ICタグを用いた流水型ダム貯水池内における土砂移動一堆積過程のモニタリング

抄録

Recently, number of in-stream flood mitigation dams which are usually empty and will store flood flow in only short period is increasing. This structure can be understand ecofriendly because it can sluice incoming sediments through bottom outlets naturally and reduce adverse environmental impacts on downstream river below dams. But there are still unknown factors such as effects of grain size on sediment passing thorough reservoir. Based on past studies, it has been noted that coarse gravels and stones bigger than a certain level may not be discharged but left in the reservoir because of the difference in tractive force in the channel upstream of the reservoir and in the reservoir although fine sediments are adequately discharged through the bottom outlet.

We conducted a field survey on the Masudagawa Dam in Shimane prefecture, a typical flood mitigation dam in Japan, by using RFID (Radio-Frequency Identification Device) technology to track the movement of gravels by several floods in the reservoir area from 2009 to 2013. Sediment transport and deposition process in reservoir area is discussed longitudinally and transversely both by tracking data of gravels and 1D/2D numerical models.