THE COOPERATING SEDIMENT FLUSHING AND THE ENVIRONEMTAL INVESTIGATION IN THE CASE OF UNAZUKI DAM AND DASHIDAIRA DAM IN KUROBE RIVER

Abstract

The cooperating sediment flushing of Unazuki dam and Dashidaira dam aims at maintaining the capacity of dam resourvers for .flood control or power generation and controling sediment through whole the Kurobe river basin including coast of Toyama bay. As the first sediment flushing from Dashidaira dam on 1991 was said to influence the river and coastal environment, it seems important to minimise the influence of sediment flushing on the environment and investigate it thoroughly. Firstly, this paper explains the indispensability of the sediment flushing of Unazuki dam. This paper also discusses the time, frequency and method of the cooperating sediment flushing and explains the environmental investigation carried out at the resourvers of both dams, the river channel of Kurobe river and the coastal area of Toyama bay.