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Groundwater table likely to go up

Posted by raindrop on August 23, 2013

Groundwater table likely to go up

Jayashree Nandi, TNN Aug 17, 2013, 06.03AM IST

NEW DELHI: Friday's rain may have done more than pose a few traffic hurdles. It's likely to have raised Delhi's groundwater table considerably.

According to a Central Ground Water Board analysis, the 50.8mm of precipitation from Thursday night to Friday afternoon has a recharge potential of about 7 crore litres. This quantity of rainwater can meet the requirements of over one lakh households for a day, considering each household requires about 500 litres of water. That's not all. CGWB officials claim that the potential could be doubled to about 14 crore litres if establishments in Delhi had artificial recharge or rainwater harvesting structures.

CGWB projected the recharge potential based on the extent of open area left in Delhi. "We have made this projection by calculating the amount of water which will seep into the ground in the open areas of Delhi. But recharge can be more than double this amount if Delhi had artificial recharge systems," superintending hydro-geologist A D Rao said.

About 142 sq km of open land out of a total of 1,440 sq km area in the city may have been recharged. "There is huge potential if buildings and establishments have artificial recharge systems installed. But we don't have data on how many establishments have the facility," he added.

Despite falling groundwater levels in various parts of the city, experts say not much progress has been made on ensuring people implement rainwater harvesting. "There is no official data at all on how much is being recharged or how many rainwater harvesting systems are in place," Jyoti Sharma, founder of Forum for Organised Resource Conservation and Enhancement, said. As of now only 350 to 400 establishments which include schools, houses and residential colonies have implemented rainwater harvesting.

"We don't know the capacity of these structures. Delhi has a capacity of retaining 350 billion litres of rainwater a year. I don't think even a 100th of that is being recharged now," adds Jyoti.

While it is mandatory for all new constructions with 100 sq m roof area to have rainwater harvesting structures, there is no monitoring of whether it's being done. Jyoti cites the Chennai example where rainwater harvesting is compulsory in both old and new constructions.