20世纪90年代无定河流域土地利用的时空变化

GIS-based study on spatial-temporal changes of land use in Wuding River Basin in the 1990s

本文基于ArcGIS平台,以LandsatTM影像解译得到的三期土地利用数据为基础,结合统计分析工作,对无定河流域20世纪90年代土地利用数量、类型及其变化进行了分析。分析得出,前后2个5年间,无定河流域耕地、林地和未利用土地都是先减少而后稍有增加,草地则是先增加后稍有减少。在10年尺度上土地利用总的动态特征是,耕地与未利用土地面积减少,林地、草地面积增加。前5年无定河流域综合土地利用动态度为0.85%,未利用土地和草地的年变化率较大,耕地与水域年变化率较低。后5年无定河流域综合土地利用动态度为0.3%,林地与未利用土地年变化率较大,耕地与水域变化率较小。最后引入单一土地利用类型相对变化率反映出无定河流域土地利用变化存在明显的区域差异。

Regional land use change is an important part of global change. The Wuding River Basin, located in the middle reach of the Yellow River, is characteristic with high sediment load in less water. Since the 1950s, various conservation measures have been adopted throughout the basin, including vegetation （trees, bushes and grasses） plantting, sand shifting control, terracing, reservoirs and dams construction, and so on. These measures have changed the underlying surface greatly. Based on Landsat TM images data in the 1990s, we analyze the spanal-temporal changes of land use of Wuding River Basin using GIS and statistic methods. The results show that the land use changed greatly in the Wuding River Basin in the 1990s. In the first five years, cultivated land, forestland and un-used land decreased obviously while grassland increased. In the second five years, the situation was reversed, grassland increased and cultivated land, forestland and un-used land decreased. During the ten years, cultivated land and un-used land reduced, at the same time, forestland and grassland increased. The rate of land use change in the first five years is higher than that of the second five years. The major change types were cultivated land turned to forestland and grassland, and un-used land converted into cultivated land and grassland. In the first five years, the rate of the land use change in the study was up to 0. 85%. The changing rates of un-used land and grassland were higher, being 3.2% and 1.94% respectively. While, in the second five years, the rate of the regional land use change was 0.3%. The changing rates of forestland and un-used land were 2.75% and 1.71% respectively. Finally, we also come to the conclusion that there are obvious spatial differences in land use changes. For forestland change, the Nalin, Lu and Dali sub-basins were greater. Glassland and un-used land changes mainly occurred in Yuxi and Hailiutu sub-basins. Conservation measures and socio-economic development were the direct causes for land use change in the Wuding River Basin.