基于分形理论的清代长城外侧城镇格局研究

Spatial structures of the urban systems outside the Great Wall during Qing dynasty based on fractal theory

分形是大自然优化的结构形式,分形城市群能最有效地占据空间。清代是长城外侧地区城镇迅猛发展时期,文中利用GIS空间分析功能和分形理论对清代长城外侧城镇体系的网格分维和聚集分维进行测定。结果表明:该区域78个治所城镇空间分布具有分形几何特征,且归绥和直隶地区分形发育度最好,围绕归化城和承德府为中心向周围密度衰减分布;伴随着点-轴系统的发展,城镇空间结构历经随机阶段、孕育阶段、发展阶段的三个演进过程。

Fractals are self- similar sets of fractional dimension. Fractal city can effectively occupy more space.Qing dynasty was the period when the regional towns developed rapidly,which laid the foundation of today＇s landscape. Based on Fractal Theory,the fractal analysis of regional towns outside the Great Wall was made,of which the aggregation dimension and grid dimension were measured. The result shows that ancient settlement distribution exhibited the fractal geometry both within part and cross region. Compared to others,the fractal geometry of towns across Guisui and Zhili region developed best,while the density of settlements gradually decayed from the Guihua and Chengde city which were as the regional centers. It＇s deduced that the regional spatial structure had experienced interactive process of random stage → embryonic stage → development stage with the development of pole- axis system.