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根据 1 999年 8～ 9月实地调查和以往文献资料、4期航片和地形图等大量信息 ,运用遥感信息解译和 GIS软件分析及 GPS定位核查 ,准确地展现了过去 50年中拉萨城市用地变化进程 ,重点分析了城市用地变化产生的生态与环境效应和问题。主要结论如下 :1拉萨城区拓展迅速 ,从 1 951年始到 1 999年 ,城区扩大了 1 0 .31倍 ,城市建设面积扩大了近 1 9倍。城区发展分为 :城市扩建初期 (1 952～ 1 965年 )、高速发展时期 (1 966～ 1 989年 )和完善期 (1 990～ 1 999年 )。 2确定了拉萨 1 951年、 1 965年、 1 970年、 1 986年和 1 989年及 1 999年城区空间结构、范围、面积 ;3拉萨市城关区人均耕地急剧减少 ,1 999年初人均耕地 0 .0 4 9hm2 ,仅为 1 964年的 77.7% ;4拉萨市生态与环境问题日益突出 ,城市环境污染急待治理等
According to the field surveys from August to September 1999 and a large amount of information such as the previous literature, aerial photographs and topographic maps of the 4th period, using remote sensing information interpretation and GIS software analysis and GPS positioning and verification, it accurately demonstrated that in the past 50 years Lhasa city The process of land use change focuses on the ecological and environmental effects and problems caused by urban land use changes. The main conclusions are as follows: 1 Lhasa urban area expanded rapidly, from 1951 to 1999, urban area expanded by 10.31 times and urban construction area expanded by nearly 19 times. Urban development is divided into: the initial urban expansion (1952 ~ 1965), high-speed development period (1966-1989) and improvement period (1990 ~ 1999). 2 The spatial structure, scope and area of urban areas in Lhasa in 1995, 1965, 1979, 1986 and 1989 and 1999 were determined; 3 Per capita arable land in Chengguan District of Lhasa dropped sharply. Per capita arable land in early 1999 0 4 9hm2, only 77.7% in 1964. 4 Lhasa’s ecological and environmental problems have become increasingly prominent, and urban environmental pollution is urgently needed