泾河流域高含沙水流的尺度效应研究

基于泾河流域1965—2014年5—9月的逐日降雨量、逐日径流量和逐日含沙量数据,选取日含沙量≥100kg/m3作为高含沙水流,分析了泾河高含沙水流的空间特征及其变化,并参考降雨量探讨变化成因。结果表明,研究期内泾河流域的高含沙水流变化可以分为3个阶段:1965—1978年为多发期,1979—1990年为略微减少期,2006—2014年为显著减少期。将泾河流域分为南北两个分支,高含沙水流具有明显的尺度效应,北支的产沙模数随流域面积增加而减少,产流模数随流域面积增加而增加,南支的产沙模数随流域面积增加而增加,产流模数也随流域面积增加而增加。南北两个分支的产流模数和产沙模数在3个阶段经历了相似的变化,先是1979—1990年略微减少,之后在2006—2014年显著减少,使最初的复杂尺度效应转变为后期简单的线性尺度效应。分析结果说明泾河流域内部各区域在水土保持措施长期实施下高含沙水流均得到有效控制。

Scale Effect of Hyper-concentrated Flows in Jinghe River Basin, Yellow River

Based on the data measured in the Jinghe River Basin (JRB) between 1965 and 2014 (including daily precipitation,runoff and concentration),the spatio-temporall characteristics of hyper-concentrated flow were analyzed.Flows with daily concentration greater than 100 kg/m3 were identified as hyper-concentrated flows.Analysis showed that,the occurrences of hyper-concentrated flows in the JRB can be grouped into three periods,which were 1965-1978,1979-1990 and 2006-2014.Hyper-concentrated flows occurred frequently before 1978,and the occurrence decreased dramatically after 2006.Moreover,the JRB is divided into two parts,the north and the south part,where the temporal distributions of hyper-concentrated flows had different characteristics.For the north part,the sediment yield modus decreased with the increasing drainage area,while the runoff modus increased with increasing drainage area.For the south part,the modus of the runoff and sediment yield both might increase with the increasing drainage area.The temporal characteristics of hyper-concentrated flow were the same in the south and north part,JRB.So,the complex effect sizes during the first period changed to linear relation gradually.Analysis indicates that hyper-concentrated flows are effectively controlled by water and soil conservation practices in the JRB.