1959-2011年北洛河上游流域径流量及其组分变化趋势和时间分配特征

以实测水文数据为基础,分析了区域水土保持措施实施和植被恢复背景下北洛河上游黄土丘陵沟壑区流域1959-2011年间径流和基流数量变化、时间分配规律和阶段特征,对流域水土保持和生态平衡、水资源保护和利用具有指导和借鉴意义。结果表明:志丹、吴起、刘家河3个水文站的年均径流深分别为37.6、27.1、31.8 mm。年均地表径流量和基流量所占比例3站平均为63.8%和36.2%。3站的年径流量和地表径流量全部表现为极显著减少趋势(P<0.001),而且地表径流量决定了总径流量的变化程度。3站基流量呈增加(P<0.01)(吴起站、刘家河站)或稳定态势(志丹站)。径流量及其组分年内分配均表现为"双峰型"。随时间推移,径流量月内分配不均匀性减弱,夏、汛期径流量占年径流量的比例急剧降低。3站冬、春季枯水期基流量均为显著增加态势,而夏、秋季稳定。1959-2011年在水土保持措施的实施和生态恢复背景下,流域径流及其组分的数量和时间分配发生了很大变化,流域水循环要素比例趋于合理。

Trend and temporal distribution of streamflow and its components in the upper reaches of Beiluo River from 1959 to 2011

The trend of streamflow and base flow and their distribution pattern and phase characteristics were analyzed in the upper reaches of Beiluo River based on the survey data from 1959 to 2011.The test results can provide some reference for the implementation of soil and water conservation,ecological balance,and the protection and utilization of water resources in the study area.The results showed that the mean annual streamflow for Zhidan,Wuqi,and Liujiahe stations were 37.6,27.1,and 31.8 mm,respectively.The average proportions of surface flow and baseflow of the three stations were 63.8%and36.2%,respectively.Both the annual streamflow and surface flow of all three stations showed a significant decreasing trend(P<0.001).The trend of surface flow dominated the reduction of streamflow.The baseflow for Wuqi and Liujiahe Sations showed a significant increasing trend(P<0.01),whereas Zhidan Station showed a stable status.The distribution within a year of streamflow and baseflow showed a"double peak"style.The monthly distribution tended to be uniform and the proportion of streamflow in flood season in annual runoff dropped dramatically over time.The base flow in both winter and spring of the three stations showed a significant increasing trend,whereas it kept stable in summer and autumn.With the implementation of soil and water conservation and ecological restoration,the volume and temporal distribution of streamflow and its components changed greatly and the proportion of the hydrological elements was prone to become reasonable in the catchment from 1959 to 2011.