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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
Expected impact of CC in Dender Basin
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3 climate scenarios
CCI-HYDR Perturbation Tool
Perturbation factors
Composite hydrograms (T= 5, 10, 25, 100, 250)
Expected impact of CC in Dender Basin
• Conceptual model
• Hydrodyn. model
– Linear reservoir
– Calculation time
10² s
– Simplification
– Calibration
– Measures
– Saint Venant
– Calculation time
104 s
– Accurate
– Detailed
Expected impact of CC in Dender Basin
• Conceptual model of the upstream Dender basin
Q river
H river
Q flood
H floodplain
Q-H
relation
Hdiike
weir
Q-V
relation
Expected impact of CC in Dender Basin
• Floodmapping of conceptual model
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Method of fictive floodbranches
Floodbranch in the lowest point
Water height as boundary of the floodbranch
Extrapolation of water height in polygon
HW
d
H (DEM)
Hw
Expected impact of CC in Dender Basin
• Simulation results (climate scenarios: red = low, orange =
mean, green = high, blue = normal) (T=10)
Expected impact of CC in Dender Basin
• Simulation results (climate scenarios: red = low, orange =
mean, green = high, blue = normal) (T=10)
Expected impact of CC in Dender Basin
• Simulation results (climate scenarios: red = low, orange =
mean, green = high, blue = normal) (T=10)
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
Adaptation Scenarios in Dender Basin
• Adaptation scenarios
– Baseline scenario = Situation before the flood 20022003
– 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
Adaptation Scenarios in Dender Basin
• Scenario 1: dikes
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T = 25 year
Climate Scenario = Mean
Blue = Baseline
Red = Scenario 1
Adaptation Scenarios in Dender Basin
• Scenario 2: weirs
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T = 25 year
Climate Scenario = Mean
Red + Green = Scenario 1
Green = Scenario 2
Adaptation Scenarios in Dender Basin
• Scenario 3: flood control reservoir
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T = 25 year
Climate Scenario = Mean
Green + Orange = Scenario 2
Orange = Scenario 3
Adaptation Scenarios in Dender Basin
• Other inundation parameters
– Water rise rate
– Water velocity in floodplains
 Historical events
Adaptation Scenarios in Dender Basin
• Other inundation parameters
– Rise rate (1995)
Adaptation Scenarios in Dender Basin
• Other inundation parameters
– Water velocity in floodplains (2002-2003)
• Criterion : < 2 m/s
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