关键词: 城镇体系, 空间结构, 交通优势度, 多维尺度分析, 可视化

Abstract:

Urban planners usually faced the problem of how to visualize the regional structure of urban with a quantitative method when the relationships among cities are complicated. Representing the regional structure of urban system with points (cities), lines (segmentation), and polygons (describing the influence area of cities), this article constitutes an analytical approach for identifying the spatial structure of cities in a region. A three-step procedure was proposed. First, cities with advantageous scales, good transportation conditions, and social and economic impacts in the region are chosen as critical nodes in the urban system, which are also considered to have potential for further development. Second, with a multi-scale analysis method, the spatial relation of the cities represented by such indices as traffic distance, time and cost, regional disparity, hours and the people, goods and capita are explored, whereby the cities are depicted as points on a Euclidean space, the distances of which reflecting the intensity of spatial interactions between cities. Accordingly, the concentration and departure of cities can be interpreted from the redefined locations. Third, the spheres of influence of the cities are examined, and the overall spatial pattern of the region, such as core, cluster and belt structures, connection and expanding directions, is clarified. The above method is applied to cities in the Xijiang Economic Region in Guangxi Province, China. The changes of urban structures over three periods are revealed, namely, when intra-city transportation mostly relied on low-hierarchy road and railway (before the 1990s), when express highways became the dominant (in the 2000s), and when a comprehensive transportation system consisting of highway, high-speed train and waterway transportation is put to use (under construction right now). It is found that, with the development of transportation system, connections among cities varied dramatically. For example, the city of Wuzhou was fairly isolated in the 1990s due to lack of railway connection with other cities, but in the 2000s, the distance was shortened by express highways and this trend will be further enhanced in the future. As a result, a triangle core and a belt structure will form in the region. The example demonstrated that the proposed approach is an effective tool for analyzing and predicting the development of regional spatial structures.

Key words: urban system, regional spatial structure, transportation advantageous scale, multi-scale analysis, visualization