Evaluation of AnnAGNPS and its applications in a semi-arid and semi-humid watershed in Northwest China

The main goal of this study was to evaluate the performance of AnnAGNPS (Annualised Agricultural Non-Point Source Pollution Model) in simulating runoff, sediment loading and nutrient loading in a semi-arid and semi-humid watershed of an area of 1481sq km, located in Northwest China. This model was first calibrated and tested by historic monitoring data and then the validated model was used to simulate the effects of non-point source (NPS) pollution management measures. The results indicate that reforestation measures, which reduce the amount of runoff, sediment, total nitrogen and total phosphorus, should be adopted in the study watershed to control NPS pollution. The model was also used to assess the effects of other measures on NPS pollution. This study concludes that AnnAGNPS has the potential to be a valuable tool for the planning and management of watersheds in the semi-arid regions of China.