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