Study Of Compound Channel Flow Characteristics

At present, many rivers in our country are still short of perfect regulation. The discharge capacity of rivers is lower. Multifarious flood disaster caused national economy extremely big loses. Therefore, flood control and reducing the disaster is a long-term and arduous assignment in our country. Generally, many natural rivers have compound channels, possessing a main channel, and one or two floodplains. The main channel carries water in low-water season. There is compound channel above bankfull stages in flood season. Because of the overbank flow, the discharge capacity of the main channel decreased. In other way, the current velocity of the floodplain is lower due to the rough floodplain. So, the velocity of the whole section is lower, and the travel time of flood wave is longer, and water lever increased. Therefore, it is important to know the flow characteristics in compound channels and the effect of hydraulic parameter on the channel's discharge capacity. This problem has been paid high attention in hydraulics and in home and abroad. On the other hand, it is urgent to resolve this problem for regulating river in practice.Flume experiment and numerical simulation were adopted to study the flow characteristics of compound section. Through reviewprevious work, the aim of the project was defined. Two-dimensional flow mathematical model was built to calculate the lateral distribution of the flow velocity in compound section, and the result of calculation was proved by flume experiment. Then, the lateral distribution of velocity and the lateral distribution of boundary shear stress were studied. Some factors, such as flow discharge and the ratio of the floodplain width to the main channel width, the flood plain roughness etc effect on discharge capacity were discussed in detail. The discharge assessment in compound channel was also discussed. Through analyzing and comparing influencing factors, some standpoints were presented in the paper. The research result can be a good reference to verifying section parameters and optimizing section design in river regulation and flood control projects.