Rainwater harvesting is basically a method of storing rainwater. The stored water is used for several domestic and agricultural purposes. We should never really let the rainwater run off and get wasted. Instead we should collect it with the help of simple techniques for usage during scarcity of water. Let’s explore the importance of rainwater harvesting, the methods and systems involved, and how it is traditionally carried out in rural India.
Rainwater Harvesting Methods/System
Basically, there are two types of rainwater harvesting methods.
Surface Runoff Harvesting
Surface runoff is basically the precipitation which falls on the surface of the earth and is eventually lost to the environment. We can make elaborate arrangements for collecting surface runoff water. For example, this can be done by providing a path into a pond or tank. This helps us in storing gallons of water which can be used for several purposes.
A system to collect surface runoff water with efficient design can actually help us in collecting huge quantities of surface runoff from roads, parks and gardens. This may be enough to sustain a small community or even a whole city! However as it contains impurities, the runoff water should be passed through the filtration process before it can be reused.
Roof Top Rainwater Harvesting
The roof of a house/building functions as a catchment area for collecting rainwater in rooftop rainwater harvesting. The water which falls on the roof will be diverted through a network/pipes to the desired pit or tank. It is regarded as one of the most economical and easy methods of rainwater harvesting.
Houses/buildings with sloping roofs install gutters on the edge for collecting the falling rain. The collected water is carried to the destination with the help of pipes or artificially created ditch. However, water collected from first rain shall be flushed out as it may contain soluble impurities.
Rainwater Harvesting in India
Traditional and ancient methods of rainwater harvesting are still being practiced in different parts of the country. They have been successful in the past and are still being deployed in rural as well as urban India. Some of the prominent traditional methods of rainwater harvesting in India are listed below-
This traditional method of rainwater harvesting is primarily followed in the tropical belt of southern states of Karnataka and Kerala. These regions with naturally occurring depressions with three high sides, are rich in laterite soil. The 3 sides will automatically function as the catchment area for collection of water in the depression. Meanwhile, a small dam is constructed on the low lying fourth end of the depression for containing the runoff.
Surangas are basically traditional water harvesting systems used in Kasargod district of Kerala. Since the soil found in this region is hard laterite, it is favorable for the construction of suranga (cave). It is like a horizontal cave excavated in the hilly terrain of the area. The water which oozes out of it is collected in a pond. Even though the method has been locally being used for centuries, it is now gradually being replaced by borewells.
The traditional rainwater harvesting method practiced in Gujarat comprises underground reservoirs which can store thousands of liters of rainwater. Currently, there are ten thousand households in Ahmedabad which are using ‘taankas’ for meeting everyday water requirements. Water that is stored in a taanka will be sealed against sunlight and therefore will remain fresh for years.
Importance of Rainwater Harvesting
It acts as an independent source of water supply during scarcity of water. Rainwater harvesting is valuable to places where rain is scarce/uncertain. Preserving rainwater is an economical option in places where fresh water is a costly commodity. The preserved rainwater can be used for several activities including washing, cleaning, gardening etc.
Rainwater harvesting can prove a blessing for victims in occasions of unforeseen natural calamities like famine and droughts. It also helps in reducing the demand of water from other natural resources like wells, ponds and lakes, hence, preventing their depletion.
Water is essential for life on the planet. It shouldn’t be wasted and every drop of it must be preserved/reused if needed. On the other hand, elaborate arrangements shall be made for collecting rainwater. It’s shocking that every year we lose thousands of liters of rainwater due to lack of awareness about rainwater harvesting. It’s high time we realize the usefulness of rainwater and start collecting it in our houses/buildings/parks for a water abundant future!
Surface runoff harvesting and roof top rainwater harvesting.