1. Expected impact of Climate Change on flooding in the Dender Basin. Results MSc thesis: Adaptive measures to reduce climate change impacts on flood probabilities. Niels Van Steenbergen & Jeroen Verbelen

2. Expected impact of CC in Dender Basin 3 climate scenarios CCI-HYDR Perturbation Tool Perturbation factors Composite hydrograms (T= 5, 10, 25, 100, 250)

3. Expected impact of CC in Dender Basin Conceptual model –Linear reservoir –Calculation time 10² s –Simplification –Calibration –Measures Hydrodyn. model –Saint Venant –Calculation time 10 4 s –Accurate –Detailed

4. Expected impact of CC in Dender Basin Conceptual model of the upstream Dender basin Q riverH riverQ floodH floodplain Q-H relation Hdiike weir Q-V relation

5. Expected impact of CC in Dender Basin Floodmapping of conceptual model –Method of fictive floodbranches –Floodbranch in the lowest point –Water height as boundary of the floodbranch –Extrapolation of water height in polygon HwHw d HWHW H (DEM)

6. Expected impact of CC in Dender Basin Simulation results (climate scenarios: red = low, orange = mean, green = high, blue = normal) (T=10)

7. Expected impact of CC in Dender Basin Simulation results (climate scenarios: red = low, orange = mean, green = high, blue = normal) (T=10)

8. Expected impact of CC in Dender Basin Simulation results (climate scenarios: red = low, orange = mean, green = high, blue = normal) (T=10)

9. Adaptation scenarios considered and the expected impact on flooding in the Dender basin. Results MSc thesis: Adaptive measures to reduce climate change impacts on flood probabilities. Niels Van Steenbergen & Jeroen Verbelen

10. Adaptation Scenarios in Dender Basin Adaptation scenarios –Baseline scenario = Situation before the flood 2002- 2003 –Scenario 1 = dikes built in 2003 –Scenario 2 = scenario 1 + adapted weirs –Scenario 3 = scenario 2 + flood control reservoirs Marke + Molenbeek Zandbergen Spatially concentrated Assumption on filling and emptying

11. Adaptation Scenarios in Dender Basin Scenario 1: dikes –T = 25 year –Climate Scenario = Mean –Blue = Baseline –Red = Scenario 1

12. Adaptation Scenarios in Dender Basin Scenario 2: weirs –T = 25 year –Climate Scenario = Mean –Red + Green = Scenario 1 –Green = Scenario 2

13. Adaptation Scenarios in Dender Basin Scenario 3: flood control reservoir –T = 25 year –Climate Scenario = Mean –Green + Orange = Scenario 2 –Orange = Scenario 3

14. Adaptation Scenarios in Dender Basin Other inundation parameters –Water rise rate –Water velocity in floodplains  Historical events

15. Adaptation Scenarios in Dender Basin Other inundation parameters –Rise rate (1995)

16. Adaptation Scenarios in Dender Basin Other inundation parameters –Water velocity in floodplains (2002-2003) Criterion : < 2 m/s

17. Adaptation Scenarios in Dender Basin Conclusions –Calculation time –Measures Dikes: most positive influence, but can cause problems upstream Weirs: positive influence, but can cause problems downstream Flood control reservoirs: small influence, but most desirable measure  Improvement of efficiency -Other possible measure: -Lowering dikes in non-built area’s