怀沙河是北台上水库入库河流，作为北京市应急水源，其水文情势对首都供水保障有重要影响。运用NAM模型构建了怀沙河降雨—径流过程模型，对模型参数进行了率定，模拟结果和实测流量过程能够较好地吻合，模拟精度纳西效率系数为0.642。利用该模型对怀沙河流域局地暴雨洪水过程及洪水的淹没分布情况进行分析后认为，流域出口处的最大流量是30.8 m3/s，与西沟水文站观测的最大流量31.0 m3/s 比较接近。

Huaisha River is one of the input rivers to the Beitaishang Reservior. As an emergency water source in Beijing, the hydrological regime in this river watershed plays an important role in the safeguard of water supply. In this paper, NAM hydrological model was used to simulate the rainfall-runoff process in the Huaisha River Watershed with a set of calibrated parameters. The research results indicated that the simulated and observed flow process curves match very well, and the simulation precision NSE (Nash- Sutcliffe coefficient of efficiency) is 0.642. This model was used to analyze the local rainstorm-flood process and flood distribution in the Huaisha River Watershed, which indicated that the maximum discharge at the outlet of the watershed is 30.8 m3/s, similar to the observed maximum discharge of 31.0 m3/s at the Xigou hydrological station.