西北地区城市空间扩展及动因分析——以宁夏固原市为例

Evolution of Typical City Space and Driving Factors in Northwest China:A Case Study of Guyuan City

城市空间扩展及动因分析是认识城市发展阶段、揭示城市空间扩展规律和机制的重要内容。针对当前西北地区中小城市空间扩展地域性特点鲜明但关注度不足的困境,研究分析了固原市的空间扩展特征及驱动因素,以期为西部地区中小城市空间扩展研究提供一定的案例价值。首先以固原市1987—2014年间的30m分辨率影像为基础数据源,在GIS和RS操作平台的支持下,判读出固原市在2000年以后进入了城市空间快速扩展期。在此基础上,利用固原市快速扩展期内3个典型阶段的高分辨率卫星影像为数据源,应用空间叠加分析法和定量分析法对2003—2014年间城市空间扩展特征进行研究,并分析其驱动力因素。研究表明,近11年来固原市城市建成区快速扩展,扩展过程表现出显著的周期性、方向性,以及形态结构趋于复杂化和扩展弹性失调等特征;产生这些特征的重要原因在于,城市自然环境和人文背景限制着城市的规模和方向,快速经济发展是城市空间快速扩展的根本动力,城市基础设施建设有着显著的指向性作用,而城市规划和政府角色起到了重要的政策支持作用。

Urban spatial expansion and motivation analysis is an effective means to understand the urban development stage,and to reveal the regularity and mechanism of urban spatial expansion.In view of the difficulties on development of small and medium-sized cities in northwestern China,it is regionalism for space expansion but lack of public attention.After investigation on space expansion features and contributing factors,the research hopes to provide some valuable experiences for space expansion of small and medium-sized cities in northwestern China.Based on 30 mresolution images of Guyuan during 1987—2014,the investigation shows that Guyuan expands more rapidly after 2000.Detailed information has been acquired by the authors using three typical periods in the development of high resolution satellite imagery as the information sources.The technique applied is referred to as the GIS and RS operating platform,supervised classification and manual interpretation of the combination of technical methods to obtain the land use data.Furthermore,the spatial overlay analysis method and quantitative analysis method are used to analyze the spatial expansion characteristics and reasons.The study demonstrates that in recent 11 years,the spatial structure of built-up areas in Guyuan has changed quickly,and the process of urban spatial extension shows the significant characters of periodicity and direction,as well as the form of complicated structure.In this case,the elastic extension process is seriously beyond reasonable spatial expansion flexibility index.It is concluded that the urban natural and cultural environment is the basis of its space reconstruction,and the rapid economic development is the important constitution of urban spatial reconstruction.Meanwhile,urban infrastructure construction and city planning as well as the government organizations play different driving role.