From the TOI; 4. If Mumbai could save all the rainwater...
Deficit to surplus: When monsoon officially arrived in Mumbai on June 25, it was its slowest onset in 45 years (the normal onset date is June 10). The city was then already drawing water from the reserve quota of the reservoirs and municipal authorities had imposed a 10% cut in water supply and a 15% cut in supply timings. However, over the weekend the city received 540 mm rain in just two days, the highest over a two-day period in a decade (the average rain for the entire month of June was 550 mm). The city's total water stock went up from about 72,000 million litres on June 27 to around 88,000 million litres on June 30. The 375 mm rain that fell between Monday and Tuesday was the maximum July rain that the city has seen over a 24-hour period since 1974. Same old story: And then the usual story followed — trains and flights cancelled or delayed (Mumbai airport's main runway is shut), commuters jostling for space at stations, vehicles negotiating potholes on crammed roads and the authorities blaming 'climate change'. See the latest updates here How many pools of water? What if all the rain that falls over Mumbai could be saved? What would it take to store that water? Let's try and calculate. A rainfall of 1 mm supplies 1 litre of water to each square metre of land. Since Mumbai's total area is 603.4 million square metres, the 375 mm of rain that fell on Monday-Tuesday means 226 billion litres of rain (375 mm of rain X 603.4 million area) fell on the city. The size of an average football field is 7,140 sq m (105 m X 68 m). So, a four-metre deep swimming pool the size of a football field would hold 28,560,000 litres of water. This means the amount of rainwater that fell on Mumbai on Monday-Tuesday could fill 7,922 football-field sized swimming pools or about 10% of Mumbai's area. And we are talking about just 24 hours of rain here. Roland Francis 416-453-3371
