CHENNAI: A study by Anna University's Centre for Climate Change and Disaster Management stated that Tamil Nadu's wetlands are among the state's strongest natural defences against climate change, flooding and rising urban temperatures. The university has also announced plans to introduce Wetland Health Cards for 65 wetlands across the state to support long-term conservation and scientific monitoring.
The study, led by Dr S Kanmani, professor and head of the department of Civil Engineering and the Centre for Climate Change and Disaster Management, found that several wetlands continue to maintain healthy ecological conditions and play a vital role in flood mitigation, groundwater recharge, biodiversity conservation and carbon sequestration.
Researchers took extensive field surveys and laboratory analyses of estuaries, lagoons, inland wetlands and river mouths across Tamil Nadu. The assessment examined water and sediment quality, ecosystem health, biodiversity, greenhouse gas impacts and the ecological services provided by wetlands.
The findings showed Mullimunnai wetland, Vellervelli Eri, Sivagalai Periyakulam, Punnakayal, Palayakayal, Manakudy Estuary and Tirupanichettikulam wetland continue to exhibit stable water quality, balanced pH levels, and relatively low pollution, indicating strong ecological resilience.
However, the study identified localised environmental stress in the Odiyur Backwater Wetland in Chengalpattu and Adyar Creek due to untreated sewage discharge, eutrophication and urban pollution.
The report highlighted that Chennai's average temperatures have increased over the past century, with urban heat island effects becoming more pronounced. It also cited the 2015 Chennai floods as a reminder of the consequences of losing wetlands and natural drainage systems.
Prof. Kanmani said wetlands function as natural climate infrastructure, noting that a single hectare can store nearly 12 million litres of floodwater, reducing flood risks while cooling surrounding areas and supporting groundwater recharge. She added that wetland restoration is not merely an environmental measure but a critical investment in building climate-resilient cities.
As part of the initiative, Anna University will prepare Wetland Health Cards and develop a comprehensive digital database covering 65 wetlands. The database will document water quality, sediment contamination and ecosystem health indicators to support restoration, long-term monitoring and evidence-based policy decisions.
The initiative aligns with the Tamil Nadu Wetland Mission and the National Plan for Conservation of Aquatic Ecosystems. The university also plans capacity-building programmes for self-help groups, local bodies and citizen volunteers on wetland conservation, waste segregation and environmental monitoring. Schools, eco-clubs and community organisations will be encouraged to participate in citizen science programmes.
The study recommended stricter control of untreated effluent discharge, habitat restoration, sustainable regulation of water inflows and protection of habitats for birds, fish and native plant species. It also called for wetlands to be recognised as critical urban infrastructure and integrated into urban master plans alongside forests, green corridors and other nature-based solutions.
The researchers concluded that protecting and restoring wetlands is one of the most cost-effective and sustainable ways to address flooding, rising temperatures, groundwater depletion and biodiversity loss, making them essential to Tamil Nadu's climate-resilient future.