Author(s): Sayumi Katayama; Yasuharu Watanabe; Taiki Kibuchi
Linked Author(s): Yasuharu Watanabe
Keywords: Check dam; Hydraulic experiment; Numerical simulation; Sediment transport
Abstract: Shiretoko Peninsula, located east of Hokkaido, was registered as a World Heritage Site in July 2005. In order to be registered as a World Heritage Site, river works located in the Shiretoko Peninsula area were evaluated for the run-up of salmonids. As a result, 13 river structures including check dams in 5 rivers were evaluated as necessary for improvement. One of these rivers, the Iwaubetsu River, has seven check dams. Five of these seven check dams were improved to be slit-type dams. In the Iwaubetsu River, the remaining two check dams are scheduled to be slit. Among the five slitted dams, there were cases where the continuity of riverbed heights upstream and downstream of the dam could be secured, but there were also some dams that could not. In order to slit the remaining two dams, it is necessary to understand the sediment movement characteristics of the slit dam. Hydraulic experiments and numerical simulations were performed to understand the basic phenomena in order to clarify the response of a river channel when a slit was made. As a result, it was found that the slitting eliminated the riverbed degradation that had occurred downstream of the check dam, and that the shape of the sandbar before and after the slitting could affect the salmon spawning environment. In addition, it was revealed that the numerical experiment almost reproduced the hydraulic experiment result and could be used for the examination of the slit width and the like.
Year: 2020