivity of fontanili springs to groundwater level changes has been already documented. In the

early 1960s excessive pumping to satisfy the industrial water demand caused a drastic drop of

the groundwater table in the shallow aquifer. At that time many fontanili in the Lombardy area

disappeared irrevocably (Minelli et al., 2002). The lowered groundwater table caused the top

borders of the fontanili spring areas in Lombardy shift significantly south regarding their original

location (Ferrari and Lavezzi, 1995).

Fig 3.10-7 ???

Fontanili springs are not natural watercourses and in order to remain in their initial form they

need to be periodically maintained. During these maintenance operations the fontanilli heads and

the channel beds are cleaned by removing the excess aquatic vegetation and sediment. The

fontanili tubes are purged to remove the residing soil particles that can block the water flow.

Also the fontanili banks have to be reconstructed and supported periodically, as with time they

tend to erode and collapse (Vitali and Moroni, 2010). The maintenance operations are a drastic

intervention in the fontanili ecosystem. Nevertheless abandoning these activities leads to

progressive deterioration of the fontanili pools that can result in vanishing of these watercourses.

90

Most of the fontanili heads are located on private property land and therefore their fate depends

on the land-owners, who sometimes fail to maintain periodical conservations of these water

resurgences. Nowadays fontanili springs are losing their primary purpose as a source of water

supply for agriculture, because other more efficient methods of water extraction are becoming

more popular. This is why these water resurgences are often abandoned, gradually buried by the

surrounding earth material, covered by plants and eventually run dry. In some cases the fontanili

pools become non-controlled dump sites filled with waste of various origin that create an

additional risk of groundwater contamination (De Luca et al., 2005). In response to this situation

the the program of rural development of the Lobbardy region for the years 2007 – 2013

accounted funding of projects aimed to recover the abandoned fontanili springs. The funding

helped reconstruct many fontanili during the recent years.

3.10.3 Major outcome from studies on selected fontanili

The Po valley represents the biggest agricultural area in Italy. 75% of the land is annually

cropped with cereals, maize, alfalfa, grass and industrial crops. Fertilizers and herbicides are

used extensively in the area. This creates a potentially high anthropogenic pressure on these

water bodies. Fontanili water is originally poor in nutrients, however elevated nitrate and

herbicide levels in water samples collected from these springs, indicate a significant impact of

diffuse agricultural contamination. The springs can be contaminated indirectly because they are

supplied by a shallow aquifer that recharges from waters infiltrating through the surface soils.

Additionally the agricultural contaminants can enter the fontanili waters directly with local

surface runoff from the cultivated fields. This risk becomes especially high immediately after

herbicide and/or fertilizer application. Unfortunately the fontanili are rarely protected from direct

inflow of runoff water as crops in the area are often grown without keeping any distance from

the fontanili banks. As mentioned before, the complex geomorphology and large recharge area of

the aquifer supplying the fontanili springs make it difficult to predict the contaminant migration

to the fontanili springs.

Selected fontanili in the Lombardy region have been under continuous monitoring. Installed

piezometers along the fontanili banks enabled measuring the shallow groundwater table level,

monitoring the groundwater physical and chemical parameters and collecting samples for

measuring nitrate and herbicide contamination. In parallel the same data was collected for the

surface water in the fontanili springs.

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3.10.4 Conceptual model for surface water – groundwater interaction

Fig 3.10-8 Conceptual model for groundwater – surface water interactions in a typical fontanili

head.

This conceptual model is demonstrated on a cross-section of a typical fontanili head with a

vertical tube that facilitates the water resurgence. The vertical tube can reach up to 10 m below

ground surface. The blue arrows show the direction of water flow. The inflow of groundwater

that supplies the fontanili is predominantly vertical, but the lateral flow can also become a

significant component depending on the local hydrology. The fontanili is supplied by the shallow

aquifer A that reaches up to 30 meters below ground level and is isolated from the underlying

aquifer B by a continuous 5-15 m impermeable layer. The water that flows out into the fontanili

fills the fontanili head, through the fontanili throat enters the fontanili channel and continues its

flow becoming a rivulet of a relatively low medium flow.

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4. Modelling of surface-groundwater interaction in aquifers

4.1 Groundwater interaction with ecosystems

Groundwater moves along flow paths from recharge areas to discharge areas within GDEs (Fig

4.1-1). Infiltration occurs when meteroric water (including retarded fractions such as snow and

glaciers) enters the ground. Water then usually moves through the unsaturated zone and reaches

the saturated part of the aquifer contributing to groundwater recharge. Some surface waters both

receive and recharge groundwater. Groundwater recharge may include contribution from

adjacent aquifers. Discharge from the aquifer occurs at springs, streams, lakes and wetlands, as

transpiration by plants with roots that extend to near the water table, and by direct soil

evaporation. Groundwater can also discharge to adjacent aquifers (e.g. downward leakage from

an aquifer to a deeper one). Groundwater typically discharges to surface water bodies where the

slope of the water table changes suddenly (e.g. Winter et al., 1998). In many cases springs are

found where geological layer and hydraulic conductivity change (Fig. 4.1-1).

Fig 4.1-1 Different types of springs. In many cases springs are found where the geological layer

and hydraulic conductivity change (modified after Fetter, 2001).

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The actual conceptual model for a given aquifer will vary locally depending on water use, slope,

topography, climate and geology. This should also include the unsaturated zone which plays a

very important role both for groundwater quantitative and qualitative aspects. Local groundwater

flow is often near the surface and occurs over short distances, i.e. from a higher elevation

recharge area to an adjacent discharge area such as small springs. Intermediate and regional

flows usually occur at a greater depth and over greater distance. Steeper and undulating

landscapes have the most local flow points. Groundwater flow is always three-dimensional, but

can often be analyzed in two-dimensional sections (Fig 1.1-1). Analysis of these flow paths is

important when studying GDEs because it can provide valuable information about potential

threats to both the quantity and quality of groundwater.

4.2 Conceptual models

A conceptual model of a GDE can is a simplified representation or drawing of the system that

include main processes effecting the ecosystem. As groundwater provides water, nutrients, stable

conditions (temperature, pH,) these processes might be needed to be included in the conceptual

model. The model must also include the overall hydrogeological setting and the specific

topography at the GDE including main inlets and outlet of water. As models are often developed

to assess impacts, a conceptual model for the impact and foreseen response is needed. For a

natural system, the order of making these models should be from hydrological, to geochemical

and then to ecological conceptual models as hydrology influence geochemistry and both

influence ecology. These models have therefore increasing complexity.

A hydrogeological conceptual model would include I) water fluxes to and from the system, II)

fluxes within the system, III) pressures in nearby aquifers and in the GDE system. The hydraulic

link between the aquifer and the GDE should be in focus. It is also important to include the

hydrology at the recharge area and the discharge areas that influence the GDEs. Shallow and

long flow paths should be distinguished as these flow paths deliver water of different

composition and quality.

