中文摘要：

以阿什河流域为研究区，在不同亚流域划分水平的情景下，应用SWAT模型模拟流域内径流、泥沙和营养物，分析了亚流域划分数量对其模拟结果的影响。结果表明，阿什河流域存在一个亚流域划分水平，当超过此划分水平时，亚流域数量的变化对产流量和产沙量几乎没有影响；径流与总氮对亚流域划分数量的敏感性相对较低，而泥沙与总磷的敏感性相对较高；在最粗略和最精细的亚流域划分之间，径流、泥沙、TN与TP的相对误差分别为24．75％、138．93％、31．34％和175％。综合年均径流、泥沙负荷和营养物对亚流域划分响应的敏感性，阿什河流域合理的亚流域划分水平为36个左右。研究结果为阿什河流域及相似地形地貌流域的水文模拟和非点源污染模拟提供了理论参考，具有一定的现实意义。

英文摘要：

In condition of different subwatershed delineation levels, Ashihe basin was selected as the study area to simulate runoff, sediment and nutrients by SWAT model. The influence of amount of subwatershed delineation on the simulation results was analyzed. The results showed that there was a delineation level existed in Ashihe basin, and the delineation would not affect the runoff, sediment and nutrients if the amount of delineation exceed this level. The sensitivity of runoff and TN to the amount of delineation was relatively low, but that of sediment and TP was relatively high. Between the roughest and the most detailed classification, the relative errors of runoff, sediment, TN and TP reached 24.75%, 138.93%, 31.34% and 175%, respectively. Considering the sensitivity of runoff, sediment and nutri- ents to subwatershed delineation, the reasonable subwatershed delineation level was set at 36. The findings have a certain significance for hydrological simulations and non-point source pollution simulations in other similar complex watersheds.