The last week brought relief and cheer to residents in Chennai as rains lashed the city and its suburbs extensively. On one side, it helped lower the mercury levels while on the other, it also offered solace to the residents of Chennai, who have had a terrible summer.
Chennai faced one of its worst summers in 2019 with the four lakes that supply water to Chennai going bone dry by June. Groundwater levels also hit a new low, adding to the city’s thirst.
However, with the Northeast monsoon active in the state, groundwater tables in the city have risen across Chennai’s 15 zones, as per data from the Chennai Metro Water Supply and Sewage Board (CMWSSB).
According to this data, the groundwater table has not only risen since October, the start of the Northeast monsoon but also risen dramatically since June.
At 0.55 metres, Sholinganallur recorded the highest rise in water levels in a month, going from 4 metres depth in October to 3.45 metres in November. Thiruvottriyur, a suburb in the northern part of Chennai saw the least rise, from 3.88 metres depth in October to 3.72 metres in November, up by merely 0.16 metres.
Meanwhile, Sholinganallur also recorded the highest watertable in the city, while Royapuram has the lowest at 6.47metres.
|Zone||Nov 2019||Oct 2019||June 2019|
|Thiru Vi Ka Nagar||4.86||5.18||8.64|
(All figures in Metres)
With Chennai receiving normal monsoon rainfall, as of Wednesday, residents hope that 2020 summer will not be as cruel as this year.
According to CMWSSB data, lake levels as of Wednesday are almost three times what Chennai’s lakes had on the same date last year. On December 4, 2018, the cumulative water stored in the city’s four lakes stood at 1.67 tmcft. On Wednesday, the cumulative water available stood at 4.73 tmcft, which is 42% of the overall capacity.
So with water tables and lake levels up, will this be enough to tide over 2020 summer?
Speaking to TNM, a senior official from the CMWSSB who did not want to be named dismissed fears of another harsh summer, stating that for the next two to three years, Chennai’s water supply shouldn’t be something to worry about. “The amount of water we have now is sufficient to be supplied till October 2020,” he said.
The CMWSSB presently supplies 650 MLD of water daily to Chennai, which is an increase over the 525 MLD supplied during the summer. Apart from good rainfall, Chennai’s Poondi reservoir is also receiving water from the Telugu Ganga project from the Krishna river, which according to the official boosts the city’s water reserves.
“Kandaleru and Sri Sailam saw historical inflows this year after six to seven years and hence we are safe. So, we will be getting another 2 tmcft for sure from Krishna. So, we will get 6-7 tmcft from the reservoirs itself,” he explained, adding that apart from this, Chennai also has desalination plants at its disposal to act as buffer sources in case of shortage.
Pointing to the fact that the rains have contributed to an increase in the groundwater levels across the city, the official said that this has led to the demand coming down for water tankers. “Given a choice nobody would want to purchase water from tanker lorries. I think it is not necessary at this point in time since groundwater levels are decent,” he added.
Water budgeting needed
However, not everybody shares the optimism of CMWSSB. K Sivasubramaniyan, Professor of water management in Madras Institute of Development Studies (MIDS) said that it is too early to predict an easy summer.
“Now we have reached 75-80% of the monsoon levels. Generally, we don't get heavy spells of rain after December 15. The next 10 days is the key. Right now we have about 40% of water storage in reservoirs in Chennai and at the maximum, this might increase to 50% holding in reservoirs by the time active rainfall period is over,” he observed. The northeast monsoon ends on December 31.
Adding that inflows from the Telugu Ganga project does help, he said that the government must ensure that the state receives 12 tmcft of water from Krishna river in the next two months. However, he warned that at the rate water is being received in Poondi right now, the maximum quantity of water that Tamil Nadu will receive from Krishna will be around 8 tmcft.
He also says that it is about time that CMWSSB starts water budgeting as a regular annual exercise between December 15 and December 30. “This will help the CMWSSB give stable supply through the year instead of giving huge amount of water at one point and restricting the supply drastically in another point," he pointed out.