EXPERIMENTAL STUDY ON THE CHANGE OF SAND FILLING AND ACCUMULATION OVER A GRAVEL RIVER BED WITH SANDY SEIMENT SUPPLY

Abstract

In this study, we conducted the open channel experiment in order to examine the effect of sediment supply upon the riverbed downstream of dams. Sediment supply practiced to restore the riverbed environment, but excessive sediment sometimes causes negative environmental effect upon the riverbed.

Our experiment aimed to understand the riverbed changes by sandy sediment supply on the gravel riverbed. The experiment used the open channel with three-layered gravel riverbed filled with sand, and the height of sand surface was measured. Flow condition was controlled by the ratio of the friction velocity and sedimentation rate (u^*/w₀) and the suspended sediment concentration.

As a result, the entrainment rate into suspension and the surface height of sand against several u^*/w₀ was obtained. The experiment result makes it possible to set the condition avoiding excessive sediment supply using the suspended sediment concentration and u^*/w₀ .