Effects of dam-induced flow regime change on downstream river morphology and vegetation cover in the Hwang River, Korea

The Hapchon Dam, located in the headwaters of the Hwang River, Korea, was completed in 1988. Due to low storage levels, the spillway has not been operated over the past decade. Thus, a new ecosystem has become established in the river downstream of the dam. This is not a common phenomenon in Korean rivers. This study investigates the effect of flow regime change on the river morphology and vegetation cover in a reach downstream of the dam following its construction. Geomorphological effects shown by pre- and post-construction surveys of the channel include channel incision over a stream length of approximately 25 km immediately downstream of the dam. Analysis of pre- and post-construction aerial photography reveals significant encroachment of riparian vegetation onto previously active bar surfaces.