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基流是河川径流的重要组成部分,也是干旱半干旱地区最重要的枯季水文特征之一.基流在维持河川径流和维护河流湖泊生态等方面具有重要意义.基于祁连山疏勒河上游出山口控制水文站昌马堡站1954-2009年的日径流资料,采用递归数字滤波法和平滑最小值法对日径流进行基流分割,对比分析基流和基流指数BFI的变化特征,并从气温和降水两方面探讨基流变化的主要影响因素.结果表明:两种方法的计算结果有差异,但平滑最小值法更适用于研究区.疏勒河上游多年平均基流量为6.07×108m3,基流变化总体上呈上升趋势,进入21世纪以后基流量增加最为显著.研究区多年平均基流指数为0.66,基流指数的年际变化相对比较稳定,但年内波动幅度较大.在长时间尺度上,降水是基流变化的主要影响因素,降水量的增加在一定程度上影响了基流和基流指数的变化.在全球变暖的背景下,气温升高导致冰雪融水的增加和冻土的退化,间接的影响了基流的变化.
Base flow is an important part of runoff and it is also one of the most important dry season hydrological features in arid and semi-arid regions.It is of great significance to maintain the runoff and maintain the ecology of rivers and lakes.According to the upper reaches of the Shulehe River in the Qilian Mountains By controlling the daily runoff data of Changmabao Station of Hydrology Station from 1954 to 2009, the daily runoff was segmented by using the recursive digital filtering method and the smoothed minimum method. The changes of base flow and base flow index BFI were compared and analyzed. And precipitation. The results show that there are differences between the two methods, but the smoothed minimum method is more suitable for the study area. The average annual base flow in the upper Shule River is 6.07 × 108 m3 The change of stream flow is generally on the rise, and the increase of base flow rate is the most significant since the 21st century.The multi-year average base flow index is 0.66 in the study area, while the base-flow index is relatively stable in the interannual period, but fluctuates more during the year. , Precipitation is the main influence factor of base flow change, the increase of precipitation affects the change of base flow and base flow index to a certain extent.In the context of global warming, The increase of ice and snow melt temperature and the degradation of permafrost caused by the increase of temperature indirectly affect the change of base flow.