International Centre for Clean Water

Towards self-reliance in water: RAINWATER HARVESTING


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Barren deserts too bear a rich diversity of life. Indiscriminate paving of all urban land has not only been a bane for city birds, which however early can not find the worms now, but it has also hindered the percolation and recharge of the groundwater table upon rain, however torrential. What is it that the water-fed regions need to learn from the water-scarce states?

More than a billion people, one-sixth of the Earth’s population live in arid places such as Israel, Sahara Desert of Africa, Thar Desert region of Rajasthan and Kutch region of Gujarat in India, among other dry places. They have deep reverence to water and possess an indigenous legacy of excellent measures of water conservation.

Rajendra Singh, “the Waterman of India” and the 2015 Stockholm Water Prize Laureate, working in Rajasthan has propelled a transformation of the place by employing ‘the Indian wisdom of rainwater harvesting.’ Coupling traditional Indian methods dating thousands of years back with the latest technology, he constructed earthen dams (called as johads) to address drought and revived dried rivers back into perennials.

In the rural and urban scenario, abusing water consumption from all primary water resources has to lead to an increase in contaminants and pollutants; this augments water scarcity problems. Rainwater harvesting is one the best and popular methods of water conservation in a sustainable way, especially in a country like India where sporadic droughts, heavy rainfall and floods are the periodic norm. India receives an average of 300-650 mm of annual rainfall. How much of it can be harvested? Scientists and practitioners assure it will meet the water demands of our population, inclusive of domestic water use, potable water use, and agriculture and drinking for animals. It involves installing a system that harvests water during monsoons for use in the dry seasons – collection, storage and use. The rainwater is harvested into storage tanks and natural water resources, to increase the groundwater table or to refill aquifers. The process involves to collect rainwater from any catchment, channelize it to a filter or a recharge well. From a filter, the water is stored in a closed tank/sump for further use. It can also be directly used for domestic purposes including drinking after filtration. From the recharge well, the water replenishes the groundwater source for borewells, open wells, and aquifers.

How can we adopt rainwater harvesting methods?

Our diverse water harvesting methods are an archaic (hence time-tested) intelligent designing – born out of survival necessity. Since the first human settlements, to survive the fury of floods and the drought, people have planned to ensure safe water supply. It evolved into an architectural marvel: many new, traditional water harvesting technologies came into existence. These technologies, being a common man’s solution and not complicated engineering, can be easily installed and implemented by individuals, communities, and institutions even now. Recalling our ancestor’s veneration for water, it is time we understood their percipience for water, and for water harvesting technologies. Reinventing the wheel, we have some stalwarts in rainwater harvesting who are the go-to professionals for their erudite guidelines on rainwater harvesting.

Guiding the common-man to take his own initiative in implementing this system to harvest rain, Mr A R Shivakumar (Scientist from Bangalore), has no water supply to his house from the state agency. The construction of his house was also done using harvested rainwater! He has created a sustainable water harvesting and a recycle system to meet the needs of his family. Not surprisingly, Mr Shivakumar first insists on unlearning certain aspects: water is every individuals’ responsibility just as it is a human right and it is not the state’s sole, centralized job of conserving and providing water; there is plenty of water – yes, we need to be prudent and respectful.

Tapping of rainwater initiates at the ‘tapping of the knowledge-source on rainwater harvesting’. An erudite app, RWH advisor, on rainwater harvesting is created by Karnataka State Council for Science and Technology (KSCST) initiative supported by the United Nations Educational, Scientific and Cultural Organization (UNESCO). This app was launched on the World Water Day, March 22nd, in 2016 to bring the rainwater harvesting information to the fingertips of the common man. Based on the input information, it provides rainwater harvesting advice such as tank capacity, potential of rainwater harvesting, cost of total implementation, local trained plumbers and also the rainwater harvesting equipment suppliers. Most often, we are aware of the importance of rainwater harvesting, but the effort, time and resource to implement is a hurdle. This app serves to overcome that.

Another portal (http://www.rainwaterharvesting.org/Urban/ThePotential.htm) by Centre for Science and Environment (CSE, New Delhi), helps one to calculate the volume of water that can be harvested based on the amount of rain received in that region and the catchment area used for harvesting water.

Close home, at Chennai, The Rain Center, provides all information on rainwater harvesting. This centre is part of the movement when Tamil Nadu was the first state in the country to impose rainwater harvesting on all public and private structures. Mr Sekhar Raghavan, its Director, has relentlessly worked in this field for many years; we have been seeing him frequently in the media news.

While the guidelines from these sources suffice to help small scale rainwater harvesting systems in place, for large areas involving industrial plants, universities, forests and agricultural lands, river catchment areas, it is a different study. It is imperative to study the terrain of expansive landscapes for the water flow direction, flood areas and the composition of the ground, etc. A hydrogeologist does this job. Equipping the college student with succinct information on this issue will sensitize the next generation. An excellent book, “Dying Wisdom” by CSE, has pigeonholed India’s water harvesting systems.

Conservation of water, thus, becomes primary to the socio-economic upliftment and prosperity of civilizations. I like to spring a question for thought and action: Can we make rainwater harvesting one of the largest water sources in India? Do you think it is possible?

Collective effort will see ‘brimming results’ ensuring self-reliance in water – for us as well as the birds who may find open spaces!

This article is written by Dr Ramya J Dwivedi. She is a Senior Scientist at ICCW. She is keen on science communication and is involved in outreach.