黑河流域上游山区基流量分割及其变化

基于黑河上游莺落峡站1954年-2011年径流资料,采用数字滤波法多种滤波方程对月流量资料进行基流分割;在此基础上,借助Mann-Kendall、Pettitt、流量不稳定系数、累积距平等方法分析研究区基流和基流指数(BFI)在年内、年际以及多年时间尺度上的变化特征。结果表明,数字滤波法分割的基流能较好地反应出不同月份之间基流量的差异及其年内变化特征;研究区夏季基流量最大,其次是春季和秋季,冬季基流量最小;BFI最小值出现在夏季,冬季BFI最大;基流量和径流量的年际变化趋势大体一致,均呈缓慢增长趋势,但基流变化相对缓和,且比较平稳;基流量序列在1979年存在显著变点,变点后基流量较变点前增加16%;多年变化中基流对径流的贡献变化幅度不大,BFI基本维持在0.27左右。

Separation and Characteristics of Base flow in the Upper Reaches of Heihe River Basin

As an important component of runoff, base flow has great significance in the maintenance of the sound ecosystems of the rivers. Base on the monthly runoff data from 1954 to 2011 in the upper reaches of Heihe River Basin, the digital filter method was used for the base flow separation, together with the traditional methods of minimum monthly average flow rate in the last 10 years and the 90% guarantee rate of the minimum average flow. The inner-annual, inter-annual and decadal variations in base flow and base flow index were investigated by means of Mann-Kendall test, Pettitt test and cumulative departure curve methods. The results showed that the digital filter method could give a satisfactory result of base flow separation over the study area. The inner-annual base flow index increased first and then decreased and had a big degree of variability. In the inter-annual variations, the trends of the base flow were consistent with those of the runoff, and the degree of discretization of the base flow was relatively low. Although the base flow had a rising trend, the change was relatively mild, and relatively stable. A significant change point was found for the base flow time series in 1979, and the average base flow after the change point increased by 16% compared with the former period. In the decadal scales, the contribution of the base flow to the runoff was not variable, with the decadal base flow index approaching 0.27.