基于分形理论的南宋巴蜀古城镇群分布研究

Research on the spatial structure of the ancient urban system in Southern Song Dynasty Bashu mountain area based on fractal theory

城镇的形成发展受地形、历史等因素的影响,呈现出一定的分形特征。分形城市群能够有效地占据空间,更好地利用地势,研究这种分形优化特征具有广阔的前景。南宋巴蜀地区的城镇群集中于长江、嘉陵江两岸,文章基于分形理论,对这一山地城池防御体系的聚集维数与网格维数进行了测定。结果表明:分别以成都、重庆为中心测定的聚集维数为0.70与0.91,预示着巴蜀地区城镇群的分布呈现非均衡趋势,其密度逐渐向四周衰减;城镇布局的网格维数与周边河流的网格维数分别为1.19和1.21,整个山城体系展现出附近河流的分形特征。

Formation and development of towns are affected by topography,history and other factors, which presents certain fractal characteristics. Fractal city can effectively occupy more space and make better use of the terrain,Research in this fractal optimization characteristic of towns shows broad prospects. Based on Fractal Theory,the test was made in Fractal analysis of the mountain city defense in Southern Song Dynasty Bashu area,in which the aggregation dimension and grid dimension of the urban system was measured. The results show that：the aggregation dimension of Chengdu is 0. 70, while that of Chongqing is 0. 91. It reveals that the distribution of the cities in Bashu region present non-equilibrium trends. ,and the density of cities gradually decay from the center. The grid dimension of the cities is 1. 19,while that of the rivers besides them is 1. 21. The fractal characteristics of these mountain cities are similar with that of the rivers nearby.