JUdy Presentation

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DISCLAIMER

The views expressed in this presentation are theviews of the speaker and do not necessarily reflectthe views or policies of the Asian DevelopmentBank (ADB), or its Board of Governors, or thegovernments they represent. ADB does notguarantee the accuracy of the data included in thispaper and accepts no responsibility for any

consequence of their use. Terminology used maynot necessarily be consistent with ADB officialterms.



Biophysical processes

Dr James Udy

February 2009

5TH NARBO IWRM Training

“Keys for Success”

Material for Slides contributed by:

Dr Badin GibbesJon OlleyFRC Environmental

Ann OliverMichelle McGawDeb Gale



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Understanding Biophysical Relationship

“key to success”

Catchment

Hydrodynamic

Biogeochemical



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SEQ conceptual model



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Nutrient flux

Algal response

Zooplankton -Grazing rates andnutrient release

Fish –

Food web andLife Cycle

Toxin Identification

Monitoring

Understanding the specifics and interactions important key to success

Modeling



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Question

What Biophysical knowledge about

Vu Gia – Thu Bon do you need to manage?

• Impact of Hydro Dam on Fish lifecycle?

• Where is the sediment coming from?

• Are their toxic effects from Mining?• What aquatic animals most sensitive to mine

effluent?



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How Biophysical processes influence

River management

• Quality of freshwater supply – Drinking water – Irrigation water source – Process water (cooling, carrier fluid etc.)

• Hydro-electric power supply

• Greenhouse gas implications – Emissions (CO2, CH4) – Storage (C in sediments) – Important for global climate modelling

Ima es: Hoover Dam & Lake Mead U.S.A. Multi le use reservoir: water su l & h droelectricit



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Biophysical Issues for River Basin

• Eutrophication – Algal blooms - often toxic – Increase treatment costs – Can cause fish kills or taste and odour

• Chemical pollution

– Due to poor catchment management – Release due to low oxygen in bottom water

• Sedimentation – Loss of storage capacity (supply security)

– Damage to turbines• Climate variability

– Emissions (CO2, CH4)



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CatchmentSources of Pollutants



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Two Types of Erosion

• Hill Slope



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Two Types of Erosion

• River Bank/ Gully

Wh T f E i



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What Type of ErosionDominates?

Suspended Sediment

Contribution

Low

Medium

High

0 10 20 30 40 505Kilometres

Vegetation

Flow data

Rainfall/PET

Land use

Riparian vegetation

DEM

Soil properties

Gully erosion

Channel geometry

Floodplain width

Stream and floodplain

configuration

Spatial data

Flow

regionalisation

SedNet model

Sediment/nutrient loads

‘local knowledge’

Modelled (e.g. RUSLE)

Data

SeDNET model include bank andgully erosion sources and spatialvariation in floodplain storage.

Prosser, I. P., Rutherfurd I.D., Olley, J.M., Young, W.J., Wallbrink,P.J. and Moran, C.J., (2001). Large-scale patterns of erosion andsediment transport in rivers networks, with examples fromAustralia. Freshwater and Marine Research, 52, 81-99.



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Hillslope vs channel erosion

• Fallout radionuclides(Cs-137 and Pb-210)

– widely used todetermine the

relativecontribution ofhillslope andgully/channel

erosion to streamsediments

0

100

200

Concentration (Bq kg-1)0 50 100 0 5 10

210Pbex 137Cs

S o i l D e p t h (

m m )



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R i / E



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Reservoir / EstuaryTrap for Pollutants

H d d i



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HydrodynamicsDetermine what happens next



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Catchment inflows

Rain input

Evaporation

Lightpenetration

Density-driven flow

Sediment resuspension

Wind

Groundwater seepage

Key processes



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Light penetrationControlled by sediment



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Evaporationchange water quantity and quality



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Rain inputChange water quality

Wi d



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Wind

Circulate water



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Wind induced circulation

Simulated by introducing free-surface evolution, free-surface

wind shear & wind momentum input into flow equations(typically RANS equations)



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Catchment inflowsSource of new water and Pollutants

Hot/ FreshCatchment inflows



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Catchment inflowsWarm water inflow

• Warm water, lower density

• Inflow “floats” on lakes’ surface

• Cooling water discharges

(power station etc.)• Forms a boundary condition on lake

• More visible and often easier to

manage because offtakes oftenbelow boundary

Image: ww.usgs.gov

Image: www.tpwd.state.tx.us



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Catchment inflowsCold water inflow ColdMore Saline



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Catchment inflowsCold water inflow

• Cold water, higher density, “plunges”

• Flows along base of lake (if colder / more dense thanbottom waters)

• Can caused sediment and nutrient resuspension

• Catchment inflows typically cooler (more dense) than

lake surface – but may be warmer than bottom water

• If inflow density = mid-lake density, flow is “intrusive”,

common phenomenon

• Often leads to contamination of offtake water more

rapidly than expected.



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Groundwater seepageGroundwater inflow and outflow



N t l t h i l ti



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Catchment inflowsNatural waters: chemical properties

Key to Analyses:

• (1) Rainwater from Menlo Park, California;

• (2) Average rainwater from sites in North Carolina and Virginia;

• (3) Composition of the Rhine River as it leaves the Alps;

• (4) Stream draining igneous rocks in the Washington Cascades;

• (5) Jump-Off Joe Creek, southwestern Oregon, wet season, November, 1990;

• (6) Jump-Off Joe Creek, southwestern Oregon, dry season, September, 1991;

• (7) Great Salt Lake, Utah;

• (8) Average seawater;

• (9) Groundwater from limestone of the Supai Formation, Grand Canyon;

• (10) Groundwater from volcanic rocks, New Mexico;

• (11) Groundwater from a spring, Sierra Nevada Mountains: short residence time;

• (12) Groundwater from metamorphic rocks in Canada: long residence time.

Source: http://www.waterencyclopedia.com/En-Ge/Fresh-Water-Natural-Composition-of.html

Rain River Sea Groundwater0.7 18 400 4,500

http://www.waterencyclopedia.com/En-Ge/Fresh-Water-Natural-Composition-of.html














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Catchment inflows

Rain input

Evaporation

Lightpenetration

Density-driven flow

Sediment resuspension

Wind

Overview

Groundwater seepage



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Impact of hydrodynamic

processes on a river basin

• Effects the way water moves

• Determines the chemistry of water

• Effect on ecological systems• Usefulness of water to end user



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Combination of:

Nutrient rich inflow

LightWarm TemperatureLack of wind



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Biogeochemical modellingBiogeochemical Cycles



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Nitrogen cycle



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Phosphorus cycle



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Carbon cycle



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Understanding How one action



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Understanding How one actionwill effect another area

“key to success”Catchment modelling

Hydrodynamic modelling

Biogeochemical modelling

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