界定西藏冻融侵蚀区分布的一种新方法

冻融侵蚀区的界定是目前青藏高原冻融侵蚀研究需要解决的重要课题之一。根据笔者和前人相关成果，该文提出了青藏高原冻融侵蚀区界定的理论依据，并在GIS技术支持下，对青藏高原的主体——西藏自治区的冻融侵蚀进行界定，系统分析西藏冻融侵蚀区的分布规律。西藏自治区冻融侵蚀区分布具有以下特点：1)冻融侵蚀区分布面积广，占西藏自治区国土面积的55．3％；2)雅江南北冻融侵蚀区分布差异明显，雅江以北分布范围广，雅江以南范围小；3)地区分布差异明显，冻融侵蚀区集中分布在那曲和阿里地区；4)冻融侵蚀是那曲、阿里、拉萨、昌都、日喀则等地区(市)最主要的土壤侵蚀类型。

A New Way for Definiting the Freezing-Thaw Erosion Area in Tibet

How to fix on the confine of freezing-thaw erosion zone in Qinghai-Tibet Plateau is one of the questions need to be resolved chiefly.Based on the author's and former researchers'work,the theory foundation of freezing-thaw erosion zoning in Qinghai-Tibet Plateau was proposed.Then the area of freezing-thaw erosion in Tibet was defined by using GIS software.By analyzing the distribution of freezing-thaw erosion area,this paper pointed out any characters of freezing-thaw erosion area in Tibet as follows:1) The area of freezing-thaw erosion is very large,accounts 55 3 percent of area of Tibet.2) The difference between north and south Brahmaputra River is obvious.The freezing-thaw area is large and distributing continuously in north Brahmaputra River,but small and distributing like island in south Brahmaputra River.3) The difference among regions is also obvious.The freezing-thaw erosion area is most concentrated in Nakchu and Ngari.4) Freezing-thaw erosion is the main erosion type in Nakchu,Ngari,Lhasa,Chamdo and Shigatse,but is not in Lhoka and Nyingtri.