IDENTIFICATION OF THE ORIGIN OF TURBID WATER FLOWING INTO KAMISHIIBA DAM AND SOIL EROSION CONTROLL WITH FLOCCULANTS

Abstract

 Kamishiiba reservoir has the problem of the turbid water inflow from the upstream catchment area. The main sediment yield is on the bare ground surface after the landslide. In this study, the surface soil and river channel sediments in the catchment area were sampled for examining the similarity with the suspended solid in the turbid water inflow to the reservoir by the mineralogical method. The topsoil of the slope suspected as the cause of the turbidity was aggregated with PIC to examine the possibility of suppressing runoff. In the PIC sprayed area, the soil erosion by raindrop impact can be greatly suppressed, but cracks that developed over time reduced resistance to surface lateral flow, and the sediment yield increases slightly.