秃尾河流域不同地形条件下土地利用动态变化

采用GIS空间分析工具,从秃尾河流域DEM数据中提取出高程、坡度和坡向3种地形因子,并与该流域1985年和2000年的土地利用类型图进行空间叠加分析,得到不同地形因子条件下的土地利用类型的分布特征,进而探讨土地利用类型动态变化对地形因子的响应。结果表明:草地、耕地和林地是该流域主要土地利用类型,1985-2000年间大部分减少的林地和草地向耕地转化;地形因子对土地利用类型的分布有显著影响,草地和耕地主要分布在1 000～1 200m高程级别、缓坡和阳坡区域内,且随着坡度和海拔的增加,两者分布呈减少态势;林地在不同的海拔、坡度和坡向级别皆有分布,但在1 000～1 200m高程级别、斜坡和阴坡区域分布比例最大;水体、未利用地和居民点及建设用地主要集中在高程为1 000～1 200m和缓坡区域,受坡向影响相对较小;16a间(1985-2000年)秃尾河流域耕地和居民点及建设用地面积在不同高程、坡度和坡向级别内都有所增加,而林地和草地面积在大部分地形因子级别内则显著减少。

Dynamic Changes of Land Use Types Based on Various Topographic Factors in Tuweihe Basin

Based on geographic information system(GIS) spatial analysis technology,the overlay analysis of the topographic factors(elevation,slope and aspect) were derived from digital elevation model(DEM),which were then applied to carry out spatial overlay analysis with the graphs of land use types in 1985 and 2000 to obtain the distribution characteristics of the land use types under different conditions of topographic factors,and to further examine the responses of the dynamic variations of the land use types to topographic factors in Tuweihe Basin.The results showed that the farmland,grassland and the forestland were the main land use types.During the period from 1985 to 2000,there was obvious transformation from grassland and forestland to farmland.The topographic factors significantly influenced the land use types.The areas of farmland and grassland took up the highest proportions at the elevation level of 1 000~1 200 m,the slope gradient of 3~8° and the sunny aspect regions,but the distribution of those two land use types decreased with the increases of elevation and slope gradient.Forestland was distributed at various elevation levels,slope gradients and aspects,but at the elevation level of 1 000~1 200 m,the slope gradient of 8~15°and the shaded slope occupied for the main regions.Elevation and slope had the significant effects on water area,non-used land and the residential land while the aspect imposes little influence.The farmland and the residential land increased in different levels of elevation,slope and aspect over these 16 years,whereas the areas of forestland and grassland gradually decreased.