Built-up area in Mumbai Metropolitan Region grew much more than population, reveals study

The rate of increase in the built-up area in the Mumbai Metropolitan Region (MMR) in the past four decades was more than the growth rate of the population in the

The rate of increase in the built-up area in the Mumbai Metropolitan Region (MMR) in the past four decades was more than the growth rate of the population in the region, revealed a study released by a professor and a former research student of the Indian Institute of Technology-Bombay (IIT-B).

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The study, which used satellite images from over four decades to study the urban growth patterns in MMR found that between 1972 and 2011, the built-up area increased by 4.5 times, from 234 square kilometre to 1,056 square kilometre, while the population grew three-fold.

The researchers studied the spread of the built-up area covered by the buildings and roads, using archived Landsat images. This data was then used to identify the direction and rate of growth of MMR, which consists of Greater Mumbai, the suburban districts and parts of Thane and Raigad districts.

“We used a technique called object-based image analysis, which we thought was best suited to understand the growth of a city like Mumbai. The idea is to use information on how the city grew in the past few decades and use it to project the future growth of the city, by eliminating the negative impacts of urbanisation,” said Prof Shirish Gedam, Centre of Studies in Resources Engineering (CSRE), IIT-B.

Gedam added that this project was a research topic for his PhD student Dr Priya Mendiratta and took five years for completion.

She said, “While promoting growth, it is likely that decision-makers may overlook environmental conservation or utilisation of public money as well as natural resources. However, if the growth directions are observed, it is possible to grow and maintain the delicate balance between development and conservation of the fragile ecology.”

The hypothesis of the study was that construction ate into cultivated lands, forests and water bodies, with the rate of increase in the built-up area being more than the growth rate of population. “The urban footprint will increase and put stress on the transport network and destroy forests and wetlands,” added Gedam.

The research shows the urban area expanded towards the areas of Vasai and Virar in the north and Bhiwandi in the east along the Central Railway line on one side, and across the Thane creek to Navi Mumbai on the other. “These three growth directions encompass the Sanjay Gandhi National Park, the Matheran Eco-Sensitive Zone and the Karnala Bird Sanctuary. Any changes to these areas directly affect the ecological system in the surroundings,” the paper stated.