The main surface and groundwater systems should be included in GDE conceptual model with

respective indicative water fluxes. A cross-section (2D) and an aerial (bird) perspective showing

main recharge-discharge patterns and flow paths and the capture zone should be included.

It can be important to include information of soil hydraulic parameters and hydraulics thresholds

(points that control water flow).

Geochemical conceptual models should include main typical concentrations found in shallow

and deep groundwater and within the GDE. A cross-section showing geological layers with

typical concentrations and flow lines is necessary to show the potential interaction and the

portion of nutrient fluxes from groundwater.

94

Ecological conceptual models should include the most important processes related to hydrology

and geochemistry. The model should include the most relevant flora and fauna and how they rely

on the environmental factors such as temperature, pH and nutrients provided by groundwater.

This could be included by a table showing most important species and their preferred

environmental habitat conditions as a range or box plot.

Impact-response conceptual models are useful to show potential known or predicted changes.

These can be scenarios based on no-change, positive change or negative change. In change

assessment the natural variability must be considered due to climate variability, changes in dry

and wet deposition patterns, and species (invasive, diseases etc.) that are not due to changes in

the groundwater system itself. The main changes and pressures must be included such as land-

use, industry, urbanization etc. The main source of water losses such as irrigation and potable

water extraction must be shown. The potential water table drawdown must be shown also

indicating the original level. Also the direction of flow before and after the pressure should be

indicated. Impacts on the ecosystem services, ecology and humans must be part of such models.

Hot-spots

In GDEs with groundwater input, the areas where groundwater flows into the system can be

located spatially in a complex manner. This creates special environmental conditions within a

more uniform environment that can be referred to as “hot-spots”. The term “hot-spots” has

recently been used in peatland literature to show e.g. sources gas emission (Morris et al. 2011).

4.3 Numerical modelling needs and approaches

4.3.1 Numerical modelling needs

Groundwater-dependent ecosystems require an allocation of water to maintain their persistence

in the landscape. The following four fundamental questions are identified as being central to the

effective management of groundwater-dependent ecosystems (Eamus et al., 2006):

1) Which species, species assemblages or habitats are reliant on a supply of groundwater for their

persistence in the landscape?

2) What groundwater regime is required to ensure the persistence of a GDE?

3) How can managers of natural resources successfully manage GDE?

4) What measures of ecosystem function can be monitored to ensure that management is

effective?

Numerical hydrological modelling is fundamental to estimate the groundwater regime that is

required to ensure the persistence of a GDE. Moreover those models should be capable to model

the responses to different management policies. More specifically models should be able to give

information about the following attributes:

1) The depth of the saturated zone.

95

2) Hydraulic head within an aquifer.

3) Groundwater flow rate.

4) Quality of the groundwater.

5) Groundwater discharge and location.

Models should be able to give information about those attributes spatially and temporally.

Moreover, in order to accurately simulate GDEs it is necessary to model groundwater in an

integrated manner. Numerical models of GDEs are needed to i) understand the temporal and

spatial variation in hydrology and hydraulics, and to ii) make scenarios of impacts of past and

future changes. Spatial variation of flow influences vegetation and species composition as the

amount of flow controls temperature and nutrient fluxes in GDE. The temporal variation is

important too as many species in GDE are adapted to stable conditions. It could be important to

simulate impacts of droughts and floods to groundwater discharge to reveal the extreme natural

conditions GDEs will have to face in the future.

The typical scenarios to be simulated are related to climate change, land use changes, drainage,

urbanization, water extraction, increase nutrient input from land-use or atmospheric fallout.

Typical land-uses are agriculture, forestry, and mining. In riverine systems dredging and

hydropower regulation is important.

The models need to simulate impacts of future changes in water and land use. This includes

change in vegetation, climate and also the socio-economic system. Sometimes policies impact

agriculture, forestry, peat harvesting etc which influence water use and this must be included in

scenarios.

In some cases the impact of biological and geomorphological processes on hydrology needs to be

included in simulations. These include impacts of biofilms and eroded sediments on stream bed

and its permeability. In the littoral zone the vegetation can influence mixing conditions. It’s

likely that vegetation has also other feedbacks on hydrology.

For climate change scenarios it is important to distinguish between climate variability and

climate change. The length of climate data record must be sufficient to separate natural cycles

and long-term trends and shifts in climate.

For winter conditions we need snow and frost models having routines that can handle the

following processes; canopy snow, ground snow accumulation and melt and in some cases soil

frost. For soil frost we need models that take into account the impact of frost on soil hydraulic

conductivity and overland flow in a realistic way.

The hydrological models need to simulate some of the following outputs: I) water fluxes to and

from the GDE: runon-runoff-evapotranspiration, II) flow patterns in the GDE, III) water level

variation in the GDE, IV) water pressure in GDE soil and adjacent aquifer, V) the size of the

GDE aquifer capture zone, VI) water flow paths in the aquifer to the GDE, VII) residence time

distribution of water delivered to the GDE from the aquifer, VIII) temperature in the GDE (this

96

might be different between aquifer and the nearby surface waters), IX) snow depth and water

equivalent, X) snow melt rate, XI) and frost depth. The most important would perhaps be fluxes

to and from the system, internal flow patterns, pressure in GDE and aquifer and temperature in

the system.

GDEs can be modeled in different ways using e.g numerical models, statistical models, water

balance calculation etc. In the sections below we present some approached and issued to be

considered in modeling of GDEs. In Appendix 1 different aspects related to recharge modeling

and I Appendix 2 surface water modeling are reviewed.

4.3.2 Water balance calculation in GDEs

In GDEs supplied by several sources of water, the water balance equation can be written to

include the contribution of groundwater. The water balance equation for a groundwater

dependent system with an upland catchment where surface water and groundwater components

are separated would be:

P + Rgwi + Rswi = ET+ Rgwo + Rswo ± ΔS

where water input is from precipitation and snowmelt (P), groundwater input from the aquifer

(Rgwi) and surface water runoff from the surrounding catchment area (Rswi). Water lost by

evapotranspiration is denoted by (ET), groundwater outflow to the aquifer by (Rgwo), and runoff

to surface waters by (Rswo). A storage term (ΔS) is needed to account for short term changes in

water levels and soil moisture. In cold conditions, additional snow and ice storage, accumulation

and melt must also be accounted for. In coastal regions, sea water intrusion must be included in

the water balance terms.

For peatlands (e,g fens) the outflow of groundwater will usually be low as the deeper soil layers

have low permeability (Kvœrner and Kløve 2008). For systems with a considerable groundwater

input and negligible groundwater output the terms Rgwo would be zero so the water balance

would be:

Rgwi + Rswi + P = ET ± ΔS + Rswo

The change in storage ΔS are regulated by surface and groundwater input and by precipitation

and ET. In dry conditions with little surface water excess, the terms Rswi and Rswo could be small

at least in some periods of the year. In cold climate the term Rswi becomes negligible in winter as

precipitation is stored in snow and surface runoff is not generated.

