汉江流域土地利用变化及空间格局分析

土地利用变化是人类活动对自然环境施加影响的显著表现形式,已成为全球环境变化研究的重要内容。基于遥感和地理信息系统技术,利用三期Landsat TM图像的解译成果,分析了安康市1985～2000年土地利用变化的结构特征及其空间差异格局。研究表明,近15年来,安康市土地利用转移量主要发生在耕地、林地、草地和水域之间．建设用地和未利用土地的转移趋势不明显。三个时段内各土地利用类型的净变化量差异比较明显。1985～1995年．耕地变化以转入为主,其中由草地转入的比重最大,占耕地总转入量的96．02％。1995～2000年,耕地以大量转出为主,共有1503．21hm2的耕地转为其它用地,其中转向林地和草地的量占耕地总转移量的比例分别是15．46％和78．77％。在行政区尺度上各种用地类型的净变化量分布比较均衡,而在垂直带空间尺度上耕地、林地和草地的净变化随海拔高度的分异较为明显。大致以1600m为界,耕地随海拔高度升高而递减,林地、草地随海拔高度升高而递增．

STUDY ON THE LAND-USE CHANGE AND ITS SPATIAL DISTRIBUTION: A CASE STUDY IN ANKANG DISTRICT

Land-use change is a key component for global environment change, and indicates the influence of human activities on physical environment. Supported by the techniques of Remote Sensing and GIS, the struc tural features and spatial patterns of land-use change in Ankang district from 1985 to 2000 has been analyzed based on Landsat TM digital data. Some interesting and significant findings have been obtained. (1) During 1985-2000, the land-use change mainly occurred in farmland, forest land, grassland and water areas, the conversion amounts of the above-mentioned land-use types accounted for 94.95%, 38.55%, 48.07%and 3.89% of the total conversion amounts respectively. Farmland increased conspicuously, meanwhile, the decrease of forestland, grassland and water areas was obvious, the unused land was kept no change. The increment of built-up areas was 215.94 hm2, mainly transformed from farmland and forestland, accounting for 60.20% and 38.80% respec-tively; (2)The net change of each kind of land-use types is easily found in each county, while there exists a con-spicuous differentiation of the net change of farmland, forest land and grassland in altitudinal direction. Delimit-ed about at l 600 meters, areas of farmland decrease with the increase of elevation while those of forest land and grassland increase along the altitudinal direction; (3)The net change of each kind of land-use types differs from each other during the three periods in Ankang district. During the period of 1985-1995, farmland was mainly transformed from other land-use types, and the amounts transformed from grassland ranked the first, which accounted for the 96.02% of the total conversion amounts of farmland(835.67 hm2). Because of the implementation of "natural forest protect" project and "returning farmland to forestland or grassland", farmland was mainly transformed into other land-use types during 1995-2000. In this period, farmland about l 503.21 hm2 were transformed into others, and the amounts of farmland to forestland and farmland to grassland accounted for 15.64% and 78.77% of the total conversion amounts of farmland respectively.