modelling bacterial levels in rivers to the coast. workshop 3 - r. falconer.pdf · modelling...
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11
Modelling Bacterial Levels in Rivers to
the Coastby
Roger Falconer
Hydroenvironmental Research Centre,School of Engineering, Cardiff University
22
Hydroenvironmental Research Centre
33
• Prof. Roger FalconerHalcrow Professor of Water Management
• Dr. Binliang LinSenior Lecturer in Hydroinformatics
• Dr. Catherine Wilson Lecturer in Eco-Hydraulics
• Dr. Bettina Bockelmann-Evans Lecturer in Environmental Hydraulics
• 12 Research Associates and Students
• 3 Academic Research Visitors
Research Team
44
• Develop hydro-environmental models to predict hydrodynamic, solute, sediment and contaminant transport processes in river, estuarine and coastal waters
• Undertake laboratory model studies and assist in field monitoring programmes to improve accuracy of processes modelled
• Improve interfaces and output devices for wider use of hydro-environmental models
Research Objectives
55
Current Research• Hydro-environmental modelling
• River and floodplain integrated modelling
• Wetland and mangrove nutrient modelling
• Vegetation impact on riverine systems
• Sediment and bio-chemical interactions
• Coastal and estuarine hydrodynamics
• Computer model solution algorithms
66
Environmental Hydraulics Challenges
77
• River basin flood risk management
• River sedimentation and morphology
• River ecology and water resources
• Domestic, agricultural and industrial effluents - point and diffuse sources
• Surface and subsurface interactions
• Land use and catchment hydrology
Typical Challenges
88
Physical Models
99
Physical Models
ScalingExpensiveInflexible
Not PortableNot Adaptable
DisadvantagesDisadvantagesDisadvantages
1010
No scalingInexpensive
FlexiblePortable
Adaptable
AdvantagesAdvantagesAdvantages
Numerical Models
1111
Numerical Models
Hydrodynamic processesWater quality processes Sedimentary processes
Solution algorithmsBoundary data
UncertaintiesUncertaintiesUncertainties
1212
Solution Procedure
1313
Decay?
Dissipation
Production?
MassMomentum
Solutes(Pollutants,Sediments,
or Metals)
dx
dy
b. Main processes occurringin each grid square
Watershed
Open Boundary?
a. Typical grid representation for river - coastal basin
LandLand
1414
• Advective-diffusion equation (with source inputs, bed and/or surface fluxes, kinetic interactions and/or particle settling)
• Continuity equation (with source inputs)
• Momentum equations (with earth’s rotation, wind shear, bed shear and turbulence)
Flow Modelling
Solute Modelling
1515
Water Quality• Physical
− Suspended Solids− Turbidity− Temperature− Radio-activity
• Chemical− Dissolved Oxygen− Bio-chemical Oxygen Demand− Nitrogen− Phosphorous− Metals
• Biological− Pathogens− Algae
1616
Collaborative Studies with CREH
1717
General Project Aims• Develop empirical relationships for bacterial
indicator levels with flow, sedimentary and bio-chemical processes in river basins
• Acquire better model representation between bacterial indicator and nutrient levels with sediment transport processes in river basins
• Refine hydroenvironmental modelling tools to provide holistic approach to river basin management and legislative compliance
• Refine models using data from 3 UK sites
1818
1. Total die-off
2. Settlement
3. Decay in darkness
4. Irradiance with decay also related to SPM
5. pH die-off
6. Temperature die-off
1. 2. 3. 4. 5. 6.