P and Rswi can be estimated for ungauged catchments from the available climate data and

regional hydrological data, such as specific runoff (mm/year). The The estimation of Rgwi is not

straight forward as the drainage area for GDEs is not always evident. The regional specific

runoff may be used to estimate the sum of Rgwi and Rswi, however, this would not separate the

two components but be a sum of upland catchment input. In many cases, the groundwater input

could be difficult to define as the groundwater catchment boundaries are not easily defined

without complex geological surveys and modelling. Difficulties in catchment boundary

determination could occur if the surface water divide is different from the groundwater divide by

97

e.g. water input is from fractures outside of the watershed. Exchange of groundwater can also

take place between aquifers at different depths through semipermeable layers. This exchange can

be quantified from the hydraulic conductivity of the semipermeable layer and the piezometric

levels in the two aquifers.

4.3.3 Surface water groundwater interaction models

Surface water bodies are integral parts of groundwater flow systems. Our models should be able

to properly simulate groundwater-surface water interaction. There are various coupling schemes

for the integration of surface water and groundwater models, for example sequential, iterative or

fully coupled (see Deliverable 5.1 for more details).

Some considerations must be made when selecting an appropriate model for a project, like the

desirable temporal duration and resolution, the objective of the model, the spatial dimensions,

and model solution method (numerical, analytical, physically based, or data driven). We can

distinguish different type of models:

1) Physical based models

a. Groundwater and surface channel flow models

b. Groundwater and watershed models

2) Operational models

a. Lumped

b. Embedding

c. Response matrix

d. Eigenvalue

Physical models can couple channel routing models with 3D/2D flow groundwater models. They

solve the partial differential equations using numerical methods. Solutions are then found for the

points or nodes defined by the space-time discretization. These models are very attractive since

they can give important information regarding of the groundwater and surface water regime;

however they are time consuming to run, especially when integrated into management models.

In the groundwater watershed models, instead of channel routing models, watershed models are

coupled with groundwater flow models. Usually in this type of models, surface water are

modelled using distributed lumped hydrologic equations, therefore the output is not as detailed as

in the distributed physical models. On the other hand, these models have the advantage that can

simulate land use, irrigation demand, evapotranspiration, surface runoff and climatological

impacts.

Operational management models were designed to handle management objectives like water

allocation. In this type of models lumped and distributed parameter models have been used to

simulate aquifers and quantify stream-aquifer interaction. Two main techniques have been used

to incorporate distributed-parameter groundwater representations in management models,

namely, the “embedding” and the “response matrix” methods (Gorelick, 1983). In the

“embedding method” the system of equations obtained by numerical approximation of the

governing groundwater flow equation is embedded within the optimization model constraint set.

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This approach results in very large constraint sets that bring numerical difficulties and carry a

high computational cost. When linearity can be accepted the principles of superposition and

translation in time are applicable, which allows the use of influence functions or response

matrices. The main advantage of response matrices is their condensed representation of external

simulation models. A third approach is the eigenvalue method (Sahuquillo, 1983; Andreu and

Sahuquillo, 1987). Hydraulic heads, flux vectors, and surface and groundwater interactions are

obtained by explicit state equations as a function of the initial conditions and external stresses in

the period.

4.3.4 Stream-aquifer interaction models

River passing through a region underlain by a phreatic aquifer may either contribute water to the

aquifer or serve as a drain. Depending on stream stage, ground water elevation, and saturation

state between streambed and the aquifer, they can be hydraulic connected or disconnected.

Hydraulic connection occurs when the water table intersects the streambed. On the other hand

when an unsaturated zone develops between the streambed and the phreatic surface, the two

water bodies are hydraulically disconnected.

When the system is hydraulically connected, the stream–aquifer relationships can be subdivided

to gaining stream where the water flows from the groundwater to the river and losing stream

when river gives water to the aquifer. The exchange fluxes depend on the hydraulic head

differences between the aquifer and the surface water, as well as the hydraulic conductivity of

the riverbed. When the water bodies are disconnected the river infiltration becomes nearly

independent of aquifer head.

However, Peterson and Wilson (1988) showed that even when the unsaturated condition is

present, the stream and aquifer may in fact be connected, in the sense that further lowering of the

regional water table could increase channel losses. At some critical depth to the water table,

however, further lowering has no influence on channel losses. At this depth, which depends

mostly on soil properties and head in the channel, the aquifer becomes hydraulically

disconnected from the stream.

4.3.5 Leakage coefficient approach

When the stream is hydraulically connected to the aquifer, the exchange fluxes between them

depend on the hydraulic head differences between the aquifer and the surface water, as well as

the hydraulic conductivity of the riverbed. Leakage into an aquifer is given by (McDonald and

Harbaugh, 1984):

riverleakage riverbed

riverbed

h hq K

d

where: qleakage is the leakage coefficient [LT-1

], Kriverbed is the hydraulic conductivity of the river

bed [LT-1

], driverbed is the thickness of the semipervious layer [L], hriver is head in the river [L] and

h is the head in the aquifer [L].

99

When combining the Kriverbed and driverbed we obtain the leakage coefficient:

riverbedleakage

riverbed

Kl

d

As the riverbed has usually a lower hydraulic conductivity than the underlying or adjacent

aquifer, the riverbed controls the leakage rate.

If unsaturated conditions prevail between river bottom and aquifer the exchange can be

approximated by (Doppler et al., 2007):

leakage leakage river riverbottomq l h z

where the hydraulic head h below the river bed is replaced by the level of the river bottom

assuming zero water pressure below the clogging layer.

Surface water and groundwater interaction is usually modelled with temporally constant leakage

coefficients. However, leakage coefficient is not constant (Blaschke et al., 2003; Doppler et al.,

2007; Engeler et al., 2011), various reasons can affect it as flood events and sediment transport

processes. Furthermore leakage coefficient depends on temperature since the hydraulic

conductivity of the riverbed, which besides its dependence on soil properties, is also controlled

by fluid viscosity:

kgK

where K is the hydraulic conductivity [LT-1

], k is the permeability [L2], g is the gravitational

acceleration [LT-2

], and ΰ is the kinematic viscosity of the fluid [L2T

-1]. The kinematic viscosity

is temperature dependent; therefore the exchange fluxes between the river and the aquifer are

also temperature dependent.

Doppler et al. (2007) found that the leakage coefficient on the river Limmat in Switzerland,

which has temperature of about 4oC in winter and about 24

oC in summer, differs by a factor of

1.7 between summer and winter.

Especially in case of larger head gradients between river and aquifer, it is relevant to take into

account that the leakage coefficient is temperature-dependent. This occurs in rivers, which have

an unsaturated zone below the riverbed, as often is the case in arid regions. Infiltration from the

river will vary as a function of temperature, and if the river only carries a small amount of water,

also diurnal fluctuations in infiltration rate (due to diurnal temperature variations) might be of

importance. It is expected that infiltration increases during the day, which could reduce the

discharge rate of such rivers (Engeler et al., 2011).

