Identifying non-point source priority management areas in watersheds with multiple functional zones.

The concept of water functional zones promotes the comprehensive supervision and scientificoversight of non-point source (NPS) pollution at the watershed scale. Therefore,understanding the spatial distributions and temporal trends in watershed priority managementareas (PMAs) is important in the study and efficient management of NPS pollution.However, no comprehensive studies of PMAs have been conducted to protect waterquality effectively in watersheds with multiple water functional zones. In this study, a newframework is presented that quantifies the perturbations of multiple spatial assessmentunits to the quality of nearby water bodies in various water functional zones. This innovativeapproach, which combines the Soil and Water Assessment Tool (SWAT) and statisticalanalysis, was applied to characterize multiple-level PMAs with a case study of theDaning River watershed in China. Based on the results, the advantage of this new frameworkis better suited to downstream areas, particularly in dry periods and severely pollutedwatersheds. This paper reinforces the view that the concept of zoning should be takenseriously in the framework of PMAs targeting. From the aspect of watershed management,these new PMAs can offer an optimal strategy for locating comprehensive and costeffectivemanagement practices at the watershed scale, particularly in large watershedsor long river systems.