Universal Soil Loss Equation (USLE) model and GIS were used to evaluate soil erosion in Longdun Reservoir watershed of Nanjing. The results showed that Longdun Reservoir watershed was moderately eroded, and the average soil erosion modulus was 4 343.46 t/km2. More than 63% of the watershed area was at the level of micro or slight erosion. The watershed area with severe erosion was very small, but it contributed to more than 70% of soil erosion amount. Soil erosion in this watershed varied with land use types, and the annual average soil erosion modulus followed the order: upland field > grass > paddy field > forest land, and the soil erosion amount followed the order: upland field > paddy field > grass > forest land. The watershed was divided into 13 sub-watersheds by GIS. The sub-watersheds 4, 5 and 10 were the areas with large soil erosion modulus, and the more attentions need to be paid to the sub-watershed 10 because of its large soil erosion modulus and soil erosion amount. The sub-watersheds 1, 9 and 12 should also be taken care of due to their large soil erosion amounts. Soil erosion amount in all sub-watersheds mainly came from the areas with high erosion grades and severe erosion. Therefore, the more attentions should be paid to the areas with high erosion potentials when the control measures are taken to inhibit soil erosion in future.

以南京市高淳区龙墩水库流域为研究对象,运用地理信息系统(GIS)和通用土壤流失方程模型(USLE)预测氮磷的污染负荷.利用SWAT模型的子流域划分模块进行流域分区,运用等标污染负荷和等标污染强度进行面源污染评价,最后通过聚类分析完成氮磷污染负荷的分级,从而确定关键源区.结果表明,研究区总磷(TP)污染强度为4.95 t·km-2,污染负荷为124.25 t;总氮(TN)污染强度为10.96t·km-2,污染负荷为274.87 t.整个流域的等标污染负荷为2.76× 109 m3,其中TN为2.75× 108 m3,等标污染负荷比为9.96％;TP为2.48× 109 m3,等标污染负荷比为90.04％,TP为流域面源污染的主要污染物.不同土地利用方式的TP和TN污染负荷和流失模数均以旱地为最高,旱地是流域内面源污染物的主要来源.