基于空间句法的扩张强度指数及其在城镇扩展分析中的应用

扩张强度指数（Expand Intensity Index, EII）是目前城市扩展数量特征研究的常用指标,用以表征城市扩张程度和速度,但该指标是从城市扩张的结果,即从城市用地面积变化角度对物质空间变化的简单描述与分析,忽略了人在空间中的感受,未能从城市扩张的动因角度揭示城市扩张特征,缺乏对城市外部空间形态演变模式的深入研究,不能反映人在城市扩展空间上的活动。本文从交通网络对城市扩张的驱动作用入手,基于空间句法,提出一种新的扩张强度指数——基于空间句法的扩张强度指数（Space Syntax Expand Intensity Index, SS-EII）,SS-EII包涵可反映空间集聚和离散程度的句法变量,可用于分析空间可达性的变化等情况。与传统扩张强度指数相比,SS-EII是基于空间句法从城市扩张的驱动力方面计算扩张强度,不仅关注城市扩张的结果,同时关注交通对城市扩张模式、方向的导向作用和人主观感知下城市空间的变化。将SS-EII应用于广东省棉湖镇2002-2014年期间的城镇扩展特征分析中,研究结果表明,SS-EII可用于分析比较建成区不同方向的扩张速率与建设状况,其计算结果与棉湖镇建成区实际扩张情况相符,与EII相关度R²达0.95以上。

Space syntax expand intensity index and its applications toquantitative analysis of urban expansion

Expand intensity index (EII) is an index commonly used to characterize the extent and speed of urban expansion. In other words, it is simply used to describe and analyze the physical spatial change from the perspective of urban area. But this index only represents the result of urban expansion neglecting the feeling of people to space and the underlying mechanisms of urban expansion. Moreover, an in-depth study is ignored on the evolving pattern of urban space and cannot reflect human activities in urban space. This paper presents a new expansion intensity index based on space syntax by considering the driving effect of transport network on urban expansion, namely space syntax expand intensity Index (SS-EII). SS-EII can reflect the syntactic variables about spatial clustering and dispersion and analyze the changes of spatial accessibility. Compared to the conventional expand intensity index, SS-EII not only cares about the result of urban expansion, but also captures the effect of transportation on the pattern and direction of urban expansion as well as the feeling of human to urban space. With Cotton Lake Town in Guangdong Province, China as an example, SS-EII is utilized to compare expansion speeds of built-up areas in different directions. It can be concluded that the result based on SS-EII is consistent to the actual situation of urban expansion and the correlation coefficient with EII is higher than 0.95.