Dynamics of Hillslope Soil Erosion in the Sanjiang Plain in the Past 50 Years
近50年来三江平原土壤侵蚀动态分析

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.