Author(s): Sohei Kobayashi; Tetsuya Sumi; Yasuhiro Takemon
Linked Author(s): Tetsuya Sumi
Keywords: No Keywords
Abstract: One of the important roles of gravel bars in river ecosystem is the exchange of water between surface and subsurface (hyporheic) that act to purify river water and locally provide calm condition of flow and water temperature. We investigated geomorphology and return flow (from hyporheic) of a gravel bar, which was formed after a dam removal in the Kuma River, Kyushu, Japan. Discharge of the return flow was 1.2which was> 3% of river discharge, 4 months after its formation. Diurnal change in temperature was smaller for the return flow than river surface flow. We also detected the return flow 19 months later, but the discharge was too small to measure. Interstitial clogging inside bar by fine materials as well as geomorphic change toward lower hydraulic gradients are possible reasons of the small return flow in the second survey.
Year: 2018