IIT-Kgp study maps where Kolkata can grow and where it must stop
Times of India | 3 August 2026
Kolkata: Kolkata’s next phase of growth must be guided by where the city can expand safely and where expansion must stop. A new IIT Kharagpur study, 'Heat island, pollution load and urban sprawl in the Kolkata metropolitan city of India during 2000–2020: implications for its sustainability’ shows that two decades of rapid urbanisation have made the Kolkata Metropolitan Area hotter, more polluted and more exposed to climate risks.
Between 2000 and 2020, Kolkata lost more than 60 square kilometres of tree cover, 18-20 square kilometres of agricultural land, 20-25 square kilometres of barren land and nearly 10 sq km of water bodies. Built-up land increased from 72% to 86%, replacing natural cooling systems with concrete, roads and dense construction. This has intensified the urban heat island effect, especially before the monsoon, when some parts of the city record temperatures 4-6°C higher than surrounding areas.
The study identifies New Town, Rajarhat, Dankuni, Barasat, Madhyamgram, Bhangar, Sonarpur, Maheshtala and Garia as major urban expansion zones over the past two decades. These areas now need stricter planning. Future construction should be directed toward already disturbed land, brownfield sites, vacant urban plots and redevelopment areas rather than greenfield expansion.
Kolkata can grow in Dankuni through brownfield and industrial redevelopment, in Maheshtala through reuse of industrial land, in existing vacant and infill areas of New Town, and within already built-up parts of Rajarhat. Vacant urban land inside the KMC area should also be prioritised for compact, planned development. These locations can absorb growth without further damaging wetlands, farmland or tree-covered landscapes.
Growth must be controlled in Barasat, Madhyamgram, parts of Rajarhat’s agricultural fringe, Behala and the Dum Dum corridor. These areas require green buffers, lower-density planning, protection of remaining vegetation and limits on further land conversion. Without controls, they risk becoming hotter, more congested and more polluted.
Urban expansion must stop in the East Kolkata Wetlands, Bhangar, Sonarpur, the Hooghly River floodplain, remaining agricultural land around Rajarhat, major lakes, wetlands and surviving tree-covered areas. These landscapes protect Kolkata by storing water, reducing flood risk, cooling the city and supporting livelihoods. Converting them into built-up land would increase heat, pollution and climate vulnerability.
The study also identifies areas needing urgent greening. Central Kolkata, Esplanade, Park Street, Dalhousie Square, Bowbazar, the New Town core and the Howrah industrial belt require more trees, parks, shaded streets, green roofs and pollution-reducing infrastructure. These are among the city’s hottest and most polluted zones because of traffic, dense construction and limited vegetation.
Kalyani, Halisahar and Kanchrapara offer important lessons for Kolkata. Their relatively cooler conditions show that planned development with adequate green cover can support growth while reducing environmental stress.