An entropy weighting–based index model for rapid assessment of agricultural non-point source pollution potential in Jiangsu’s plain river network

The assessment of agricultural non-point source (AGNPS) in plain river network areas has always been a challenge due to its complex water regulation and storage mechanisms. It is urgent to construct a simple and accurate method for assessing AGNPS pollution in plain river network areas. In this study, an entropy weight method–based index model (EWM-APPI) was constructed to assess AGNPS pollution potential in the plain river network areas in Jiangsu Province. The results showed that the AGNPS potential in Jiangsu Province showed significant spatial differences, increasing from southeast to northwest. In the northern part of Jiangsu Province, 53.79% of the area was high AGNPS potential (IV&V) which was mainly influenced by Cultivating Loading Index. The Bivariate Global Moran’s I showed significant spatial positive correlations (P < 0.05, |Z|> 2.58) between the calculated pollution potential values and the measured total nitrogen (TN), total phosphorus (TP), and ammonia nitrogen (NH₃-N) concentrations during abundant and flat water periods. This demonstrated that the EWM-APPI model accurately reflected the spatial and temporal heterogeneity of the AGNPS pollution potential in Jiangsu Province. In addition, the model uses administrative boundaries in combination with high-precision raster data to overcome the inability to delineate watershed boundaries in plain river network areas and can accurately identify AGNPS priority control areas. The results of this study provide new insights into the prevention and control of AGNPS in plain river network areas.