Combined simulation system for propagation of flood in plain rivers and its application

On the basis of the digital river basin and software HEC-RAS, the methods to treat the topography data of the flood channel and the flood flowing and retarding basin as well as the simulation of flood diversion project were studied. The approaches for automatic generating the upper and lower reaches boundary conditions and initial condition were suggested. The combination simulation system for flood propagation in the plain rivers was developed by combining the flood routing through the channel with that through the flood flowing and retarding basins. The system was applied to simulate the flood wave evolution under the different operation scenarios of the flood flowing and retarding basins and as the core of the system for real-time flood forecasting and operation in a river basin. The output of the system was adopted to evaluate the effects of flood flowing and retarding basins on flood propagation. The combination simulation system presented in this paper was validated by the data obtained from the Wangjiaba and Linhuaigang inter-reaches located in the Middle Huaihe River basin. There was a big flood all over the basin with several flood peaks in 2007. The first flood peak was used to calibrate the model parameters of the system and the following flood peaks were used to verify the system. The result indicated that the numerical solution of the hydraulic model based on HEC-RAS was stable with high simulating precision and the characteristics of flood propagation were described precisely.