基于GIS的多因子土壤冻融侵蚀强度分级评价——以长江上游为例

Grading Evaluation of Multi Factor Soil Freeze-thaw Erosion Intensity Based on GIS——A case study of the upper reache of the Yangtze River

冻融侵蚀是仅次于风蚀、水蚀的第三大土壤侵蚀类型。以长江上游地区为例,采用气温年较差、最大冻结深度、活动层厚度、高程、年降水量、坡度、细粒土含量、植被盖度、坡向这9个冻融侵蚀的影响因子作为评价指标,采取标准化值赋权重加权求和的方法,实现了该区冻融侵蚀强度的相对分级,并且讨论了该区冻融侵蚀的空间分布特征,旨在为该地区的水土保持研究以及生态环境建设提供参考。分析结果表明:研究区内冻融侵蚀总面积约为55.8×10^(4)km^(2),主要为强烈侵蚀和极强烈侵蚀,分别占研究区冻融侵蚀总面积的30%和25%,主要分布在五道梁-沱沱河以东、康定-九龙-香格里拉以西地区。随着青藏高原气候变暖、多年冻土退化、冻融灾害的增加,未来冻融侵蚀可能呈现增加的趋势,这对区域生态环境修复及工程建设带来了新的问题。

Freeze-thaw erosion is the third largest type of soil erosion after wind erosion and water erosion.Taking the upper reaches of the Yangtze River as an example,we use annual temperature difference,maximum frozen depth,thickness of active layers,elevation,annual precipitation,slope,the content of fine grained soil,the vegetation coverage,slope to the nine freeze-thaw erosion factors as evaluation index,and weighted sum of standardized values method was adopted to realize the freeze-thaw erosion intensity relative to classification.The spatial distribution characteristics of freeze-thaw erosion in this area are also discussed in order to provide reference for soil and water conservation research and ecological environment construction in this area.The analysis results show that the total area of freeze-thaw erosion in the study area is about 55.8×10^(4)km^(2),which is mainly intense erosion and extremely intense erosion,accounting for 30%and 25%of the total area of freeze-thaw erosion in the study area,and mainly distributed in the areas of Wudaoliang-Tuotuo River east and Kangding-Jiulong-Shangri-La west.With the warming of the Qinghai-Tibet Plateau,the degradation of permafrost,and the increase of freeze-thaw disasters,freeze-thaw erosion may show an increasing trend in the future,which brings new problems to the regional ecological environment restoration and engineering construction.