# Cu07821 ppt9 recapitulation

Hogeschooldocent at Hogeschool Zeeland,Hz University of applied sciences.
Dec. 16, 2015

### Cu07821 ppt9 recapitulation

1. Watermanagement “Recapitulation”
2. Goal Course Watermanagement • Knowledge of the working of the water system, how it works, what has an influence on what, what are you aiming at, which processes take place • Policy
3. Goals • Optimal circumstances for farmers and nature, optimal water table and gain • Prevention of water trouble, fulfill on the rainfall event NBW, 1:25 year shower, Stowa • Prevention of water shortage? No guidelines exist, even for a dry period, maintain the water level? • Water framework directive, European directive, ecological quality. Is about the quality of the water system itself. • Prevention of salination?
4. Model Sobek • Area 1 500 ha gsl +0,8 m Depth drainage 1 m Summer level (weir) -0,3 m , freeboard 1,1 m • Area 2 500 ha gsl +0,1 m Depth drainage 0,7 m Summer level (pump) -0,7 m , freeboard 0,8 m
5. De Zeeuw Hellinga Higher factor, faster discharge of water to the ditch
6. • Infiltration 99 mm/hour !! • Depression 5 mm • μ=0,060 storage in soil • Drainage De Zeeuw Hellinga • No seepage • Pump 11 mm/day = 1,27 m3/s • Precipitation 96 hour 100mm, 4 days • Calculated steps 5 min, for 1 month
7. Used Rainfall 1:25 year 96 hours, type long, lengthened to 1 month
8. Oversight Summer Initial GWL = Open water level
9. Questions • What is the percentage surface water? • Surface water max 11,2 ha = 1,1 % • μ=0,060 storage soil • How much m3 of water can be stored in a layer of 10 cm soil, in an area of 1000 ha. • 1000 x 10.000 x 0,1 x 0,06 = 60.000 m3 • What is the amount of precipitation in m3? • 1000 x 10.000 x 100/1000 = 1.000.000 m3 • How much water will be discharged (max)? • 11/1000 x 4 x 1000 x 10.000 =440.000 m3
10. More questions • Give an estimate of the storage in the surface water. • Average height (1,1 + 0,8)/2 = 0,95 m • Assume rectangular ditch • 11,2 x 10.000 x 0,95 = 106.400 m3
11. And more questions! • Suppose the entire area of 1000 ha is flat, will it submerge? (simpel approach to the problem) • Rainfall 1.000.000 m3 • Discharge pump 440.000 m3 • Storage surface water 106.400 m3 • Storage in soil 0,95 x 10 x 60.000 = 570.000 m3 • Total of storage + discharge =1.116.400 m3 • Answer is no, differences in height are needed, so the water can flow to the lowest points.
12. Calibration!!!! • Which information do you need for a good calibration? • Precipitation • Variances in water level • GWL at the start of the rain shower • Discharge of the pump • Model that can be modified
13. Summer, maximum wl
14. Surface runoff Gebied 1= 0
15. Groundwater discharge
16. Infiltration
17. Storage on land (mm)
18. Groundwaterlevel
19. Summer, larger culvert
20. Winter • Area 1 gsl +0,8 m Depth drainage 1 m Winter level (weir) -0,5 m , dry height 1,3 m GWL is 0,5 m below ground surface level • Area 2 gsl +0,1 m Depth drainage 0,7 m Winter level (pump) -0,9 m , dry height 1,0 m GWL is 0,5 m below ground surface level
21. Winter, maximum wl
22. 10 ha open water extra downstreams
23. Winter pump capacity 2 m3/s
24. Water level lowered 0,2m + 5000 m2 storage
25. Small culvert round 600 mm
26. Other possibilities • Heighten the land • Discharge partly to another area. • Less drainage?
27. Effects of bad maintenance • Culverts closed with dirt • Pump capacity is lower • Collapsed banks, lower storage and lower discharge • Plants growing in ditch (problem?)