The Hindu: Published on 24th Oct 2025.
Why in News?
The northeast monsoon has arrived earlier than usual in Tamil Nadu for the second consecutive year, bringing excess rainfall across several regions. This situation has intensified flood risks, especially as water inflows from Kerala’s Mullaperiyar Dam coincide with Tamil Nadu’s own heavy rains. Authorities are concerned about the double inflow threat, damage to infrastructure, and public health challenges arising from prolonged waterlogging and flooding.
Background:
Tamil Nadu’s main rainy season is the northeast monsoon (October–December).
Kerala, on the other hand, receives rain primarily during the southwest monsoon (June–September).
The Mullaperiyar Dam, situated in Kerala but operated by Tamil Nadu, is a crucial link between the two States’ water systems.
In recent years, climate change has made monsoon patterns unpredictable — rainfall now tends to occur in short, intense bursts rather than evenly distributed showers.
Historically, Tamil Nadu has viewed “excess rainfall” as beneficial for agriculture, but changing climate realities are challenging this assumption.
Key Issues:
(a) Urban Flooding
Cities like Chennai and Theni are witnessing flash floods due to poor drainage and over-concretization.
Heavy rainfall overwhelms stormwater drains and causes waterlogging in low-lying areas.
Power cuts and transport disruption are becoming frequent during such spells.
(b) Agricultural Losses:
Waterlogging damages crops, reduces soil fertility, and washes away topsoil.
Fungal diseases and pests thrive in high-moisture conditions.
Financial losses for farmers are significant, particularly in delta regions.
(c) Public Health Concerns:
Stagnant water becomes a breeding ground for mosquitoes and causes diseases like malaria, dengue, leptospirosis, and Japanese encephalitis.
Sewage overflow during floods contaminates water sources, increasing risk of gastrointestinal infections.
(d) Infrastructure Damage:
High water table levels weaken building foundations, roads, and bridges.
Basement flooding, mold growth, and cracks appear in older structures.
Repair and rebuilding costs burden both households and the State exchequer.
(e) Mullaperiyar Dam Factor:
The Mullaperiyar Dam in Kerala’s Idukki district supplies irrigation water to Tamil Nadu.
During intense rainfall, Kerala’s catchment areas fill the dam quickly, forcing Tamil Nadu to open shutters.
The released water flows both toward Kerala’s Idukki lowlands and Tamil Nadu’s Vaigai basin, creating a double flood impact.
Currently, all 13 shutters of the dam are open, worsening flooding in Theni district and adjoining areas.
Current Situation on the Ground:
Theni and nearby districts are witnessing flooding in farmland and residential areas.
Tamil Nadu is struggling to handle simultaneous rainfall inflows — its own monsoon and the overflow from Kerala.
The State Disaster Management Authority is on high alert, monitoring water levels in Vaigai, Thamirabarani, and Cauvery basins.
Rescue operations and preventive evacuations are underway in affected zones.
Environmental and Economic Impacts:
Soil erosion and loss of nutrients affect long-term agricultural productivity.
Water contamination reduces drinking water safety.
Damage to public infrastructure (roads, bridges, power lines) incurs huge financial costs.
Economic activity and transport are hampered by prolonged flooding.
Psychological stress and displacement affect the social fabric of flood-hit communities.
Role of Climate Change:
Climate change is increasing the frequency of short-duration, high-intensity rainfall.
Traditional flood control measures and drainage infrastructure are proving inadequate.
The pattern indicates a shift from predictable monsoons to erratic extremes, calling for adaptive strategies in both urban planning and agricultural management.
Government Measures & Needed Steps:
Continuous monitoring of dam levels and river inflows through satellite and IoT-based sensors.
Development of integrated flood management plans involving both Kerala and Tamil Nadu.
Urban redesign focusing on natural drainage systems, wetland restoration, and rainwater harvesting.
Strengthening public health surveillance during and after flood periods.
Creating climate-resilient agricultural practices and compensation mechanisms for affected farmers.
Conclusion:
- The Tamil Nadu flood situation underscores a larger climate reality — “excess is not always good.”
- Rainfall abundance, when combined with poor urban design, inter-State water dependencies, and rising temperatures, can quickly turn into disaster. A balanced and coordinated approach between States, coupled with modern flood management and climate adaptation strategies, is essential to protect lives, livelihoods, and infrastructure in the years ahead.