Colmation process can also affect the leakage coefficient. Colmation is the retention processes

that can lead to the clogging of the top layer of the riverbed sediments; which directly affects the

leakage coefficient. Clogging of the river increases the hydraulic resistance; this resistance is

strongly spatially variable within the riverbed. Moreover the resistance can be time-dependent

due to transient sedimentation and erosion or biochemical processes. Doppler et al. (2007) found

100

that the leakage coefficient on the river Limmat changed by a factor of 2.7 after a major flood

event.

Colmation can be affected by several activities, like increased sewage lading often leads to

clogging by promoting the development of dense mats, or by causing the sedimentation of an

organic layer on the river bed (Sophocleous; 2002). In many streams gradual colmation occurs

naturally through the deposition of fine material during low discharge, alternating with a

reopening of the interstices during flooding or exfiltration (decolmation) (Sophocleous; 2002).

For the formation of a clogging layer it is also important whether infiltration or exfiltration

conditions prevail. Infiltration conditions favour the forming of clogging layers; on the contrary,

such a layer formation may be inhibited in the case of exfiltration conditions.

The assumption of a linear relationship between the specific leakage rate and the hydraulic head

difference between the aquifer and the river is not necessarily valid. High river stages lead to

inundations of adjacent land and enhanced bank infiltration, for such situations the leakage

coefficient is apparently larger than in a normal situation.

Beside the leakage coefficient there are other factors that can affect the river-aquifer interaction.

One of the factors is the distribution of the hydraulic properties of the aquifer below the riverbed;

the distribution of the hydraulic properties in the aquifer can be highly heterogeneous. The

exchange fluxes between the river and the aquifer also depend on the geometry of the riverbed as

well as the orientation of the river with respect to the main flow direction of the groundwater

(Woessner, 2000), both of which may vary over time due to variable flow regimes and the

related sedimentation and erosion processes.

A major difficulty is the determination of the leakage coefficient. It can be locally measured by

seepage meters which measure the infiltration flux (Murdoch and Kelly, 2003); however due to

the spatial heterogeneity of the riverbed and the surrounding hydrogeological settings, a local

seepage measurement is expected to give only local information. The infiltration rate of losing

river reaches can be also assessed by differential river discharge measurements. The usual way to

estimate leakage coefficients is by model calibration using head data, tracers have been also

used.

4.3.6 Future modeling needs

GDEs comprise a range of various ecosystems with different hydrogeology setting and hydraulic

contacts with aquifers and surface waters. To understand the hydrology of GDEs, fully integrated

models will be useful where the interaction with surface water or sea water can be included. In

cold conditions winter climate, snow and frost processes must be included in models. For

management of aquifers connected to GDEs impacts of management must be included in models

and scenarios. Besides hydrologic and hydraulic model development, models need to be linked

to geochemistry, biology and management of aquifers.

101

In many cases models must include heat transport , which is important for ecosystems and

needed when impacts of climate change are predicted. The main impact on GDEs is change in

water balances and temperature. The use of air temperature alone to predict changes GDEs is not

sufficient. Also the feedback that biological and geomorphological processes have on flow need

to be considered in modeling (e.g. flow resistance produced by biofilms, plants, and sediments).

Non-linear behavior need to be considered in the leakage coefficient.

A clear need is also to gain more information on the hydraulic contact between aquifers and

GDEs to obtain realistic boundary conditions.

102

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Appendix 1 Groundwater recharge models - basic approach: Piston flow model

Recharge models - basic approach

The main phenomenon governing interaction between surface and ground water is ground water

recharge. It has usually been modelled using a discrete model of flow in aeration zone. If even

the applied model is of the one-dimensional type (meaning actually a vertical cylinder), it may

be seriously complex and difficult to use, just because of the spatial distribution of parameters.

A large number of detailed data on infiltrating stream is needed by that complicated model. In

case when only the general groundwater movement is to be considered, rather than the

infiltration itself, the full model can be quite uneconomical to use

In this case a model which needs only a couple of most important data, but which would be

simpler in use, is much more needed, if, however, it is able to describe a fully unsteady process.

The above conditions are met by the piston model of infiltration (PM), now under development.

Fig A1-1 Schematics of water circulation in soil aerated zone.

Net precipitation computing

Net precipitation computing is usually done in a separate module (as a computer

implementation). It is used for determining of how much of precipitation can infiltrate further

into soil/ground. Simplified model is used in PM, using Turc equation [1]. For that model the

following data is needed: mean sun radiation (from astronomical tables), mean local

114

temperature, known local precipitation, type of vegetation (as for assessment evapotranspiration

level) and rhisosferic width. These are readily-available data, model based on them can be used

for further analysis using main module of PM. There is however a possibility of using the

Penmann-Monteith evapotranspiration model [2], if all data for this model can be collected. (as

for Turc equation, plus the following: Earth surface mean albedo, cloud cover, water vapour

pressure, wind speed).

Evapotranspiration in dry soils can be greatly reduced (even the transpiration part can be

entirely stopped), as plants stop do grow. That process begins when the suction height (meaning

the height which must be cleared by water-conducting capillary vessels in the plant) equals to

7m. For 160m there is final cessation of breathing activity - last part of wilting point [3]. As the

dry soils have high insulation properties (for heat and vapour transport) on surface level, direct

evaporation can be ignored here, so evapotranspiration equals to transpiration (which, as stated

above, can be close to zero).

Real evapotranspiration must then be calculated based on rhisisferic zone moisture, so moisture

characteristics must be known - for current PM model it is based on Corey-Brooks [4] formula.

Net precipitation is therefore computed the following way: Potential evapotranspiration is

determined based on actual precipitation data (from meteorological records). Then biota

evapotranspiration is assessed (taking into account: rhisosferic width, dominant vegetation type,

current vegetation season). Finally actual evapotranspiration is calculated (with above

mentioned remarks).

Effective precipitation and infiltration determination using piston model

Modelling of moisture content changes can be based on classical piston model with a sharp

wetting front of Green-ampt [5], and on the model of unsaturated infiltration and moisture

redistribution formula of Morel-Seytoux [6].

Moisture content after the front passing is considered to be constant, not depending on duration

of infiltration process and actual position of the front (therefore it can look like “a piston” of

moisture – hence the name of the model). Process of moisture change is modelled in such a way

that it can be described using a few basic parameters. Unavoidable distortion of the description

of the process is not significant for the purpose of the model.

In PM model it is assumed that active capillary zone is completely saturated, and that passive

zone has maximal moisture content. Residual moisture (meaning moisture between last vetting

front and capillary zone) is constant in profile of aerated zone, but it can be changing in time,

depending on recharge balance.

