中文摘要：

运用地理信息系统（GIS）结合美国通用水土流失方程（USLE），根据研究区现状合理选择USLE方程中土壤侵蚀各因子的计算方法，求算出三江平原1954年、1976年、1986年以及2000年的坡面土壤侵蚀量分布图，据此了解了该区域2000年土壤侵蚀现状，近50年来的土壤侵蚀动态、各县市侵蚀状况以及讨论了不同流域的土壤侵蚀状况，得出以下结论：三江平原现主要以轻度侵蚀尤其以轻I型侵蚀为主；该区近50年来侵蚀面积一直处于增加趋势并且侵蚀强度逐年加重，表现为低侵蚀强度面积比例的减少和高侵蚀强度面积比例的增加，侵蚀强度等级越高，增加越明显；穆棱、鸡西、鸡东、依兰、桦南、佳木斯、双鸭山等县（市）从上世纪50年代开始一直都是侵蚀比较严重的地区，七台河县（市）由20世纪50年代侵蚀不严重的县（市）逐渐变为目前三江平原侵蚀最严重的地区之一；就各流域来说，穆陵河流域一直是侵蚀面积最大的地区，而以挠力河流域侵蚀面积增加最大；通过分析以期为该区域的侵蚀防治、开展水土保持等政府宏观决策行为提供科学依据。

英文摘要：

The Sanjiang plain is one of the most important areas for commercial grain production in China. During the past 50 years, it has experienced soil loss due to improper land use. For this study, land use maps for 1954, 1976, 1986 and 2000 were created based on Landsat/MSS data from 1976, Landsat/TM data from 1986 and 2000 and a 1954 topographic map, along with expert knowledge. DEM data, soil maps and rainfall data were also obtained. Using GIS and USLE, we selected appropriate methods to calculate each factor in the USLE and evaluated the hillslope soil erosion of the Sanjiang plain over the past 50 years. Results show that light erosion dominated the Sanjiang plain and acute soil erosion was almost nonexistent. The area affected by soil erosion has increased over the past 50 years, with eroded area in 2000 totaling 1.4 times the eroded area in 1954. The intensity of soil erosion has increased, especially high-intensity erosion, for which the ratio of soil erosion increased more than that of low- intensity erosion. Muling, Jixi, Jidong, Yilan, Huanan, Jiamusi and Shuangyashan counties have seen the most serious erosion in the Sanjiang plain over the past 50 years. Meanwhile, Qitaihe shifted from being a low-erosion county in 1954 to become the county with the most serious erosion in 2000. Muling watershed had the largest eroded area, and Naolihe watershed had the largest increase in eroded area, from 1 272.90 km2 in 1954 to 4 620.93 km2 in 2000. This analysis provides a scientific basis for erosion control in the Sanjiang plain and provides reasonable suggestions for management and decision-making in terms of agricultural and development policies.