フラッシュ放流における土砂供給が付着藻類の剥離に与える付加効果の推定

抄録

The flushing flow is a small scale flood induced by artificial water release from a reservoir to improve river environments downstream of dams. To increase the effect of the flushing flow and to eliminate a discontinuity of the sediment flow due to the dam, sediment has been supplied in the downstream reach of the dam. This study aims to estimate the effect of sediment supply on the removal of the attached algae during the flushing flow. A experimental channel with a section paved by the gravel with attached algae sampled by the Johge River was been used, and a shear stress acting on the bed materials during the flushing flow was represented. The effects of flow rates of water and sediment on the removal rate of the attached algae were investigated.

Based on the experimental result, we clarified that sediment particle with 10 mm in diameter efficiently removed the attached algae compared with identical sediment flow rate with 1 mm diameter sediment. Finally, we proposed a simple method to design optimal flow rates for water and sediment supply.