The cities in India are expanding at an alarming rate every year and cities like Hyderabad, Bangalore and Pune have become some of the fastest growing metropolitan cities in India. The growing population and its consumption patterns have created a rising demand mainly on limited water resources. When the Municipal Water Supply of these cities could not cope up with the this demand of providing water to everyone and to all the areas the private companies saw this as a profitable venture to trade in water causing bore wells and lakes to dry up due to over-exploitation of ground water. To add to the crisis, the tankers travel long distances to pump water from the lakes situated in the surrounding suburban and rural areas apart from the city lakes thus depriving the farmers of their supply for agriculture, challenging their livelihood, endangering their biodiversity, adding more traffic and pollution.
Ironically, Hyderabad receives 700 mm average rainfall annually, considering GHMC area of 600 sqkm accounts to 4200 Million Cum. More than 90% of rain water goes into drains and gets carried away from city as infiltration into ground varies between 3% to 5% only under natural conditions & this further reduces with increased urbanisation. Natural replenishment of ground water reservoir is a slow process and is often unable to keep pace with this incessant downpour, concrete jungles/ roads, reducing open/ public places and excessive exploitation of ground water. The city receives abundant rains, gets flooded with every rain and many of the borewells go dry between January to June but with improvised rain water harvesting (RWH) methods the infiltration rate can be increased to 10%. Hyderabad is situated on Deccan Plateau which is mainly underlain by rocks. Regular methods of recharge pits are not very successful at all places because we can find sheet rock/ boulders beneath the proposed RWH pit or sometimes due to clay soil also where the percolation is minimum or not possible. The rainwater reaching the deep aquifers vertically is more important at present times than travelling horizontally through the weathered zone.
Rain water harvesting was in practice for many centuries/widely practiced all over the world & regarded as solution or supplement to address the increasing mismatch between available water resources and its rising demand. RWH feasibility is a site specific as site decides the design and design decides the cost, which requires minimum expertise / knowledge offers many benefits and its cost will be almost zero when it’s done during the construction stage only.
Inverse BoreWell (IBW) method of Rainwater harvesting (RWH) is widely promoted by SMARAN wherein dry or abandoned bore wells and even working borewells (WBW) if there are more than two available are converted into recharging structures. In our city we find thousands of borewells abandoned (depths ranging from 120 ft to 1000 ft) when they go dry because of over extraction in the area or low ground water levels. The residents keep planning for new bore well points and for more depth to extract ground water while ignoring an abandoned bore hole in their premises which is worth thousands to lakhs of rupees.
SMARAN considers those abandoned or dry bore holes as an asset and the IBW method of RWH will use those existing deep, dry and abandoned bore holes for artificial recharge. In this method huge volumes of rooftop area rain water (60 thousand liters / 100 sq. mtrs. rooftop area per annum) collected from the buildings and also from selective surface areas are channelized through the rain water outlets to the proposed site into the RWH pit with proper silt traps before the pure rain water is allowed to dribble into the deep aquifers via borewell/ hole casing. Once this method implemented, the borewel /hole keeps adding the rain water to the ground water deposits whenever rain occurs there by increasing the life, yield & quality of existing bore wells in their premises as well neighboring areas. SMARAN extending RWH technical support to GHMC, communities, Institutions etc and to name a few successful projects done are to NIFT at Madhapur used to require 15 water tankers per day has become tanker less campus now and one more is with Nature cure Hospital at Balkmapet.
This method increased the ground water level at many sites in the city, reduced the gap of average dry period from January to June, abandoned borewells also has become productive apart from neighboring borewells yield and continuous access to groundwater for the community is assured in a short time depending on the potential available, which is a site specific and the history of abandoned / dry boreholes is to be verified before such structures proposed. Best period for implementing such proposed structures are from end of rainy season to the start of the rainy season since the execution will be continuous and will not delayed due to rains if its implemented during monsoon period as chances of material and labour getting wasted.
There are thousands of abandoned borewells in city dried up due to the depletion of groundwater and having more than one borewell in any premises in the city should not be ignored, they can be revived, made productive and can be used to replenish the aquifers which is the main source of sustenance for the community.
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