基于RS和GIS的沙漠-黄土过渡带土地沙漠化分布与变化研究--以陕北榆林地区为例

选择毛乌素沙漠和黄土高原过渡带——陕北榆林地区作为研究区域，在地理信息系统支持下，对两个不同时期的遥感影像进行了解译，总结了该区10余年来沙漠化土地景观特征，分析了土地沙漠化空间格局的动态变化规律。结果表明，研究区内沙漠化土地形势仍十分严峻，沙漠化土地面积占土地总面积的67．7％，其空间分布具有明显的不平衡性，表现为西北部和中部区域沙漠化程度较为严重，土地沙漠化空间分布的不平衡性与该区自然因素和土地利用方式的空间差异有关。经过几十年的积极治理与改造，该区土地沙漠化过程逐渐趋于稳定。通过探讨土地沙漠化的成因，认为自然环境与人类行为的相互作用及在时间尺度上的矛盾造成了该区持续的土地沙漠化过程。

A Dynamic Study of Land Desertification in Desert-Loess Transitional Zones Based on RS and GIS:A Case Study of Yulin Area

In this paper the land desertification of desert loess transitional zones in Yulin area is studied from TM images in a geographical system (GIS). It is found that the desertification in Yulin remains rather severe. The desertified land accounts for 67.7 percent of the total land area. The distribution of desertified land shows obvious spatial imbalance, with severe desertification in northwestern regions and weak desertification in southeastern regions. This imbalance is attributed to the differences in physical factors and land-use patterns. The process of desertification in Yulin area tended to become stable between 1987 and 1999 as a result of positive efforts. In the end the cause of desertification is discussed. It is believed that the interaction and contradiction between the natural process and the human activity may lead to the development of desertification.