With the rain lashing several parts of the State, residents of Chennai and its suburbs have but only one fear: what will happen to them during the northeast monsoon or earlier, if there is a cloudburst during the southwest monsoon.
Chennai can face inundation this year too in the event of incessant rain as it was the case when Cyclone Michaung struck the city in December 2023, Chief Secretary Shiv Das Meena has said. On May 25, he inspected the problem areas in the Greater Chennai Corporation’s Zone 10 (Kodambakkam), Kovalam Basin, Anakaputhur, Pammal, Chitlapakkam, Irumbuliyur, Guduvanchery, Polacheri, and Thiruporur.
All the rainwater from the lakes in Kancheepuram and Chengalpattu districts must pass through the Chembarambakkam lake, the Buckingham Canal, the Cooum and the Adyar in Chennai city to reach the sea, and this is the main reason for inundation, Mr. Meena has said. There are 25 waterbodies upstream of the Chembarambakkam reservoir. From the catchments of this reservoir, water is flowing to the Adyar from 340 waterbodies, of which nearly 240 are upstream of the Mudichur lake.
He has said, “The State is working on many solutions. Additional passageways are being created for water in many areas to quickly drain into the sea. Roads near the waterbodies may be flooded, but we expect the water to recede faster. Last time, the situation was unprecedented. We are continuously improving the storm water drain network in the southern region [of Chennai], including Kovalam. Desilting will also be done. But if there is continuous heavy rain this year too, some inundation may take place. We have to prepare mitigation and relief measures, and we are working on them.”
R. Srinivasan, 36, says that for the first time, flooding up to 3 to 4 feet was noticed in his area — Pattunool Chathram in Sriperumbudur — during the cyclone in December 2023. “We have never seen water entering homes. Further, owing to incomplete storm water and sewage drains in the township, wastewater entered the lanes. The two-laning of the Kundrathur-Sriperumbudur State Highway reduced the size of the 10-foot culvert abutting it, causing water from the Sriperumbudur lake to enter the township.”
After several parts of Chennai were marooned last year, Arappor Iyakkam, under the aegis of ‘Makkal Medai’, released an audit of the flooded areas, setting forth the reasons for inundation and solutions.
Among them was the Medavakkam Sitheri lake, in Ward 8 of Ranganathapuram, Medavakkam Panchayat, Chengalpattu district, which is surrounded by Vijayanagaram and Ranganathapuram upstream and CBI Colony downstream. It receives water from the Nanmangalam reserve forest through canals crossing the Medavakkam-Tambaram Road. In 2023, the lake breached, flooding R.G. Nagar and CBI Colony, according to the audit.
“No maintenance activities, such as desilting, hyacinth removal, garbage removal, or bund maintenance, were done by the Block Development Officer or St. Thomas Mount Union. After the 2021 floods, a temporary canal was built, but it was not completed. This increased the flood risk. In 2023, the ‘Madagu’ inlet was not excavated, and this led to more flooding. A partially completed canal worsened the situation. The overflow from the lake floods Medavakkam (CBI Colony) and Vengaivasal (R.G. Nagar) before reaching the Perumpakkam lake. Suburban development closed the existing canals, causing frequent flooding. The only outlet for surplus water to reach the Perumbakkam lake through R.G. Nagar was blocked by multi-storey apartments. A small outlet through private land is insufficient, leading to the demolition of apartment walls each monsoon to allow water to flow,” the audit says.
In Sunnambu Kolathur village, the Keelkattalai lake overflowed, causing water stagnation for four days at Kagithapuram, Ambedkar Salai, Judges Colony, Bagyalakshmi Nagar, Raja Nagar, Krishna Nagar, Manimegalai Nagar, Engineers Avenue, Unmai Nagar, LIC Nagar, Rajeswari Nagar, and Viduthalai Nagar Extension. The ground floors, vehicles, and motor pumps were submerged, says the audit.
“The flood was caused by 13 lakes connected to the Keelkattalai lake surplus water canal which conveys the water to the Pallikaranai marsh. Poorly built retaining walls and encroachments, including a house and a coconut grove, narrowed the canal at a right-angle turn,” the report says.
Sunil Jayaram, an environmentalist at Chitlapakkam, says some missing links of the storm water drains have to be fixed by the local body. “The houses do not flood here, but daily life was affected by inundation of roads. The drains that connect the interior roads to the Sembakkam lake are only 2 feet wide and need revamping,” he adds. Pammal and Anakaputhur also faced a similar situation.
“The Thirupananthal lake at Krishna Nagar at Pammal near Pallavaram is surrounded by encroachments, which have reduced the lake’s capacity by 80%. As a result, the lake overflows, causing floods. This lake is critical both for water storage as well as flood prevention as this is one of the few remaining lakes in the area, apart from the Sooriyamman lake,” according to the audit.
Tambaram Government Hospital, Vetri Theatre, Thiruneermalai Junction, GST Road, Kattabomman Nagar, Mallika Nagar, Radial Road, RKV Avenue, Thiruthani Nagar, and Renuga Nagar were flooded. Further, the audit says the English Electric Nagar (East), a new residential-cum-commercial area, is flooded repeatedly as the surplus water canal from the Putheri lake to the Keelkattalai lake passes through this area.
Haris Sulthan of Arappor Iyakkam argues that apart from structural solutions, a survey of the groundwater recharge level and the original capacity of the waterbodies in Chennai and its suburbs, removal of encroachments, blocking of further development around sensitive locations and preservation of floodplains would help to improve the situation.
