大理河流域不同时间尺度水沙变化影响因素及趋势研究

近几十年来黄河中游水沙特征有所改变,以黄河中游典型流域大理河为例,通过分析流域气候及下垫面变化.探求流域产流、产沙量变化的原因及趋势.结果表明:流域水土保持措施的减水、减沙效益从1972年后开始显现,1960年代至1990年代,大理河流域产流、产沙量出现了一个先减少再增大的过程.以1960年代为基准,1970年代降雨与下垫面产流能力对流域产流量减少的影响比较接近(51.7%.42.2%),而在1980,1990年代降雨的影响要小于下垫面产流能力的影响(1980年代为27.0%,64.1%;1990年代为38.4%,54.9%);但在汛期尺度上,降雨、下垫面产流能力对流域产流量的影响此消彼长,随时间变化看不出什么规律.受气候以及水土保持措施等的影响,未来大理河流域多年平均尺度下流域产流量、产沙量将会减少,但在某些小的时间尺度(次暴雨)内的产流量、产沙量将有增大的可能;水力侵蚀将会减少,但风力侵蚀却有加强的趋势.

Analysis on Variation Characteristics and Tendency of Runoff and Sediment at Different Time-scale in Dali River Basin

In recent decades,changes of the characteristics of water-sediment relationship occur in the middle Yellow river.Regarding Dalihe river as a case,the causes of the changes as well as their developing trend were explored to study their responses to the changes of climate and underlaying surface.Results demonstrated that,because of soil and water conservation measures significant reductions of runoff and sediment vields happened since 1972,and the runoff and sediment yields presented firstly increasing and then reducing processes from 1960s to 1990s.Compared with 1960s,precipitation and underlaying surface had comparable effect on runoff generation(51.7%,42.2%)in 1970s,however,the runoff generation ability of underling surface had stronger impacts on runoff reduction than that by rainfall in 1980s and 1990s(27.0%,64.1%;38.4%,54.9%).At the flood scale,there was no significant rule between the runoff generation ability by precipitation and that by underlaying surface.Affected by climate change and soil and water conservation measures,runoff and sediment yields would reduce at annual scale in the future,whereas,at some small scales the yields of runoff and sediment could increase,and soil erosion by water agent would reduce and thatby wind would increase.