Satellite Based Observations of the Dynamic Expansion of Urban Areas in Southern Italy Using Geospatial Analysis

Understanding the size distribution and dynamic expansion of urban areas is a key issue for the management of city growth and the mitigation of negative impacts on environment and ecosystems. Satellite time series offer great potential for a quantitative assessment of urban expansion, urban sprawl and the monitoring of land use changes and soil consumption. This study deals with the spatial characterization of the expansion of urban area by using geospatial analysis applied to multidate Thematic Mapper (TM) satellite images. The investigation was focused on several very small towns close to Bari, one of the biggest city in the southern of Italy. Urban areas were extracted from NASA TM LandSat images acquired in 1999 and 2009, respectively. To cope with the fact that small changes have to be captured and extracted from the TM multitemporal data sets, we adopted the use of (i) spectral indices to emphasize the occurring changes and (ii) geospatial statistics for capturing the spatial patterns. The urban areas were analyzed using both global and local geospatial analysis. This approach enables the characterization of the pattern features of urban area expansion and improves the estimation of land use change. The obtained results show significant changes linked to urban expansion coupled with an increase of irregularity degree of the urban border from 1999 to 2009. This variation is also connected with the expansion of the economic activities in the area of concern along with and the population growth.