Monday, September 6, 2010

Reuters AlertNet - Rainwater harvesting helps ease water shortages in Bangalore

Reuters AlertNet - Rainwater harvesting helps ease water shortages in Bangalore

Rainwater harvesting helps ease water shortages in Bangalore
18 Feb 2010 13:22:00 GMT
Written by: AlertNet correspondent

Bangalore, India's Silicon Valley, has seen a huge increase in new construction in recent years, leading to worsening water shortages. REUTERS/Stringer

By Marianne de Nazareth
Marianne de Nazareth, who is based in Bangalore, India, is a freelance journalist with an interest in climate change issues.
BANGALORE, India (AlertNet) - With the population soaring in this capital of India's Silicon Valley, water is running out. As wide green gardens have been replaced with apartment blocks, boreholes have been running dry and many residents now buy their water on a daily basis from tanker trucks that creep through the city's notorious traffic.
But on the outskirts of the city, an innovative rainwater harvesting effort is recharging the area's depleted groundwater, suggesting how cities around the world might be able to ward off what some analysts fear will be increasing conflict over water shortages.
"With the population literally bursting out of the city's seams and water getting scarce, the need of the hour is to employ rainwater harvesting on a war footing," said Jeff D'Lemos, a retired engineer and rainwater harvesting specialist who is spearheading the project.
In Bangalore's Bellandur district, open fields have over the last three years been replaced with a sea of apartment blocks. Because city water lines don't yet run to the area, residents buy their water by the tanker truckload.
Residents used to draw water from wells. But now "each apartment block has 30 flats so we can look at an average of 120 people living in one building," D'Lemos said. If each person uses 100 litres per day, "no wonder all the bore wells around are going dry."
The solution may lie in rainwater harvesting, which has recently been made mandatory for all new housing construction in Bangalore, according to John Furtado, a city planner.
D'Lemos, who worked many years in the Middle East, is leading a push to gain acceptance of the technology in Bangalore by installing some of the early systems at prices just over cost.
He recently finished putting in place pipes to harvest the rainwater from the roof of one large private house in the district. The water discharges into a sump which is used to recharge the house's dry well.
"The geology of Bangalore's soil is clay on top, soft rock lower, medium rock below that and granite at the bottom," D'Lemos explains. "Therefore one cannot just dig shallow holes where the rain collects and expect that to replenish the water table. The clay soil prevents that. So, there are three options to harvest rain water," he said.
Rainwater can be collected off the roofs of houses and sent to fill an underground sump, or directed to recharge the borehole. A third option is to channelise the water into an open well, D'Lemos said.
From a rooftop area of 200 square meters, the house recently fitted with rainwater harvesting pipes should collect 16,000 liters of rainfall a year if Banglore sees average rainfall of a meter a year, D'Lemos said.
In a nearby apartment block, a water tanker unloads water for residents. They used to need to buy two tankers each day to survive, said Santosh Hebbar, one of the residents, at a cost of $700 a month.
"Now with Jeff setting up the rainwater harvesting system, in just a few days we have cut down buying two tankers to one ... In a matter of a few months all our investment in the system will be recovered," Hebbar said.
The project is so new, however, that it is still "very difficult to convince the residents about the efficacy of the project," he said.
He strongly supports making rainwater harvesting mandatory in India.
"In Detroit in the United States, which I just visited, in the Ford (Motors) plant all the roofs are covered with lawns which suck in the rain like sponges and the water is directed to a filtration system. The factory received a UNESCO (United Nations Educational, Scientific and Cultural Organization) award for the effort," Hebbar said.
The rainwater harvesting systems are expected to ease pressure on the Bangalore Municipal Corporation, which has seen a huge volume of requests for new water supply connections as the city expands. The systems may also provide a means to help the southern Indian city cope with the more varied and intense rainfall that is expected as climate change takes hold.
D'Lemos hopes rainwater harvesting will take off in popularity after residents see the value of the early systems he has installed.
"I want to start a movement here in Bangalore, a self help movement, to educate people to help themselves," he said. Plentiful rain in Bangalore recently presents an opportunity "to capture that plenty and recharge the water table that we have been depleting for 40 years."
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