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基流是河川径流的重要组成部分。在干旱半干旱地区,基流对于维持水源的稳定性及持续性、确定河流生态需水等方面具有重要作用。因此,基流分割结果的准确性至关重要。本文以黄河流域上游小流域为研究区,分别使用滑动最小值法和数字滤波法对典型年进行基流分割,然后用数字滤波法对1980-2014年日均径流进行基流分割,并分析基流的变化趋势。研究表明,数字滤波法在干旱半干旱地区具有较好的应用效果,滑动最小值法分割的基流结果偏小;在特定研究区的参数难以确定时,应结合两种方法的优点确定最佳的基流分割方案。研究区1980-2014年的平均基流指数为0.69,高于全国平均值0.26、西北诸河区的0.57及黄河区的0.43;趋势分析显示,研究区的年径流、基流、BFI的增长幅度分别为0.086(m3/s)/10a、0.169(m3/s)/10a、0.038/10a。MK趋势检验结果显示,年径流未通过10%的显著性检验,增长趋势不明显;基流和BFI分别通过了2.5%和1%的显著性检验,增长趋势显著。
Baseflow is an important part of river runoff. In arid and semi-arid regions, the base flow plays an important role in maintaining the stability and sustainability of water sources and in determining the ecological water requirement of rivers. Therefore, the accuracy of the base-flow segmentation results is crucial. In this paper, the small watershed in the upper reaches of the Yellow River Basin is taken as the research area. The sliding minimum method and the digital filtering method are respectively used to separate the typical years. Then, the digital filtering method is used to divide the daily average runoff from 1980 to 2014, Flow trends. The results show that the digital filtering method has good application effect in arid and semi-arid regions, and the sliding minimum method has a small base flow segmentation result. When the parameters of a particular study area are difficult to determine, the best combination of the two methods should be determined Base flow segmentation scheme. The average base flow index of the study area from 1980 to 2014 was 0.69, higher than the national average of 0.26, 0.57 in the northwest and 0.53 in the Yellow River. The trend analysis showed that annual runoff, base flow and BFI increased Respectively, 0.086 (m3 / s) /10a, 0.169 (m3 / s) /10a, 0.038/10a. The results of MK trend test showed that the annual runoff did not pass the significance test of 10%, and the growth trend was not obvious. The base flow and BFI passed the significance test of 2.5% and 1%, respectively, and the growth trend was significant.