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| July
1, 2001 |
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| July
1, 2001 |
        Do it at home For a good harvest |
News you can use |
When Rajmohan Gandhi established the Moral Rearmament Society (Asia Plateau) in Panchgani in I964, the concept of rainwater harvesting was incorporated into the architecture so that residents would have water round the year. In the eighties, a hawaldar called Anna Hazare of water-starved Ralegaon Sidhi, a village in Aurangabad, Maharashtra, saved water flowing from a hillock by introducing run-offs to the village ponds. Continuous water harvesting put an end to Ralegaon's water woes.
Save water on a rainy day: Delhi CM Shiela Dixit before the pit in her house where rainwater from the rooftop is stored
Like Gandhi and Hazare many social activists have shown that rainwater harvesting is probably the best solution to water scarcity. "It makes ecological and financial sense to harvest rainwater for short-term use and long-term improvement of the water table," says Sekar Ragavan, research fellow at the Centre for Policy Studies, Chennai. "Water from tankers is unreliable and expensive."
Hydrogeologists say the average annual rainfall of 1,200 mm in Chennai if harvested completely can yield 700 litres of fresh ground water per 2,400 square foot. "Over extraction of water and wastage of rainwater have led to shortage of water," says Sekar, who started his water campaign in 1995. It took him four years of dogged effort to persuade people in his Besant Nagar locality to harvest rainwater.
In 1996 the Chennai administration tried, in vain, to make rainwater harvesting mandatory for every building blueprint.
Delhi did just that, and Chief Minister Shiela Dixit herself harvests rainwater in her house. Trying to emulate her are 180 resident welfare associations under the Bhagirdari scheme.
The Public Works Department, on its part, has identified 500 buildings for water harvesting and hopes to get at least 200 of them ready in July. The New Delhi Municipal Council has marked out all the major parks in the city for water harvesting.
The PWD in Chennai, too, is doing its bit. "We have brought out booklets which help the public identify which areas are best suited for rainwater harvesting," says A. Veerappan, joint chief engineer (ground water), PWD. But people lack enthusiasm, he laments, because there are alternatives. Water conservation activists unanimously say that urbanites are hooked to the idea of Ôpiped water' and harvesting rainwater is not on their priority list.
In Andhra Pradesh, the government took up rainwater harvesting in a big way last August with the Neeru Meeru (Water and You) programme. Now in its third phase with a budget of Rs 40 lakh, the programme started with desilting water bodies, and constructing percolation tanks. The government does water harvesting in public places like parks and playgrounds, and encourages the citizens to do it at home.
Though the gujarat government has subsidised bore wells, farmers plan to recharge wells by harvesting rainwater (in pic, tribals at a harvesting site in meghraj)
The coastal village of Chellanam in Kochi never has enough water for its 40,000 residents. The little water supplied by the water authority from a river 40 km away comes at odd hours. Moved by the plight of the people and inspired by the tradition of storing water underground, a local government official called V.T. Sebastian developed a harvesting system which directs rainwater from the rooftops to underground tanks through PVC pipes. The panchayat gives a family Rs 1,000 towards setting up the system which costs Rs 3,000. Today, thanks to the system, around 300 families are self-sufficient in water.
"The water has been tested and found to be uncontaminated," says K.J. Anto, who has been harvesting water for the past eight years. However, Kusumam John, president of the panchayat, feels there is a danger of water in septic tanks in small house plots seeping into the storage tanks.
"If we can drink water piped from reservoirs open to bird droppings, water harvested and purified by the natural process underground is a safer bet any day," says Indukanth S. Ragade, vice-chairman of Alacrity Foundations, Chennai. In 1993, Alacrity began harvesting rainwater by connecting a pipe from the terrace to a well in its office at T. Nagar. Since then, almost 140 of its housing complexes have benefited, and maintenance expenses are negligible. "We ask the flat associations to clean the water drains when the monsoons approach," says Ragade.
