Study on river engineering oriented to cotroll of river formation and vegetation

点击翻译按钮获取中文摘要

In fluvial stream with vegetation zone along side wall, low frequency fluctuation of transvers velocity brings alternate lateral bed load transport. Since the bed shear stress near vegetation zone changes rapidly in the transverse direction, net lateral bed load remain after the average of one period of fluctuation. It causes longitudinal sand ridge formation ; furdermore it accompanies a longitudinal sorting in case of graded meterials. We conducted the flume experiment to demoustrate the above phenomena, and explained it by using the model of non-equilibrium bed-load transport.Next, based upon the such a basic model, we tried to explain the more complicated situation. During floods, the flow is forced to penetrate into vegetation zone but the high resistance discharges the flow in vegetation zone toward the main channel. In such a condition, the sediment transport process is also degenerated. We conducted the experiment of the flow and the bed load transport in the transition reach of flow with vegetation zone. And then we applied the sediment transport model, and clarified the tempral and spatial variation of the channel bed.