河道外貯留ダムの類型化とその河川の土砂連続性への影響に関する研究

Abstract

Off-stream reserving system is a countermeasure of reservoir sedimentation, downstream degradation, river continuum, and so on. We extracted off-stream reservoirs from all dams in Japan, and classified them in three groups according to the main purpose of the reservoir. We revealed that the three groups can be distinguished by relationship between the main-stream catchment area and reservoir capacity. We also conducted field survey on riverbed sediment, water quality and benthic invertebrates in an off-stream reserve system, the Dodairagawa Dam, to examine its effects on riverine environment. Based on dimensionless shear stress and invertebrate community, natural riverbed condition was maintained in the downstream as well as the upstream of the system.