渭河下游河道冲淤变化对洪水演进特性的影响

基于三门峡水库建库后渭河下游河道演变及洪水过程实测资料,采用实测资料分析,理论分析和数值模拟相结合的方法,分析了渭河下游河道发生冲淤变化对洪水特性的影响。结果表明:自水库建成至2003年间,渭河下游河道发生淤积萎缩引起渭河洪水演变特性发生了显著地改变,渭河下游洪水位抬升、洪水传播历时延长以及洪峰削峰率增大,而这些洪水特性也是造成渭河下游河道发生淤积萎缩的主要原因。2003年之后,因渭河下游河道水沙条件的变化,洪水洪峰流量大幅度减小,河道出现冲刷,漫滩流量相较于先前减小,使渭河下游洪水位下降、洪峰传播历时缩短、洪峰削峰率不断减小。

Impact of erosion and siltation on flood evolution characteristics of Weihe River downstream

Based on the measured data of the river evolution and the flood process in the Weihe River downstream after the building up of Sanmenxia Reservoir, the impacts of the Weihe River downstream channel sedimentation and shrinkage on flood characteristics were analyzed by combining the measured data analysis, the theoretical analysis and the numerical simulation. The results showed that the Weihe River downstream channel sedimentation and shrinkage caused significant changes in the evolution characteristics of the Weihe River flood, resulting in rising the flood level, prolonging the flood peak propagation time and increasing flood peak clipping rate of the Weihe downstream. And those are also the main reason for the Weihe River downstream sedimentation and shrinkage.Due to the change of water-sediment conditions in the Weihe River downstream after 2003, that is, the flood peak discharge significantly decreased and the river channel was flushed, the floodplain discharge decreased compared to the previous. It led to decline in the flood level, shortening in the flood peak propagation time and decrease in peak-clipping rate.