基于“耦合距离”的长江中游城市群一体化空间范围定量测度

国内外研究者贡献了大量城市群边界识别研究的成果,但少见从城市群一体化角度定量界定城市群空间范围的研究,不足以给盲目"组群"、不合时宜"入群"的"城市群病"问题提供可行的解决方案。该文借用金属价键理论,定位城市群为内部个体共享共建资源、以整体形态与外部合作竞争、边界范围具有时空可变性的"利益共同体",在此基础上,构建了城市群一体化动态耦合关系模型,以"耦合距离"为媒介测度了长江中游城市群一体化区域规模与空间范围。研究结果表明:(1)泛武汉城市圈、环长株潭城市群分别具备发展边界半径100、150 km城市群一体化区域的潜力,长江中游城市群较长时期内不具备发展边界半径超过200 km的条件;(2)城市群等级层次分明,泛武汉城市圈环长株潭城市群环鄱阳湖城市群,武汉、长沙区域中心性强,但均不具备绝对中心辐射能力;(3)二级城市群中,环长株潭城市群发育程度最高,泛武汉城市圈中存在"洼地",环鄱阳湖城市群出现"脱群"现象;(4)长江中游城市群目前实际空间范围包括"武汉—黄冈—孝感"及"长株潭—益阳",不到原规划规模的1/4,具备形成"武汉长沙"双中心一体化的城市群模式的潜力。研究结论为决策长江中游城市群一体化发展规划提供了科学参考。

Quantitative Evaluation of Integration of the Urban Agglomeration Along the Middle Reaches of Yangtze River Applying Coupling Distance

Researchers have contributed many theories and approaches to figure the boundary of agglomerations and draw the urban agglomeration a reasonable scale, but few studies have quantitatively defined the spatial scope of urban agglomeration from the perspective of integration, which cannot cure the “urban agglomeration disease” such as forming groups blindly and join an urban agglomeration untimely. This study first positions the urban agglomeration as a spatially and temporally variable “community of interests” that cooperating and competing with other systems while internal individuals sharing resources. Then, authors launch a dynamic coupling relationship model of integration of urban agglomeration to test the interactions (include strengths and directions) among the central city and lower-tiered cities around it; applying the theory of metal valence bond that describes the atomic interaction by exchanging electrons internal and external, consistent with the principle of mutual attraction of element allocations among cities. On this basis, defining “coupling distance” and corresponding formula to express the direction and intensity of that interaction, to calculate the integrated region and boundary range of the urban agglomeration. Resort to this theoretical frame, authors first analyze the spatial-temporal changes of blocking effects of the urban agglomeration in different spatial distances. Second, calculating the spatial-temporal changes of the coupling distance among the cities, and then judge the situation and level of urban agglomeration integrating to conclude the suitable spatial scales of the urban agglomeration. In this paper, authors conduct an empirical study on the urban agglomeration along the Middle Reaches of the Yangtze River that including urban agglomeration of Pan-Wuhan, Ring of Changsha-Zhuzhou-Xiangtan urban agglomeration and theurban agglomeration around Poyang Lake, and the analysis results show that:(1) Urban agglomeration of Pan-Wuhan and Ring Changsha-Zhuzhou-Xiangtan urban agglomeration can develop the radius of the integrated regions up to 100 kilometers and 150 kilometers respectively, and the urban agglomeration along the Middle Reaches of the Yangtze River cannot expand the boundary radius exceeds 200 kilometers at present.(2) In terms of the hierarchical system, Ring of Changsha-Zhuzhou-Xiangtan urban agglomeration is second to urban agglomeration of Pan-Wuhan and both exceed the urban agglomeration around Poyang Lake; but the urban agglomeration along the Middle Reaches of the Yangtze River has no heart yet.(3) Analysis of Maturity shows that Ring of Changsha-Zhuzhou-Xiangtan urban agglomeration surpasses the other two as several depressions exist in the middle of urban agglomeration of Pan-Wuhan and two cities are away from the urban agglomeration around Poyang Lake.(4) The members of the urban agglomeration along the Middle Reaches of the Yangtze River are Wuhan, Huanggang, Xiaogan, Changsha-Zhuzhou-Xiangtan urban agglomeration and Yiyang, is smaller to a quarter of the original planning; and “Wuhan & Changsha” will shape into an integrated center.These results offer a scientific reference to the integrated development planning of the urban agglomeration along the Middle Reaches of the Yangtze River.