An integrated source apportionment method by incorporating spatial location information and source-transfer-sink simulation

Source apportionment is key to water quality protection, but most researches ignore the specific location of non-point sources and the source-transfer-sink processes that led to inaccurate results of source apportionment. Thus, a new source apportionment method was developed by integrating the location information and the interaction of sources as well as the source-transfer-sink processes. The source layers were generated by the integrated disparate and spatially distributed datasets that included remote sensing data, low-cost information, and considered the interaction between sources. The transfer layers were generated by the application of a physics-based model with derived inputs from models. The sink layer was constructed based on a laconic matrix calculation. The new method was applied in the Hangbu River of Chaohu Lake basin, China. Based on the results, the new method showed advantages of a more precise location, such as the sub-watershed No. 4 was no longer the key source area of total nitrogen (TN) using traditional method. The planting industry was the largest source accounting for 37.33% of TN contribution and 37.40% of total phosphorus (TP) contribution. The concise structure of the new method can also reduce the operation time by 93%. The hotspot grids were identified, which only cover 27.52% and 21.97% of the total watershed but contribute to over half of the TN and TP loads. This new method can be applied to other large watersheds, and provide management advice that span farm-gird-watershed scales for landowners and producers. • New source-transfer-sink method was proposed for source apportionment. • Remote sensing and the source interaction were considered for precise source information. • The physical-based model and matrix calculation were integrated for multiple processes.