複列砂州と網状流路の形成過程に関する実験

Abstract

In many rivers on alluvial fans, streams show braided patterns. Even during small floods, stream patterns change rapidly and radically, and main streams often attack river bank, flowingalong the lowest course of the braided patterns. It is, therefore, very hard to maintain the safetyof braided rivers. One of main reason of this difficulty is ascribed to little knowledge on hydrauliccharacteristics of braided streams. Behaviors of higher mode of bars and formation of braidedstreams have been investigated by means of detailed hydraulic experiments conducted in threeflumes of much different width. Results were described on metamorphoses of bed configurationand stream bed variations, as well as hydraulic conditions. Hydraulic properties of double rowbars are compared with those of alternate bars. A tentative criterion of formative conditions ofbraided streams and multiple row bars was proposed being based both on a mode definition ofbed configuration and results of the comparison of hydraulic characteristics of bars.