大伙房水库控制流域土壤侵蚀评价及其影响因素分析

Evaluation of Soil Erosion Based on GIS in the Drainage Basin of Dahuofang Reservoir and Its Influencing Factors

以大伙房水库控制流域为研究区域,采用修正的通用土壤流失方程（RUSLE）为评价模型,以地理信息系统软件Arcview3.3为分析平台,通过数字高程模型、土地利用类型和土壤类型等空间数据与属性数据,获取基于栅格数据的小流域土壤侵蚀量和侵蚀强度,对大伙房水库控制流域的土壤流失量进行了定量化分析;采用土壤侵蚀综合指数评价了研究区土地利用、坡度及土壤类型对区域土壤流失的影响程度。结果表明：大伙房水库控制流域大部分地区土壤侵蚀模数小于50t·km^-2·a^-1,总体上水土保持良好;不同用地类型上,旱地的土壤侵蚀最为严重,水田次之;不同坡度等级中,0°-3°的土壤侵蚀强度最强,25°以上的土壤侵蚀强度最弱;各种土壤类型中,水稻土的侵蚀强度最重,暗棕壤最轻。

Recently, increasing nutrient concentrations have been observed in many surface waters in China and soil erosion is the main contributor to water pollution. The socio-economic and physical factors which cause soil erosion therefore need to be addressed. Based on the platform of Arcview 3.3, soil erosion in the drainage basin of Dahuofang Reservoir was evaluated using Revised Universal Soil Loss Equation （RUSLE）. The factors related to soil erosion are input to Arcview in raster, which include DEM, landuse types and soil types. Then cells based on soil loss and erosion intensity were calculated based on map algebra. The results indicate that：a）soil loss in most areas was less than 50 t·km^-2 ·a^-1 in 2000, meaning that there was proper soil and water conservation in the studied areas; b）the order of the descending degrees of soil erosion in different landuse types was dryland, wetland, and middle coverage grassland. In general, erosion on dryland was more serious than on any others; among various soil types, erosion on paddy soil was the worst while Dark-Brown soil was the slightest; in the case of different slope gradients, soil erosion at the grade of 0～3 degrees was the worst while soil erosion at the grade of more than 25 degrees was the slightest; and c）the worst soil erosion areas were the agricultural fields. The socio-economic factors were the key factors which influenced the problems of runoff and erosion.