以杭州市中心城区为研究区,以1991、1996、2000、2005年LandsatTM/ETM+为数据源,通过缓冲区分析、SLEUTH模型等方法,分析杭州市城市扩展情况和预测4种可能方案。SLEUTH模型校正结果最终的Compare和Lee-Sallee值分别为0.95和0.59,与近期城市用地数量和形态较为吻合,但在反映城市波动增长和新组团开发时存在不足。SLEUTH模型生成了现有发展趋势、交通引导、农田适度保护、紧凑城市等4种预测方案。与历史趋势相比,预测方案的面积呈线性增加,扩展热点继续向外围组团转移,扩展阶段为多核心发展。扩展强度空间分布上符合幂函数形式,距CBD12km和距城市边缘500m处为转折点,未来扩展强度均低于历史水平。若延续现有趋势,城市开发量为189km2,耕地年均消耗量为9km2。从规划角度来看,适当的农田保护措施可抑制城市扩散,交通可引导城市新区开发和减缓主城区压力,紧凑城市可使城市分布集中,从而可节约用地和调控城市形态。
Rapid urbanization often results in intensive land use change especially in the urban area of China. Simulation of urban expansion thus captures increasing research interests. Taking the metropolitan area of Hangzhou as a case study, this paper utilized the urban growth model of SLEUTH to forecast the urban growth of Hangzhou in four alternative scenarios based on four Landsat TM/ETM+ images(e.g. 1991, 1996, 2000 and 2005). Through generating buffers from the CBD and urban fringe area, the research explored the past change process and projected the future urban pattern. The results indicated that Compare and Lee-sallee were 0.95 and 0.59 respectively in the calibration process of SLEUTH, and the amount and morphology of simulatcd urban were more consistent with actual situation in 2005 than in the past. Due to the complex behavior of urban systems, SLEUTH was unable to simulate wave-like process of urban growth and potential development. Based on different assumptions, four scenarios were simulated by SLEUTH model, which included Maintain Status Quo, Expanded Roads, Moderate Farmland Protection and Compact City. The urbanization process could be divided into three phases including radial urban growth from 1991 to 1996, spatially contiguous expansion from 1996 to 2000, and multi-nuclear development from 2000 to 2005.Urban area would increase linearly and urban morphology would continue to be multi-nuclear from projected scenarios. The hotspot area featured by intensive urban growth would shift from urban center to new developed area outside. The growth intensity declined in power function and it would be less in the future than in the past. It would decrease gradually in the area with the radius of 12 km from CBD or 500 m from urban fringe. Urban area would increase by 189 km2 and farmland would reduce by 9 km2 per year from the result of MSQ. Urban area would be restricted by MFP from urban encroachment, and pushed to new developed area by ER from over crowded area and concentrated in the edge of the existing urban area by CC. Urban plan and land use planning can help to save farmland and adjust urban morphology.
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