Additional space to be created in Cholavaram water body to deal with city’s increasing needs

Nearly 135 years after it was built, the reservoir in Cholavaram, one of the storage points for the Chennai’s drinking water supply, is being spruced up. To tackle the city’s growing water needs, additional space for storage is being created in the reservoir.

Once the project is completed in a couple of weeks, the level of the full reservoir would be raised by one foot, to hold an additional 200 million cubic feet (mcft) of water. At present, it has a capacity to store 881 mcft.

The additional storage will equal one week’s drinking water supply for city residents. Currently, Chennai Metrowater draws around 35 mcft from the city’s reservoirs to provide 830 million litres of water daily.

Smallest storage

The Cholavaram reservoir, located nearly 25 km north of Chennai, is the smallest of the four water bodies – the others are in Red Hills, Chembarampakkam and Poondi – that supply drinking water to the city. Though water is not drawn directly from it, the reservoir often saves the city from a water crisis. Whenever storage dwindles in the reservoir in Red Hills, water is discharged into a nearly 5 km-long channel, to enhance storage and sustain drinking water supply.

Every year, the reservoir gets filled during northeast monsoon and the surplus water is released through a weir, a structure constructed to let excess water flow into the Kosasthalaiyar river. Storage, which can dip to a minimum – such as the 91 mcft it had on Tuesday – can go up rapidly to its optimum level during the rainy season.

Rs. 50 lakh project

To prevent rainwater from draining into the sea, the Water Resources Department took up the project to increase the storage at a cost of Rs. 50 lakh.

Pointing to the work being carried out on the weir, which resembles a staircase, a WRD official said the weir had been designed in such a way so as to reduce the velocity of surplus water escaping into the sea. “We can increase the crust of the weir by only one foot. Otherwise, the increasing water level will inundate surrounding villages including Nallur and Poochiathipedu,” the official said.

While the increase in storage level means more water for the city as Chennai Metrowater purchased the rights to use these resources entirely for the city many decades ago, this will also ensure water availability in Cholavaram and 40 other nearby villages, including Erumaivettipalayam and Siruniyam.

V.S. Lingam, a resident of Cholavaram, said: “There are many packaged drinking water units here as groundwater is available within 20 feet. Increasing the water level will help recharge ground water and help residents and farmers in the surrounding villages.”

Meanwhile, a tender to strengthen and widen the reservoir’s earthen bund at a cost of Rs.7.96 crore is being examined.

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