洪水径流系数的尺度效应研究

Study on scale effect of flood runoff coefficient

洪水径流系数是表征降雨径流过程的一个重要参数,以往对径流系数的尺度效应基本上是在坡面或者小流域上进行观测或试验。通过统计滦河流域6个中大尺度子流域汛期的暴雨洪水过程,计算了各场暴雨洪水的径流系数,发现径流系数随着流域面积的增大而减小,并分析了产生这种趋势的原因。结果表明,降雨空间分布不均匀性、单位面积地下径流出流能力及下渗都能引起径流系数的尺度效应。认识径流系数的尺度效应,对于研制开发不同尺度的、具有物理机制的流域水文模型,防洪减灾具有一定的指导意义。

Runoff coefficient is a very important parameter to describe runoff dynamics： The scale effects on runoff coefficients have been observed by several researchers on plots or small watershed, however, little research has been done on meso-scale and large-scale catchments. So six meso-scale and large-scale sub-basins of the Luanhe River Basin were selected for calculating the runoff coefficients of single event during 1956 -2002 . An obvious reduction in average event runoff coefficients from 0.43 （Liuhe basin） to 0.10 （Luanhe basin） was found with increasing basin area. Through the analysis, we show that the spatial variability of rainfall, the groundwater discharge ability and infiltration are the important factors leading to the decrease of runoff coefficients. The scale effects on runoff coefficient is very important to development of a physically-based hydrological model and flood control and disaster reduction.