近50年兰州城市空间扩展模拟及其未来预测

利用高分辨率航片、Landsat TM影像和土地利用现状图,建立兰州市1949-2005年城市扩展G IS空间数据库,应用改进的SLEUTH模型,重建兰州市1949-2005年城市空间扩展过程,并情景模拟未来扩展趋势。采用两种不同历史年份跨度情景、校准SLEUTH模型。研究表明:该模型客观地重建了兰州市1949-2005年城市动态扩展过程;两种不同情景预测仍将继续沿河谷扩散发展,在城市增长方式与空间分布上既相似又有显著差异:情景1预测城市扩展趋势快于情景2预测,更接近于现实城市扩展趋势;情景2预测对城市扩展控制较严格,更趋向于可持续发展。建议近期内加强兰州建成区内部土地利用空间结构优化与空间置换,进而加快城市职能的空间置换,同时为未来发展预留一定的土地储备和发展空间。

Simulation and Prediction of Urban Spatial Expansion of Lanzhou City

This paper discusses a simulation and analysis of urban spatial expansion of Lanzhou City using remote sensing data, GIS and SLEUTH model. The historical data were derived from 1:50 000 land use maps in 1949 and 1976, aerial photos in 1959, 1980 and 2001, and Landsat TM images in 1986, 1993 and 2005. Two different scenarios were designed for the calibration and prediction to explore the impacts of policy and social and economic factors on urban expansion. The first scenario was designed as the continuation of the trend during the period of 1949 - 2005 with all the eight data sets; while the second one was designed as the continuation of the trend during the period of 1986 -2005 with the recent four data sets. Nine boom cycles during the period of 1949 - 1959 and two boom cycles during the period of 1959 - 1976 were derived by SLEUTH model for the first scenario, the former nine boom cycles were caused by the fast expansion spurred by the five main projects, and the latter two boom cycles were mainly caused by the chaotic expansion at the end of the Cultural Revolution and the investment at the beginning of the "Fifth Five-year Plan". One boom cycle in 1993 was derived for the second scenario, which was caused by the abolishment of the Vegetable Production Base Protection Law. The bust cycles were not simulated correctly due to the insufficient historical data during the period of 1959 - 1976. It can be concluded that the calibrations under two different scenarios were satisfactory. There were not only the obvious differences between the predicted results under the two different scenarios, but also some similarities in the growth form. The trends of urban growth under the two different scenarios were similar with the simultaneous occurrence of diffusive growth and coalescence growth, while the growth of the first scenario was faster and closer to the reality than the second. The advantages and disadvantages of SLEUTH model are also discussed.