Infiltration is then calculated the following way: non-saturated infiltration (for maximum two

wetting fronts, when hydraulic head = 1.0), then saturated but non-submerged infiltration (with

hydraulic head determined by recharge) and finally submerged infiltration (with hydraulic head

115

determined by height of submersion). For the latter maximum soil moisture holding capacity is

considered, surface flow forms when it is exceeded.

Infiltration speed, and therefore recharge volume of deeper ground layers, can be restricted by

decreasing hydraulic head (slowing of moisture movement) caused by shallow-lying ground

water table. (it is “supported infiltration” as opposed to “free infiltration”). PM model can be

used for both types of infiltration.

Precipitation events happen from time to time, but mostly (between those events) moisture

content within soil is determined by moisture redistribution process. It allows for movement of

existing wetting fronts near surface and concerns only the zone above first front. Redistribution

effect appears only when recharge from precipitation falls below maximum moisture

conductivity. In case when evapotranspiration is the only process moisture will be taken (using

capillary suction) from deeper ground layers. Darcy-Buckingham formula is used to describe

this:

k

zDk

z

hkv w

s d

d

d

d

d

d,

for entire blocks with constant moisture content (humidity). Dw means here moisture

diffusion coefficient. In PM moisture redistribution is calculated taking into account above

mentioned “supported infiltration”.

Model use, field examples

PM can be used for GDE current state monitoring, as it allows for predicting of ground water

recharge values, which are very important for that type of biota.

Overall functioning of GDE areas can be predicted, concerning periodic, seasonal and

permanent climatic changes. Impact of human development (in form of surface cover changes

and ground water table position) on GDE also can be addressed. That infiltration model can

also be used for unsteady infiltration simulations for other models, concerning functioning of

the entire ground water reservoir –including models build on MES principle.

All of above mentioned assumptions were used to build a computer model of ground water

recharge for data collected for Wiercica river catchment area (sląskie voivodship on border with

łodzkie in southern-central Poland.

Wiercica is a medium right-side tributary of river Warta). Hydrogeological data needed for

modeling were taken from detailed research of that area done for local tape water distribution

company (Wodociągi Częstochowskie). That research was a part of protection and

rehabilitation effort for ground water reservoir, called GZWP 326. Meteorological data were

from polish meteo authority – IMGW (albeit indirectly). Data concerning land cover and

vegetation came partly from CORINE Land Cover 2000 Programme [7] and partly from other

sources [8].

116

There are a few requirements for a functioning water infiltration model.

Firstly it should be able to show the real mechanism of infiltration. Amount of infiltration

should be computed in the time scale, at given intervals. All of the results shall be prepared in

such a way that other models (concerning ground water bodies movement - for example) can

use it, including its spatial distribution.

Secondly, all the developed models (including infiltration ones) must be prepared in such a way

that the data needed for them (for calculations) can be easily obtained. It is especially important

for models which are supposed to describe a larger area. Use of very advanced methods may be

greatly hampered by lack of suitable data for their actual operation. If there is no other choice

simplified models for some parts may be considered (like substituting a simplified Turc

evapotranspiration model instead of the full model in PM).

Models should be easy for practical use and their results must be as straight forward as possible.

It is not an easy task, as it must not lose the actual physics of the process.

For the Piston Model of unsteady infiltration the following data are required:

Soil parameters:

- filtration coefficient

- conductivity exponent (as for Irmay-Awierjanov)

- porosity coefficient

- residual moisture

- capillary height

- aerated zone depth

- type and state of vegetation coefficient (as for Turc equation)

Precipitation diagram (hydrogram) parameters:

- time interval

- initial precipitation

- duration of analysis

In addition detailed precipitation data is required, that is: time and intensity of precipitation

event (in mm), temperature at that moment, mean solar radiation (for evapotranspiration

calculations).

The results are: net amount of water infiltrating into the saturated zone, soil layer (layers) cross-

section diagrams with moisture and vetting fronts.

117

As for now land use and vegetation characteristics (for evapotranspiration calculation) are

described by one coefficient ("type and state of vegetation"). Works are underway to do it in a

more comprehensive way.

What do we expect in the future?

In the near future we shall finish refining the model internal structure ("supported infiltration").

Evapotranspiration module (in the computer implementation) should be able to receive data

directly from other models (for example based on Penmann-Monteith standard model). We will

start work on using the already developed model on a wider area, thus trying to build a quasi-2D

approach.

References:

[1] Turc, L Estimation of irrigation water requirements, potential evapotranspiration: a

simple climatic formula evolved up to date Ann. Agron, 12, 13-49, 1961

[2] Allen, R.G.; Pereira, L.S.; Raes, D.; Smith, M. (1998). Crop Evapotranspiration—

Guidelines for Computing Crop Water Requirements. FAO Irrigation and drainage paper 56.

Rome, Italy: Food and Agriculture Organization of the United Nations.

[3] Kowalik p, Eckersen h, Water transfer from soil through plants to the atmosphere in

willow energy forest Ecol. Model. Vol. 26, pp251-284

[4] R.H. Brooks and A.T. Corey (1964). "Hydraulic properties of porous media". Hydrological

Papers (Colorado State University).

[5] Green, W.H. & Ampt, G.A. (1911) Studies on soil physics, 1.The flow of air and water

through soils. J. Agric. Sci. 4, 1-24.

[6] Morel-Seytoux, H.J. (1984) Some recent developments in physically based rainfall-

runoff modeling; Frontiers in Hydrology; Water Resources Publications: Littleton/Colorado.

[7] European Environment Agency – Corine Land cover data – version 15

[8] Jan Marek Matuszkiewicz / Potential natural vegetation of Poland; IGIPZ PAN:

Warszawa 2008

[9] Potencjalna roślinność naturalna; Internetowy Atlas Polski; Pracownia Kartografii i GIS

IGIPZ PAN

118

Appendix 2 Surface water models

Surface water models have two different components, a hydrodynamic component where the

transport due to flow and turbulence is handled and a kinetic component where the

biogeochemical reactions and the ecological behaviour are handled. The transport processes are

very dynamic and should be represented in a temporal resolution of seconds to minutes, where

kinetic processes are much slower and can be represented on the order of hours. Several surface

water models available nowadays have either a transport component or both components. In this

section some examples of surface water models that have both components were described.

Surface Water Models for Rivers and Streams

QUAL2E/QUAL2E-UNCAS

QUAL2E is a steady stream water quality model developed by United States Environmental

Protection Agency. It is not supported anymore; however it is the “ancestor” of many stream

water quality models such as QUAL2K, HEC-RAS Water Quality Components or SWAT

Stream Water Quality sub model. Therefore it is worth to be described in this section.QUAL2E

and QUAL2-UNCAS are very well known generally purposed water quality models applied to

many streams of the world so that their reliabilities are approved. QUAL2E-UNCAS was

designed to perform uncertainty analysis. QUAL2E uses a simplified representation on stream

hydraulics and solved one dimensional advection diffusion reaction equation to simulate

transport and conversion of water quality constituents. The model discretizes the stream into

computational elements, which represent completely mixed reactors that exchange material

through advection and dispersion (Fig A2-1). The state variables and their kinetic relations are

shown in Fig A2-2.

