武陵山区女儿寨小流域次降雨径流与产沙特征

 以武陵山区女儿寨小流域为研究区,根据流域2004—2008年77场典型降雨径流观测资料,研究流域次降雨径流与产沙特征。结果表明:77场降雨中,以25.0～49.9 mm和50.0～100.0 mm的降雨为主,占降雨总数的67.53%,降雨强度以10～40 mm/h为主;降雨量与径流深和产沙模数呈现较为显著的线性相关性,降雨量、径流深及降雨侵蚀力对产沙模数均有明显影响,其中以径流深和产沙模数的拟合效果最好,R2达0.684 7;在对降雨、径流、产沙共12个指标进行相关性分析的基础上,对径流深、洪峰流量、产沙模数、降雨侵蚀力4个主要指标进行多元逐步回归拟合,R2均在0.85以上,并通过显著性检验,回归方程拟合效果较好,可用于相关指标的定量计算;流域的产沙量主要取决于几次大的暴雨,汛期的降雨决定流域的产流产沙状况。研究结果可为流域水土流失监测和预报、水土保持措施合理配置等提供相应参考。

Characteristics of runoff and sediment yield for rainfall events in Nverzhai small watershed of Wuling Mountain area

Taking Nverzhai small watershed in Wuling Mountain area as study area,the characteristics of runoff and sediment yield events based on 77 typical observed rainfall events in 2004—2008 were studied.The results showed that the rainfall amounts of 77 events were mainly between 25.0-49.9 mm and 50.0-100.0 mm,which held 67.53% in total rainfall.Rainfall intensity were mainly between 10-40 mm/h.Sediment yield of watershed mainly depends on several large rainstorms.Rainfall in flood season would determine the amount of runoff and sediment yield of watershed.It was showed that there was a comparatively obvious linear relationship between rainfall and runoff depth and sediment yield.Rainfall,runoff depth and rainfall erosivity had significant effects on sediment yield.Fitted linear regression equation of runoff depth and sediment yield were optimal,its regression coefficient were 0.684 7.Based on correlation analysis of 12 indexes about rainfall,runoff and sediment,multiple stepwise regression analysis about four main indexes of runoff depth,flood peak,sediment yield,rainfall erosivity were completed.The value of R2 of regression equation were all bigger than 0.85 and passed significance test.This showed that the fitted effect of regression equation were better.This equation can be used to calculate relevant indexes.This results can be used for monitoring and forecasting of soil and water loss as well as plan of soil and water conservation.