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

- The concept of water functional zones was incorporated into prioritization of PMAs.
- The prioritization of PMAs in different hydrological periods were compared.
- More cost-effective PMAs were provided, especially for downstream areas.
- This paper highlighted the water quality protection during the dry period.

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

In this study, a new framework for targeting priority management areas (PMAs) was designed for watersheds with multiple water functional zones. This new approach is based on hierarchical calculations that quantify the perturbation of multiple spatial assessment units to the water quality of nearby water bodies. Based on the results, this new tool offers an optimal strategy for locating comprehensive and cost-effective management practices at the watershed scale.197