城市居住空间扩张的多主体模拟模型研究

Multi-agents Model for Simulation of Urban Residential Space Evolution

借助GIS技术,本文构建了包含微观智能主体和环境主体的城市居住空间演化的多主体模型,旨在探讨城市居住空间增长的过程中市场机制和计划机制之间的相互作用和消长规律。模型分析总结了城市居住空间增长过程中城市居民、住宅开发商和城市政府的目标函数,认为城市空间扩张形态和土地集约利用水平主要取决于土地市场发育状态的不同阶段及城市政府的土地利用决策。通过调整城市政府主体的土地利用和环境政策设定了城市居住空间扩张的紧凑型、松散型和适度型3种情景类型,以ArcGIS和VC为运行环境实现情景模型,为城市政府的土地利用规划政策提供事前指导。以武汉市的洪山和武昌两区为实验区,分别模拟了基于3种规定情景下1998-2008年期间的居住空间演化情况,并与实验区居住空间的实际演化情况进行了形态、土地利用结构变化和土地利用社会效用的概略对比分析,结论为实验区1998-2008年的居住空间扩张基本属于适度型,但尚需要加强城市的内城市化。

Multi-agents model（MAS） is an effective tool for studying and simulating complex social and eco-nomic systems.MAS model itself does not have complicated modeling steps,but gives a modeling ideas and mechanisms of ＂from micro to macro and from bottom to up＂.In China,market mechanism and planning mecha-nisms are the major driving and regulation forces of urban residential space evolution.This paper builds an ur-ban residential space expansion model based on GIS and MAS that contains micro intelligent agents and envi-ronment agent,aiming to investigate the interactions between the market mechanism and planning mechanism in the process of urban residential space transformation.On the basis of the cognition of the behavior characteris-tics of the market mechanism agents of urban residents and property developers,the model analyzes the impact of the two market mechanism agents on the evolution direction of urban residential space,and the paper points out that under the policies of state-owned urban land in China,the urban government＇s land supply decides the urban residential evolution patterns and the total benefits of residential land development.Thus,by adjusting the land use and environment protection policies of urban government,the model sets three policy scenarioes and achieves the preview of the evolution of residential space for each scenario,which can provide guidance for land use planning in advance.Wuchang and Hongshan districts in Wuhan city are chosen as the experimental ar-eas.By the MAS model the paper compares the land use structure and land use benefits in the process of the resi-dential space evolution from 1998 to 2008 among the three scenarioes and the actual situation respectively.Some main conclusions can be drawn as follows from the model’s outputs.Firstly,there are always intersec-tions between the real residential space evolution and the models’ simulated results under different scenarioes,which means that because of the influence of macroscopic environment,urban government may adjust its land use policy,natural environment protection policy and so on in different periods.this is just one of the characteris-tics of Chinese real estate market.Secondly,urban residents’residential favor can affect the spatial form and the speed of urban residential spaces’ growth.The third is that compared with land redevelopment of the old urban area,newly developed land in inner suburban districts has a lager proportion in the evolution process of the resi-dential space from 1998 to 2008 in the two experimental districts.In fact,the government of Wuhan city had fo-cused on the development of new residential land in the suburban fringe areas before 2004,but the emphasis has been transferred to the old city transformation and land redevelopment after 2004.