青藏高原沙漠化土地空间分布及区划

Spatial Distribution of Aeolian Desertification on the Qinghai-Tibet Plateau

利用野外调查数据、遥感影像和已有研究成果,构建了一套适用于青藏高原沙漠化土地的分类分级指标体系及遥感解译标志。以此为基础,选取目视解译法监测青藏高原沙漠化土地的空间分布特征。结果表明:2015年青藏高原沙漠化土地面积392 913km^2,占高原土地总面积的15.1%,主要包括沙质沙漠化土地、砾质沙漠化土地和风蚀残丘3种类型。沙漠化土地以中度和轻度沙漠化土地为主,重度和极重度沙漠化土地面积仅占沙漠化土地总面积的12.2%。空间上,沙漠化土地集中分布在高原的北部和西部地区,其他地区零散分布。自东南向西北,沙漠化土地面积逐渐增大,沙漠化程度不断加重。以沙漠化土地空间分布数据(面积、类型、程度、空间特征和驱动因素)为基础,结合气候、地貌、第四纪沉积物和人类活动等数据,将青藏高原沙漠化区划分为雅鲁藏布江半干旱高山宽谷沙漠化区、藏北青南高寒高原面沙漠化区、柴达木干旱盆地沙漠化区、黄河上游半干旱河流盆地沙漠化区和"三江"流域湿润半湿润高山沙漠化区。

Using field investigations in the Qinghai-Tibet Plateau to develop a desertification attribute set,we established an interpretation index system for Landsat TM remote sensing images to identify the distribution and severity of aeolian desertified land（ADL）.Using this system,we obtained current data on the area of ADL and its spatial distribution through visual interpretation of the Landsat data.We found that 15.1% of the plateau（392 913 km^2）suffered from aeolian desertification;this was mostly sandy ADL,gravel ADL,and aeolian yardangs.Most ADL was slight to moderate,but severe and extremely severe desertification occupied 12.2% of the plateau（47 946 km^2）.ADL was scattered throughout the plateau,but concentrated mostly in the western and northern parts.From the southeast to the northwest,the distribution of ADL changed gradually from a sporadic distribution with small areas to a continuous distribution over large areas,and the severity of desertification tended to increase.Regional differences in climate,landforms,Quaternary deposit type,and human activities accounted for the spatial distribution.We divided the plateau into five sub-regions based on the ADL characteristics（area,type,severity,spatial distribution,and cause）：the Qaidam Basin arid desertification sub-region,high and cold northern Tibet and southern Qinghai desertification sub-region,semi-arid mountainous desertification sub-region of the Yarlung Zangbo River watershed,the semi-arid desertification sub-region of the upper reaches of the Huanghe River watershed,and the humid mountainous desertification sub-region of the Nujiang River,Lancang River,and Yangtze River watersheds.