Tenders to be called for flood mitigation measures in Chennai’s southern suburbs

The Water Resources Department has prepared estimates for the project, worth ₹70.5 crore, to provide relief to residents living around the Adyar river’s floodplain areas, such as Mudichur, Varadarajapuram and West Tambaram, that witnessed inundation during last year’s northeast monsoon.

The Water Resources Department (WRD) is in the process of calling for tenders to carry out improvement work in Adyar river, and build a bypass channel from the Somangalam tributary to the Adyar to mitigate flooding in southern suburbs.

The department has prepared estimates for the project, worth ₹70.5 crore, to provide relief to residents living around the floodplain areas, such as Mudichur, Varadarajapuram and West Tambaram, that witnessed inundation during last year’s northeast monsoon.

Residents of the southern suburbs wanted the department to accelerate the work. According to the WRD, the Adyar, which has an average width of about 30 m, falls short in flood carrying capacity due to rapid urbanisation. Though the river flow has been defined, the maximum flood level of the river is higher by four feet to six feet than the adjacent areas, leading to issues in draining flood water into the river.

One of the solutions proposed was to construct a bypass channel from the Somangalam tributary to the Adyar river along Outer Ring Road to decrease inundation at Mudichur and Varadharajapuram.

The Somangalam tributary drains surplus water from a group of tanks, including ones in Manimangalam and Somangalam, into the Adyar river. This led to a rise in flood levels of the river and the inundation of areas such as Royappa Nagar and Mahalakshmi Nagar in Mudichur.

The bypass channel would absorb a part of the floodwater discharge of the Somangalam tributary and reduce flood level in the river near the confluence point. This would help drain rainwater from abutting areas. The channel with a capacity to carry 850 cusecs (cubic feet per second) would drain water in the downstream portion where the river was wide, officials said.

Moreover, flood protection walls of 4 metre height would be constructed in the vulnerable and narrow portions between the 6th and 19th kilometre of the waterway. The department also proposes to deepen the river by an average of 2 m in flood prone areas to carry additional flow.

Dense rocks at the Thiruneermalai stretch of the river would also be removed to ensure smooth flow. The work would be taken up in the portions, including from Vandalur-Walajabad Road to Thirumudivakkam Road, to increase the carrying capacity of the river, officials said.

The projects were waiting for tenders to be called for and processed. Once that was done, work would be completed within a few months, officials added.