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冲淤面积分配模式是一维水沙数学模型中需要处理的技术问题之一,合理选择冲淤面积分配模式能够保证一维模型的计算精度。本文首先建立了用于模拟实际游荡型河流复杂断面形态下洪水演进的一维水沙耦合模型。然后以黄河下游游荡型河段为研究对象,利用下游1992年实测高含沙洪水过程资料对所建模型进行了验证,计算值与实测值吻合较好。最后采用一维模型中常用的五种冲淤面积分配模式计算了该场次高含沙洪水过程,分析了不同分配模式对模拟结果的影响。结果表明:等厚度分配模式的计算效果相对较好,按子断面流量分配与按挟沙力分配两种模式的计算精度相当。冲淤面积分配模式对流量及水位影响相对较小,而对含沙量及河道冲淤过程影响较为明显,尤其对于淤积严重的河段。
The distribution model of erosion and siltation is one of the technical problems to be solved in one-dimensional mathematical model of water and sediment flow. A reasonable choice of the distribution model of erosion and siltation can ensure the accuracy of one-dimensional model. This paper first established a one-dimensional water and sand coupling model for simulating the flood evolution under the complicated cross-section of the actual wandering river. Then, taking the wandering reach of the lower Yellow River as the research object, the model was verified by using the data of the measured sediment concentration in the lower reaches in 1992. The calculated values are in good agreement with the measured values. Finally, five flood and silt distribution models commonly used in one-dimensional model were used to calculate the high silt-flood process and the effects of different distribution models on the simulation results were analyzed. The results show that the equivalent thickness distribution model is relatively good, and the calculation accuracy of the two models based on the flow distribution of sub-section and that of sand distribution is the same. The distribution pattern of erosion and siltation has a relatively small influence on the flow and water level, but has a significant effect on the sediment concentration and river erosion and sedimentation, especially for the seriously silted river.