Effect of sediment replenishment on downstream reaches of dams: case study of the Futase Dam

Abstract

Beginning in 2003, a sediment replenishment project was started around the Futase dam, involving the annual removal of around 10, 000 m3 of sediment, for a cumulative total of approximately 100, 000 m3, from two sites above the dam, and sediment replenishment downstream; we monitored the effects on river ecosystems downstream of the dam. In particular, this paper discusses the effects of sediment replenishment on river bed evolution downstream of the dam based on past surveys and on changes in the number and composition of benthic fish (Japanese fluvial sculpin) and invertebrate species that are sensitive to changes in river bed material. A one-dimensional simulation of future bed evolution due to continued sediment replenishment is also presented.