Chennai

Two tanks in Minjur to be linked to combat seawater intrusion

The Water Resources Department (WRD) plans to combine the Voyalur Periya Thamarai and Voyalur Mamanikal tanks, near Minjur, to create a new waterbody with increased storage capacity.

This is to enhance groundwater recharge in the region that is grappling with seawater intrusion.

The department proposes to create a new waterbody on the lines of the ongoing project to increase the storage capacity of the Kattur and Thathamanji tanks. WRD officials said the storage capacity of the waterbodies in Voyalur would be increased from the existing 100 million cubic feet (mcft) to about 300-400 mcft once the project is completed.

Field study

“We are in the process of preparing estimates and conducting a field study of the project. Several irrigation lands in the region may be provided up to 150 mcft for cultivation from the proposed waterbody, and the remaining amount could be used for supplying drinking water to surrounding villages,” an official said.

Height of weir

Besides desilting and strengthening the bunds, the WRD plans to increase the height of the weir, a structure that allows excess water to flow out automatically. This would also help in adding storage capacity.

As raising the height of both the bund and the weir may flood the land in the foreshore area, the land level will also be raised with silt.

The combined tank will be spread over 4.24 sq km and will benefit areas at least within a 5 km radius. The WRD is also simultaneously building dykes and checkdams across Araniar river to arrest seawater intrusion.

According to a recent study by the Department of Geology, Anna University, the Ponneri, Panchetti and Minjur coastal belt continues to be affected by seawater intrusion and the ingress has extended up to 18 km inland, near Vannipakkam, in 2019.

On the ongoing project, officials said nearly 25%-30% of the work to increase the storage at the Kattur-Thathamanji tank at a cost of ₹62.36 crore had been completed so far. The storage capacity would be enhanced from 58.27 mcft to 350 mcft.

Besides benefiting an ayacut area of 648.73 hectares, the water can also be used for the city’s water needs. The ongoing work would be completed by the upcoming northeast monsoon, officials added.

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Printable version | Apr 19, 2021 3:01:43 AM | https://www.thehindu.com/news/cities/chennai/two-tanks-in-minjur-to-be-linked-to-combat-seawater-intrusion/article33967106.ece

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