ktot = ks + (kd + f(Io,SPM))f(pH) f(T)
• Bacterial decay known to depend upon many parameters such as:-
Bacterial Decay• Hydroenvironmental models tend to use
constant values for decay rate or T90:
k = constant or k = φ(Temp)
1919
• Depth reduces effect of sunlight on decay (increases T90 value)
Effect of water depth on die-off ([SS]=10mg/l)
0
10
20
30
40
50
60
0 500 1000
Irradiance at waters surface, Io (W/m2)
Dept
h av
erag
ed T
90 (h
ours
)
Z=0.2m
Z=0.3m
Z=0.5m
Z=0.75m
Z=1.2m
Z=1.8m
Z=2.9m
Z=4.5m
Bacterial Decay
2020
Bacterial Decay• Suspended solids reduce effect of sunlight
on decay (increase T90 value) Effect of suspended solids on die-off
(Z=1m)
0
10
20
30
40
50
60
0 500 1000
Irradiance at waters surface, Io (W/m2)
Dept
h av
erag
ed T
90 (h
ours
)
[SS]=0.5 mg/l
[SS]=1 mg/l
[SS]=2 mg/l
[SS]=4 mg/l
[SS]=8 mg/l
[SS]=16 mg/l
[SS]=32 mg/l
[SS]=64 mg/l
2121
• Darkness to sunlight leads to increase in decay rate (reduction in T90 value)
1
10
100
1000
1 10 100 1000 10000Sunlight strength (Irradiance) W/m2
Faec
al C
olifo
rm T
90 (h
ours
)
Pommepuy et al. (1992),seawater.
Auer and Niehaus (1993),hypereutrophic lake.
Evison (1989), cleanfreshwater, 15 degC.
Evison (1989), cleanseawater, 15 degC.
Bellair et al., (1977), seawater18.5-26 degC
Sarikaya and Saatchi (1987),waste ponds, 25-30 degC.
Sarikaya et al. (1987), wasteponds, 26-31 degC.
Sarikaya et al. (1987), batchstudy, 24-27 degC.
Bacterial Decay
2222
Enteric Bacteria Fluxes• Bacteria in river and estuarine waters
primarily exist in two forms:Free-living bacteria moving with currents Adsorbed bacteria may beattached to surface of sediment particles and moves with sediments
• Adsorbed bacteria moving with sediments may be deposited on bed and subsequently re-suspended or desorbed to water column
• Free-living and adsorbed bacteria undergo decay processes - which are highly dynamic
2323
Enteric bacteria
water columnWastewater outfallsCatchment runoffWater birds
input
AdvectionDiffusion/dispersion
outputOverall reduction
Die-off
Deposition
Sediment re-suspension
Enteric Bacteria Fluxes
2424
Cardiff Bay
2525
Cardiff Bay Study
2626
grid cell size
50m x 50m
3-D Numerical Model
10 15 20 25 30 35 40 45 50 55 60
10 15 20 25 30 35 40 45 50 55 60
40
45
50
55
60
65
70
75
80
40
45
50
55
60
65
70
75
80
-8m
-6m
-4m
-2m
0m
2m
4m
6m
8m
10m
12m
14m
Queen AlexandraDock
RiverEly Depth
RiverTaff
BARRAGE
2727
Tracer Calibration
2828
Field MeasurementsMarch 2002, characterising
cold, overcast conditionsJuly 2002, characterising
hot, sunny conditions
2929
Monitoring Sites
3030
Measured Data• River discharges measured continuously at
upstream flow gauging stations
• Faecal coliforms and streptoccoci sampled daily at most sites by Harbour Authority
• Coliforms and streptococci measured hourly in day-light during field monitoring period
• Sunlight intensity measured hourly over Bay and also with depth at several key sites
• Temperature, pH and DO etc. also monitored
3131
0
700
07:00 08:00 09:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00
07:00 19:00
Light Intensity
coun
ts/1
00m
l
100
Faecal ColiformFaecal Streptococci
Bacteriological measurements : Eastern Dock SiteBacteriological measurements : Eastern Dock SiteBacterial Decay
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Time
0102030405060708090
100
08:30 10:30 12:30 14:30 16:30 18:30
Rad
iatio
n in
put (
x 10
µm
ol/m
2/s)
Surface0.1 m0.5 m1.0 m1.5 m2.0 m2.5 m3.0 m3.5 m
Light variation with depth : Eastern Dock SiteLight variation with depth : Eastern Dock SiteBacterial Decay
3333
0.1
1
10
100
1000
11-Sep-88
30-Mar-89
16-Oct-89
04-May-90
20-Nov-90
08-Jun-91
25-Dec-91
12-Jul-92
28-Jan-93
16-Aug-93
T90
hour
s
1
10
100
1000
10000
100000
FC c
