自然地理因素对城镇体系空间结构影响的样式分析

Pattern Analysis of Spatial Structure of Urban System Dominated by Physical Geographic Factors

由于微波可以对地表的微起伏、建筑及地表粗糙度等具有敏感的响应 ,使得雷达遥感在这些方面研究中成为最有用的工具之一。本文利用由加拿大遥感中心 PCI提供的Radarsat Scan SAR数据 ,对黄、淮、海平原城镇体系空间结构提出自然因素影响下的样式研究。自然条件是城市形成和发展的自然基础。本文通过自然地理因素中水文 (河流、古河道 )、地形这两个重要要素对城镇体系空间结构形成的影响 ,分析了华北平原区在不同要素影响下的城镇体系空间结构样式 :1在水源充足的准“均质”河北冲积平原上 ,基本满足六边形形成条件 ,但由于周边中心地发展竞争力不同 ,故使得正六边形发生畸变——覆盖面积减小而周长却保持不变 ;2构建了在一条河流影响下的六边形网络结构朝五边形网络演变的模型 ;3构建了在平行状河流作用下六边形网络向四边形网络演替的模式 ;4指出了在水源充足的狭长地理空间 。

Radar remote sensing can detect micro relief, building, vegetation distribution, surface roughness and water content sensitively. It is a very useful means for these studies. Based on Radarsat Scan SAR data supplied by Center of Canadian Remote Sensing (CCRS), the pattern of spatial structure of urban system dominated by physical geographical factors is studied in Huang-Huai-Hai plain. Physical geographic condition is foundation for urban forming and developing. A case studies patterns of spatial structure of urban system in different physical geographic factors (i.e. river, paleo channel, and landform) in Huang-Huai-Hai plain. The results are listed as follows: (1) In peneplain with plenty water resource, hexagonal spatial structure of urban system can be formed. Due to differential competed function of central places, the hexagonal system is distorted. The result is that the area covered is decreased and the girth is unchanged——but every border is usually unequal; (2) A pattern of pentagonal system evolves from hexagonal system controlled by a river; (3) A pattern of quadrilateral develops from hexagonal system under two parallel rivers; (4) The equal distance distribution of central places in narrow geographic space has its special reasons. The results are very important for understanding urban's formation and development and urban plan in Huang-Huai-Hai plain.