Study on seasonal channel flood routing model coupled with leakage term

In view of the serious problem of seasonal river leakage in arid or semi-arid areas of northern China, in order to improve the simulation accuracy of flood routing in the basin, we established a seasonal channel flood routing model which couples the traditional hydrodynamic flood routing model with channel leakage. We used the Horton infiltration model to describe seasonal river infiltration and solved the coupling problem between river channel leakage and flood routing model based on Saint-Venant equations. Then, the model was discretized and solved with the Preissmann four-point partial-node implicit scheme and chasing method, and the FORTRAN calculation program was developed. Finally, the model was tested with measured data of the Dagu River basin. The results indicated that the simulated values of water level and flow process in Shawan and Nancun were consistent with the measured values, and their trends of variation were also consistent. The simulated time for the flood peak to reach the cross-section was basically the same as the actual time. The relative error ranges between the measured value and the simulated value of water inflow and leakage in all the channel segments of the study area were -1.66%-0.36% and -3.09%-3.72% respectively. It can be concluded that this coupled model can satisfy the need of flood for ecasting under the present condition.

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