fu/1
00m
l
3 day running average T90 (hours) 5 day running average FC (cfu/100ml)
Die-off Found to be Seasonal
3434
Artificial Neural Networks
Input LayerHidden Layer
Output LayerInpu
t Var
iabl
es
Output
1,1w1,2w
1x
2x1w
2w0w
+
1+
∑=
=N
iijij xwF
1, xe
xf−+
=1
1)(Sigmoid Equation
Back propagation Algorithm
3535
K K KT d S= +
Dynamic Decay Rate
( )[ ] sunlight for ratedecay conditionsdark for ratedecay
tIfKK
S
d
===
629.0236.063.2
givesdataofanalysisANN
IK T +=
3636
Millennium Stadium
3737
Varying day/night TVarying day/night T9090 values values -- 4 pm releaserelease
70,000
45,000
60,000
30,000
20,000
10,000
0
Faecal Coliform
counts/100ml
Model Simulation
3838
70,000
45,000
60,000
30,000
20,000
10,000
0
Faecal Coliform
counts/100ml
Varying day/night TVarying day/night T9090 values values -- 4 am releasereleaseModel Simulation
3939
River Ribble and Fylde Coast, U.K.
4040
Fylde Coast
London
Blackpool
LythamSt Anne’s
Ribble Estuary
River Wyre
Southport
Fleetwood
Compliance point
4141
Blackpool
Lytham St Annes
River Ribble
River DouglasRibble Estuary
River Wyre
Bathing water
Pumping station
Treatment works
Key
Southport
Water Assets• £500 million
invested from 1993 – 1996
• 3 major sewage treatment works
• 5 pumping stations with storm outfalls along coast
4242
Background• Failure to meet EU Bathing Water standards
• Storm sewers and sewage works discharging into rivers and coast thought to be cause
• Combined storm water and sewer overflows discharge into water courses and rivers
• Field surveys undertaken to establish inputs and failure levels at compliance points− Surveys unable to provide definitive conclusions − Data did not allow for impact of proposed capital
improvement works to be assessed
4343
BWD 76/160/EEC
4444
Coliform Sources
Creature
Faecal production (g per day)
E. coliper g
faeces
E. coliload (per
day)
Human 150 1.3x107 1.9x109
Cow 23600 2.3x105 5.4x109
Hog 2700 3.3x106 8.9x109
Sheep 1130 1.6x107 1.8x1010
Ducks 336 3.3x107 1.1x1010
Turkeys 448 3.0x105 1.3x108
Chickens 182 1.3x106 2.4x108
Gulls 15 1.3x108 2.0x109
4545
Objectives• Develop hydroenvironmental modelling tool
• Quantify impact of sewage inputs into Ribblebasin on coastal bathing water quality
• Investigate influence of various parameters such as wind, tidal range, river discharge, etc
• Allow for continuous and intermittent inputs
• Incorporate diffuse source inputs and new boundary inputs as data become available
• Propose management strategies for basin
4646
Project Strategy
Integrated modelling approach Integrated modelling approach -- predicting predicting microbiological water quality indicatorsmicrobiological water quality indicators
Coastal ModellingCoastal Modelling River ModellingRiver Modelling CSO ModellingCSO Modelling
4747
Study AreaTidal limit for rivers Ribble, Darwen and Douglas Seaward boundary close to 25m contour in Irish SeaNarrow rivers feed into wide estuary and coastal zone−Riverine boundary limit < 10m−Coastal boundary limit > 40km
Many effluent discharges occur along river reachesComplex hydrodynamic processes along river basin
4848
Linked 3/2-D and 1-D Models
326000 330000 334000 338000 342000 346000 350000 354000 358000 362000418000
422000
426000
430000
434000
7mile
3mile
Tarleton Lock
Bullnose
PenworthamBlue Bridge
Darwen Boundary
Douglas River
Ribble Boundary
Downstream Boundary
Measuring Water Elevation
Tide Survey
Measuring Discharge
4949
Estuary Bathymetry
405000
410000
415000
420000
425000
325000 330000 335000 340000 345000 350000
Bed elevation aboveOrdenance Datum (m)
< - 8.0-8.0 to –6.0-6.0 to –4.0-4.0 to –2.0-2.0 to 0.0 0.0 to 2.0
4.0 to 6.0 > 6.0
2.0 to 4.0
5050
1-D Model Setup
• 5 riverine reaches - each of length 50km
