降雨时空不确定性对小流域洪峰模拟的影响评估

Assessing the Impact of Rainfall Spatial-Temporal Uncertainty on Flood Peak Simulation in Small Mountainous Catchment

山丘区小流域洪峰模拟结果与降雨时空分布密切相关。以河南省荥阳市王宗店流域“7·20”山洪灾害为例,构建了15种时空分布的10 min尺度降雨情景,综合采用中国山洪水文模型和方差分析理论评估降雨时空情景变化对洪峰模拟的影响。结果表明:中国山洪水文模型可以较好地模拟“7·20”暴雨洪水过程。不同时间情景下10 min降雨量均匀分布模拟得到的洪峰流量较小、峰现时间较晚;非均匀分布时最大10 min降雨量发生时间越晚,模拟得到的洪峰流量越大、峰现时间越晚。空间情景变化主要影响洪峰流量模拟,采用泰森多边形法模拟得到的洪峰流量最大。时间情景变化是洪峰流量和峰现时间模拟结果不确定性的最主要来源,空间情景变化和时空情景耦合变化仅影响洪峰流量模拟。

Flood peak simulation in small mountainous catchments is closely related to the spatial-temporal distribution of rainfall process.Taking the“July 20”flash flood disaster occurring at Wangzongdian catchment in Henan Province as an example,15 rainfall scenarios of 10-minute time step were designed with different spatial-temporal variability,based on China flash flood hydrological model and analysis of vari-ance were adopted to assess the impact of rainfall uncertainty on flash flood peak simulation.The results show that China flash flood hydrologi-cal model performs well for the“July 20”event.For temporal scenarios,the uniform distribution of 10-minute rainfall induces a smaller sim-ulated flood peak flow and a later time to flood peak.In the case of non-uniform distribution,the later the maximum 10-minute rainfall oc-curs,the larger the simulated flood peak flow and the later the time to flood peak are.While,spatial scenario change mainly affects the simu-lated flood peak flow,and the maximum flood peak flow is obtained by using Thiessen polygon method.Temporal scenario change is the main uncertainty source for flood peak simulation in both flow and time.Spatial scenario change and the spatial-temporal scenario change only affect the flood peak flow simulation.