基于CA的城市地价变化与规模扩展耦合作用研究——以石家庄市为例

Study on the Coupling Effect of Urban Land Price Change and Scale Expansion Based on CA:Taking Shijiazhuang City as an Example

元胞自动机(CA)越来越多地用于模拟城市系统复杂变化,但模拟过程中基本未考虑城市地价。该文以石家庄市城市建成区为研究区,采用GIS与CA动态耦合方式,引入"灰度"原理,建立了地价约束下的城市规模扩展模型,分1987-2000年、2000-2006年、2006-2010年、2010-2015年4个阶段进行了城市规模扩展模拟,得出地价变化与规模扩展之间的耦合作用关系。结果显示:1)地价约束下城市用地规模与实际匹配程度较高,4个阶段LeeSallee模拟形状指数分别为0.52、0.58、0.61、0.62。城市用地扩展方向、速度、形式在各阶段呈现不同特征。2)地价约束下城市用地形态紧凑度均高于实际形态,城市用地效益较高。3)实际城市规模限定下城市核心地价增长速率低于城市平均地价增长速率,4个模拟阶段地价衰减参数呈逐阶段降低趋势,分别为0.258、0.230、0.205、0.184,表明随着城市规模的增大,城市用地趋于节约、集约化,城市地价空间结构差异趋于缓和。

Cellular Automaton(CA)has been increasingly used to simulate the complex changes of urban system.However,the urban land price was not taken into consideration in these simulations.In this study,the built-up area of Shijiazhuang city was taken as the study area,and the model of urban scale expansion under the control of land price was established by using the dynamic coupling method of GIS and CA and the principle of grayscale.Four research stages,including 1987-2000,2000-2006,2006-2010,and 2010-2015 were respectively divided to simulate the expansion of urban scale,and the relationship between land price change and urban scale expansion was concluded.The results show that:1)Under the control of land price,the urban land use scale is well matched with the reality.The simulated shape index of Lee-Sallee at the 4 research stages are 0.52,0.58,0.61 and 0.62,respectively.The direction,speed and form of urban land expansion show different characteristics in different stages.2)Under the control of land price,the compactness of urban land use is higher than that of the actual form,and the efficiency of urban land use is also higher.3)Limited by actual urban scale,the growth rate of land price in urban core is lower than that of the average land price in urban,and these parameters of land price attenuation present a decreasing trend in the 4 simulated stages,which are 0.258,0.230,0.205 and 0.184.It can be concluded that,with the expansion of urban scale,urban land use is becoming more and more intensive and economized year by year,and the differences of spatial structures in urban land price is getting smaller.