Jaco van der Gaast The Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands 1...

Jaco van der GaastThe Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands

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Water Management Tools

Jaco van der Gaast

The Winand Staring Centre

Wageningen, The Netherlands

A Spatial Solution to Calculate Optimum Surface Water Target Levels Using a Water Management Decision Support System


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Contents

• Introduction

• The model Swap

• Input Data

• Groundwater modeling

• Crop growth

• Results

• Conclusions

• Near future


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IntroductionWMTools is a Water Management Decision Support System that integrates a hydrological dynamic model with ArcView GIS to provide decision support

for optimum water target-level calculations in relation with crop production for lowland areas.


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IntroductionThe system combines high-resolution spatial

information

with time

and depth

dependent information.


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Swap: System definition

• Unsaturated and saturated top-soils

• 1-D column• Surface water

systems• Regional flow

as lower boundary

Crop evaporation

Precipitation

Crop growth

Drainage/infiltration

Seepage\percolation

Soil evaporation

Integrated modeling of the Soil-Water-Atmosphere-Plant system


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transpiration

Saturatedzone

Plant

precipitation

soil-evaporation

Surface waters

Deep Groundwater

surface runoff

- Transport of:soil watersoil heatsolutes (salts, tracers)

- Influenced by:Water repellencySwelling and shrinkingHysteresis

interception

Swap: Integrated modeling of the

Soil-Water-Atmosphere-Plant

system

Atmosphere

drainage/subsurfaceinfiltration

drainage/subsurfaceinfiltration

deep percolation/seepage

Unsaturatedzone


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Input data

Elevation

Land use

Soil

Topography


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Data: High-resolution elevation data

• Laser scanning• Density of 1 point per 16m²

• Accuracy: STD 15 cm

Average error 5 cm


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Data: Surface water system• Interaction with surface water

• Multi-level drainage at regional scales


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Data: Surface water system

• Ditch density• Drainage

resistance• Drainage levels• Control unit

size• Weir

characteristicsRegional groundwater

flow system

Drainage tochannels

Drainage to (open)field drains

Drainage totrenches

saturatedsoil profile

avg

Local to sub-regional flow system


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Groundwater modeling

GIS-input:• Seepage• Surface

water

system• Soil • Crop• Meteo• Elevation


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Groundwater modelingRelationship between elevation and groundwater

Calculations for eight years on a daily basis


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-40 -20 0 20 40 60 80 100 120 140 160Elevation (cm)

-180

-120

-60

0

Gro

und

wat

er le

vel (

cm)

Wheat high Wheat lowPotato high Potato lowGrass high Grass low

Average Groundwater Level(Clay soil, Weir Crest: Winter -130, Summer -110)


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15



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Crop growth: Yield reduction

D

TactWater-limited yield reduction

Transpiration reduction

-40 -20 0 20 40 60 80 100 120 140 160Elevation (cm)

70

80

90

100

Rel

ativ

e Y

ield

(%

)

Reduction due to wetnessReduction due to droughtTotal reduction

Crop yield reduction(Potato on Clay Soil)


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Crop growth: Groundwater level

-40 -20 0 20 40 60 80 100 120 140 160Elevation (cm)

70

80

90

100

Rel

ativ

e Y

ield

(%

)

-180

-120

-60

0

Gro

und

wat

er le

vel (

cm)

(->) Average high groundwater level(->) Average low groundwater level(<-) Relative Yield Potato

Relative Crop Yield and Groundwater Level(Clay soil, Weir Crest: Winter -130, Summer -110)


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Crop growth: Effect of soil type

-40 -20 0 20 40 60 80 100 120 140 160Elevation (cm)

70

80

90

100

Rel

ativ

e Y

ield

(%

)

Clay on PeatLoam

Relative crop yield for different soil types(Potato, Weir Crest: Winter -130, Summer -110)


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Crop growth: Effect of water management

-60 -20 20 60 100 140Elevation (cm)

70

80

90

100

Rel

ativ

e Y

ield

(%

)

Weir Crest: Winter -150, Summer -130Weir Crest: Winter -130, Summer -110Weir Crest: Winter -110, Summer -90

Relative crop yield for different water management schemes(Potato on Clay Soil)


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Crop growth: Different crops

-40 -20 0 20 40 60 80 100 120 140 160Elevation (cm)

70

80

90

100R

elat

ive

Yie

ld (%

)

Wheat PotatoGrass Maize

Relative Crop Yield for different crops(Clay soil, Weir Crest: Winter -130, Summer -110)


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Results: Traditional method

Relative Yield<8080 - 82.582.5 - 8585 - 87.587.5 - 9090 - 92.592.5 - 9595 - 97.5No Data

Relative crop yieldSoil mapSoil

Mn15A-VIMn22Ap-VIMn25A-IVMv81A-IV


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Results: Relative crop yieldsRelative Yield

<8080 - 82.582.5 - 8585 - 87.587.5 - 9090 - 92.592.5 - 9595 - 97.5No Data

Weir crest: Winter -150, Summer -130Average relative yield: 90.1%




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Conclusions

• The system can be used to optimize water target levels in order to optimize crop yields in lowland areas.

• The use of high-resolution spatial data makes the results more accurate.

• The combination of high-resolution spatial information with time and depth dependent information in one system, gives more and easier access to the information needed for analyzing the results.


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Conclusions• Groundwater

– High groundwater levels are almost not effected by elevation

– Low groundwater levels nearly follow the terrain profile

– Groundwater fluctuations decrease by increasing elevation

– The relation between groundwater level and elevation is affected by transpiration reduction

• Crop growth – Elevation and soil type are important factors for

crop yields

– Water management can change the optimum crop growth in relation with elevation


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Near future• Automatic optimization • Crop rotation• Optimization on farm-company level• Nutrient-limited crop growth

• Economics – Cost effectiveness– Profits

• Variation of parameters – Soil physics– Fuzzy soil map– Drainage– Bottom boundary


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More information:

• Look at our web-site: www.sc.dlo.nl

• Contact:Jaco W.J. van der Gaast MSc

DLO Winand Staring Centre (SC-DLO)

Department of Water Management

P.O.B. 125, 6700 AC, Wageningen, The Netherlands

tel: +31 317 474293, fax: +31 317 424812

e-mail: [email protected]

Jaco van der Gaast The Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands 1...

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