三峡水库建设期秭归县土地利用变化与地形因素的关系

分析水库建设期秭归县地形因素对土地利用变化的影响，对后三峡管理运行期土地资源保护与自然社会协调发展具有重要意义。使用1992、2007年两期1∶50 000土地利用分类结果和10 m DEM数据等，基于GIS栅格运算，研究秭归县15 a来土地利用变化与地形因素的关系。结果表明：旱地、园地是变化面积最大的地类，而园地、人工表面是面积增长率最高的地类。旱地、园地变化在地形的分异呈现互补性，主要发生在海拔＜800 m、坡度＜25°、非阳坡地区；灌木林在海拔＞1 100 m、坡度范围15~45°及阳坡、半阳坡面积增加较多，乔木林向灌木林转换主要发生在海拔>1 100 m、坡度25~35°、阳坡及半阳坡地区；乔木林减少面积最多在35~45°、阳坡地区；草地减少主要发生在低海拔、15~35°、阴坡地区。建设时期下的各种政策是这些变化发生的主因。在未来人口增长、经济发展条件下，缓解人地关系压力必须合理规划土地资源，保障土地利用集约化

RELATIONSHIP BETWEEN LAND USE CHANGES AND TOPOGRAPHIC FACTORS IN ZIGUI UNDER THE PERIOD OF THE THREE GORGES PROJECT

To protect land resources and promote harmonious development of nature and society in the Three Gorges Reservoir Area during latter period of the Three Gorges(TG)Dam management,it was important to analyze the effects of topographic factors on land use changes.With high-resolution(10 m)DEM and 1∶50 000 land use classifying results in 1992 and 2007,the paper studied the relationships between land use changes and topographic factors including altitude,slope and aspect in detail by GIS grid calculation techniques during 1992~2007.Results showed that dry land and garden had the biggest changing areas,garden and man-made area had the highest growth rate against their original areas in 1992 respectively.There was a complementary relationship between variations of dry land and garden on their distributions of different topographic factors.Dry land were major land use types converted to garden,and these happened areas mostly located in altitude zones below 800 m,slope zones below 25° and aspect zones of 0~157.5° and 247.5~337.5°.Increasing areas of shrub mostly located in altitude zones greater than 1 100 m,slope zones from 15° to 45° and aspect zones of 112.5~292.5°.Areas of forest converted to shrub mostly happened in altitude zones above 1 100 m,slope zones of 25~35° and aspect zones of 112.5~292.5°.Decreases of forest mostly happened in slope zones of 35~45°,aspect zones of 157.5~247.5°.Decreases of grass mostly located in zones with lower altitude,slope zones of 15~35° and aspect zones of 22.5~67.5° and 337.5~360°.Major causes of these land use changes were various kinds of policies.In order to deal with possible imbalance of relation between human and environment,we should strengthen the ability of land use planning and make intensive management of land resources in future.