张掖市甘州区1959～2009年间城市扩展分析

Analysis on the Urban Expansion in Ganzhou District from 1959 to 2009

利用锁眼、MSS、TM影像和地形图及其他辅助数据,提取张掖市1959、1968、1977、1986、1997、2009共6个年份的城市建成区范围和面积,利用空间重心转移模型、扩展强度指数、扩展速度指数、紧凑度指数、面积变化、城市用地扩展系数等指标,分析了近50a来城市土地利用扩张的空间变化特征。结果表明,50a间张掖市城市建成区扩展5.71倍,其中1986年之前属于缓慢扩展阶段,1986年之后属于快速扩展阶段。在1959～1986的27a间,建成区面积仅扩展258.42hm2。1986～2009年期间,随着改革开放和西部大开发战略的实施,建成区面积增加了1 995.11hm2,是前27a的7.73倍。1959～1977年期间,城市重心偏移量小,1977～1986年期间,虽然城市扩展面积较小,但城市主要向西和西北方向扩展,重心开始向西北偏移,偏移量较大;1977～2009年期间,由于城市向东和东北方向扩展,城市重心开始向东和东北方向偏移,偏移量都很大,最大达到629.79m。城市紧凑度在1959～1968年间急剧下降;在1968～1997年间逐渐趋于稳定后又略有下降,1997～2009年开始慢慢上升,该市后期土地的集约化以及城市基础设施和公共资源的利用效率有所提高。城市用地扩展系数在1959～1986年期间小于1.12,城市用地规模扩展不足(1977年前后比较特殊),1986～2009年期间,城市用地扩展系数大于1.12,城市用地规模扩展过快。

The built-up boundaries and areas of Zhangye City in Ganzhou region in 1959,1968,1977,1986,1997 and 2009 are extracted from keyhole,MSS,TM images,topographic maps and other auxiliary data.The analysis on the spatial expansion of the land use over the past 50 years is based on the spatial center of gravity transfer model,urban expansion intensity index,urban expansion rate index,compactness index,area change,expansion index of urban built-up area etc.Studies show that the area of the built-up region expanded 5.71 times during the 50 years.The expansion was in the low growth stage from 1959 to 1986 while it was a rapid growth stage from 1986 to 2009.The built-up region is expanded only 258.42 hm2 from 1959 to 1986 due to the influence of natural disasters and the ＂cultural revolution＂.However,its built-up region area has increased 1 995.11 hm2 which is 7.73 times as the change in early 27 years from 1986 to 2009 due to the overall progress of the reform and opening-up,the implement of the Western Development Strategy.The offset of the city barycenter is little from 1959 to 1977.Although the expansion area of the city is little between 1977 and 1986,the main expansion direction of the city is west and northwest which causes the city barycenter shifting to northwest quite a large.The barycenter of the city began to shift to the east and northeast with a more offset and the most can reach to 629.79 m from 1977 to 2009 due to the expansion of the city is mainly towards the east and northeast.The compactness of the city declined sharply between 1959 and 1968,however,it is opposite between 1997 and 2009.The change of the compactness of the city became stable from 1968 and 1997.The city land use scale expansion is insufficient from 1959 to 1986 due to the expansion index of urban built-up area is less than 1.12,but it is opposite between 1986 and 2009.