Analysing urban sprawl and spatial expansion of Kolkata urban agglomeration using geospatial approach

Since the last quarter of the twentieth century, India has been witnessing predominantly outward expansion of most large megacities in the form of sprawl, and peripheries have been engulfing many small towns and villages rather than accommodating the migrants from rural areas in the city core. Amidst this transformation, the condition of people living in peripheral areas becomes precarious which is explained by ‘degenerated periphery’. In this backdrop, the present study aims to assess the spatiotemporal urban expansion of different municipal areas and municipal corporation areas of Kolkata urban agglomeration of West Bengal, India, during 1990–2015. Landsat Thematic Mapper and Landsat 8 OLI satellite data of the years 1990 and 2015 along with Shannon’s entropy model and urban built-up index were used to assess the spatial dispersion of and consistency of urbanization. The investigations reveal a rapid increase of built-up areas outside the municipal boundaries during the last two and half decades. Shannon’s entropy at local level is computed, which shows dispersed unplanned urban growth, specifically in the outskirts of the city. The study indicates that the core of the city has experienced negative growth. Land use and land cover change analysis revealed that the built-up area has increased drastically over the study periods. The agriculture land and open land have transformed into built-up area, indicating the sprawl growth within the Kolkata urban agglomeration. The overall result shows that urban expansion of Kolkata urban agglomeration is not compact in nature and it is an evidence of concentration of sprawl growth over the municipalities.