Chennai Identifies 219 Vulnerable Spots as Northeast Monsoon Prep Ramps Up

The Greater Chennai Corporation has identified 219 vulnerable locations, including low-lying areas and stretches along the Old Mahabalipuram Road and East Coast Road, as part of its preparations for the Northeast monsoon, Commissioner G.S. Sameeran said on Wednesday.

Speaking after inspecting precautionary works at the Adyar estuary, the Commissioner said the Chief Minister had reviewed monsoon readiness with departmental officials on September 8 and September 22 and issued a series of directions. These included desilting the estuaries at Ennore, near Napier Bridge on the Cooum, at Besant Nagar on the Adyar and at Muttukadu in Kovalam, besides continuous monitoring and follow-up action at these sites.

Acting on these instructions, the Water Resources Department has taken up 200 projects at an estimated cost of ₹42 crore, of which close to 48% of the work has been completed.

On the Adyar, the Commissioner noted that the river is a dynamic system where erosion occurs on one side daily. While the stretch within Corporation limits runs 17.7 km, the river is about 42 km long in total and draws water from several catchment areas. He said flows from the Chembarambakkam catchment through Tiruneermalai can touch 30,000 cusecs at high levels, while water from Orathur, Nanmangalam and Somangalam can converge at Tiruneermalai and bring in about 19,000 cusecs. The urban area adds a further 15,000 cusecs, meaning flood-time flows of up to 70,000 cusecs have reached the estuary, with a peak of 72,000 cusecs recorded at one point. Under normal conditions, the river can carry about 35,000 to 40,000 cusecs. Widening the estuary is among the works under way, since a narrow mouth can cause backflow.

On Arcot Road, complex stormwater work has been restricted to night hours because of ongoing Metro Rail projects, with a contingency plan using 100-HP motors ready to pump water where gaps remain. Around Pallikaranai, where urbanisation has altered historical water bodies, cut-and-cover drains and weir arrangements have been planned to manage major watersheds and marsh flows.

At the 219 vulnerable low-lying locations, large campuses and metro stations will follow staggered pumping protocols to prevent immediate road flooding. Readiness is further supported by 1,320 motor pumps and 72 rescue boats, along with cash advances issued to the Fisheries Department for rapid response.

According to a press release, desilting of 1,10,211 silt catch pits has been completed in the first phase, while 65,076 pits have been covered in the second. Stormwater drain connectivity works have been taken up at 105 missing locations covering 922 metres, with 37 completed and 68 in progress.

Desilting is under way across 1,683 km of stormwater drains, of which 1,102 km has been finished. Desilting and water hyacinth removal have been carried out in 44 waterways maintained by the Corporation, 13 canals maintained by the Water Resources Department, and the Cooum, Adyar and Buckingham Canal. Improvement works covering 8,439 metres have been taken up in the Captain Cotton Canal, Secretariat Colony Canal, Otteri Nullah and Virugambakkam Canal, of which 6,977 metres has been completed.

Branches of 60,141 trees were pruned between January 1 and September 21, 2026, the release said. An online system for volunteer registration has also been developed, and monitoring is being carried out through Integrated Command and Control Centres at the Ripon Buildings complex, the Corporation headquarters, and three regional offices.