Water stocks dip, Upper Vaitarna hits zero

Storage in water reservoirs in Maharashtra less than the average of last ten years

June 18, 2019 01:34 am | Updated 01:34 am IST - mumbai

High tide on Monday sees huge waves near the Koliwada at Worli. The IMD has said that the delayed southwest monsoon is expected to hit the State by June 21.

High tide on Monday sees huge waves near the Koliwada at Worli. The IMD has said that the delayed southwest monsoon is expected to hit the State by June 21.

Despite moderate rainfall in Mumbai and its suburbs since the beginning of June, there is no significant rise in the levels of lakes that supply water to the city. In fact, the city’s water stock has dipped to 6.23%, the lowest in three years as on June 17. The useful content (live water stock) in Vaitarna lake has hit zero while it is 1% at Bhatsa.

The monsoon has missed its date with Mumbai this year. The initial delay was due to late arrival of monsoon in Kerala. However, the weatherman is expecting further delays despite southwest monsoon arriving in Kerala on June 8. While Cyclone Vayu brought showers to the city, it has resulted in a delayed monsoon. According to the IMD, the conditions are likely to become favourable for further onset of monsoon later this week.

Owing to Vayu, the city received 140mm rainfall or 13.98% since June 1 as against the season’s average of 2,514mm. The situation was similar last year, when the city received only 7.79% rainfall by June 17. On June 17, IMD’s Santacruz observatory recorded 1.8mm rainfall.

The rainfall in the catchment areas of the seven lakes supplying water to Mumbai is also scanty even as the demand continues to be the same.

Mumbai requires 14.47 lakh million litres to last an entire year. As on June 17, the stock stands at 90,196 million litres or 6.23%, enough to last another 27 days. The figure was 2,17,645 million litres or 15.04% last year and at 18.87% in 2017.

So far, the Vihar lake system has received 139mm rainfall while Tulsi has received 225mm, the highest of the seven. But these lakes are the smallest and located within the city limits. The total rainfall for the remaining five lakes stands at less than 50mm since June 1.

This has resulted in Upper Vaitarna lake having no useful content (no water) anymore. Its ‘live storage’ has hit zero. The lake’s lowest drawable level is 595.44 meters, but as on June 17 it stands at 590.25 meters. The BMC will now have to draw 70,838 million litres from the lake’s dead stock.

The situation in Bhatsa lake is no better, with only 1.16% ‘useful content’, owing to which BMC will have to draw 1 lakh million litres from its dead stock. Tulsi and Modak Sagar lakes are slightly better off.

However, BMC has assured Mumbaikars there is no need to worry. “Even though Vaitarna lake’s live stock has dipped, we can always draw from its dead stock. It is meant for such situations. Vaitarna system is made up of Upper Vaitarna, Middle Vaitarna, Modak Sagar and Tansa lakes. The system has water to last till July 31. Even Bhatsa system has water till July 31,” said a senior officer from BMC’s Hydraulic Engineer’s department. Together, the Vaitarna system has 11.31% stock.

Meanwhile, Skymet managing director Jatin Singh on Monday noted that the performance of southwest monsoon had not been impressive so far, neither in terms of rain nor its coverage. “Weather models indicate some very good rain in Mumbai around June 25. This could be Mumbai’s first heavy spell this monsoon. It will be good for denizens of Mumbai and the State machinery to take cognizance of this,” Mr. Singh said. In the western region, the total live storage available in reservoirs is 10% of total live storage capacity of these reservoirs.

The storage during corresponding period of last year was 13% and average storage of last ten years during corresponding period was 17% of live storage capacity of these reservoirs. “Thus, storage during current year is less than the storage of last year and is also less than the average storage of last ten years during the corresponding period,” Mr. Singh said.

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