Mumbai: Thursday’s showers add 10 days’ water stock to city’s lakes

Rains lash a street in Bandra on September 7. Pic/Shadab Khan

The ample rainfall received on Thursday, after a break of more than a month, improved the lakes' water stock significantly. All seven lakes received more than 100 mm of rain in 24 hours and the stock increased by 41,000 million litres (ML), which is sufficient for 10 days. The stock is now over 93 per cent. It may improve due to the showers witnessed on Friday and the percolation effect whereby water runs downwards through the tiny gaps between rocks and soil particles, subsequently saturating the underlying rock. This helps to replenish water bodies.

Amid the monsoon, a dry spell was witnessed in the first week of August. Though there were intermittent spells, the water stock of lakes didn't improve significantly. On Thursday morning the total stock of all seven lakes was 90 per cent. At 6 am on Friday, the stock improved by three per cent.

The BMC had imposed a 10 per cent water cut on July 1, when the lake stock was less than seven per cent. But thanks to heavy spells, the water stock increased to 74 per cent on July 31 and the water cut was withdrawn on August 9 when the lakes had more than 81 per cent stock. But as predicted, the stock didn't improve much thereafter due to the scarcity of rain. The city may not face water cuts if the total water stock is 100 per cent at the end of September.

There are seven lakes that supply water to the city. Two, Tulsi and Vihar, are within the city limits while the Bhatsa, Tansa, Upper Vaitarna, Middle Vaitarna and Modak Sagar are on its outskirts. Tulsi overflowed on July 20, Vihar and Tansa started brimming over on July 26 while Modak Sagar was full on July 27. On Friday, two gates of Middle Vaitarna opened after a heavy spell.

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All the lakes have the combined capacity to store 14.47 lakh ML of water. The combined stock is now 13.48 lakh ML while it was 14.26 lakh ML on September 8 last year.