36 Trichy wards at high risk of heat wave: Study

Trichy: More than half of Trichy city is highly or very highly vulnerable to heat waves and subsequent public health and environmental impacts, a study led by Tamil Nadu govt has found. Titled ‘Urban Heat Island (UHI) Assessment and Strategic Guidelines for Urban Cooling, the study was conducted in Chennai, Coimbatore, Trichy, and Tirunelveli by state govt's Tamil Nadu Green Climate Company (TNGCC) and International Council for Local Environment Initiatives (ICLEI), South Asia.Ward-level heat risk index compiled based on parameters such as land surface temperature (LST), urban heat island (UHI), and built-up areas has categorised 16 wards in Trichy city as ‘very high-risk,' and another 20 as high-risk, most prone to heat stress. The study called for targeted approach like urban greening and urban cooling drives to mitigate heat stress challenges.Trichy city was chosen as it is in the interior region and rapidly urbanised at the cost of green cover. According to the Land Use Land Cover (LULC) analysis, the report said the green cover or vegetation area in Trichy city as of 2024 stands at only 3% of the total area, but the built-up area accounts for 59%. A normalized difference vegetation index (NDVI) study conducted to ascertain dense vegetation has revealed that only three wards in the city — Srirangam (ward 1), Ananda Avenue (ward 18), and Kamaraj Nagar (ward 37) — have more green gardens. Wards like Rockfort (ward 14) and Big Bazaar Street (ward 19) have low green cover but high built-up areas. Areas like Ariyamangalam, Palpannai Junction, and Central Bus Stand have high land surface temperatures. "Both residents and authorities are not encouraging open green spaces. Vacant spaces are closed with paver blocks or concrete mixture. So obviously, heat risks will increase," S Vijayakumar, a city-based senior architect, said.Urban heat islands, which mean areas that are significantly warmer than surrounding rural areas, have increased in Panjapur, Trichy airport and Karumandapam vicinity. Based on heat hazards (land surface temperature), exposure (population density), and vulnerabilities (limited green space), the study has found 17 wards to be of low and very low heat risk. It categorised 12 wards in the medium-risk category, but 36 wards under high to very high heat risk categories. "Even the existing green covers are concentrated in educational institutions across the city. Public should come forward to enhance green cover in their own properties too," V Anand Gideon, dean, extension activities, Bishop Heber College, said. The study has also listed ward-level urban cooling interventions such as cooling roofs (reflect sunlight), community parks, improved thermal ventilation in slum areas, and restoration of public tanks. "We have identified vacant properties within the city to raise green cover under the Miyawaki method. After the election, work will commence to increase the green cover," a senior corporation official said.