119

Fig A2-1 Model network of QUAL2E (Brown and Barnwell, 1987)

120

Fig A2-2 QUAL2E Kinetics

Even though not supported by USEPA anymore, the source code can still be found on the

Internet so that integration of QUAL2E to more comprehensive multimedia watershed models is

possible so that it could be a component of a modelling framework dealing with groundwater

dependent ecosystems.

QUAL2K

QUAL2K (or Q2K) is a river and stream water quality model that is intended to represent a

modernized version of the QUAL2E (or Q2E) model (Brown and Barnwell 1987). QUAL2K is

similar to QUAL2E in the following respects: It is one dimensional along the stream channel.

The channel is well-mixed vertically and laterally. Steady state hydraulics with non-uniform,

flow is simulated. The heat budget and temperature are simulated as a function of meteorology

on a diurnal time scale. All water quality variables are simulated on a diurnal time scale. Point

and non-point loads and abstractions are simulated. QUAL2K has a more comprehensive

representation of surface water quality than QUAL2E. The enhancements are listed below:

121

- Carbonaceous BOD speciation: Q2K uses two forms of carbonaceous BOD to represent

organic carbon. These forms are a slowly oxidizing form (slow CBOD) and a rapidly

oxidizing form (fast CBOD). In addition, non-living particulate organic matter (detritus)

is simulated. This detrital material is composed of particulate carbon, nitrogen and

phosphorus in a fixed stoichiometry.

- Anoxia: Q2K accommodates anoxia by reducing oxidation reactions to zero at low

oxygen levels. In addition, denitrification is modelled as a first-order reaction that

becomes pronounced at low oxygen concentrations.

- Sediment-water interactions: Sediment-water fluxes of dissolved oxygen and nutrients

are simulated internally rather than being prescribed. That is, oxygen (SOD) and nutrient

fluxes are simulated as a function of settling particulate organic matter, reactions within

the sediments, and the concentrations of soluble forms in the overlying waters.

- Bottom algae: The model explicitly simulates attached bottom algae.

- Light extinction. Light extinction is calculated as a function of algae, detritus and

inorganic solids.

- pH: Both alkalinity and total inorganic carbon are simulated. The river's pH is then

simulated based on these two quantities.

- Pathogens: A generic pathogen is simulated. Pathogen removal is determined as a

function of temperature, light, and settling.

The state variables of QUAL2K are given in Table A2-1

122

Table A2-1 State variables of QUAL2K.

Variable Symbol Units*

Conductivity s mhos

Inorganic suspended solids mi mgD/L

Dissolved oxygen o mgO2/L

Slowly reacting CBOD cs mgO2/L

Fast reacting CBOD cf mgO2/L

Organic nitrogen no gN/L

Ammonia nitrogen na gN/L

Nitrate nitrogen nn gN/L

Organic phosphorus po gP/L

Inorganic phosphorus pi gP/L

Phytoplankton ap gA/L

Phytoplankton nitrogen INp gN/L

Phytoplankton phosphorus IPp gP/L

Detritus mo mgD/L

Pathogen X cfu/100 mL

Alkalinity Alk mgCaCO3/L

Total inorganic carbon cT mole/L

Bottom algae biomass ab mgA/m2

Bottom algae nitrogen INb mgN/m2

Bottom algae phosphorus IPb mgP/m2

Constituent I

Constituent ii

Constituent iii

123

Fig A2-3 illustrates the mass balance around any computational element. The model kinetics is

illustrated in Fig A2-4 whereas the state variables and processes subjected to sediment diagnosis

are illustrated in Fig A2-5.

iinflow outflow

dispersion dispersion

mass load mass withdrawal

atmospheric

transfer

sediments bottom algae

Fig A2-3 Mass balance for a QUAL2K segment.

dn

upipo

h

e

d

s

s

s

sodcf

re

se

se se

se

s

s

mi

s

Alk

s

X

hnano

nnn

cf

hcs

oxox

mo

ds

rod

rda

rna

rpa

IN

IPa

p

r

s

u

e

o

cT

ocT

o

cT

o

cT

o

cT

dn

upipo

h

e

d

s

s

s

sodcf

re

se

se se

se

s

s

mi

s

Alk

s

X

hnano

nnn

cf

hcs

oxox

mo

ds

rod

rda

rna

rpa

IN

IPa

p

r

s

u

e

o

cT

ocT ocT

o

cT

o

cT

o

cT

Fig A2-4 QUAL2K Kinetics. Kinetic processes: dissolution (ds), hydrolysis (h), oxidation (ox),

nitrification (n), denitrification (dn), photosynthesis (p), respiration (r), excretion (e), death (d),

respiration/excretion (rx). Mass transfer processes are reaeration (re), settling (s), sediment

oxygen demand (SOD), sediment exchange (se), and sediment inorganic carbon flux (cf)

124

CH4 NO3

NO3

NH4d PO4p PO4d

NH4p NH4d

PO4p PO4d

CO2 N2

N2

POC

cf o na nn pioJpom

NH4p

CH4(gas)

POP

DIAGENESIS METHANE AMMONIUM NITRATE PHOSPHATE

AE

RO

BIC

AN

AE

RO

BIC

WA

TE

R

PON

Fig A2-5 Sediment oxygen demand and diagenesis in QUAL2K.

The state variables and processes, especially incorporation of sediment cycles makes QUAL2K a

good template water quality model for groundwater dependent streams. QUAL2K is

implemented within the Microsoft Windows. It is programmed in the Windows macro language:

Visual Basic for Applications (VBA). Excel is used as the graphical user interface. The model

itself is written in Fortran, but the source code is not supplied. However, the core of the model

uses text based input and produces text based output so that using it as a steady state river water

quality engine in larger modelling problems by input output level coupling is possible.

EPD-RIV1

EPD-RIV1 is a system of programs to perform one-dimensional dynamic hydraulic and water

quality simulations. The computational model is based upon the CE-QUAL-RIV1 model

developed by the U.S. Army Engineers Waterways Experiment Station (WES). This modelling

system was developed for the Georgia Environmental Protection Division of the Georgia

Department of Natural Resources and the U.S. Environmental Protection Agency.

EPD-RIV1 is a one-dimensional (cross-sectionally averaged) hydrodynamic and water quality

model. It consists of two parts, a hydrodynamic code which is typically applied first, and a

quality code. The hydraulic information, produced from application of the hydrodynamic model,

is saved to a file which is read by, and provides transport information to, the quality code when

performing water quality simulations.

125

The water quality code can simulate the interactions of 16 state variables (Fig A2-6), including

water temperature, nitrogen species (or nitrogenous biochemical oxygen demand), phosphorus

species, dissolved oxygen, carbonaceous oxygen demand (two types), algae, iron, manganese,

coliform bacteria and two arbitrary constituents. In addition, the model can simulate the impacts

of macrophytes on dissolved oxygen and nutrient cycling.

