土地沙漠化是当今世界所面临的最大的环境-社会经济问题之一.由于其危害的严重性和分布的广泛性,使之成为全球共同关注的热点.黄河源区位于青藏高原的东北部,特殊的地理位置决定了其生态环境非常脆弱.近年来在自然因素和人为不合理经济活动的共同作用下,区内生态环境退化加剧,表现为土地沙漠化,草场退化和水土流失加剧等过程.在软硬件系统支持下应用GIS和遥感技术,结合前人研究成果和野外调查,通过基于知识的多重判据复合分类实现多源信息的集成,对黄河源区沙漠化现状进行了系统研究.研究结果表明,到2000年,黄河源区的沙漠化面积已达13434.8 km2,占整个研究区面积的14.65%.沙漠化主要发生在高平原地区和北部的共和盆地,且已草场沙漠化为主,耕地沙漠化面积极少.在野外调查的基础上,对源区沙漠化的特征做了简要的分析,指出共和盆地的沙漠化以地表粗化、沙丘活化和流沙入侵为主;而高平原地区的沙漠化主要是由于植被严重退化后形成裸地或"黑土滩型"退化草场.造成区内沙漠化强烈发展的原因是多方面的,包括地质构造背景,区域气候变化,人类不合理的经济活动和鼠害等,而超载过牧是其中最重要的原因.文章最后以共和盆地为例,分析了源区严重的超载过牧形势并提出了沙漠化防治的对策.%Land degradation is a great threat to the world in the future, and it is not merely an environmental issue, but has been a social and economic problem as well. The source region of the Yellow River is located in the northeast of the Qinghai-Xizang Plateau, and its eco-environment is very fragile due to its special geographic location. The eco-environment degrades very quickly by natural factor together with human being factor in these years, in which desertification ranks the first. However, previous studies on the desertification were mainly focused on the Gonghe Basin, and the systematic research was unavailable. This study showed, for the first time, the present status, classification and spatial distribution of land desertification in the whole region, based on the data obtained through field investigation and Landsat TM image (4, 3 and 2 bands) of September 2000. According to our research, the desertified land in the study area mainly concentrated in the Gonghe Basin and Upland Plain Area, and the total area of desertification land is 13434.8 km2, or 14.65% of the entire land in the aim region.
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