基于交通可达性与城市竞争力的城市腹地范围识别——以长江中游城市群为例

通过构建相应指标体系,采取主成分分析法测度长江中游城市群城市竞争力。在GIS软件支持下,基于时间成本距离栅格的交通可达性分析,利用场强模型,对2015年长江中游城市群31个城市腹地范围进行识别。研究发现：长江中游城市群城市竞争力空间分布差异较大,最大值和最小值相差达5.84倍,与行政级别具有一定关联性。从交通可达性来看,1 h圈空间范围主要集中在中心城市附近,≥3 h圈主要分布在远离省会城市的外围地区,以及岳九咸（岳阳、九江和咸宁）省际交界区。长江中游城市群城市间交通发展缺乏统一规划与协调性,内部交通联系较为薄弱。从空间场强来看,高场强区集中于中心城市及其周边地区,低场强区分布于交通通达性较差的边缘与外围地区,尤其是省际边界地区。场强空间分布与城市竞争力与交通可达性分布具有较强的吻合度,但省际间协同发展程度低。城市腹地范围来看,湖北省大部分城市腹地面积较小,江西省城市腹地面积相对广阔,湖南城市腹地面积居中,三大省会城市腹地面积远超过其他城市,意味着长江中游城市群业已形成以省会城市为多中心的复合型极核发展格局,但内部一体化程度偏弱。从腹地与行政范围的层叠结果来看,城市腹地与市域行政范围吻合度较差,省会城市扩伸率要高于其余城市,而且三大省会城市的域外腹地面积比例远高于其他城市,九江、岳阳、宜昌、常德、新余、景德镇等地域外腹地面积比例也较高。总体来说,长江中游城市群仍停留在子圈内一体化的阶段,还未实现三圈融合和高度一体化发展阶段。

Recognition of Urban Hinterland Based on Transportation Accessibility and Urban Competitiveness: A Case Study on the Middle Reaches of the Yangtze River

Through the construction of a corresponding index system, the competitiveness of cities in the middle reaches of the Yangtze River in 2015 was measured using principal component analysis, and based on their road traffic layers, the accessibility of cities was measured using GIS grid cost distance spatial analysis technology.Then, the entire spatial field strength was simulated using the field strength model, and the hinterland of the cities was extracted according to the maximum principle. This was done to effectively define the spatial scope of the urban agglomeration in the middle reaches of the Yangtze River. The spatial distribution of urban competitiveness in the middle reaches of the Yangtze River was found to be quite different, and the difference between the maximum and minimum values was 5.84, which is related to the administrative level. In terms of accessibility, the1-h circle mainly concentrates in the vicinity of the central part of the city, and the 3-h circle and above mainly distributes in the periphery far from the provincial capital city as well as in the Yue-Jiu-Xian provincial boundary area. There is a lack of unified planning and coordination regarding inter-city traffic development in the middle reaches of the Yangtze River, and internal traffic links are relatively weak. Regarding spatial field energy, the high field energy area was concentrated in the central city and its surrounding areas, while the low field energy area was distributed in the marginal and peripheral areas with poor traffic accessibility, particularly in the provincial border areas. The spatial distribution of field strength was in good agreement with the distribution of urban competitiveness and traffic accessibility;However, the degree of inter-provincially coordinated development was low. From the perspective of urban hinterlands, the hinterlands of most cities in Hubei Province are smaller, the hinterland of Jiangxi Province is relatively vast, the hinterland of Hunan City is medium sized,and the hinterland of the three provincial capitals is much larger than those of other cities, which means that the urban agglomeration in the middle reaches of the Yangtze River has formed a complex polar nuclear development pattern with the provincial capital cities as the multi-center However, the degree of internal integration is weak.From the overlapping results of the hinterland and administrative scope, the consistency between the urban hinterland and the municipal administrative scope is poor. Cities with an expansion rate that is greater than 1.1 were mainly Wuhan, Changsha, Nanchang, Yichang, Changde, Pingxiang, Xinyu, Jingdezhen, and Yingtan. Cities with an expansion rate above 0.9 and less than 1.1 mainly included Hengyang, Loudi, and Yueyang. In Xiangyang,Tianmen, and Qianjiang, the expansion rate of other cities was less than 0.9. In addition, the proportion of extraterritorial hinterland of the three major provincial capitals was found to be much higher than that of other cities. The proportion of extraterritorial hinterland of Jiujiang, Yueyang, Yichang, Changde, Xinyu, and Jingdezhen was also higher. Generally, urban agglomeration in the middle reaches of the Yangtze River has stayed consistent at the stage of integration within the sub-circle and has not yet realized integration of the three circles or highly integrated development. This study attempted to identify the spatial range of urban agglomerations by using GIS quantitative analysis technology, and we provide reference for optimization and integration of the urban spatial structure of urban agglomerations in the middle reaches of the Yangtze River.