Tracing the main sources and spatial distributions of pollutants and quantifying the effects of various factors on soil erosion and pollution loads are important to allow appropriate management systems to be developed for large complex watersheds and allow water pollution to be controlled efficiently and economically. A distributed water, sediment, and pollutant model was used to qualitatively and quantitatively assess temporal and spatial variations in water and sediment characteristics and nitrogen (N) and phosphorus (P) loss distributions in a basin from a macroscopic point of view and to trace the sources of pollutants, using the Jialing River Basin as an example. Changes in N and P losses in the basin caused by various management practices were assessed. The results indicated that the average annual water and sediment yield in the study area were 103–857 mm and 2.4–1274.1 t/ha, respectively. The loss of total N and P were 1.1–21.6 kg/ha and 0.01–11.2 kg/ha. The spatial distribution varied greatly, but the annual variation trend was relatively stable. The contribution of N from industrial point sources reached 1973 tons, which was dominant. And the total N distribution in the watershed was closely related to woodland. Total P pollution was most severe for cultivated land. The P load caused by fertilization reached 805 tons, which was significantly more than the point source discharge. Assessments of the effects of implementing various management practices in the watershed indicated that N losses would be decreased more effectively by filter belt in woodland than by other practices. The total N loss would be reduced by 4.4% for every 0.5 m filter belt added to woodland. The losses would be decreased more effectively by a cultivated land filter belt and controlling fertilizer application than by other practices. The 0.5 m filter belt of cultivated land can reduce total P by 5%, and reducing fertilization by 5% can reduce total P by 7.3%. Understanding the temporal and spatial distributions of pollutant sources in a river basin and tracing pollutant sources will allow appropriate management practices to be implemented in key areas to effectively control pollutants.

追踪污染物的主要来源和空间分布，量化各种因素对土壤侵蚀和污染负荷的影响，对于为大型复杂流域开发适当的管理系统以及有效和经济地控制水污染非常重要。使用分布式水、泥沙和污染物模型，从宏观角度定性和定​​量地评估流域内水沙特征的时空变化以及氮 (N) 和磷 (P) 损失分布，并追踪流域中污染物来源，以嘉陵河流域为例。评估了由各种管理实践引起的流域中 N 和 P 损失的变化。结果表明，研究区年平均产水量和产沙量分别为103-857 mm和2.4-1274.1 t/ha。总氮和磷的损失分别为 1.1-21.6 公斤/公顷和 0.01-11.2 公斤/公顷。空间分布变化较大，但年变化趋势相对稳定。工业点源氮贡献达1973吨，占主导地位。流域全氮分布与林地密切相关。耕地总磷污染最为严重。施肥引起的磷负荷达到805吨，明显高于点源排放。对流域内实施各种管理措施效果的评估表明，林地过滤带比其他措施能更有效地减少氮损失。林地每增加 0.5 m 滤带，总氮损失将减少 4.4%。与其他做法相比，通过耕地过滤带和控制施肥可以更有效地减少损失。耕地0.5m滤带可降低全磷5%，减少施肥5%可降低全磷7.3%。了解流域内污染物来源的时空分布，追踪污染物来源，将有助于在重点区域实施适当的管理措施，有效控制污染物。耕地5m滤带可降低全磷5%，减少施肥5%可降低全磷7.3%。了解流域内污染物来源的时空分布，追踪污染物来源，将有助于在重点区域实施适当的管理措施，有效控制污染物。耕地5m滤带可降低全磷5%，减少施肥5%可降低全磷7.3%。了解流域内污染物来源的时空分布，追踪污染物来源，将有助于在重点区域实施适当的管理措施，有效控制污染物。