The pattern of urban spatial growth in Nanjing since 1979

Urban spatial growth pattern has become a hot topic of geographic science and urban research.After the land reform initiated in 1987,cities in China are facing a new development wave.With the rapid growth of urban space,urban sprawl emerges.Modeling an urban growth pattern is the prerequisite to understanding the urbanization process of China.This paper presents a spatial analysis method of using remote sensing and GIS,and models major patterns of urban spatial growth in the period of 1979~2007 by a case study of Nanjing City.Firstly,the remote images are registered to the GIS data.Secondly,five land cover classes are identified from the images.Then,the different urban spatial growth patterns are established by mobile window calculation technology.It is found that the main spatial growth pattern of inner city is filling and the main spatial growth pattern of outer city expands during 1979~1988;the main spatial growth of inner city is slow and the main spatial growth pattern of outer city expands with linear and clustered features during 1988~2000;expansion and cluster patterns have been relatively obvious since 2000.This paper discusses the features of urban spatial growth of Nanjing.During 1979~1988,urban spatial growth of each district is slow,and the inner growth is in excess of suburban growth,with the peak value of urban growth appearing 5km away from the city center.During the period of 1988~2000,urban growth of suburban areas is in excess of inner city,with the peak value of urban growth appearing 6~13km away from the city center.The most insensitive growth appears in the southeast part of the city,and the growth of each aspect is relatively insensitive except the east and west.During the period of 2000~2007,urban growth of suburban areas is at high speed,and the peak value of urban growth appears 5~17km away from the city center.The most insensitive growth appears in the southeast,and the urban growth of each direction is insensitive except the west,and the development trend of urban areas is towards the north and south.The influencing factors of urban spatial growth are very complex,the main ones of which are social and economic development.Besides,the guideline of urban planning and impact of urban spatial structure are quite obvious.Other driving forces are also important,such as the rebuilding of inner city,new towns development,construction of infrastructure and development zones,population incensement and economic development.The results show that 80% of urban spatial growth emerges in the urban planning districts during 1979~2007,and that each period and direction of urban growth are affected by new towns development,as wellas construction of infrastructure and development zones.