Numerical Computation And Analysis Of Discharge Capacity Of Compound Channel

Flood disasters occurred frequently and severely in most plain rivers in China, that are made of floodplains and main channels. In flood period, when the water level exceeded the height of the main channel, the main channel and flood plains carried the total discharge together. Many of their were severe siltation and not enough flood capacity in many rivers because of a variety of natural reasons and human activity, so that the life and property security of people were threatened. River improvements, for example cutoff works and flood diversion, must be performed. On the other hand, levees were often rebuilt or realigned to increase flood control standard and make the best of riparian land resources. All these works are related to discharge capacity of compound channel. Optimum design of the cross-section of compound channel is very important, so the study of discharge capacity of compound channel is significant to the flood control and river improvements.First, the previous research works were reviewed and summarized,then numerical computation was used in this paper. Finite volume method was employed to establish the plain 2D modeling of regular compound channel by comparing different numerical methods. The modeling was verified by the measured data in the former flume test. Finally, on the basis of consideration of two typical regular compound channels (one had one main channel, the other one had two main channels), flow division ratios of main channel and floodplains, water-surface gradient were calculated and analyzed under different conditions, such as different discharge areas of floodplain and main channel, different floodplain roughness and different shapes of cross-section. Results will not only be a useful value for theory of river hydraulics but also be a good reference for design of the cross-section in the practical river regulation.