基于RUSLE的2010年商南县土壤侵蚀特征分析

目的]以长江源头陕西省商南县为例,分析县域土壤侵蚀空间分布,为正确认识与防治长江上游水土流失和做好水土保持防治工作提供科学依据。方法]基于Landsat TM7和ETM+影像,获取商南县2010年土地利用信息,采用修正通用土壤流失方程(RUSLE)确定方程中各影响因子,对商南县土壤侵蚀现状进行定量评价。结果]林地是商南县主要土地利用类型,占县域总面积的87.05%,其次是耕地(9.43%)、居民地(2.82%)、水体(0.64%)、未利用地和草地(0.06%)。受坡耕地和低覆盖林草地的影响,商南县2010年土壤侵蚀较严重,平均侵蚀模数4 953.76t/(km2·a)。受侵蚀(轻度以上)面积1 319.3km2,占总面积的57.03%。强度和极强度侵蚀级别面积所占比例为24.10%,其次为轻度侵蚀级别,面积为14.31%,中度和剧烈侵蚀级别面积分别为6.23%,12.39%。剧烈和强度侵蚀主要分布在北部、中部及东南部的山区地段的坡耕地。虽然强度和剧烈侵蚀级别面积比例不是很高,但对该县总侵蚀量的贡献最大,达到52.29%。结论]不适宜的土地利用是引起严重土壤侵蚀的主要原因;应将县域北部、中部及东南部山区的坡耕地作为防治的重点。

Analysis of Soil Erosion in Shangnan County Based on RUSLE

Objective] In order to understand and prevent the soil erosion in the upper reaches of the Yangtze River correctly, and to provide scientific basis for preventing and controlling the soil and water conservation, Shangnan County of Shaanxi Province, which is in the source of the Yangtze River, was taken as an example for analyzing the spatial distribution of soil erosion.Method] Based on the Landsat TM7 and ETM⁺ images, the information of land use in Shangnan County in 2010 was obtained. Using the revised universal soil loss equation(RUSLE), the present situation of soil erosion in Shangnan County was quantitatively evaluated and studied.Results] The main land use type in Shangnan County is forest land, accounting for 87.05% of the total area of the county, followed by cultivated land(9.43%), the residents(2.82%), water(0.64%), unused land and grassland(0.06%). Soil erosion of Shangnan County in 2010 is serious because of the slope land and low covered forest grassland, and the average erosion modulus was 4953.76 t/(km²·a). The erosion area(worse than light erosion) reached 1319.3 km², accounting for 57.03%. The total area of intensity erosion and more intensity erosion accounted for 24.10%, followed by the light erosion area, which accounted for 14.31%. The area of middle erosion and most intensity erosion accounted for 6.23% and 12.39% respectively. The area of most intensity erosion and intensity erosion is mainly distributed in the slope land of the northern, central and southeastern mountain area. Although the area ratio of most intensity erosion and intensity erosion is not very high, they has the biggest contribution to the total erosion amount of the county, up to 52.29%.Conclusion] Inappropriate land use is the main cause of serious erosion. Therefore, the main object for the prevention in Shangnan County is the slope land of the northern, central and southeastern mountain area.