Sriperumbudur, Oragadam among critical heat hotspots in Tamil Nadu, finds report

Chennai: Sriperumbudur and Oragadam – home to some of the leading electronics and automobile manufacturers – had a minimal built-up area of about 5 square kilometres but have expanded to about 25 square kilometres over 40 years, at the cost of traditional irrigation tanks and surface water bodies, leading to their emergence as critical heat hotspots.

Not just these industrial blocks, but 94 of the 389 blocks surveyed in Tamil Nadu have reported significant increases in heat intensification, including ecologically sensitive hill blocks like Kodaikanal and Mayiladumparai, due to rapid urbanisation, according to the study Urban Growth and Thermal Stress: A Decadal Assessment of Built-Up Area and Climate Interactions.

The study, conducted by the State Planning Commission of Tamil Nadu, noted that field-level evidence from blocks such as Kundrathur, Sholavaram, and Sriperumbudur suggests that the disappearance of traditional irrigation tanks and surface water bodies has compounded the local warming trend.

“Without these water bodies serving as natural thermal regulators, the urban environment becomes more vulnerable to heat accumulation and slower nocturnal cooling, aggravating the urban heat island effect,” the report added. Sriperumbudur and Oragadam – which boast massive industrial parks owned by government and private firms – are home to Hyundai, BMW, Daimler, Renault-Nissan, Dell, Samsung, Foxconn, and Salcomp, among other major companies.

Sriperumbudur and nearby Kundrathur had a minimal built-up area of about 5 square kilometres in 1985, but now they have expanded to about 25 square kilometres and 21 square kilometres, respectively. The report has also provided ample grounds for activists to raise concerns about the greenfield airport planned for Chennai in Parandur, about 30 km from Sriperumbudur, whose construction is likely to destroy several water bodies.

While flagging heat as a major issue requiring government focus, the report suggests targeted adaptation strategies, since the correlation between urbanization and elevated heat levels is especially pronounced in regions where natural water bodies have either shrunk or disappeared entirely.

The report states that the dual challenge of rapid urbanization and a significant rise in temperature warrants urgent attention. It adds that overlaying urbanization data with heat exposure assessments provides compelling evidence that land use changes, particularly built-up area expansion, are closely associated with rising thermal stress.

Preservation and integration of green infrastructure, enforcement of zoning regulations to control haphazard expansion, adoption of climate-responsive building practices, and expansion of urban cooling measures—such as tree-lined avenues, green roofs, and water-sensitive urban design—are some of the measures the report recommends to the government.

“Open spaces and water bodies in Chennai have been destroyed enough, as reports suggest that the built-up area in the city was 74 percent as of 2015. The city has no long open spaces, and water bodies have shrunk from 48 square kilometres in 1990 to 18 square kilometres now,” Prabhakaran Veeraarasu, Environmental Engineer at Poovulagin Nanbargal, an NGO, told DH.

While the dataset highlights several blocks with severe thermal stress and concurrent urbanization, it also reveals a broader spatial trend: clusters of high-heat zones radiating outward from urban cores into previously low-density rural or peri-urban areas. Veeraarasu emphasized the need for the third master plan for Chennai city to focus on water bodies and urged the government to prioritize preserving the traditional water tank system.

“The disappearance of the water tank system is one of the reasons for flooding in the Sriperumbudur region. Destroying water bodies and building concrete structures are among the main causes of heat, floods, and droughts. The heat effect is due to concrete structures, as nighttime land surface temperature (LST) is much higher in about 80 blocks in the state,” he added.

Many blocks that were primarily agricultural in 1985 have seen over 10 square kilometres of land converted into built-up space by 2015. Such shifts signify a critical transition in land functionality -- from resource-generating to heat-retaining surfaces, the report said.

It added that the implications extend beyond temperature increases to include loss of ecological services, increased surface runoff, and lowered groundwater recharge potential. As urban imperviousness grows, the landscape’s ability to mediate climatic extremes diminishes, thereby reducing the region’s climate resilience.