清水沟水库溃坝对主河道行洪过程影响数值模拟研究

Numerical simulation of the effect of Qingshuigou Reservoir dam break on the flood process in the main stream

溃坝洪水危害巨大。为研究支沟溃坝对主河道洪水过程的影响,采用集成HLLC近似黎曼求解器的二维水动力模型,模拟研究了支沟清水沟水库溃坝洪水对主河道大理河行洪过程的影响。模拟结果表明:计算水位与实测洪痕吻合度较好,证实所建模型能较为精确地模拟溃坝洪水演进过程;清水沟水库溃坝对大理河上下游均有影响,上游会发生明显的壅水现象,流量具有先下降后上升再下降至稳定的趋势;最为关心的下游洪峰呈现出先增加再下降至稳定的过程,并不是简单的叠加计算,而与上下游关系密切。该成果对于防治支沟溃坝在主河道形成洪水具有一定的指导意义。

The dam-break flood is always disastrous. To study the effects of branch dam-break flood on flood process,a 2-D hydrodynamic model integrating HLLC approximate Riemann solver was used to simulate the effects of dam-break flood in Qingshuigou Reservoir on flood process in Dali River. The simulation results showed that the calculated water level agreed well with the measured flood mark,confirming that the model is able simulate the evolution of dam-break flood in a reliable way. The dam-break of Qingshuigou Reservoir has obvious effects on both the upstream and downstream of Dali River. A backwater phenomenon and discharge tendency of decreasing-increasing-decreasing to stable were observed in the upstream reach of the Dali River. Regarding the flood discharge in the downstream,it increased firstly and followed by a descending pattern then became stable,instead of a simple superposition. This research can help guide the prevention the flood in the main stream caused by the dam-break floods in branch channels.