清涧河流域的水文情势变化阶段及其特征

 为探讨清涧河流域不同阶段的水文变化特性,分析流域水文变化的原因,通过定量指标结合定性原则,筛选了清涧河流域内的代表性雨量站,在此基础上,建立了具有一致性的1955—2002年的降水量序列资料;采用滑动平均和有序聚类分析方法,对选定的水文序列进行阶段划分,并统计分析各阶段降水、径流的变化特性;结合流域水土保持措施状况,进一步讨论引起流域水文变化可能的原因。结果表明:清涧河流域的水文序列可划分为3个阶段,分别为:1955—1979、1980—1989和1990—2002。与第1阶段相比,第2、3阶段汛期和年降水量呈减少趋势;第2阶段径流量小于第1阶段,第3阶段平均径流量大于前2个阶段。各阶段年降水量与径流量之间具有正相关关系,但点群散乱,相关性不好;各阶段暴雨特性和水土保持措施数量、质量的变化,是流域水文变化的主要原因。

Variation phases and its characteristics of hydrological regime of Qingjianhe River basin

The representative rainfall gauge stations were selected firstly according to quantitative indexes and qualitative principle. And then, rainfall series from 1955 to 2002 which has good consistency was established based on the selected rainfall gauge stations. Adopting moving average method and serial cluster analysis method, hydrological series in the basin was divided into three phases according to annual runoff coefficient variation. Finally, variation characteristics of precipitation and runoff in each phase and the possible reasons which may cause runoff variation were further analyzed based on practical situation of soil and water conservation measures in each phase. And the results show that three divided phases of hydrological series are 1955-1979, 1980-1989, and 1990-2002. Comparing with rainfall and runoff in the first phase, annual precipitation and rainfall in the flood season from June to September in the second and the third phases have presented decreasing trends. Although runoff in the second phase is less than that in the first phase, runoff in the third phase is greater than that in the first two phases. Annual runoff amount and annual precipitation in each phase have bad positive correlation relationship. Hydrological regimes are up to characteristics of storm pattern, quantity and quality of soil and water conservation measures.