Author(s): G. Rongen; U. Fumihiko
Linked Author(s):
Keywords: Flood risk; Dike failure; Overtopping; Climate change
Abstract: In 2016 Hokkaido was hit by various typhoons which led to floods in the city Obihiro and the surrounding catchments. These events raise questions about what kind of floods can be expected in a future, uncertain trough climate change. The Dutch risk based approach (VNK2) offers a method to deal with these uncertain future scenarios. The challenge however is applying the approach to a specific Japanese river system. Typhoon induced rainfall events around Obihiro will lead to flash floods in the relatively steep rivers. The strength of the dikes protecting the surrounding area depends on the type of flash flood. For overflow higher water levels or floods with longer durations lead to a higher chance of failure. Flash floods can also lead to large erosion. This can degrade the stability of the dike or even erode it completely. The flood risk in Obihiro is assessed by combining the probabilities of extreme water levels with the strength of the dikes under these conditions. Since the strength dependents on the water level this leads to a complex risk assessment. At the end of the research in fal l 2020, we expect to have an understanding of Japanese failure modes in a probabilistic context, and use this information to calculate flood risk now and in the future.
Year: 2020