Avishek G. Dastidar F OR THE residents of Som Vihar apartments in New Delhi, expressions like "aquifer recharge", "catchment area" and "sub-soil percolation" are part of everyday parlance. It's not they are all experts in the field of hydrology. It's just that one of their biggest daily concerns is whether the water table in South Delhi is being adequately replenished.

Som Vihar residents started rainwater harvesting at a time when very few had even heard of the term. Since 2002, they have been ensuring that every trickle of rain that falls within their boundary wall goes into the soil and adds to the ever-depleting water table. "It is not a cosmetic project, it is our lifeline," says R.S. Deswal, head of the management committee of the residents' welfare association.

It all started in the early nineties, when authorised water supply to the colony started decreasing, largely because of the increasing population of the booming Capital. It was then that the residents started drawing from their reserve-two tube-wells.

By 2000, the level of the wells had sunk to such low that it was harder and harder to pump up water. "The Jal board's supply was around 10 kilo litres per day against the need for 450 kilo litres (450,000 litres) per day. So we were heavily depended on groundwater," says Deswal. So they decided to do something about it.

Designed by the engineers of the Central Ground Water Board, one of the Capital's first society-level rainwater harvesting projects (RWH) started in 2002. It cost Rs 6 lakh. "With an area of 28,000 sq meters to catch the rain, the water available for recharge is 9,840 cubic meter, stopping depletion," he says. Calling the achievement pathbreaking, Delhi government reimbursed the cost of installation.

Grounded in the future

Delhiites are waking up the fruits of harvesting rain. No more is it unusual or rare to install RWH at home.

The Delhi Jal Board organises the Best Rainwater Harvester Award, which had 48 shortlisted nominations last year. Som Vihar, for instance, has won the award this year.

It's popular with schools too. The Shri Ram School (TSRS) Vasant Vihar, Mother's International Aurobindo Marg, and Mira Model School Janakpuri, are a few awarded by the DJB. TSRS has the oldest RWH project of them all and has been putting back 1,890 cubic meter (1,890,000 litres) of rainwater into the water table for the past ten years. "It is usually an instant hit with kids. They love the idea of catching the rain and putting back for future use," says Madhu Bhatnagar, head of Environment Initiatives at TSRS.

But it's not that one can harvest rain only in large scale.

Ruchi Singhal, an interior designer has set up a RWH system in her Saket home with considerable success, enough for the Delhi Jal Board to award her with an award last year. In her relatively smaller set up of only 300 sq meter of catchment area, Ruchi's installation harvests around 94,000 litres of rainwater each year. "But I don't really know much of the the technicalities of it. We just wanted to harvest rain and do something for the environment. So we asked the Centre for Science and Environment (CSE) to designed it for us when we built this house four years ago. It cost us around Rs 12,000," she said.

A necessity in Delhi

The CSE has been giving free consultation to individuals who want to install RWH mechanism. "More people are willing to spend on RWH systems now than before because over the years, the rate of groundwater extraction has far outpaced the rate of recharge. In south Delhi, it is 254 per cent," said Salahauddin Saiphy, head of CSE's rainwater harvesting cell.

In Delhi, the dependence on tubewells has intensified over the years, taking a toll on water table. "People kept spending Rs 40,000-50,000 every two years to increase the depth of their tubewells because the water table kept falling. So people are now realising that spending once and for all to arrest the falling water table is better than spending every two years," he said. The CSE has given technical assistance to 800 families in Delhi so far.

"Once we got into doing it, we realised that it is actually easier than we thought. It is important to spread the practice around your neighbourhood and further, because one or two people doing it in isolation does not help in the long run," said Bhatnagar.

So this monsoon, go catch the rain.

EIGHTH IN THE SERIES

Head for ecology

Leading by example, the Rashtrapati Bhawan went completely eco-friendly this month went with the launch of Project Roshini. Apart from harvesting rainwater, the President's Estate has become plastic-free and installed systems in place for solid waste management, liquid waste management including water recycling, increasing green cover, energy conservation, promoting renewable sources of energy and replacing liquified petroleum gas (LPG) with compressed natural gas (CNG).

The total demand for water

alone is about 2 million litres each day (730 million litres a year). This is because 7,000 people live on the estate that is spread over 133 hectares (1.33 sq. km). Apart from water for the estate's 3,000 visitors each day, water is also needed for the historic gardens, such as The Mughal Gardens.

Fastfacts

Collection and storage

of rain water that otherwise runs off from catchment areas like roofs, parks, open grounds, pits etc is called rainwater harvesting. The idea is to send the water to the ground and replenish the water table.

There are several methods to harvest water, such as rooftop collection and channeling, or through the setting up of collection pits around the house.

What is the actual potential of saving water?

A concrete, tiled and paved area of 100 sq meters is capable of yielding about 55,000 litres of rainwater (one average bucket holds 15-litres of water. You do the math) annually. Factoring in Delhi's inhabited areas out of its total area of 1,483 sq km and an annual rainfall of 611 mm, the Capital can save up to 40 thousand litres annually. It is four times the annual drinking water requirement of a five-member family.

A few examples from Delhi Harvesting in Jawaharlal Nehru University and IIT-Delhi has led to a rise of between 0.5 m and 1 m in ground water level in South Delhi.

Tube-wells have started yielding more due to artificial recharging by Jamia Hamdard University

Water harvesting (including treated effluent) around Hauz Khas lake increased groundwater in open wells and observation wells around the lake.

Lodhi gardens, The Shri Ram School have water harvesting systems in place.

What is the cost of setting up a harvesting system?

The cost of installation depends on the catchment area. Delhi Jal Board has approved 189 cases for grant and has released funds for 117, amounting to Rs 56.3 lakh. These 117 schemes will yield about 3.25-lakh cubic meter of rainwater annually for recharging groundwater.

Source: CENTRAL GROUND WATER BOARD AND DELHI JAL BOARD

URL:http://epaper.hindustantimes.com/artMailDisp.aspx?article=28_07_2008_015_001&typ=0&pub=264