BEDFORMS AND SEDIMENT TRANSPORT RATES IN MEANDERING CHANNEL INFLUENCED BY FLOODPLAIN ROUGHNESS

抄録

The aim of this paper is to improve an understanding of physical processes involved in sediment transport mechanisms and bedform evolution in a two stage meandering channel. In this study, a laboratory flume was used since it is difficult to observe bedforms and to obtain sediment transport rates in natural rivers during flood. A series of experiments were conducted to measure stage-discharge data, sediment transport rates, and bedforms in a meandering channel with different roughened floodplains for overbank flows. Detailed measurements have shown that the bedforms considerably vary with different water depths and floodplain roughness. The sediment transport rate increases while the flow is inbank, and once the flow is overbank, it starts decreasing till at a certain water depth and then increasing again. The bedforms have ripples and dunes at a water depth when a minimum sediment transport rate occurs. The water depth at the minimum sediment transport rate also varies due to floodplain roughness.