CHENNAI: A comprehensive new study led by the National Institute of Technology, Trichy, has issued a stark warning about the rising flood vulnerability along the Tamil Nadu coast — including Chennai, Puducherry, and five other key districts — with 91% of the region projected to fall under high or very high flood risk categories by 2100.
Published in Geoscience Letters and reported by The Times of India, the study points to unchecked urban expansion, rapid land-use changes, shrinking water bodies, and increasing erratic rainfall driven by climate change as the chief culprits. Districts identified as high-risk include Chennai, Chengalpet, Kancheepuram, Cuddalore, Nagapattinam, and Puducherry.
The findings draw on satellite imagery, machine learning models, and future emission scenarios (SSP370 and SSP585), under which flat terrains and low-lying coastal zones are shown to become increasingly susceptible to floods. According to the authors, even under moderate climate change conditions, the percentage of flood-prone zones is expected to rise steadily through 2050, and drastically by 2100.
Key coastal cities like Chennai are particularly vulnerable due to dense urbanisation and degraded natural drainage systems. “It’s not just about more rain, it’s about shorter, more intense downpours that overwhelm land without proper drainage,” explained M V Ramana Murthy, former director of the National Centre for Coastal Research.
Regions like Nagapattinam and Vedaranyam are also undergoing alarming changes — from coastal erosion to land use shifts in aquaculture — while places like Tuticorin and Ramanathapuram are seeing agricultural and salt pan land swallowed up by industry or scrubland.
The researchers recommend the immediate use of machine-learning based flood maps to define strict zoning laws and halt development in vulnerable coastal stretches. “This study should serve as a wake-up call,” said G Sundarrajan of Poovulagin Nanbargal, adding that planning authorities must rethink how coastal growth is managed.