关键词: 临界雨量, 分布式水文模型, 降雨量, 空间分布, 山洪灾害

Abstract: Critical precipitation is an important basis for flash flood early warning, which is affected by precipitation, soil water content and underlying surface characteristics, and the spatial distribution of precipitation is one of the important factors. Taking Gaotihe Watershed in Chongyang County, Hubei Province as an example, we discussed the influence of precipitation spatial distribution on critical rainfall for early warning of flash floods. The distributed hydrological model(HEC-HMS) and trial method were respectively used to calculate the designed flood and critical precipitation, the precipitation spatial distribution coefficient was proposed and the relationship between precipitation spatial distribution coefficient and critical rainfall was analyzed. The results show that the critical rainfall is the largest when the precipitation reduces from upstream to downstream, while it is the smallest when the rainstorm center is located in the downstream, indicating that the precipitation spatial distribution has a significant effect on critical rainfall. Therefore, in the flood warning practice, we should adjust early warning index based on the actual precipitation spatial distribution.

Key words: flash flood, critical precipitation, distributed hydrological model, precipitation, spatial distribution