Experimental Study on Evolution Characteristics of Bedload Transport Motion in Main River with Tributary Action

The channel confluences are hackneyed,but the sediment transport motion at the confluence and main rivers considering the tributary effect isare very complicated.Based on flume experiments of the flow and sediment,the evolutionary process of bedload motion in main river with tributary action including three different cases has been discussed,namely without branch channel flow,branch channel flow only with clear water,branch channel flow with both water and sediment.The bedload transport rate and its accumulative sediment transport amount with the increase of time were recorded and analyzed for different discharge ratios q~* of the branch channel flow Q_b to combined tail-water flow Q_t in each case.The results demonstrated that the characteristics of bedload transport and local scoured bedform strongly depend on the flow and sediment conditions from tributary and the relationship between main and tributary rivers as far as hydraulic factors was concerned.