Water harvesting is nothing new to rural Tamil Nadu where during the British rule 39,000 tanks were built in the eri system. The system has tanks at regular intervals on the gradient. Rainwater would reach the first tank, and overflow to the tank on the next gradient, and so on. An NGO, Dhan Foundation in Madurai, is now restoring about 100 irrigation tanks in and around Madurai.
Parallel movements in rural Gujarat and Madhya Pradesh have resorted to constructing check-dams on rivulets and streams, gullies, contour trenches, bunds and small infiltration tanks besides planting trees to fight drought. Individuals as well as the government are chipping in to save water and improve the water table.
"Only one thing has remained constant here, the steady decline of water table. Water, once available at 35 feet depth, is now sunk down to 60 feet and below," says Fr Peter D'souza of the Catholic Church in Meghraj of Sabarkantha district in Gujarat.
Fr D'souza, along with the tribal farmers, has set up check-dams. "Even though Sabarkantha has six large and medium dams supplying water to Ahmedabad and Kheda, tribal farmers are at the mercy of the monsoons. With the tribals facing the third consecutive drought this year, wheat cultivation has become a thing of the past," he says.
Recharging ground water: A pit in Ahmedabad to store rainwater
Though the government has subsidised bore-wells, the farmers do not want even to deepen old wells. They plan to recharge wells by harvesting rainwater. In Navagam alone, eight check-dams have come up along with innumerable contour trenches and bunds since last February. "In Meghraj, the government spent Rs 3.40 crore last year on relief works, mainly de-silting village ponds and constructing check-dams," says Fr D'souza. Drought-proofing the region, he believes, would also arrest migration by improving agriculture and generating employment.
"By June 2001, we would have constructed 10,000 check-dams," says Revenue Minister Vajubhai Vala. The check-dams are being constructed as part of the Sardar Patel Participatory Water Harvesting Project.
Check-dams in Sagar district in Madhya Pradesh are part of a water conservation movement led by District Collector B. Rajagopal Naidu. Over the past four years it has become a people's movement with the public contributing Rs 6 lakh besides free work. In Sagar alone around 55,000 structures including ponds, percolation pits, wells and check-dams have been constructed. The Rajiv Gandhi Watershed Development Mission has started a project to bring water to all villages, and Dewas district, prone to desertification, has adopted rooftop rainwater harvesting.
The idea is to stop wastage and make the urban non-agricultural communities feel that protecting water is their responsibility, too. "We lived with a misconception that it was the government's duty to supply water and the people were free to use or even waste water," says Kartikeya Sarabhai, director, Centre for Environment Education, Ahmedabad. "Only recently have we realised that supply side management alone will not work."
"It is the micro-level efforts that will benefit at the macro level," say Chitra and Viswanath, Bangalore. The architect-and-engineer couple incorporated rainwater harvesting in the plan when they built their home in 1995. This was calculated to yield 80,000 litres of water every year.
"The method involves designing down pipes for rain, separating the first 2mm through a first flush system, filtering the rainwater through a gravel-and-sand filter and storing it in sumps. The overflow is used to charge ground water wherever feasible. A rule of thumb for Bangalore is about 6,000 litres of storage for 100 sq. metre roof area," explains Viswanath.
The duo formed the Rainwater Club, a confederation of like-minded architects and engineers. The club has brought out a booklet in English and Kannada (Tamil and Malayalam versions are due shortly) on how to harvest rainwater.
"People from all over the country have come and seen the system," says Chitra. The couple has also designed harvesting systems for the chemical engineering department of Indian Institute of Science, Bishops Cotton Girls school, and several residences.
They have also implemented a pilot system at Escort-Mahle-Goetze factory in Yelahanka. "We started with harvesting about 1.2 million litres of water a year. Ultimately about 67 million litres of water will be harvested every year saving Rs 37 lakh a year," says Viswanath.
