近30a来长江源区沙漠化时空演变过程及成因分析  

Land desertification monitoring in the Source Region of Yangtze River from 1975 to 2005 and the analysis of its causes

作　　者：胡光印[1] 董治宝[1] 逯军峰[1] 颜长珍[1] 魏振海[1] 

机构地区：[1]中国科学院寒区旱区环境与工程研究所沙漠与沙漠化重点实验室,甘肃兰州730000

出　　处：《干旱区地理》2011年第2期300-308,共9页Arid Land Geography

基　　金：国家自然基金重点项目(40638038)

摘　　要：通过遥感与地理信息系统技术对1975-2005年长江源区沙漠化发展状况进行了监测,监测结果显示:长江源区有大面积的沙漠化土地分布,在这30 a间,沙漠化土地面积明显增加,尤其是极重度沙漠化土地的增加最为明显。长江源区不同程度的沙漠化土地总面积从1975年的31 118.3 km2增加到2005年的33 923.25 km2,增加了2 804.9 km2,即从占整个源区面积的21.87%增加到23.83%。其中,极重度沙漠化土地面积增加3 067.49 km2,重度沙漠化土地面积减少912.82 km2,中度沙漠化土地面积增加800.95 km2,轻度沙漠化土地面积减少397.4 km2,潜在沙漠化土地面积增加246.68 km2。长江源区是我国最大的无人区之一,人类活动较少,因此,人类活动对该地区的沙漠化发展影响较小,自然因素是导致长江源区沙漠化发展的主要原因,其中自然因素中的气温迅速上升是导致该地区沙漠化发展的主导因素。To obtain the spatial-temporal information of land desertification in the source region of the Yangtze River,Landsat MSS images in 1975 and Landsat TM images in 2005 were used to monitor the desertification land with the assistance of RS and GIS techniques.To accurately classify the desertification land,we investigated the study area at the beginning of this research by taking a series of photographs of each type of desertification land and recording its geographic coordinates using a global positioning system(GPS) receiver,and then finding the corresponding desertification land in the remote-sensing images at those geographic coordinates to build an interpretation symbol database for use in subsequent image interpretation.In addition,we digitized the topographic maps at a scale of 1:100 000 to provide vector data,then transformed the vegetation and soil maps to the same projection mode and coordinate system so that they could be overlaid on the other images to provide assistance with image interpretation.Visual interpretation was based on image characteristics such as the color,shape,size,shading,texture,structure,and relative spatial distribution of each class of desertification land.In addition,the abovementioned ancillary materials were used to improve the accuracy of the classification.This comprehensive analysis and logical reasoning skills are both necessary during the process of visual interpretation,so the interpreters must possess abundant geoscience knowledge.According to the result of visual interpretation,there is large area of desertification land distributes in the source region of the Yangtze River.During the thirty years,the desertification land increased quickly,especially the increase of very severe grade of desertification land.The desertification land increased by 2 804.9 km2 from 3 1118.3 km2 in 1975 to 33 923.25 km2 in 2005,its percentage increased from 21.87% to 23.83%.The increase areas of very severe desertification land,severe desertification land,moderate desertification land,light des

关 键 词：长江源 沙漠化 遥感监测 青藏高原 

分 类 号：X171[环境科学与工程—环境科学]