• 153 cross-sections included along rivers
• Interpolation between cross-sections to reduce effective spacing to 50m
• 922 interpolated cross-sections in total
• Discharges specified at upstream limit
• Diffuse source inputs along any node
FASTER (Flow And Solute Transport in Estuaries and Rivers)
5151
2-D Model Setup
• Developed by Water Research Centre (Iran) and used by HRC at Cardiff University
• Finite volume unstructured triangular mesh
• Higher order TVD scheme for advection
• Sub- and super-critical shallow water solver
• 17 water quality indicators included in model
• High quality animations and output included
HEMAT (Hydro-Environmental Modelling and Analysis Tool)
5252
• Bathymetric data obtained from:− LIDAR (Light Induced Direction And Range) − Sidescan sonar mounted on survey vessel− Admiralty chart used to compliment data
• Seaward boundary data provided by POL
• High grid resolution for estuarine basin
• Modelled tested extensively against field data
• Model used to predict coliforms and sediment
2-D Model DetailsHEMAT (Hydro-Environmental Modelling and Analysis Tool)
5353
Hydro-Environmental Modelling and Analysing
Tool - HEMAT
Water Research CentreWater Research CentreTehran Tehran -- IRANIRAN
Bristol Channel Application
Hydroenvironmental Hydroenvironmental Research Centre Research Centre -- CardiffCardiff
5454
Mesh Generator Interpolator Solver GUI Post-processor
Hydro-Environmental Modelling and Analysis Tool
5555
Mesh Generator Interpolator Solver GUI Post-processor
Hydro-Environmental Modelling and Analysis Tool
5656
Mesh Generator Interpolator Solver GUI Post-processor
Hydro-Environmental Modelling and Analysis Tool
5757Hydro-Environmental Modelling and Analysis Tool
Mesh Generator Interpolator Solver GUI Post-processor
5858
Grid Resolution in Estuary
5959
Simulation of Flooding - Drying
6060
Flow Calibration
53 54 55
Wat
er E
leva
tion
(m) Model
Measured
-4-3-2-10123456
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52
-0.5
0
0.5
1
1.5
2
2.5
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55
Tim e (hours)
Spee
d (m
/s)
Model
Measured
-500
50100150200250300350400
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55
Tim e (hours)
Dire
ctio
n (d
eg)
Model
Measured
Time (hours)
Time (hours)
11 Milepost
3/12/98Emax=4.7%
Emin=1.9%
Emax=13.0%
Emin=9.7%
Emin=2.2%
6161
Ribble EstuaryModel Calibration
11 milepost
11 May 1999 Wet Weather Neap Tide
6262
19 May 1999 Dry Weather Spring Tide
Ribble EstuaryModel Calibration
11 milepost
6363
Predictions• Baseline scenario predicted for mean inputs
• Various flow, tide and wind conditions studied
• Impact of different waste water treatment strategies and inputs considered
• Diffuse source inputs included from field data
• River discharges and inputs from CSOs and water treatment works studied individually
• All key locations along rivers, estuary and bathing waters analysed for coliform levels
6464
Coliform Predictions
6565
Coliform Predictions
6666
Coliform Predictions
6767
Ribble EstuaryModel Predictions
11 milepost
6868
Conclusions
6969
• Computational models increasingly powerful tools for managing aquatic environment
• Hydroenvironmental models depend heavily upon field data and empirical relationships -increasingly requiring interdisciplinary team
• Hydroinformatics tools linked with hydro-environmental models offer scope for online approach to river basin management
• Considerable scope for improving models
General Comments
7070
Addendum
7171
“Acknowledging uncertainties in river basin management is a
strength, for which youwill not be thanked”
HRH The Princess RoyalHRH The Princess Royal
Cardiff University, 2002Cardiff University, 2002
7272
Thank You