Rain Water Harvesting Systems for Combating Water Crisis

What is rainwater harvesting (RWH)?

Rainwater harvesting is a technique of collection and storage of rainwater into natural reservoirs or tanks or the infiltration of surface water into subsurface aquifers (before it is lost as surface runoff). RWH is a simple, easy and cost effective technique of aggregating water and delivering it to water resources like borewells. RWH has the potential to overcome problems caused by drought and water scarcity.

Water and Rain

As much as 97% of the world’s total water is in oceans, 2% is locked in the polar caps and only the balance 1% is fresh water.  Of this 1%, India’s share is 4% whereas our population share is 18% of the world’s population[1].

Water Cycle

As much as 85% of drinking water schemes in rural areas of Maharashtra depend on groundwater. Due to the drought-like conditions over the last few years, groundwater extraction rate has exceeded the recharge rate. Desperate farmers are using tankers to irrigate pomegranate orchards in Solapur. Rains help to maintain the ground water table through natural percolation, besides maintaining surface water levels. RWH is expected to play a major role in bringing depleted water levels up.

Potential of rainwater harvesting

The average annual rainfall in India is about 1120 mm. Within Maharashtra, the average rainfall is about 1300 mm but varies between 400 mm and 6000 mm across the state. Using the state average of 1300 mm, the average annual RWH potential per acre would roughly be 4.4 million litres [2].

The total amount of water received in the form of rainfall over an area is called the rainwater endowment of that area. Out of this, the amount that can be effectively harvested is called the water harvesting potential.

Source: http://www.rainwaterharvesting.org [3]

Rainwater harvesting case studies 

Solapur district (Maharashtra)

One instance where a RWH system has been successfully implemented is Green Land Society 2 at Vimannagar, Pune. Previously, the water table at Green Land Society 2 was at 250 feet depth but after the implementation of RWH system under the guidance of Col. Shashikant Dalvi (rainwater harvesting expert), the water table has moved up to 40 feet. Earlier tankers were necessary during the summer season but no water tanker has been summoned for the last 13 years due to the RWH system. Water is now available 24 hours to about 200 people living in the building. The roof area of the building is 10,000 square feet, and around nine lakh litres of water is saved every year by RWH, leading to a raised water table and increased water availability.

Another example where rainwater harvesting has been implemented is in the Chinchani village of Gram Panchayat Pirachi Kuroli (Pandharpur taluka) of Solapur district. RWH systems were placed on 55 homes in the village and water was conserved by digging a recharge pit. Mohan Anapat, a social worker from this village, has taken the lead in the implementation of this project with the support of the Rotary Club.

Like these, more and more people and organizations are focusing on RWH since unsustainable extraction of groundwater is reducing the water table at alarming rates, and recharging of groundwater through rainwater harvesting is seen as a dependable solution.

Rainwater harvesting expert Col. Shashikant Dalvi (Retd.) guiding farmers in Gadegaon village, Solapur district, Maharashtra in Jagar Panyacha programme, organized by Save Indian Farmers

According to Col. Shashikant Dalvi, from 1500 square feet roof area, it is possible to harvest 1 lakh litres of water during the rainy season. He emphasized on changing our outlook about water from Use & Discard to Use, Recycle, Reuse, Recharge, Conserve and Discharge.

“We are facing severe water crisis due to deforestation, leading to the imbalance of the environment,” Bharat Bhalke, a member of the legislative assembly (MLA) of Maharashtra from the Pandharpur-Mangalwedha constituency, said.

“Odhe aapanch bujawale aahet, tali-bandh aapanch phodale aahet, panlot kshetravar aapanch atikraman kele aahe, hya babi atishay gambhir aahe” [We (farmers/villagers) have buried the water streams, we have broken the bunds, we have illegally captured the watershed area. This is a serious problem in terms of the environment and water security].

Pipriya Tehsil (Madhya Pradesh)

A rainwater harvesting system for tubewell recharge is implemented in Pipriya Tehsil of Madhya Pradesh under the guidance of Col. Shashikant Dalvi. A tubewell recharge pit is dug by members of the community, with holes that allow water without sediment to go down into the tubewell. Stones and rocks are filled in the recharge pit for water filtration.

Pune (Maharashtra)

The following are the Pune Municipal Corporation’s proposed RWH projects:

Source: Pune Municipal Corporation

Promoting a RWH movement

According to central and state government resolutions, it is compulsory to have RWH systems on the buildings of local government bodies. But RWH systems are not functional or operational at many government offices. These systems are broken due to the use of poor quality material and ignorance of officials regarding the maintenance of RWH systems.

Some measures that can be taken to overcome the present water crisis include:

1. Financial support for RWH: The material for installing RWH systems should be available at subsidized rates. MLAs, MPs and non-government organizations (NGOs) should fund RWH systems in their area. RWH projects should be initiated at public places like schools, health centres and gram panchayats.
2. Citizen awareness campaigns educating the public about the potential & benefits of RWH systems to improve the falling water table.
3. Strict implementation of RWH policies by local bodies.
4. Training of local officials on RWH systems & testing before issuing NOCs to new buildings as well as old buildings.
5. Mandating that borewells are to be dug only with permission from the local government and approved only if it is combined with an undertaking to recharge water levels using RWH systems.
6. Planned replacement of old water pipes to reduce leakage in a phased manner.
7. Policy-level progress on water conservation issues.
8. Encouraging all homes to build a RWH system.

References

[1] http://parjanya-rwh.blogspot.in/

[2] www.parjanyarwh.com

[3] http://www.rainwaterharvesting.org

_____________________________________________________________________________________________________________About the Author

Yashwantrao Yadav is a Doctoral Scholar from Tata Institute of Social Sciences (TISS), Mumbai working on Information Communication Technology (ICT) in Farming. Inputs from Col. Shashikant Dalvi are acknowledged.