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    自动基流分割法在黄土高原水蚀风蚀交错区典型流域适用性分析

    Suitability analysis of automatic baseflow separation methods in typical watersheds of water-wind erosion crisscross region on the Loess Plateau, China

    • 摘要: 黄土高原水蚀风蚀交错区生态环境脆弱,河川基流量的多少及其变化对维持该区生态系统健康具有重要意义。利用黄土高原水蚀风蚀交错区窟野河流域多年实测径流资料,研究国内外常用的滑动最小值法、HYSEP法和数字滤波法3类共8种自动基流分割方法在该研究区的适用性。结果表明:1)8种方法所得年均基流指数差异较大,最大为0.6515,最小为0.3305,而滤波法中的F2(Chapman-Maxwell法)和F4(Eckhardt法)法估算的结果最为稳定可靠,均值分别为0.3868和0.3305,标准差分别为0.0428和0.0461;2)F2和F4法分割的基流过程线与实际更吻合,2种方法估算的年基流量与实际观测值的验证效果最好,Nash-Sutcliffe效率系数分别为0.691和0.718,平均相对误差分别为9.83%和5.05%,F2和F4法估算的基流结果均能客观稳定地反映该研究区的基流状况,适合于该研究区进行基流分析;3)从F2和F4 2种方法估算值的平均值来看,窟野河流域基流量近50年来呈现减少趋势,其减少量占总径流减少量的41%。

       

      Abstract: The water-wind erosion crisscross region on the Loess Plateau is the main source of the coarse sediments of the Yellow River, where eco-environment is very fragile. The baseflow is of great significance to maintain sustainable development of the river ecosystem in this region. In order to test the applicability of automated baseflow separation methods on the water-wind erosion crisscross region on the Loess Plateau, several commonly and widely used methods including minimum smoothing method, HYSEP and recursive digital filter were tested by the runoff data of Kuyehe Watershed. The results show that there were significant difference of baseflow indices of eight methods with the maximum 0.6515 and minimum 0.3305. The statistical characteristics of annual baseflow indices that were used Chapman-Maxwell filtering method and Eckhardt filtering method to estimate are the best with the mean values 0.3868 and 0.3305, respectively, and the standard deviation 0.0428 and 0.0461, respectively. The baseflow discharge curves are smooth, which accords with realistic base flow condition. The verification results show that Nash-Sutcliffe efficiency coefficients were 0.691 and 0.718, respectively, and the average relative errors were 9.83% and 5.05%, respectively. Therefore Chapman-Maxwell filtering method and Eckhardt filtering method separate most objective and stable base flow, which could be used as optimal base flow separation method in this study area. The mean baseflow estimated by Chapman-Maxwell filtering method and Eckhardt filtering method showed a significant negative trend in the near 50 years and the reduction of baseflow account for 41% of the total runoff.

       

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