Gates of Chembarambakkam reservoir opened after 5 years

Good flow: Water released from the Chembarambakkam reservoir seen flowing in Adyar river near Saidapet.  

After nearly five years, the shutters of the Chembarambakkam reservoir were opened on Wednesday as a precautionary measure to prevent inundation, particularly in the upstream stretches.

From the initial 1,000 cubic feet per second released from the reservoir at noon, the Water Resources Department (WRD) released 5,000 cusecs into the Adyar river through the 14 shutters around 6 p.m.

With a steady increase in inflow to nearly 5,000 cusecs (cubic feet per second) and to maintain the water level close to 21.98 ft., the Water Resources Department decided to discharge the water with flood warnings.

The reservoir’s storage stood at 3,115 million cubic feet (mcft) against its capacity of 3,645 mcft. It may be recalled that Krishna water was being diverted to the waterbody until a few days ago. It received rainfall of about 10 cm till 6 p.m. on Wednesday.

Officials of the WRD noted that the measure to open the floodgates ahead of time was taken to avoid any backflow in the upstream stretches or the Adyar river’s tributaries. The release would be gradually raised at 500 cusecs per hour depending on the inflow of rainwater.

The WRD had increased the water release to 6,000 cusecs at 8 p.m. on Wednesday. Officials noted that the Adyar river carried a flow of 13,000 cusecs, which included flood water from other tanks and upstream. The water release will be maintained at 7,000 cusecs by night and again regulated by Thursday. “We expect the river to carry up to 20,000 cusecs by Thursday morning, given the heavy rainfall over the catchment areas due to Cyclone Nivar,” an official said.

The storm surge expected due to the Cyclone Nivar may not have a major impact on the Adyar river and is not likely to lead to flooding. Areas such as Rayappa Nagar and Mahalakashmi Nagar in Varadharajapuram, Mudichur and West Tambaram had localised flooding of 2-2.5 feet on Wednesday.

It would be regulated till Thursday, and the goal was to maintain the reservoir’s water level at 22 ft., which was 2 ft. below its total capacity.

“Only eight lakes out of 25 waterbodies upstream of the Chembarambakkam reservoir have filled up so far. Surplus from a few tanks upstream are draining into the waterway and it may be carrying 7,000 cusecs on Wednesday. The Adyar river has been widened to carry about 70,000 cusecs safely at Saidapet, and the maximum capacity is now nearly 1 lakh cusecs,” an official said.

According to Kancheepuram collector Mageswari Ravikumar, water release from Chembarambakkam reservoir was increased to nearly 9,000 cusecs of water around 10.30 p.m. corresponding to the inflow and heavy rains.

Residents need not fear flooding in the Adyar river as water release was being done in a controlled manner, taking into account flood water draining from the upstream reaches too, officials said.

Flood warning was issued to low-level areas along the river and surplus courses such as Kundrathur, Sirukalathur, Tirumudivakkam, Tiruneermalai and in the city limits. The WRD also discharged water from tanks in the tail-end of the river such as Manimangalam and Nandivaram to maintain their level 2 ft. lower than capacity.

An advisory of the Central Water Commission noted that the Adyar river may carry a flow of 16,000 cusecs-18,000 cusecs near Saidapet against 1 lakh cusecs in 2015 flood due to intense rains on Wednesday. The two other major reservoirs have been getting steady inflows too.

Other reservoirs

While the Poondi reservoir, mostly gets Krishna water as inflow, the Red Hills reservoir received an inflow of 2,500 cusecs at 6 p.m. and its water level stood at 18 ft. against a total capacity of 21.20 ft.

Sources said the shutters of the Red Hills reservoir could also be opened on Thursday, but only depending on the inflow and rainfall. Initially, about 500 cusecs may be released. The water level may be maintained at 20 ft.

However, the Poondi reservoir needs another 1,000 mcft to fill up and the inflow is expected to rise double from the present 2,000 cusecs till Thursday morning. There were not many chance for the floodgates to be opened, an official said.

In Kancheepuram and Chengalpattu, 148 tanks of the total 909 tanks maintained by the WRD have filled up so far. Nearly 254 tanks have reached above 75% of their storage capacity. The water level at the Pillaipakkam tank, which drains into the Chembarambakkam reservoir, has reached 12.08 ft. against at total capacity of 13.20 ft. The water level of another tank in Sriperumbudur, located upstream of Chembarambakkam, has touched 16.19 ft. against 17.90 ft. and is being monitored by the WRD.

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Printable version | Jan 22, 2021 9:21:43 AM |

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