Year after year, whenever the floodgates of the Chembarambakkam Lake are opened, most of the downstream localities in Chennai’s southern suburbs get submerged, causing the residents untold hardships and financial distress.
The major reasons are the weak bunds along the course of the Adyar through which surplus water enters the residential areas, the failure to increase the capacity of several lakes, and the absence of check-dams. Therefore, residential areas adjoining the river — such as Mudichur, Manimangalam, Somangalam, Varadarajapuram, Thiruneermalai, Pammal, and Anakaputhur — get flooded.
P. Damodaran, former president of the Mudichur village panchayat, says the reason for the flooding is the poor desilting of the big lakes surrounding Mudichur. Mudichur and Varadarajapuram are surrounded by the Manimangalam Lake, Vandalur Periya Eri, Mudichur Periya Eri and Sikkanah Eri, he points out.
Except for Sikkanah Eri, all other waterbodies are maintained by the Water Resources Department. If the authorities strengthen the bunds of the river, desilt the lakes properly, and maintain the flood gates well, flooding will not happen in more than six wards of the village, he says.
The Adyar, which runs 42 kilometres before it drains into the sea, passes through Mudichur for nearly 10 kilometres. To prevent the Adyar water from flowing into the residential areas, the bunds of the river should be heightened and gates should be installed to prevent the excess water from entering the residential areas. The need for check-dams across the Adyar has been highlighted several times. The government proposed to build one at Varadarajapuram in 2019, but the project remains incomplete, he says.
The residents of Thiruneermalai, Chromepet, Nemilichery, Kovilambakkam, and Sunnambu Kolathur demand desilting and restoration of the lakes at Thiruneermalai, Narayanapuram, Nanmangalam, Nemilichery, and Sembakkam.
Social activist V. Santhanam points to the poor maintenance of the Thiruneermalai Lake and Veeraraghavan and Chitheri, the supplementary lakes. He says that if these lakes are desilted and deepened, rainwater can be saved to rejuvenate the waterbodies. The residents of Kovilambakkam and Sunnambu Kolathur have been demanding measures to protect the Narayanapuram Lake, which is being polluted with the discharge of sewage.
M. Kasi Raju of Kovilambakkam says excess water from the Narayanapuram Lake, one of the important waterbodies, flows into the Pallikaranai Marsh. But the waterbody is in a poor state owing to the dumping of garbage and discharge of sewage. The residents have been demanding that the lake be declared a bird sanctuary because migratory birds flock to it.
A senior official says that after Cyclone Michaung wreaked havoc in southern suburbs in December last, the Water Resources Department is preparing proposals to restore the flood-affected waterbodies and channels.
Water Resources Department officials say a cut-and-cover drain to link Medavakkam Lake and Anai Eri has been proposed through Thiruvalluvar Salai to a distance of 1.5 km. The project requires no land acquisition and the road is relatively wide. Measures are also being taken to provide a flood regulator and repair the surplus weir of the lake. A link will be established between the lakes at Moovarasanpattu and Madipakkam.
As for the waterbodies in the southern suburbs, the senior official says the Chennai Metropolitan Development Authority is involved in a proposal for restoration of several lakes, and ₹100 crore has been budgeted for the project.
The restoration is aimed at lake-front development and rejuvenation. The waterbodies around Mudichur, Perumbakkam, Velachery, Sembakkam and Madambakkam, and Adambakkam will be covered. Estimates are being prepared for calling for bids. These measures will prepare the areas for intense rain, the official says.
Several other missing links between various waterbodies have also been identified on the southern fringes of the city. The Water Resources Department is preparing proposals to restore the links that have vanished over the years because of urbanisation and encroachment. Among the proposals is one to bridge the gap between the waterbodies at Moovarasanpattu and Keelkattalai. Officials say that an additional cut-and-cover channel will be built to convey surplus water from the Sembakkam Lake to Nanmangalam. The existing surplus course, which is 20-metre-wide in its initial reaches, becomes narrow en route.
An additional link is being proposed to take water from the Narayanapuram Lake to the Pallikaranai Marsh through the Radial Road. This will help to mitigate floods in the surrounding areas and conserve resources, the official adds.
The official denies the charge of poor desilting, saying that monsoon preparedness projects are carried out methodically in all waterways, including the surplus courses. The surplus courses of the Pappan channel and the Nanmangalam Tank and the Perumbakkam surplus course were cleared of debris, silt and weeds ahead of the northeast monsoon. The Water Resources Department engaged floating machinery for the Keelkattalai surplus course so far as the Narayanapuram Tank to clear the vegetation.