基于地形梯度的三峡库区万州区土地利用时空变化分析

Analysis on Spatiotemporal Variations of Land Use Change in Wanzhou District of Three Gorges Reservoir Based on the Terrain Gradient

采用2000年、2007年和2014年TM影像数据以及万州区DEM数据,运用GIS和RS技术、土地利用图谱变化模式、地形位指数以及地形分布指数等方法对万州区土地利用变化进行了研究。研究结果表明:在2000—2014年万州区林地和耕地面积占研究区总面积的92%以上,万州区土地利用类型以耕地和林地为主;耕地、林地、草地和未利用地面积减幅分别为1.08%,0.33%,0.04%,0.01%,呈现减少的趋势;水域和建设用地面积增幅分别为0.64%,0.81%,呈现增加的趋势;耕地、水域和建设用地在较低地形梯度区域的分布指数均大于1,主要分布于较低的地形梯度区域,草地在中高地形梯度区域的分布指数大于1,主要分布于中高地形梯度区域,林地在高地形梯度区域的分布指数大于1,主要分布于高地形梯度区域;万州区土地利用变化模式以稳定型为主,转移面积332 670.71 hm^2;前期变化型次之,转移面积2 629.44 hm^2;然后为后期变化型,转移面积2 600.57 hm^2;稳定型在不同地形梯度区域内分布均匀,前期变化型和后期变化型主要分布于低地形梯度区域内。该研究为土地资源的可持续开发利用以及科学、合理地布局土地利用规划提供参考依据。

We applied the combined methods including GIS and RS technology, land use map changing pattern, terrain position index and topographic distribution index, and used TM image data and DEM data of Wanzhou District from 2000, 2007 and 2014 to gain the knowledge about the land use changes in Wanzhou District. The results showed that woodland and cultivated land were the main land use types which cover 92% of the total area. The reduction rates of cultivated land, woodland, grassland and unused land were 1.08%, 0.33%, 0.04% and 0.01%, respectively, showing the decreasing trend. The growth rates of water area and construction area were 0.64% and 0.81%, respectively, showing the growing trend. The distribution index of cultivated land, water area and construction area in the lower terrain gradient area were greater than 1, indicating that they mainly distributed in the lower terrain gradient area. Meanwhile, the distribution index of grassland in the middle-high terrain gradient area was greater than 1, showing that grassland mainly distributed in the middle-high terrain gradient area. Nevertheless, the distribution index of woodland in the high terrain gradient area was also greater than 1, leading to the fact that woodland mainly lay in high terrain gradient area. Last but not least, the land use change pattern of Wanzhou District had 3 types including the stable type, the early change type and the late change type, the stable type was the main type that covered the area of 332 670.71 hm^2, the early change type covered 2 629.44 hm^2 and the late change type covered 2 600.57 hm^2. The stable type had a uniformly distribution among different terrain gradient areas while the early type and the late type both favored in the lower terrain gradient area. This study can provide references for the sustainable development and utilization of land resources and rational layout of land use planning in the future.