Problems and recommendations for non-point source pollution identification in China

Non-Point Source(NPS)pollution is a new field of study in China.Four estimation methods for NPS load that have been used in China are summarized.These are total measured load in a section minus reported point source loads,unit load method,hydrograph separation method and SWAT model estimation.The conditions for the use of these methods in China and North America were analyzed,and the differences in application of these methods between two areas were contrasted.The authors also discussed the probable errors resulting from using these methods to estimate NPS load in China,and believe that the first three methods would overestimate NPS load in Chinese situations to a large degree.The application of the SWAT model in China has not been characterized as a distribution physical model,for which calibration data for individual land types for runoff are not available in China and which is also likely to lead to substantial errors as the American situation is very different than in much of China.Finally,some recommendations for NPS load study and NPS pollution control are proposed.