Current status and problems of non-point source pollution load calculation in China

Calculation of the load of non-point source pollution (NPS) is of considerable significance in the control of total water pollution. In order to analyze the current status and problems of NPS load calculation in China, the authors provide an overview of previous relevant studies, and summarize the methods by which the NPS loads have been calculated that are commonly used in China. These include export coefficient models, empirically based models, and physically based models. The authors also discuss the problem of NPS load calculation in four respects: The definition of NPS, the difference between the amount of NPS generated and the amount discharged, NPS load calculation in plains regions, and the differences in NPS characteristics between North America and China, regard the key factors underlying NPS research is the load calculation models and methods adapted to the characteristic of study area. Finally, some recommendations for these problems are proposed, including strengthening the cooperation in the research fields of empirical studies, theory studies and model developments, and developing models and methods adapted to the environmental characteristics of China.