Studies On The Pole-axis Analysis Method Of Regional Spatial Structure Take Yangtze River Delta As An Example

In this paper, a "Pole-Axis" spatial analysis method based on the existing regional spatial structure theory is proposed. Taking Yangtze River delta as a case, the spatial structure of Yangtze River delta town nodes under the homogeneous district background, the "Pole-Axis" spatial structure of Yangtze River delta under the functional region background and the evolution process and the development situation of Yangtze River delta "Pole-Axis" spatial structure are studied.The general technical route of "Pole-Axis" spatial structure analysis is that taking point elements, including town node, traffic node (port, airport, railway station, highway interchange), and linear elements (waterway, railway, highway, land way) in regional spatial structure to do various spatial combinations and analyzing the spatial accessibility, the spatial diffusion and the spatial attracting scope of point elements based on linear elements. According to three different conditions, the count of nodes without weight is 1, the count of nodes without weight is greater than 1, and the count of nodes with weight is greater than 1, the time accessibility evaluation model based on traffic network of nodes and the time-distance attenuating diffusion model based on traffic network of nodes are proposed. On the base of these models, the spatial attracting scope model of nodes based on time accessibility, the minimal seed algorithm based on time accessibility and the value diffusing algorithm based on polygonal grid fast filling are proposed. SSAIS is developed using MapX, controls of MapInfo, and Delphi, Borland visual programming tool. SSAIS can be applied to "Pole-Axis" spatial analysis.Taking 16 provincial cities in Yangtze River delta as research unit, 16 prefecture-level and above level cities and 76 counties, county-level cities are abstracted to 16 and 76 spatial nodes. The spatial structure of town nodes in Yangtze River delta under the homogeneous district background is analyzed from five aspects, including spatial distribution, comprehensive strength, spatial accessibility, spatial diffusion and spatial attracting scope.Taking 16 prefecture-level and above level cities in Yangtze River delta as town nodes and taking port, airport, railway station, highway interchange as traffic nodes, this paper researches town nodes spatial diffusion with waterway, railway, highway and land way as axes and traffic node including port, airport, railway station and highway interchange spatial diffusion with land way as axes. The paper evaluates the regional accessibility of town node based on land traffic network, analyzes the isochronous area and daily-communication-area of town node and makes off the spatial attracting scope of town node and traffic node based on time accessibility.The paper chooses the land traffic network of 1985, 1995, 2006 and 2020 as research axes. Taking 16 prefecture-level and above level cities in Yangtze River delta as town nodes and taking port, airport, railway station, highway interchange as traffic nodes, this paper analyzes the evolution process and the development situation of town node and traffic node spatial diffusion based on land traffic network, the evolution of spatial pattern of town node regional accessibility and dynamic transformation of town node isochronous area and daily-communication-area.