複断面河道における低水路幅の違いが砂州物理環境および魚類生息環境へ及ぼす影響

抄録

The riffle-pool structure that forms on alternate bars at the low-flow stage of a river provides important habitat for various organisms. The alternate bar is important for river organisms because the ecosystem depends on the physical conditions that forming the alternate bar. The formation of alternate bars depends on channel conditions, such as the channel width, slope, sediment diameter, etc. In this paper, we focus on the formation of alternate bar shapes in two downstream reaches of the Yada River that differ in the width of the low-flow channel. We investigated differences in physical condition, water temperature distribution, and the presence of fish in each of the two areas. The characteristics of bar shape and migration depended on the width of the low-flow channel. Water temperature also had a great influence on the presence of fish in summer. The exchange condition of subsurface and surface flows, which affects the water temperature distribution, depended on the bar shape.