高强度人类活动作用下考虑河道下渗的河网洪水模拟

Modelling the flood behavior in a river network considering the streambed infiltration and its application in Haihe River basin of China

模拟河道洪水运动的现有圣维南方程组,因没有考虑河道下渗行为,难以满足地下水位持续偏低、河道长期干涸等受人类活动高强度作用地区的洪水模拟需要。论文推导了考虑河道下渗的圣维南方程组,采用Preissmann四点隐式差分和模块化建模技术,耦合河道汊点、闸坝群联合调度、蓄滞洪区吞吐洪水等计算模块,并遴选霍顿下渗公式为河道下渗模拟方法,构建了考虑河道下渗的河网洪水模拟模型。将该模型应用于海河流域漳卫河水系,采用1982、1988和1996年3场实测洪水对模型进行率定和验证;根据不同年代河道断面、设计洪水和岳城水库的不同调度方式,设计了8种情景进行模拟,得出如下结论：综合考虑河道下渗与设计洪水变化,50年一遇设计洪水恩县洼可以不启用,河道行洪最高水位下降0.03~0.20 m,这对流域洪水出路的科学安排与防洪格局调整具有重要指导意义。

Saint-Venant equations is widely used in simulating flood movement behavior in a river network so far, but those river network flood simulation models based on Saint-Venant equations do not work in some basins locating seasonal river and affected by human activities highly due to without considering chan- nel transmission seepage loss, where the riverbed is very dry before the flood coming every year and the groundwater table is so low that it is in the disconnect with surface water. In the paper the Saint-Venant equations considering seepage loss is deduced according to the mass equation, and then the generalized model simulating flood behavior in a river network considering channel seepage loss, by using four point im- plicit difference scheme and modular modeling technique, and coupling some internal boundary numerical processing technique including river junction, darn group joint scheduling, flood storage area in-out flood water and so on, with Horton infiltration formula using for simulating channel seepage behavior. The general- ized model above is applied to Zhangwei river system, a subbasin of the Haihe river basin, and is calibrat- ed and validated using the three measured floods in 1982, 1988 and 1996; and then simulated eight sce- narios for 50 year design flood. The simulation results show that the model is effective and a conclusion can be drew as follows： one of the detention basins, Enxianwa, may be able to be canceled and maxi- mum floodwater level of river reaches fell by 0.03-0.20m averagely. It has a very important guiding significance for the reasonable arrangement of basin flood way and adjustment of flood control pattern.