Nature has endowed India with huge water resources. We have perennial rivers like Ganga, Brahmaputra, Yamuna, Beas and others along with their tributaries and distributaries besides in North and Eastern India, we have spring fed and rain fed rivers in central and peninsular India-the major among these being- Godavari, Krishna, Narmada, Tapti and Kaveri.
These huge potential water resources notwithstanding, we are facing a water crisis across the country. Over the years, rising population, growing industrialisation and expanding agriculture have pushed up the demand for water. Monsoon is still the main hope of our agriculture.
Water conservation has become the need of the day. Rainwater harvesting is a way to capture the rainwater at the time of downpour, store that water above the ground or charge the underground water and use it later.
This happens in open areas as well as in congested cities through the installation of required equipment. The collection and storage of rainwater from run-off areas such as roofs and other surfaces has been practised since ancient times in India. It is particularly useful where water supply is inadequate. If the collection and storage equipment is designed carefully it is possible for a family of four persons to live for a year in areas where annual rainfall is as little as 100 mm. Observations in some other countries like Zimbabwe, Botswana and Israel have shown that up to 85 per cent of all measurable rain can be collected and stored from outside catchment areas.
This includes light drizzle and dew condensation which occurs in many parts of the country during drier months. A study has shown that if the rainfall is 635 mm per year, the run-off from a suitable catchment area can be as high as 500 mm. An area covering one hectare may yield 5000 kilolitres of water in the year-enough for 500 heads of cattle for six months. One ml