Chennai

Action plan to protect city from climate change

Chennai’s trysts with monsoon are often volatile and determine the abundance or scarcity of resources the following year.

In a concerted effort to protect the city from the vicious cycle of flood and drought, the Water Resources Department is preparing a comprehensive action plan for better water management and reducing the impact of climate change-related natural calamities on the city.

Last year, nearly 32 tmcft of surplus water was released from the Poondi reservoir alone following heavy inflow and only 15-20% of the resources were conserved due to lack of sufficient storage facilities. In 2020, 20 tmcft of water was discharged from the reservoir during monsoon.

“We are chalking out project proposals under the ‘Chennai City Water Supply Augmentation, Flood Mitigation and Resilient to Climate Change’. We are considering about 900 proposals. This will be an attempt to address different challenges in making the city self-reliant in water supply and provide nature-based long-term solutions in the city’s river basins, including the Adyar, the Kovalam and the Kosathalaiyar,” said an official.

If the projects are executed, nearly 22 tmcft of additional water can be conserved.

Among the various strategies are conservation of floodwater runoff with new reservoirs and revival of nearly extinct or long neglected waterbodies and climate adaptive measures.

Given the change in weather pattern, including increase in intense rains in short spells, the department plans to revive waterbodies in the Chennai metropolitan area. “Many of these are affected by encroachments and rapid urbanisation. We plan to identify such lakes that act as an ecological balance in boosting groundwater and reduce localised waterlogging,” the official said.

Kolathur lake is a fine example of highly encroached and exploited waterbody that had scope for rejuvenation. Similarly, lakes in Rajakilpakkam, Arabatheri near Avadi and Puthagaram near Ambattur, are not used for irrigation or drinking water needs. “We will have to revive the vanishing supply and surplus water channels to sustain restoration of such lakes,” the official said.

In a bid to conserve runoff water, there are plans to create new reservoirs in the catchment areas of the city’s basins. For instance, Ramanjeri, upstream of Poondi, and Nemam, above Chembarambakkam reservoir, are being considered to be developed as storage facilities.

Besides deepening the lakes in Thiruninravur, Sriperumbudur and Pillaipakkam, feasibility study would have to be initiated for intra-Basin transfer of floodwater. Transfer of surplus water from catchment areas near Oragadam in the Adyar Basin to the Palar through Neenjal Maduvu and feed surrounding lakes is one of the proposals.

The department is planning climate adaptive remodeling of waterbodies. Flood regulators would be constructed in lakes such as Porur to transfer or discharge existing water to prepare the waterbodies for sudden and heavy inflow during rains.

“Siltation remains a major challenge that has reduced storage capacity of lakes. Afforestation in catchment and foreshore areas is planned to reduce silt deposits. Silt traps or trenches of masonry or rubble structure will be built in the river beds or lake beds to trap the silt carried by floodwater,” said an official. The department plans to submit the proposals to the State government for studies to be taken up for feasibility of the projects.


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Printable version | Feb 13, 2022 7:13:26 am | https://www.thehindu.com/news/cities/chennai/action-plan-to-protect-city-from-climate-change/article38336275.ece