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Save water, live better
Rahul Kamat
The highest annual rainfall in India is recorded in Cherapunji, Assam - 15,000 mm per year, and yet the state and the country suffer from acute shortage of drinking water. That's because rainwater is not stored, but carelessly allowed to drain away. In the past 10 years, some extraordinary efforts have been made in countries like Germany, USA, Australia, Africa, China and even India to harvest rainwater.
The International Rainwater Catchments System Association (IRCSA) is the world's recognised body on the subject, actively promoting the inclusion of rainwater harvesting in border water management strategy. Water harvesting has proved that it not only improves ecology, but also solves water shortage and results in better living standard.
Rainwater harvesting can play versatile roles in cities. In a huge like city like Mumbai, the RWH system has the potential to provide at least 50 per cent water requirement. It will provide supplement water for houses, institution and industries. It will enable to recharge groundwater and prevent water salinity ingress in coastal aquifers. The necessity to implement this system in urban cities will mitigate the impact of floods and also provide adequate soil moisture for plants and trees.
For instance, take the example of the greening of Jhabua in Madhya Pradesh, which solved its water problems by simply cleaning up old tanks, checking dams, bunds and rainwater wells. However, the most-publicised rainwater harvesting system is set up at the Rashtrapati Bhawan in New Delhi. Even Coca Cola is parenting with the Central Ground Water Authority, local governments and communities to help combat water scarcity and depleted groundwater tables in Delhi and other states.
"One good example is the mediaeval desert city of Jaisalmer, with an annual rainfall of 100 mm. This bustling trade centre collected rainwater in a system of wells and canals to supply millions of liters of water to the city. In sharp contrast, Cherrapunji faces regular water shortage because the torrential downpour is allowed to go waste," says Sunita Narain, Director CSE.
Before implementing the RWH system, one should know what it means. Rainwater harvesting involves capturing rainwater by channelising its flow into tanks or diverting it from roofs via pipes into underground reservoirs. Broadly, the rainwater can be harvested by two methods in urban cities - store it in containers above ground or below it. Or recharge into soil for withdrawal later by ground water recharging basis. Talking to Project monitor Mumbai-based Dr. Ajit Gokhle explained, "The projects are designed in a way that they require minimum recurring expense and involve communities from the start, ensuring local ownership of each project."
Borewells International of Mumbai has executed many projects, which include Andheri Sports Complex, Sanjay Gandhi National Park, Sun-N-Sand hotel and others. Devendra Shah, proprietor of Borewells, says, "Our major project in Mumbai was for Hiranandani Group. We did rainwater harvesting in Hiranandani Powai for 15 lakh liters day on 'No Water No Money' i.e. on the guaranteed basis. In Mumbai 50 projects are underway, including the BEST bus depot at Colaba.
Since water is a state subject, many states in India have regulated policies for rainwater harvesting, such as the Karnataka government, which is going to set up rainwater resources centres in 27 districts. The Delhi government is contemplating a legislation that will make it necessary for all builders to fix rainwater-harvesting systems in all new buildings, offices and apartment complexes in the city. "The Delhi government is giving cash support of Rs 50,000 to each colony that goes in for installing rainwater harvesting projects," says Rajnish Bahel, RWA President.
In Delhi, as trains connect more parts of east and south, Delhi Metro will recycle construction waste and even initiate rainwater harvesting at its stations.
Even governments of Madhya Pradesh, Maharashtra, Haryana and Tamil Nadu have already initiated follow-up measures. In Tamil Nadu, Kerala rainwater harvesting has been made compulsory. The Mumbai Municipal Corporation has made rainwater harvesting mandatory to properties with plot area over 1,000 sq. metres. This condition will also be made applicable to existing buildings in the near future. BMC will supply 90 lpcd instead of 135 lpcd to ensure RWH will supplement the gap.
"Water management authorities need to come up in cities that will be in charge of overall water resources including piped water, surface water in lakes and ponds, ground water and rainwater," notes S. Vishwanath, Rainwater Club. "Even the Central Ground Water Board (CGWB) has been studying groundwater depletion in the country. CGWB has issued a notification that no new tube wells must be dug. The reasons for the depletion of groundwater have been attributed to change in cropping patterns, like wheat growing areas switching to paddy, free power to farmers and easy access to tube well technology," says B.P. Radhakrishna, the Geological Society of India.
At the end of the day, rainwater harvesting has to become the people's movement because water management is the order of the day - with RWH as a key component.
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Salt 'n Sweet! |
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Desalination plants are cropping up everywhere to augment the supply of scarce potable water, reports
Poonam Singh
For water scarcity problem, desalination appears to be one of the solutions. Since India has a vast coastline, there is great potential for desalination. A desalination plant of high capacity can be installed whereas a low capacity one can be mobile.
The Bhabha Atomic Research Centre is extensively engaged in R&D for desalination. In the process, BARC has discovered various methods of desalination, which include Reverse Osmosis (RO), Multistage Flash (MSF), Low Temperature Evaporation (LTE) and others.
BARC has set up several small desalination plants in rural Rajasthan, Gujarat, Andhra Pradesh and Tamil Nadu that produce 30,000 liters per day drinking water. The technology has been transferred to about seven parties who have set up desalination plants in water scarcity areas. The technology for domestic water purification has been transferred to about 13 parties.
Dr. P.K. Tewari, Head of Desalination Department, BARC, says, "Several of them have launched the product in the market. Hundreds of such units have been sold out in a short span of time in different parts of the country. We are also trying to develop technology to use nuclear energy to power desalination plants."
The rejected effluent from a desalination plant contains a number materials and sources of chemicals like indium, germanium which are used in high technology aeronautical industry.
However, the cost is a factor that is still ambiguous, as desalinated water at source is cheap as 5 paise per litre. If this water is used in nearby areas, it will be cheaper as compared to tanker supplied water in urban areas. However, if desalinated water is transported to distant areas, its cost will go up. "The efforts to make desalination more cost-effective are going on. The cost of water by conventional means is becoming costly day by day. On the other hand, the cost of desalinated water is coming down due to technological innovations. In another 6-8 years, the cost of desalinated water may become cheaper in many water-stressed coastal areas," says Tewari.
The government has also realised that relaying on groundwater sources will not help. Therefore it is taking an initiative to promote desalination projects to facilitate drinking water in costal areas. One such project which is being considered for implementation is a Rs 1,000 crore plant in Chennai. The government has also approved a Rs 9 crore desalination plant at Bheemunipatnam in AP. States like Orissa, Tamil Nadu and Pondicherry are also under consideration for similar projects.
Since India is an emerging economy, a lot of infrastructure development is taking place. More industrial growth requires more water, hence India, like China, will have a large market potential for desalination.
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[2 May 2005]
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