細砂河床における網状流路の形成実験

Abstract

Braided rivers flow not only on coarse material beds but also on fine materlalones. Fundamental studies were previously very few on the formation of sand barsand braided streams, especially on fine sediment beds. Detailed experiments on theprocess of multiple bar formation and stream braiding were carried out on fine sandbed. Hydraulic characteristics of bedform variations were discussed andexperimental results were classified into three groups corresponding to flow regime, which was slightly different from that predicted by a previous criterion because oflow sediment Reynolds number of about 5. Formative conditions were made clearfor multi-mode bar formation and stream braiding on beds covered with varioustypes of flow regime. Corresponding to small depths, evaluated values of suspendedsediment load from measured hydraulic quantities was very low and its effect wasnot found on bar formation of multiple modes.