大兴安岭盘古河流域基流分割及特征分析

Segmentation and characteristic analysis of baseflow in Pangu River basin in Daxing anling Montains

基流在水文过程中起重要的作用,不同流域基流所占的比例不同,选择科学合理的基流分割方法,获得较准确的基流量,对于保证流域的生态水量至关重要。根据盘古河流域盘古站1988—2015年日径流资料,采用基流指数法、时间步长法和数字滤波法3大类7种方法,并结合流域退水常数进行基流分割研究。利用Nash-Sutcliffe效率系数,同时采用平均相对误差(MRE)评估不同基流分割方法的计算结果精度。结果表明:7种方法均能实现基流过程的分割,但不同方法的分割结果存在一定差异;数字滤波法F2计算得到的基流分割过程线最稳定,Nash-Sutcliffe效率系数最高(0.851),平均相对误差最小(7.992%),是盘古河流域较为适宜的基流分割方法;年内基流指数总体呈现出先减后增的趋势,在融雪期持续减小,在生长季呈现上升趋势,强降雨之后则先减后增。

Baseflow plays an essential role in the hydrological process,and the proportion of baseflow varies in different basins.Choosing a scientific and reasonable river baseflow segmentation method to obtain accurate baseflow is crucial for ensuring the ecological water balance in the watershed.Based on the daily runoff data from 1988-2015 at Pangu Station in the Pangu River Basin,a river baseflow segmentation study was carried out using seven methods in three categories,namely baseflow index method,time step method and digital filtering method,and combined with the basin recession constants.Utilizing Nash-Sutcliffe efficiency coefficient and using Mean Relative Error(MRE)to evaluate the accuracy of calculation results for different base flow segmentation methods.The results indicate that:all seven methods are able to achieve the segmentation of baseflow process,but there are certain differences in the segmentation results of various methods;the baseflow segmentation process line obtained by the digital filtering method F2 is the most stable,with the highest Nash-Sutcliffe efficiency coefficient(0.851)and the smallest average relative error(7.992%),which is a more suitable method for segmentation of baseflow in the Pangu River Basin;the baseflow index during the year generally shows a trend of decreasing and then increasing,decreasing continuously during the snowmelt period,showing an increasing trend during the growing season,and decreasing and then increasing after heavy rainfall.