基流分割方法在寒旱区流域的适用性分析

Suitability Analysis of Different Baseflow Separation Methods in Cold and Arid Watershed

基流作为寒旱区流域的重要水分补给,在维持生态系统安全和水资源合理规划等方面发挥着重要作用,确定适合该区环境特点的基流分割方法尤为重要。基于数字滤波、滑动最小值(BFI)、时间步长(HYSEP)三类方法对我国西北寒旱区黑河流域上游莺落峡水文站1954~2012年的逐日流量进行基流分割,对三类共9种基流分割方法在研究区的适用性进行比较分析。结果表明:(1)9种方法计算所得年内基流量变化趋势均符合黑河流域特点,但不同月份降雨量的差异对基流分割结果的影响显著;(2)滑动最小值法和时间步长法对不同年份的基流过程有更好的辨识度,且滑动最小值(B1)法、滑动最小值(B2)法、时间步长(H3)法所得的多年平均基流指数与已有实验研究得到的结果相近,结果可靠,同时各法基流指数统计结果表明9种方法所得基流序列均较为平稳,年际变化平缓;(3)时间步长(H3)法得到的基流过程线符合流域汇流规律,与斜线分割法的确定性系数显著优于其它各法(R2=0.825,p<0.001)。综上,时间步长法中的局部最小值(H3)法综合考虑了年内基流量变化特征、年基流指数稳定性、径流过程线合理性三个方面,在黑河上游流域进行基流分割最为适宜。

Baseflow is an important component of runoff. Investigation on the baseflow separation methods is of significance for realizing hydrological cycle and water resources management in cold and arid regions. The Heihe River Basin is located in typical cold and arid regions in the Northwest China. Based on the observed runoff time series from 1954 to 2012 at the Yingluoxia station, one of the hydrological stations in the upper reaches of the Heihe River,the suitability of the 9 baseflow separation methods in the Heihe River Basin was analyzed,including digital filtering, BFI and HYSEP methods. The results show that：（1） the inner-annual baseflow trends estimated with the 9 kinds of methods notably conform to the characteristics of the Heihe River Basin, but the baseflow separation results are significantly affected by the precipitation in different months;（2） both BFI and HYSEP can better identify the baseflow process of dif ferent years,the average annual baseflow indices of B1, B2 and H3 are close to the isotope results, and the statistics of annual baseflow indices with the 9 baseflow separation methods show that the baseflow sequences are relatively smooth and gently decadal variation;（3） the baseflow and duration curve estimated by H3 can objectively reflect the recession hydrograph,and the determination coefficients between H3 and constant-slope separation method are superior to other methods（R2=0.825,p0.001）. From the above analysis, H3 is expected as the most suitable baseflow separation method for the upper reaches of the Heihe River, which can give a comprehensive consideration of the inner-annual baseflow trends, annual index stability and process curve rationality.