THE EFFECTS ON SUBSURFACE FLOW AND CHEMICAL PROPERTY IN A SANDBAR WITH NO VAGETATION BY RIVER BED CHANGE

Abstract

Recently it is recognized that subsurface water zone under river sandbars has functions of habitat for benthos and microorganism/microbe living in substrate, and that some of those remove materials from the water or change physicochemical characteristics. In this study, the relationship among the water level profile and water quality of subsurface and surface water is investigated in a sandbar with no vegetation. Additionally the effects on those relationships by bed shape change due to flood also monitored. As a result, we found out that the exchange of the surface and subsurface water decreases because of the change of surface water property as the boundary condition for subsurface flow, and low permeability substrate at the part of entrance of subsurface flow. Furthermore, the water movement in the sandbar is studied through the investigation of the water quality. Estimated characteristics both of flow and water quality are explained each other.