Fig A2-6 State variables and processes of EPD-RIV1 model.

EPD-RIV1 is equipped with a graphical user interface, pre-processor and postprocessor, however

the hydrodynamic and water quality computation engines are found as separate exe files and they

accept text based input data, so that coupling EPD-RIV1 with other models on input/output level

is easy and straightforward. If a source level coupling is required, the user can still use CE-

QUAL-RIV1, which is open source and slightly different from EPD-RIV1 only.

126

Surface Water Models for Lakes, Reservoirs and Estuaries

WQRRS (HEC, 1978)

It is a one dimensional dynamic model which calculates the temporal variations of state variables

in vertical dimension (z) for reservoirs and horizontal dimension (x) for rivers. WQRRS is an

acronym for Water Quality for River and Reservoir Systems, and was created by U.S. Army

Corps of Engineers (USACE), Hydraulic Engineering Centre (HEC). The model is intended to

simulate the effects of reservoir systems on river-reservoir systems. Yet, process kinetics and

water quality state variables covered in the WQRRS makes it also useful for ecosystem

modelling in lagoons. In addition to the many water quality state variables; phytoplankton,

zooplankton, fish, and benthic organisms can be simulated by the model. The reservoir module is

a horizontally well mixed and vertically layered one dimensional transport and aquatic ecology

model (Fig A2-7, Fig A2-8 and Fig A2-9).

127

Fig A2-7 Model domain of WQRRS Reservoir Module.

128

Fig A2-8 Transport as considered by WQRRS Reservoir Module.

129

Fig A2-9 State variables and processes considered in WQRRS.

130

The river module is a one dimensional stream ecology model that has additional state variables

dealing with aquatic invertebrates. The model network and computational elements are similar to

the structures in QUAL2E; however WQRRS River module is a fully dynamic model with more

advanced capabilities. The stream hydrodynamics are simulated using 6 different options, from

simple backwater computations for steady flows to the solution of the full St. Vernands

equations with all nonlinear terms.

WQRRS was coded with FORTRAN IV which usually runs on relatively old computer systems.

The last known port of WQRRS to PC’s was conducted in early 1990’s and the executables have

incompatibility problems with modern operating systems such as 64 bit ones. The executables

use/create text based input and output files so that they can be coupled with other

watershed/groundwater modelling software on input/output level. At least for reservoir module

there is an alternative solution if source code level coupling is required. EGOLEM is a

modification of WQRRS. Gönenç et al. (1990) rearranged the reservoir module of original

WQRRS designed for old main frame computes to enable it running on IBM-PC compatible

systems. No alteration has been made in the process kinetics and other module properties of the

original model, and it was used successfully in water quality simulation of Küçükçekmece

Lagoon (Gonenc et al., 1997). Source code is still available.

CE-QUAL-R1 (Environmental Laboratory, 1995)

It is a modification of WQRRS Reservoir model by U.S. Army Corps of Engineers (USACE),

Waterways Experiment Station (WES), so that it can also simulate iron and manganese, and as

well as anaerobic conditions. The transport is handled similar to WQRRS Reservoir module (Fig

A2-7 and Figure A2-8), however the aquatic kinetics have been enhanced (Fig A2-10). As seen

in Figure x.11 the model has two components, one for simulating transport and temperature and

another one for simulating reservoir water quality and ecology.

131

Fig A2-11 State variables of CE-QUAL-R1

CE-QUAL-R1 provides a very good template as an aquatic ecology template for groundwater

dependent ecosystems. It is free, however only part of the source code that is dealing with

transport and temperature simulations (CE-THERM-R1) are open. The last executables of the

full model developed for MS-DOS and do not correctly run on modern operating systems.

However using a virtualization environment such as DOS-BOX it is possible to couple CE-

QUAL-R1 with other modelling software such as groundwater modelling software on

input/output level.

CE-QUAL-W2

It is a two-dimensional model which does both hydrodynamic and water quality simulations in

longitudinal and vertical dimensions (x, z). It is suitable for applications in rivers (also large

rivers), reservoirs and estuaries. Water quality state variables constituted in the model are

temperature, salinity, dissolved oxygen, CBOD, organic material composed of carbon, nitrogen,

132

and phosphorus (dissolved and labile, dissolved and refractory, particulate and labile, particulate

and refractory), ammonia nitrogen, nitrate nitrogen, phosphorus, dissolved and particulate silica,

multiple groups of phytoplankton, epiphytes and zooplankton (Fig A2-12).

Fig A2-12 State variables of CE-QUAL-W2.

LDOM : Labile dissolved organic matter

LPOM : Labile particulate organic matter

RDOM : Refractory dissolved organic matter

RPOM : Refractory particulate organic matter

CBOD : Carbonaceous biochemical oxygen demand

133

It was developed by Portland University and Supported by U.S. Army Corps of Engineers, and

latest version of the model is CE-QUAL-W2 3.7 with open source code. One drawback of the

model is that sediment processes are not touched upon adequately, yet it has been claimed by the

developers that new versions of the software will be simulating sediment process in more detail.

CE-QUAL-ICM (Cerco and Cole, 1994; Cerco and Cole, 1995)

This model is capable of simulating sediment processes in detail, and was developed by U.S.

Army Corps of Engineers (USACE). However, it only includes water quality code and to run the

model outputs of CH3D hydrodynamic model (or compatible outputs from another model), are

necessary. The model is mainly designed and optimized for estuaries and coastal ecosystems.

Together with the CH3D, CE-QUAL-ICM can make water quality simulations in three spatial

dimensions. The state variables and their relations are illustrated in Fig A2-13.

Fig A2-13 State variables and their relations in CE-QUAL-ICM.

134

A copy of the software and the source code can be obtained by contacting the developers. CE-

QUAL-ICM is written in FORTRAN 77 and uses text based input and output so that coupling it

with other models is easy and straightforward.

Surface Water Models for General Application

WASP (Water Quality Analysis Simulation Program)

WASP is a well known dynamic water quality/water ecology model. It has been developed for

three decades and is supported and distributed by USEPA. WASP is a general purposed water

quality/ecology model applicable to streams, lakes, estuaries and the coastal ocean. As shown in

Fig A2-14, it is a so called “box model” based on integrated finite differences methods, where

the control volumes (model segments) and their water exchanges (links) are defined in the model

domain.

Fig A2-14 WASP model network.

WASP has a simplified hydrodynamic transport modelling capabilities more suitable to model

shallow and vertically well mixed channel networks; however it has a generalized hydrodynamic

interface that allows easy one-way linking of results from more sophisticated other multi

dimensional hydrodynamics models that can represent large lakes, estuaries and coastal

ecosystems. WASP has several modules: EUTRO (for simplified eutrophication analysis),

135

Advanced eutrophication module, HEAT (for temperature, suspended solids with simplified

bacteria simulation capabilities), TOXI (for toxic organic chemicals, but no ecological

interaction with organisms) and Mercury (a modified version of TOXI optimized for mercury

cycle).

