黄丘一区小流域洪水输沙特性研究

<正> 长期的土壤侵蚀,把黄丘一区地表切割成千沟万壑的形态,坡陡流急,干沟沟底比降1％～3％,支毛沟比降更大。一遇暴雨洪水,当汇集坡面来水来沙后,沟岸侧蚀、沟底下切、沟头前进严重,形成沟道网络的高含沙水流,其含沙量500～1000kg/m~3,最高可达1700kg/m~3。由于含沙量大,水流容重和粘滞性增加,紊动减弱,成为非牛顿二相流,具有流变性质。本文根据绥德水保站及有关站(所)的实测资料和研究成果,对黄丘一区小流域洪水输沙特性作一分析。

Study on the Characteristics of Flood Runoff and Sediment Transport in the First Subregion of Gullied Rolling Loess Region

The flood in a small watershed in the first subregion of gullied rolling loess region, usually rises and falls all at a sudden,the hydrograph of flood discharge is basically similar with that of the sediment discharge,usually in a shape of a single peak . The peak of the hydrograph of sediment concentration slightly lags behind the peak of flood discharge. After the peak,the sediment content varies a little,but the discharge of flow varies greatly and high sediment load transported by small discharge of flow is usually formed. When the discharge of flow is more than 5. 0m3/s,the sediment content stablized at about 800kg/m3. The relationship between the discharge at the turning point prior or after the peak(Qa or Qn)and the watershed area(F)may be represented as:Qa=0. 1345 + 0. 211F and Qn = 0. 024 + 0. 019F respectively;and the relationship between modulus of sediment transport (Ms) and modulus of runoff (M) in one flood event may be represented as Ms= 0. 62M. This paper also introduces the relationships between annual runoff and rainfall from July to August,annual modulus of sediment transport and annual runoff.