采用线性关系和非线性关系对沙颖河流域的地下水退水曲线进行拟合对比，基于改进的SWAT（soil and water assessment tool）模型对沙颖河流域径流过程进行模拟，并采用Nash-Sutcliffe效率系数、百分比偏差及确定系数等3个指标对模拟效果进行评价，在此基础上，分析沙颖河流域径流过程的年内和年际变化特征。结果表明：沙颖河流域地下水退水曲线非线性关系拟合比线性拟合效果好，基于此建立的模型模拟结果较好；沙颖河流域地表径流、壤中流和基流分别占径流量的55.5%、25.4%和19.1%，冬季径流主要由基流补给，径流年内分配与降水变化基本一致，具有明显的季节变化和不均匀性；1961-2014年径流量呈上升趋势，地表径流和基流的波动与径流的变化基本一致，呈上升趋势；1961-2014年壤中流呈下降趋势。

The groundwater recession curve in the Shaying River basin is fitted and compared by linear and nonlinear relatio ships. Based on the improved SWAT(soil and w ater assessment tool) model, the runoff process of the Shaying River basin was simulated, and the simulation effect was evaluated by the Nash Sutcliffe efficiency coefficient, percentage deviation, and determination coefficient. On this basis, the annual and interannual variation characteristics of the runoff process w ere analyzed. The results show that: the non-linear fitting of the groundwater recession curve in the Shaying River basin was better than the linear fitting, and the simulation results of the model based on the non-linear process were good; the surface runoff, the interflow, and the baseflow accounted for 55.5%,25.4%, and 19.1% of the runoff, respectively, the runoff in winter was mainly supplied by the baseflow, the annual distribution of runoff was consistent with the change of precipitation,with obvious seasonal change and nonuniformity; the fluctuation of surface runoff and baseflow is consistent with the change of runoff, showing an upward trend, while the interflow shows a do wnward t rend from 1961 to 2014.

清华大学水沙科学水利水电工程国家重点实验室及宁夏银川水联网数字治水联合研究院联合开放研究基金资助课题（sklhse2020-Iow11）；国家自然科学基金（51509222；51279183）