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

2. Jaco van der Gaast The Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands 2 Contents Introduction The model Swap Input Data Groundwater modeling Crop growth Results Conclusions Near future

3. Jaco van der Gaast The Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands 3 Introduction WMTools 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.

4. Jaco van der Gaast The Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands 4 Introduction The system combines high-resolution spatial information with time and depth dependent information.

5. Jaco van der Gaast The Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands 5 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

6. Jaco van der Gaast The Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands 6

7. Jaco van der Gaast The Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands 7 Input data Elevation Land use Soil Topography

8. Jaco van der Gaast The Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands 8 Data: High-resolution elevation data Laser scanning Density of 1 point per 16m² Accuracy: STD 15 cm Average error 5 cm

9. Jaco van der Gaast The Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands 9 Data: Surface water system Interaction with surface water Multi-level drainage at regional scales

10. Jaco van der Gaast The Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands 10 Data: Surface water system Ditch density Drainage resistance Drainage levels Control unit size Weir characteristics

11. Jaco van der Gaast The Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands 11 Groundwater modeling GIS-input: Seepage Surface water system Soil Crop Meteo Elevation

12. Jaco van der Gaast The Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands 12 Groundwater modeling Relationship between elevation and groundwater Calculations for eight years on a daily basis

13. Jaco van der Gaast The Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands 13 Groundwater modeling Relationship between elevation and groundwater

14. Jaco van der Gaast The Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands 14 Groundwater modeling Relationship between elevation and groundwater

15. Jaco van der Gaast The Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands 15 Groundwater modeling Relationship between elevation and groundwater

16. Jaco van der Gaast The Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands 16 Crop growth: Yield reduction D T act Water-limited yield reduction Transpiration reduction

17. Jaco van der Gaast The Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands 17 Crop growth: Groundwater level

18. Jaco van der Gaast The Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands 18 Crop growth: Effect of soil type

19. Jaco van der Gaast The Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands 19 Crop growth: Effect of water management

20. Jaco van der Gaast The Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands 20 Crop growth: Different crops

21. Jaco van der Gaast The Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands 21 Results: Traditional method Relative crop yield Soil map

22. Jaco van der Gaast The Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands 22 Results: Relative crop yields Weir crest: Winter -150, Summer -130 Average relative yield: 90.1% Weir crest: Winter -130, Summer -110 Average relative yield: 90.1% Weir crest: Winter -110, Summer -90 Average relative yield: 87.7%

23. Jaco van der Gaast The Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands 23 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.

24. Jaco van der Gaast The Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands 24 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

25. Jaco van der Gaast The Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands 25 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

26. Jaco van der Gaast The Winand Staring Centre, P.O. Box 125, 6700 AC Wageningen, The Netherlands 26 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: J.W.J.vanderGaast@sc.dlo.nl