HYPORHEIC FLOW CAUSED BY BAR MORPHOLOGY ON CHUM SALMON SPAWNING AREA

摘要

To understand relationship among bar morphology, hyporheic flow and chum salmon spawning environment, the cross sectional profile, simultaneous water level distribution around bar and hypoheic flow were surveyed. Numeric calculation was also conducted to understand hyporheic flow path. The results revealed that a river water elevation difference between bar crest and front, generates welling up hyporheic flow around bar front. Numeric calculation also revealed flow path of hyporheic flow which sink into river bed on the bar crest and well up on the bar front. Spawning redds were mainly found around bar front where hyporheic flow well up. Thereby, we conclude that bar morphology contribute generating suit hypoheic flow for spawning environment on bar front.