After nearly 200 years, officials from the Tamil Nadu Water Resources Department (WRD) Thursday began desilting the Chembarambakkam reservoir, one of the four reservoirs that provide drinking water to Chennai at Kundrathur.
A WRD official who is in charge of the desilting process told indianexpress.com that a government order to desilt the lake had been received about four to five months ago. However, it had been delayed owing to the completion of formalities.
Elaborating on the process, the officer said that it would take eight years for the entire lake, which has a storage capacity of 3645 million cubic feet (mcft), to be desilted completely. “151.80 lakh cubic metres of silt will be removed and transported through 25.30 lakh lorry loads”, he said.
The lake will be desilted using a revenue model where contractors will pay the government a sum to remove the silt from the reservoir and use it for building bunds and other infrastructure. “Through this model, the government will receive an income of Rs 191.27 crore after the silt is sold to the highest bidder,” said the official.
The WRD has already chosen a contractor for the project after issuing tenders but the details are yet to be disclosed by the government.
Although the lake has a storage capacity 3645 mcft, years of silt accumulated on the bed has restricted storage to 80 per cent of its capacity. “We will be restoring close to 536 mcft of storage to the lake, the way it was 200 years ago”, said the official.
Located in a rain shadow area, Chennai has traditionally relied on water drawn from the Chembarambakkam, Poondi, Cholavaram and Red Hills reservoirs to provide drinking water to citizens. However, poor rainfall last year and accumulation of silt robbed the reservoirs from storing water for years, which culminated into an acute water crisis in Chennai this summer.
The WRD official assured that the water being stored in the reservoir would remain untouched during the process. “Desilting work and supply of water will occur simultaneously. We might not be able to arrange for lorries to carry the silt during heavy rainfall but apart from that, desilting will occur continuously for the next eight years. Work will only be halted briefly during the monsoon season,” he said.
Apart from Chembarambakkam, the officer said that the WRD had already begun desilting the Cholavaram and Red Hills reservoirs and would commence work on Poondi shortly. Regarding other lakes and ponds in the city that require desilting, the officer said the agency was in talks with the Greater Chennai Corporation (GCC).
After this, periodical desilting of the reservoirs would be done after assessing the amount of deposit in the lake beds every few years.