分形维数在城市排水管网规划中的应用

Application of Fractal Dimension in Urban Drainage Pipe Network Planning

城镇体系空间结构是城镇体系的重要特征之一,对其的定量研究对城市规划具有重要意义.以分形理论为基础,采用集聚维数研究了东莞市各镇区体系的空间相关性.结果表明:镇区之间的集聚程度不大,其大小与经济发展状况和地理位置有较好的对应关系.通过对几个镇区排水管网的长度-半径维数的测算,揭示出镇区排水管网也具有分形特征.综合分析镇区排水管网的规模指标数值可发现规划中存在的问题,并提出如下调整措施:①对于排水管网分形维数较好,规模指标欠佳的镇区,应加快排水管网的规模建设;②对于排水管网规模指标较好,而分形维数较差的镇区,应优化排水管网的平面布置规划;③对于排水管网分形维数及规模指标均欠佳的镇区,需要从排水管网的平面布置规划和建设规模两方面进行优化和调整.

Spatial structure is one of the major characteristics of urban systems.Quantitative study on urban spatial structure is of great significance in urban planning.On the basis of fractal theory,the spatial correlation of urban systems in towns of Dongguan City was investigated by adopting a fractal dimension.The results showed that the centralization of towns in Donguan was low,and the aggregation level was closely related to economic development and geographical location of the towns.The fractal features of the drainage pipe networks in several towns were determined through measurements of the fractal dimensions of length-radius.Problems in the drainage pipe network design were found based on the integral analysis of scale indicators.In conclusion,it is essential to optimize and adjust the planning of the drainage pipe network for certain towns： 1） in towns where the fractal dimensions of the drainage pipe network are good and the scale indicators are poor,the construction scale should be advanced;2） in towns where the scale indicators are good and fractal dimensions are poor,the layout of the drainage pipe network should be reallocated and optimized;3） in towns where both the fractal dimensions and scale indicators are poor,the layout and construction scale of the drainage pipe network should be advanced and optimized.