Abstract:

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