Basic Investigation about Hydro-Geomorphologic and Vegetation Cover Changes on the Regulated River - A Case of the Downstream River of Andong Dam/Imha Dam on the Nakdong River

조절된 하천의 수문지형학적 변화와 식생 피복의 변화에 관한 기초 조사 - 낙동강 안동댐/임하댐 하류 하천 사례

A hydro-geomorphologic change in a sand bed channel reach and vegetation expansion by changes in the How regime is analyzed in this study. Field and aerial photo surveys, basic hydrological analysis about flow regime change due to two dams, Andong Dam and Imha Dam, on the upstream river and computer modeling are conducted. Two Dams in the study reach have obviously affected downstream channel in many ways including the bed particle coarsening, vegetation expansion on the sandbars and following river channel braiding. The phenomenon of no vegetation on the large point bar in front of Hahwe Village seems due to disturbance of the sandbar surface probably due to the cross flow in the meander reach during the flood. Another reason for no vegetation is that the sandbar on this reach has lower subsurface water lovels, as compared with the others in the up- and downstream of the reach where vegetation expanded, which would hinder vegetation from germinating and growing on the sandbar.