Assessment and zoning of non-point source pollution by multi-criteria analysis: A case study in the watershed of Beizhai
基于多准则分析的非点源污染评价和分区——以北京怀柔区北宅小流域为例

Due to difficulty and high cost in controlling non-point source pollution, it was necessary to categorize the sources for planning and management. In this study, the process of "Risk assessment-Planning and zoning-differentiated management" was developed to assess the non-point source pollution. A new "risk assessment" tool based on multi-criteria analysis was developed. Three criteria were formulated to characterize land cover indicator (L), runoff indicator (R) and distance indicator (D), and the weight of pollution was also computed by improved method for order preference by similarity to ideal solution (TOPSIS). Combining with the results of risk assessment, the area was divided into five categories of management planning zones according to the principle of "appropriate protection, priority planning, focus and management". Afterwards, by adopting the technology of BMPs and ecological engineering, "differentiated management" was carried out on these five categories of management planning areas. The process of "Risk assessment-Planning and zoning-Differentiated management" can not only evaluate the various sources of pollution, but also quantitatively provide the scientific scheme for the management of non-point pollution sources. In addition, the method was applied to the watershed of Beizhai. The results show that this process can avoid subjective and limited application, and can provide a reference to non-point source pollution assessment and management for watershed.