土壤侵蚀对土地利用和降雨变化响应和空间分布特征——以金沙江一级支流小江流域为例

ASSESSMENT OF THE SOIL LOSS ASSOCIATED TO LAND USE AND PRECIPITATION CHANGE IN THE XIAOJIANG RIVER BASIN,SOUTHWEST CHINA

全球变化引起了一系列环境效应,土壤侵蚀是全球变化最为敏感环境效应之一。选择生态极其脆弱区小江流域作为研究对象,通过遥感影像和雨量站点获取3期土地利用和降雨变化信息,结合区域基础地理信息数据,利用通用土壤流失方程(USLE模型)对该区域土壤侵蚀对土地利用和降雨变化的响应进行了分析。研究表明:(1)降雨量在1981～1990年为降雨量较小年份,1991～2000年为降雨量较大时间段,2001～2005年降雨量开始急剧减少;(2)1987、1995和2005年的平均侵蚀量分别为:70.58、80.08和79.81t/(hm2.a),中度侵蚀以上面积分别占总面积的29.92%、33.83%和33.18%,其中极强度侵蚀分别占9.15%、12.81%和12.63%;(3)在分布特征上,强度侵蚀和极强度侵蚀主要分布在小江流域的中下游地段。极强度侵蚀主要分布在中海拔区域(1 600～2 800m),所占的比例呈持续下降的趋势,但在高海拔区域,极强度侵蚀呈增加趋势;同时,极强度侵蚀集中分布在高坡度段(>35°)上,占其面积的85%以上,且呈持续增加趋势,在中坡度段(15°～35°)上,极强度侵蚀呈现明显的减少趋势。USLE模型可以较好的反映出全球变化条件下土壤侵蚀效应,为合理开发土地资源和人类经济活动提供科学依据。

Global change lead to a series of environmental effects.Soil erosion is one of the most sensitive environmental effects to global change.This paper select Xiaojiang basin which one of the most fragile ecological environment as study object.Land use and precipitation changes of three periods was obtained using remote senses and rainfall stations,meanwhile the soil erosion response to land use and precipitation change were analyzed according to USLE model and basic geographical information data.The results show that the precipitation has there periods in which the precipitation is low from 1981 to 1990 is high from 1991 to 2000,and the precipitation decreased sharply from 2001.The average soil loss values is 70.58,80.08 and 79.81 t/（hm2·a） in 1987,1995 and 2005 respectively,and the percent of area of above moderate degree is 29.92%,33.83% and 33.18% in 1987,1995 and 2005 respectively.The extreme high degree of soil loss is 9.15%,12.81% and 12.63% in 1987,1995 and 2005 respectively and increased continued.At meanwhile,we analysis the distribution and change in different altitude and slop.The USLE model can be used to assess the soil loss response to global change.It also indicates that USLE associated to GIS model is a useful and efficient tool for evaluating and mapping soil erosion risk and providing scientific basis for land resource management and economic activities.