Author(s): Kenichiro Kobayashi; Tetsuya Sumi; Moe Ohata

Linked Author(s): Kenichiro Kobayashi, Tetsuya Sumi

Keywords: Kasumi dike; Flood simulation; Shallow water equation; Distributed rainfall-runoff/flood-inundation model; Nature-based solution

Abstract: Recently in the river works of Japan, the value of nature based solutions is reconsidered since very extreme flooding considered due to climate change is often happening and this cannot be prevented by the river works of current safety level. As it may be difficult to build full continuous dikes to prevent flooding from rivers, the function of Kasumi-dike is now reanalyzed. Kasumi-dike has multiple spaces (or apertures) between dikes, thus the river flood flow can overflow from the river to the retention space where the energy of flood flows is dissipated. Likewise, it can reduce the flow amount to the downstream for a certain period of time which can earn the time for the evacuation downstream as well. The aperture of Kasumi-dike is normally e. g. a hundred meter. Therefore, high resolution simulation such as 5m is necessary to simulate the flow around the dike. For this purpose, a shallow water equation model with parallel computing function is applied. However, even with the parallel computing, it is not wise to expand the detailed flood simulation area too large with the 5m resolution, thus the detailed flood simulation area was surrounded/nested by a distributed rainfall-runoff/flood-inundation model with 250m resolution. By doing this, the flood flow from the catchment scale to the, relatively large but still local scale area around dike, can be well simulated continuously. As a case study, in the paper, the analysis of Kasumi dike at Kameoka city in Kizugawa river catchment is presented.

DOI: https://doi.org/10.3850/978-90-833476-1-5_iahr40wc-p0663-cd

Year: 2023