荒瀬ダムの撤去が直下流域の土砂動態および流れに与えた影響

抄録

Variations in sediment budget, bed topography and flow fields have been investigated in a upstream and downstream reachs of Arase Dam, which was in the final stage of the partial dam removal, in the Kuma river, Kyushu district. A relatively large scale gravel bar, which was newly formed in the downstream by the flood in June 2015 after the partial dam removal, has been changed by floods in the rainy season 2016. The results of field survey showed that stable secondary currents of the second kind have existed in main channel of left side of the gravel bar and a lentic habitat in subchannel of right side of the bar has lost most of sprig water through subsurface of the bar by gravel deposition caused by floods in 2016.