Resource conservation (Rainwater Harvesting)

Any new development project must have rainwater harvesting structures. If there’s a place where the water table is shallow and harvesting will not be possible, rainwater has to be stored and used so that dependence on ground water or municipal supply for secondary (non-drinking) uses is reduced. Similarly, wastewater has to be treated and used for purposes like gardening to augment other water resources. This seems to be the first practical and sensible step the authorities concerned have taken to conserve and utilize natural resources.

New airports coming up across the country may be glass and steel structures, but they promise to come with a conscience. Since the Union urban development ministry has long made it mandatory for all new big projects to harvest the rain, both the Airport Authority of India (AAI) and private developers say their new projects are going to be green buildings.

Accordingly, the AAI has is going to harvest the rain at all its project sites. They did that in Lucknow and harvesting structures were put up at Udaipur airport recently. All airports are gearing up to harvest the rain.

AAI is installing sewage treatment plants also at all big sites. The idea is not to have any discharge into already choked municipal drains. The waste water will be recycled and used for gardening. The AAI is in fact looking at green building concept for all its future projects so that they are water and energy efficient.

Steps like these could well be the only way for sustainable development in places like Delhi where the airport is in the southwest part of the city – a declared stressed area. The water table here is a very low and sub soil reserves in the entire area are saline. Government agencies have not been able to give adequate water to the nearby residential area. The GMR-led Delhi International Airport (P) Ltd (DIAL) is aware that it will have to look for innovative ways it meet its future water requirement.

The central Ground Water Authority (CGWA) has made rainwater harvesting mandatory in all institutions and residential colonies in notified areas (south and south west Delhi and adjoining areas like Faridabad, Gurgaon and Ghaziabad). DAIL is carrying out rainwater harvesting at IGI Airport. It has installed meters on the bore wells in the airport premises to monitor water consumption. Accordingly more than fifty rain water harvesting structures are spread at various points along the storm water drains within the operational area of IGI Airport.

In the upcoming Terminal and new runway area, rainwater structures are being designed along the proposed drainage network, open areas and new terminal buildings. The basic premise of this design would be to recharge IGI airport groundwater levels by allowing the run off water from both the paved and unpaved area to recharge the aquifers via the rainwater harvesting structures.

There is no way for mega projects to meet their water requirements except this. In places were the water table is shallow, developers will have to store rain water and use that for secondary purposes. A mega project was coming up at Ambala where the water table is so low that harvesting will not be possible. They were asked to store rain water and use it to prevent exploitation of the ground water.

Take the case of Mumbai. Some large office buildings at Nariman Point started recycling waste water even some 10 years back. Considering the tall buildings and the population using them saving in regular water supply and bore well water will be substantial. The present population of Mumbai is 1.25 crore and the total requirement works out to be 4,200 mld (million liters per day). Which means that with the present production of 3,420 mld, there is a shortfall of 780 mld. A simple solution to meet the water shortage and improve the quality of ground water lies in rainwater harvesting. It is not only easy to install and cost effective but also undoubtedly the best way to meet the current water crisis. In this article we take a look at 4 easy methods to harvest rainwater.

Benefits of Rain Water Harvesting

1. Quality of groundwater improves
2. Raises the level of groundwater
3. An ideal and the most cost effective solution to meet water crisis.
4. Decreases water logging in low lying areas

Recharge Pit: Dig a deep pit. After excavation fill the pit with pebbles and boulders. Direct the rainwater collected at roof and other sources that discharge into pit. Make sure that water is silt free and clean the pit regularly.

Gravity Head Recharge Well: The roof top rainwater is channeled to a well and it recharges due to gravity. It is suitable where land availability is limited and land pit is overlaid by impermeable soil. Though a bit expensive this method recharges groundwater quickly and effectively.

Abandoned Well: This is by far the most popular method and yields good results. A dry or unused well is used as recharge structure the recharge water is guided through a pipe to the bottom of well to avoid scouring of bottom. Take care to clean the well before making it a recharge structure. Add chlorine to well water periodically to avoid contamination. It is suitable for buildings with roof area of 1,000 + sq m

Abandoned/Running Hand Pump:

Same as abandoned well method (3), here a running or abandoned hand pump is used instead of a well. It is suitable for smaller buildings of roof area up to 150 sq m. This is very cost effective method and water can be used for household purposes after adding chlorine.

Saurasrashtra in Gujarat state of India was once starving from acute shortage of water. Each and every household including villages had wells to harvest rain water which they were able to use throughout the year. Other can as well take a lesson from this.

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