GIS支持下不同坡度的土壤侵蚀特征分析

Analysis of Features of Soil Erosion Under Different Slope Based on GIS

利用地理信息系统技术对不同坡度等级情况下的土壤侵蚀特征进行了分析。首先,利用地理信息系统软件从DEM数据中产生坡度数据,将其分级为6个等级。然后与土壤侵蚀数据集进行叠加统计分析,从而得到不同坡度等级情况下的土壤侵蚀特征。本文研究表明:(1)坡度等级从2～5级,轻度以上水蚀所占百分比逐渐降低。(2)在所有坡度等级上,轻度以上风蚀所占百分比均在86.8%以上。在第2坡度等级上,风蚀综合指数最高,而在第5坡度等级上,风蚀综合指数最低。(3)冻融侵蚀综合指数的最高值出现在第3坡度等级上,其最低值出现在第6坡度等级上。(4)在各个坡度等级上,均以水蚀为主,均在46%以上,其最高值为73.8%,出现在第4坡度级上。此外,在第1坡度级上,风蚀占次优势,而在第2～6坡度等级上,冻融占次优势。(5)坡度等级在1,2和3级上,其轻度侵蚀所占百分比和土壤侵蚀综合指数均相对较高,而在坡度等级4,5和6级上,轻度侵蚀所占百分比和土壤侵蚀综合指数均相对较低。这主要是由于在坡度等级较低的情况下,人为活动比较多,土地利用程度较高,对植被和土壤的破坏较大,从而导致这种反常现象。

The features of the soil erosion under the different slope grade were analyzed here by using Geographic Information System. The slope is gotten from DEM created from the elevation contour, and classified into six grades. The soil erosion dataset gotten by visual interpreting LANDSAT TM imagery were overlain with the slope grade. It is show that (1) the percentage of the water soil above slight is gradually decreasing from slope grade two to five. (2) the percentage of the wind soil erosion above slight is more than 86.8 percent in every slope grade. In the slope grade two, the wind soil erosion index is the highest. In the slope grade five, the wind soil erosion index is the lowest. (3) The highest of the frozen soil erosion index appears in the slope grade three. The lowest appear in the slope grade six. (4) The water soil erosion dominates every slope grade, and the wind soil erosion sub-dominates in the slope grade one. The frozen soil erosion subdominates in the slope grade two to six. (5) In the slope grade one, two and three, the percentage of the soil erosion above slight and soil erosion index are higher, but in the slope grade four, five and six, they are lower. The main reason is that people use land in lower slope more intensively than that in higher slope, they damage vegetation and soil in lower slope more strongly than that in higher slope.