Similarly, in the Naroda Industrial Estate of Ahmedabad, the Vikram Sarabhai Centre for Development Interaction has given a successful demonstration of how water from the rooftops and ground can be harvested through a recharge pit. At least 50 industrial units have shown interest in adopting the method.
Rainwater harvesting may only be the proverbial drop in the country's quest for water. But "if the Government of India decides, it can reuse, recycle and harvest water in both urban and rural areas," says Kartikeya Sarabhai. "It's a simple issue of priority."
Farwa Imam Ali/Chennai, Anosh Malekar/Meghraj, Lalita Iyer/Hyderabad, Deepak Tiwari/Bhopal,Do it at home
Dig a hole 4m wide near your house till you reach the water level. Go one more metre deep and put a layer of charcoal which acts as a strainer. If required, use an iron sheet all around to keep the pit from collapsing. Remove the sheet after you put charcoal and one and half metres of river sand. Insert two 2-inch PVC pipes, perforated at the lower ends, and 25 cm apart. Cover the perforated ends with net to prevent stones and other particles from coming up. Connect one pipe to the roof. A strainer at the top will keep leaves and other wastes from going down along with the rainwater. Insert a hose in the other pipe which has a foot valve at the bottom. Connect this pipe to an electric pump.
Rainwater displaces the dense hard water underground. If water comes up to the surface, put half a metre of ordinary sand on top of river sand. This will prevent the water from overflowing. Once a week, pour bleaching powder solution through the pipe on the roof. This will keep the water pure underground.
For a good harvest
Rooftop harvesting is the best way to collect rainwater. All one needs is a roof and a sump, well or tank to store the water. For residential requirements, harvesting systems cost between Rs 5,000 and Rs 30,000 depending on the size of the premises, nature of soil and the technology involved.
The best time to harvest is during intermittent rains. Harvesting cannot be done when there is a constant downpour since the soil will not absorb beyond a point.
To collect rainwater in houses and apartments, direct rainwater from the terrace to the ground through drain pipes to a filter tank and open wells or to percolation or absorption pits and wells below the soil surface. These can be covered with slabs to facilitate pedestrian and vehicular movement on the ground.
You can also use a percolation pit 4 to 8 m deep, depending on the nature of the soil, and 25 cm wide. It is filled with pebbles and river sand on top and a square or circular collection chamber to arrest silt at the top.
Another option is an absorption well, constructed using cement rings of 2 to 6 ft diameter. Depth depends on the nature of the soil, and the diameter depends on the number of rooftop pipes likely to be connected.
In areas where the soil is clayey up to about 15 feet, go for a percolation well of 10 ft to 15 ft and a hand bore pit within this well up to a similar depth. Insert a PVC pipe of 6 inches diameter into the bore.
In apartments, water falling in the open space around the complex can be collected through a gutter with a perforated lid. Lead the collected water through pipes into a recharge well 1 m wide and 5 m deep.Designer roofs
Slope the roof to drain water towards the storage system. Keep the roof uncluttered and easy to clean.
While casting the roof, place a Ôfloor trap' near the inlets of the water pipes to the ground.
Roofs should have a gutter of PVC or zinc sheet to collect water and channel it to the pipe.
To carry water down use 90mm diameter PVC pipes resistant to UV rays. Four pipes would be sufficient for 1,000 to 1,200 sq. ft area.
Use a floor trap where the water enters the drain below or a piece of sponge at the mouth of the pipe.
Filter rainwater before storage. A PVC bucket with gravel, sand and charcoal is a good filter. A PVC drum with sponge at the inlet and outlet is also a filter.
Plan your storage system beforehand. It can be a roof-level storage tank, ground level drum or masonry tank, underground sump or a tank partly below ground.Keep it clean
If water does not contain any organic material and if it is stored in a clean container it can stay for a long time. Use alum or chlorine to clean the water. Always boil and filter water used for drinking.
Sources/Sekar Ragavan, Alacrity and Chitra Viswanath
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