The Analysis about the Change of land-use in Lanzhou by GIS

The urban built-up areas in Lanzhou mainly lies on two valley-shaped basins on the east and west of city. According to the relief map of valley-shaped basins whose scale is 1∶5000, the article shows that the disciplinarian of space time difference about land-use extension in Lanzhou city from 1950 to this day, and clarifies the pattern and mechanism of space time transference about land use in city based on the investigative data on the spot including May-August and October-November of 2002, cadastre of Chengguan region and other correlated materials. The article discusses some problems on the aspect of environment etc. which exist in this kind of city land use's pattern on the background of valley-shaped basins. The paper not only particular discusses the collectivity changes about urban land but also idiographic analyze inner transference about changes of urban land use from space and time. Then this paper discusses mechanism and reason that these changes happened. At first, it is because of the restriction of landform:Lanzhou city is a valley-shaped basins city, the valley-city is a type of city whose main part has formed and developed in the valley.Second, it is the human beings themselves that they use urban land incorrectly. Known through this paper, along with the urban economy development, the city scale extends continuously. Some obvious changes have taken place in the urban land use; the proportion of industry descends continuously, while the proportion of commerce rises obviously. The movement of urban land replacement happened more intensively,and this happened mainly between industry and other types of land use, at the same time, the new-style residence rises quickly, in the future, the spatial differentiations of urban land use will be more and more intensive. It particularizes a lot of problems about environment and natural calamity that resulted in by this kind of change. In the end of the paper, the author brings forward some measures to solve problem. It can give birth to a certainty use for references to else valley-shaped basins city's development.