耦合渗漏项的季节性河道洪水演进模型研究

针对北方干旱或半干旱区季节性河道渗漏现象严重问题,为提高流域洪水演进模拟精度,在传统水动力学洪水演进模型基础上耦合河道渗漏项,构建季节性河流洪水演进数学模型。采用霍顿入渗模型描述季节性河道渗漏过程,解决河道渗漏量计算及与基于圣维南方程组洪水演进模型耦合问题;并利用Preissmann四点偏心隐格式与追赶法对模型离散和计算,开发FORTRAN计算程序;最后以大沽河流域实测资料进行验证。结果表明,沙湾庄和南村断面水位与流量过程的模拟值与实测值吻合且变化趋势一致,洪水峰面到达断面模拟时间和实际时间基本一致,研究区各河段来水量、渗漏量的实测值与模拟值相对误差范围分别为-1.66%~0.36%、-3.09%~3.72%,所建模型可满足在现状条件下进行洪水模拟预报的需要。

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.