The Water Resources Department (WRD) is preparing a detailed project report incorporating proposals for flood control and climate adaptive infrastructure as part of a comprehensive restoration of the Adyar river in a few years.
The ambitious proposal would have projects for conservation of resources. The department is focusing more on the upper reaches of the river to execute work for flood mitigation and integrated improvement.
The department is studying the feasibility of widening the 25-km portion of the river wherever needed between Adanur and Manapakkam to reduce inundation in surrounding areas, including Tambaram and Mudichur.
For instance, the portion of the river between Vandalur and Wallajahbad Road and Padappai and Thirumudivakkam is narrow and only 15-20 metre wide at some stretches. Areas along those stretches got flooded whenever the river flowed at its peak level.
Officials said the stretch of the river along southern suburbs had a capacity to carry about 14,000-15,000 cusecs. Even if it carried 18,000 cusecs of water, it would spill over to surrounding localities.
The department is surveying the possibility of widening the river at vulnerable portions near Adanur, Nandivaram and Urapakkam and acquiring lands wherever necessary. There are plans to widen the river to about 50-60 metre to increase its carrying capacity up to 25,000 cusecs.
Besides bridging the missing links, there are plans to create additional macro drains near Urapakkam and Guduvancherry to divert surplus water into the river. “We are also checking the possibility of replacing bund with retaining wall in flood-prone areas to enhance carrying capacity of the river.
For instance, a 20-metre bund on either side of the river can be replaced with a 10-metre retaining wall to gain additional space,” said an official.
Similarly, flood regulators would be provided in tailend waterbodies such as Adanur and Mannivakkam that drain surplus water into the river. A suggestion to create new reservoirs in places such as Orathur was under study.
A few tanks in urban pockets of the Adyar basin without ayacut area and less sewage pollution would be converted as sources of drinking water supply for Chennai. Some of the tanks in Nemam, Mannivakkam, Nandivaram and Sriperumbudur were being considered for this.
Once the feasibility study was completed, encroachments would be enumerated and lands that were yet to become urbanised would be acquired for the project. Work may be taken up in packages depending on the funding agency, the officials added.