三峡库区重庆段城市空间扩展及形态时空演变研究

A STUDY ON URBAN SPATIAL EXPANSION AND SPATIAL EVOLUTION OF CHONGQING SECTION IN THE THREE GORGES RESERVOIR AREA

由于时代的局限性以及地理单元的独特性,以往城市空间结构理论的研究热点多集中于经济较为发达的东部地区或特大型城市,对于欠发达西部地区的中小城市关注不够。基于RS与GIS技术,通过1995年、2000年、2005年、2010年、2015年5期TM遥感影像提取城市建成区数据,利用城市空间扩展强度和速度指数、紧凑度、分形维数及形状指数对三峡库区重庆段20 a间城市空间扩展及形态演变定量分析。得出以下结论及建议:(1)随着时间增长,城市空间扩展强度及速度总体呈上升趋势,紧凑度持续降低,城市建成区面积逐年递增,城市扩展极不稳定;(2)城市空间形态受重大事件影响易发生"突变",随着时间的沉淀,空间形态再发生"整合";(3)1997年重庆直辖以来,前10 a的移民安置工程为城市形态的"突变"提供了良好契机。2007年之后,在经济发展作为城市空间扩展的核心动力支撑下,研究区城市扩展主流模式侧重于沿一到两个方向扩展,形成"一心两辅"的发展态势;(4)在未来城市发展规划中,应坚持可持续发展理念、合理规划用地布局,优化产业结构,加强环境保护,避免"边发展、边污染"的被动局面,同时结合自身交通运输条件的优势,在各个方向上形成依附在中心城镇周围的腹地并作为未来扩展的基础,构建副中心城市,将城市形态有序沿城市发展中心蔓延,形成"一核多翼"的发展态势。

Due to the limitation of the times and uniqueness of geographical unit,the former research hotspots of city spatial structure theory mainly focused on the economically developed eastern regions or hyper-megalopolis,but paid insufficient attention on small and medium-sized city in the underdeveloped western regions. Based on RS and GIS technology,this paper made quantitative analysis on the 20 years urban spatial expansion and morphological evaluation of Chongqing Three Gorges Reservoir Area,by employing urban spatial expansion intensity and speed index,compactness,fractal dimension and shape index as well as extracting built-up area data based on the five TM remote sensing images of 1995,2000,2005,2010 and 2015. At last,we summed up the following conclusions and suggestions. Firstly,the intensity and speed of urban spatial expansion shows an increasing trend on the whole,while the compactness keeps cutting down and urban built-up area increases year by year,suggesting that the urban expansion was unstable. Secondly,when suffering from mega events,the urban spatial morphology will be prone to abrupt changes,and as time goes by,the spatial morphology will be integrated again. The third,at the first decade since Chongqing became a municipality in 1997,the resettlement project offered a good opportunity for the sudden change of urban morphology. After 2017,the key mode of urban expansion in research area is in one or two directions,which has formed the development trend of ＂one center,two auxiliary＂under the core drive of economic development. And the forth,in the planning of future urban development,it should adhere to sustainable development,rationally planning land use,optimizing the industrial structure, strengthening environmental protection, and avoiding the passive situation of ＂developing with pollution＂. Meanwhile,combined with the transportation advantages,the hinterlands should be established all around center town as the foundation for future expansion of constructing sub-central city,aiming at forming the city morphology along the developing center in terms of ＂one core,multiple wings＂.