Urban structure in Kolkata: metrics and modelling through geo-informatics

摘要

Urbanization connotes to the growth of a metropolis on being subjected to criteria such as economic, social and political forces as well as the geomorphology of the metropolis. As population and its activities increase in a city, the boundary of the city expands to accommodate growth along the urban fringes, leading to fragmented urban morphology, thereby impacting local ecology. Towns and cities had bloomed post-independence in India, causing changes in the land use along the myriad landscapes and ecosystems of the country. These urban ecosystems were a consequence of unplanned development of industrial centres and uncontrolled growth of residential colonies, which altogether became hubs for economic, social, cultural, and political activities. A visualization of the past trends and patterns of growth enable the planning machineries to plan for appropriate basic infrastructure facilities (water, electricity, sanitation, etc.). This communication analyses the spatial patterns of Kolkata municipality- the 13th most populous and 8th largest urban agglomeration in the world. It has been one of themost prominent urban areas in eastern India which was once considered the capital of India during the erstwhile British colonial rule. The spatial patterns of urbanization of Kolkata with 10 km buffer have been analysed using temporal remote sensing data with zonal gradients and spatial metrics. The study area was divided into four zones and each zone was further divided into concentric circles of 1 km incrementing radii to understand the patterns and extent of urbanization at local levels. Its land use analysis has revealed a decline of vegetation from 33.6 % (1980) to 7.36 % (2010). During 2010, Kolkata's built-up had constituted 8.6 %, water bodies comprised of 3.15 %, whereas other categories made up about 80.87 %. Increased Shannon's entropy during the last decade highlights the tendency of sprawl that necessitated policy interventions to provide basic amenities. Spatial patterns through metrics indicated a compact and simple structured growth at the centre of the city and a distributed complex shape in the buffer region. Further, these metrics indicated that the city is on the verge of becoming a single large urban patch that would affect its ecological integrity. Temporal analyses of spatial patterns of urbanization help the city administration and city planners to visualize and understand the growth of the city so that they can provide better resource planning to create a sustainable city.