These modules are not coupled to each other and run separately. For example, one cannot run

Advanced Eutrophication Module together with TOXI and simulate the inhibition effects of toxic

chemicals on primary production. However the modules can be run sequentially and the results

from one module can be directly imported by the next module. An example is to import the

temperature results produced by the HEAT module into the EUTRO module.

The water column variables and processes in the Advanced Eutrophication Module is illustrated

in Fig A2-15. The Advanced Eutrophication Module allows interaction between surface water

quality and sediment diagenesis processes as well (Fig A2-16).

Periphyton Biomass

D : C : N : P : ChlIP

IN

Periphyton Biomass

D : C : N : P : ChlIP

IN

Phytoplankton BiomassGroup 3

D : C : N : P : Si: Chl DOGroup 2D : C : N : P : Si: ChlGroup 1

D : C : N : P : Si : Chl

TICH2CO3 – HCO3

- – CO32-

TotalAlkalinity

Particulate Detrital OM

SiPNCD

Particulate Detrital OM

SiPNCD

Dissolved OM

Si

P

N

CBOD1

CBOD2

CBOD3

Dissolved OM

Si

P

N

CBOD1

CBOD2

CBOD3

Inorganic Nutrients

NO3PO4SiO2 NH4

Inorganic Nutrients

NO3PO4SiO2 NH4

pHpH

atmosphereatmosphere

uptakeexcretion

uptakeexcretion

Inorganic Solids

S3S1 S2

Inorganic Solids

S3S1 S2

oxi

dat

ion

oxi

dat

ion

nit

rifi

cati

on

photosynthesis and respiration

death

dissolution

mineralization

sorption

Fig A2-15 State variables and processes in the water column.

136

G1

G2

G3

DissolvedParticulate

Reaction Products


Reaction Products

Dissolved

ConstituentParticulate

Organic Matter

Products

ProductsReactions

Surface

Exchange

Sedimentation

Diagenesis

Sedimentation

Sedimentation

Reactions

Mixing Diffusion

Net

Settling

La

yer

2L

ay

er 1

Wa

ter

Co

lum

n

G1

G2

G3


Reaction Products


Reaction Products

Dissolved

Constituent

Dissolved

ConstituentParticulate

Organic Matter

Particulate

Organic Matter

ProductsProducts

ProductsProductsReactions

Surface

Exchange

Sedimentation

Diagenesis

Sedimentation

Sedimentation

Reactions

Mixing Diffusion

Net

Settling

La

yer

2L

ay

er 1

Wa

ter

Co

lum

nL

ay

er 2

La

yer

1W

ate

r C

olu

mn

Fig A2-16 Water column and sediment interaction incorporated in the WASP Advanced

Eutrophication Module.

TOXI module contains a detailed representation of the following chemical processes:

Hydrolysis, Ionization, Oxidation, Volatilization, Photolysis and Biodegradation As illustrated in

fig A2-17. TOXI can simulate the reactions of three chemicals among each other in many

combinations.

WASP is a windows based application. It is free but not completely open source. Even though it

is a GUI based computer application, WASP still allows text based input and output so it can be

coupled with other models such as surface runoff or multi species ground water transport models

easily. This is an important advantage. Another advantage is that it is a very well known model

and has been applied to many aquatic ecosystems. WASP has a limited representation of aquatic

ecology that does not reach beyond primary production. Effect of zooplankton on phytoplankton

can be included as a forcing function, however other effects of zooplankton such as grazing on

detritus is not considered. Ecological processes are not coupled with water quality especially if

toxic chemicals are of concern. Another disadvantage is that the model segments are not allowed

to dry which jeopardizes the application of WASP on geographical compartments such as

ephermal rivers or wetlands that are examples for groundwater dependent ecosystems.

137

Fig A2-17 Reactions in TOXI

138

AQUATOX

AQUATOX assess dynamic effects of various stressors such as temperature, toxic chemicals,

nutrients, sediment; which is applied to aquatic environments from experimental tanks to lake

systems. AQUATOX known as a process based model, since it simulates the transfer of biomass,

chemicals and energy from one compartment to another in an ecosystem by simultaneously

computing the daily chemical and biological processes. Process-based models are not based on

statistical relationships, opposed to that empirical models could establish that correlation

between the existing variables, but do not explain the reasons or the mechanism of the

relationship (Park & Clough, 2009). Moreover, AQUATOX also predicts both direct and indirect

effects of chemicals in the aquatic ecosystems to the resident organisms, besides their

environmental fate. The model fills the gap between chemical water quality and biological

reaction and provides a better understanding by linking them together (Park & Clough, 2009).

AQUATOX outclasses many other models by its capability of multi-compartment ecosystem

modelling, while others can provide few biological compartments. It also includes plants,

invertebrates and fish, and expresses their physical and chemical interaction with the ecosystem

(Park & Clough, 2009). State variables of AQUATOX are listed below:

- Phytoplankton (multiple species)

- Periphyton and submerged aquatic vegetation (multi species)

- Planktonic and benthic invertebrates (multi species)

- Zooplankton, zoobenthos and fish (multi species)

- Forage, game, and bottom fish

- Nutrients and dissolved oxygen

- Organic and inorganic sediments

- Toxic organic chemicals (up to 20 different chemicals simultaneously)

- Perfloroalkylated Surfactants (bioaccumulation only)

Due to the fact that AQUATOX is a process-based model, it predicts the environmental fate and

ecological effects of the various environmental stressors by simulating various numbers of

biological and ecological processes which are the actual links between the system components,

the organisms. The main biological processes and processes environmental fate by different

processes are listed below:

- Photosynthesis and respiration

- Food consumption

- Growth and reproduction

- Natural mortality

- Lethal and sublethal toxicity from organic toxicants, ammonia and low dissolved oxygen

- Trophic interactions

- Changes in biological communities under changing environmental conditions

- Sloughing of periphyton due to high stream velocity

- Smothering of benthic organisms by suspended and bedded sediments

- Nutrient cycling and oxygen dynamics

- Release of phosphorus from anaerobic sediments and sediment diagenesis

139

- Calcite precipitation and removal of phosphorus under alkaline conditions

- Partitioning of organic toxicants to water, biota and sediments

- Toxic organic chemical transformations

- Bioaccumulation through gills and diet

The structure of the model makes it very valuable if ecological effects of external forces are to be

quantified for an aquatic ecosystem. Therefore it is a good template for an aquatic ecology

component of a modelling framework for groundwater dependent ecosystems. Moreover its

source code is open. The only disadvantage of the model is that it is more suited for shallow

water bodies and it provides an oversimplified representation of vertical stratification for deeper

ones. This disadvantage is a minor one for GENESIS project, since most of the groundwater

dependent ecosystems are shallow.

References

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