Flood, Drought Alert By TN’s El Niño Expert Advisory Panel
The committee warned of more than normal rainfall and intense cyclones and severe urban flooding from October to December during the northeast monsoon
Chennai:With the Tamil Nadu government’s expert advisory committee on El Nino delivering a multi-hazard warning for 2026-27 and 2027-2028 cycles, including severe floods during rainy season and severe drought during summer, the government is speeding up its flood mitigation work as well as desilting of water bodies and canals to store water.
The high-level committee, constituted by Chief Minister C. Joseph Vijay, comprised climate scientists from IIT Madras, Anna University and weather experts and it submitted its report giving a multi-hazard warning from the last months of 2026 to 2028. The committee warned that El Nino should not be equated only with drought and it also triggers extreme and contrasting weather paradoxes.
The committee warned of more than normal rainfall and intense cyclones and severe urban flooding from October to December during the northeast monsoon. Since the rains will not be uniform throughout the state, there will be deficiency of rainfall in several areas followed by severe heat stress and water scarcity in 2027.
Severe floods are predicted for the coastal districts of Chennai and Cuddalore, besides landslides and sudden flash floods in the hilly terrains of the Nilgiris, Coimbatore and Dindigul. The panel has recommended the deployment of advanced drones for damage assessment, search and rescue routes and tracking of waterlogged terrain.
One of the major recommendations of the El Nino expert committee is to ensure that every critical river basin, agricultural tank and storm channel is heavily desilted to accommodate sudden volume of flood water. To face the summer drought, the government has been asked to secure alternative drinking water sources.
Extensive flood mitigation works were carried out in Chennai and its surrounding districts from 2022 and the number of highly vulnerable flood zones in the city has come down from 800 in 2015 to 219 in 2026.
The flood mitigation works are being carried out in major geographical basins, including Kosasthalaiyar in north Chennai, Kovalam in south Chennai, Otteri nullah zero point to the Cooum river drain project for western Chennai, Tidel Park and south IIT campus area and widening of canals, including the Captain Cotton canal and Virugambakkam canal.
The Kosasthalaiyar basin project, covering 651 km, has been completed and Kovalam basin project is in the final stages. The stormwater drains for a distance of 1,102 out of the 1,683 km had been desilted and more than 1,320 high-power dewatering motor pumps are strategically stationed near subways and chronically waterlogging areas to manually drain stagnant water.
The boulders blocking the flow of water into the Cooum have been cleared. The CMDA is completing the restoration of 10 major urban lakes, including Retteri, Velachery, Puzhal and Perumbakkam.
Around Chennai, a total of 51 lakes have been rejuvenated and the government is studying how to convert the Moovarasampet quarry into a balancing reservoir to take the sudden urban floodwater from the neighbouring areas to avoid flooding. The major scheme to relieve Velachery and OMR is the widening and clearing of the Okkiyam Maduvu channel. This would ensure that the water drained from the Pallikaranai marshland flows smoothly into the Buckingham canal without causing floods in the residential areas.
The flood mitigation works in Pallikaranai is being speeded up since the marshland serves to drain the floods from Velachery and areas of south Chennai. A channel, at a cost of Rs. 91 crore, is being constructed to drain 1,000 cubic feet of water per second to protect Velachery, Semmenchery and Perumbakkam from sudden floods.
The drainage network project, at an estimated cost of Rs. 73 crore, along the Old Mahabalipuram Road to Thoraipakkam, is nearing completion in the Sholinganallur zone. There will be no flooding in residential areas along the Old Mahabalipuram Road since the water will quickly drain into the Buckingham canal.
The Pallavaram-Thoraipakkam radial elevated bridge has become a bottleneck for 2 km, obstructing the flow of water, and the government is planning to replace it with an elevated bridge at a cost of Rs. 450 crore to allow the smooth flow of water. Water hyacinth accumulation in peripheral lake linkages like the Navalur lake are being cleared using floating excavators.
