GIS and remote sensing based urban sprawl detection and its implications on sustainable development

This paper analyzes the urban sprawl dynamics using geospatial techniques. Sprawl is studied for three temporal periods of 1975, 1990 and 2009 using GIS and Remote Sensing techniques in conjunction with Shannon's entropy. Urban sprawl characteristics, causes and effects are reviewed and analyzed with respect to Greater Visakhapatnam. Sprawl pattern is mapped and measured from various viewpoints to identify the specific local factors which control the growth pattern in the study area. Visakhapatnam is a fast developing port city and recording rapid rate of urbanization. With increasing population and ever increasing demand of land the new extensions of the city have taken place. It is expanding in all possible directions resulting in large scale changes in urban land use which affects the physical and social environment of the city. The city has gained real importance from 1970 onwards due to location of many industries which had resulted in considerable spread with the establishment of new residential colonies. The spatial growth of the city has been restricted by physical barriers on the north, south and east. Visakhapatnam city is growing along the southwest, northwest and northeast directions. The rate of land development is as high as 789% during the 35 year of study period while the population growth rate is 266%. Thus the per capita land consumption has increased markedly and it is true especially in the peripheral zones a strong indicator of sprawl. The distribution of population density in various wards also justifies the above characteristic of sprawl - "dense core and dispersed suburbs". The higher entropy values at different points during the study period indicate high rate of sprawl even in early seventies and sustained throughout. Therefore the entropy approach is proved to be efficient to identify measure and monitor the spatio-temporal patterns of urban phenomena.

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