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

• 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– Linear reservoir

– Calculation time 10² s

– Simplification

– Calibration

– Measures

• Hydrodyn. model– Saint Venant

– Calculation time 104 s

– Accurate

– Detailed

Expected impact of CC in Dender Basin

• Conceptual model of the upstream Dender basin

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

Hw

d

HW

H (DEM)

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 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

Adaptation Scenarios in Dender Basin

• Scenario 1: dikes– T = 25 year

– Climate Scenario = Mean

– Blue = Baseline

– Red = Scenario 1

Adaptation Scenarios in Dender Basin

• Scenario 2: weirs– T = 25 year

– Climate Scenario = Mean

– Red + Green = Scenario 1

– Green = Scenario 2

Adaptation Scenarios in Dender Basin

• Scenario 3: flood control reservoir– 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