[Non-point source pollution simulation under land use change scenarios in Hun-Taizi River watershed.]

Non-point source (NPS) pollution has become a major source of water pollution in recent years. The research of NPS pollution mechanism and control has an important scientific and practical meaning. To study the effect of land use change on NPS pollution load, near future land use of Hun-Taizi River watershed was simulated under three scenarios based on CLUE-S model, including urban planning, historical trend and ecological protection scenarios. NPS pollution was simulated based on SWAT model. The simulated results of SWAT were compared with measured data. The response of NPS pollution to land use change and landscape pattern was studied with the combination of the two models in three land use scenarios. The results showed that the NPS pollution simu-lation with SWAT had high accuracy, which showed the suitability of SWAT model in the study area. The NPS pollution load increased under urban planning and historical trend scenarios but decreased under ecological protection scenario. The difference in three scenarios indicated that land use and landscape pattern impacted NPS to a certain extent, which showed that scientific ecological construction could effectively reduce NPS pollution load. This study provided a new study case for NPS pollution research at watershed scale, a scientific basis for implementation of non-point source pollution control and best management practices, and a reference for related policy making.