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Alternate thoughts on rainwater harvesting

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Why rainwater harvesting only, why cannot we use that can be used to recharge 100 times more water than conventional rainwater harvesting system?

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Alternate thoughts on rainwater harvesting

  1. 1. ALTERNATE THOUGHTS ON RAINWATERON RAINWATER HARVESTING D K Singhal July 2016
  2. 2. Rainwater Harvesting 2 In today’s time of depleting ground water level, availability of less and less water, RWH appears asavailability of less and less water, RWH appears as a potential solution. Many environmentally cautious people have already installed RWH systems in their houses, offices and other buildings. For buildings having a bigger rooftop area, RWHFor buildings having a bigger rooftop area, RWH installation is mandatory. Alternate Thoughts on Raiwater Harvesting, July 2016
  3. 3. So, Why Alternate Thoughts 3 Today, we see a lot of installations, though many more need to be installed.more need to be installed. Still, one is unable to understand the true cost of water recovered. Let us imagine a hypothetical case. There is a three story building built in 400 m2 area, with a rooftop area of 250m2, occupying 12 families with an average family size of 4. Alternate Thoughts on Raiwater Harvesting, July 2016
  4. 4. Rainwater Harvesting 4 The annual rainfall in the area is 800mm. The residents have installed a RWH system.The residents have installed a RWH system. Now, if there is a rainfall of say 20 or 30mm in a day, first 2-4mm rainfall is absorbed by the roof. In case there is a rainfall of more than 80mm in a day, all of the rainwater quantity (20KL) cannot be stored easily if you are using this water directly. (You need very high storage volume and capital cost.) Alternate Thoughts on Raiwater Harvesting, July 2016
  5. 5. Rainwater Harvesting 5 If you recharge this water to the ground, yes; you may recover maximum volume of rainwater; butmay recover maximum volume of rainwater; but that means a boring in the ground having a suitable capacity thus costing a lot of money. Alternate Thoughts on Raiwater Harvesting, July 2016
  6. 6. How Much Water do You Get? 6 Anyway, the basic point, here is something else. If we consider we are able to collect and reuse orIf we consider we are able to collect and reuse or recharge 50% of the total rainwater, the collected quantity will be around 100,000 liters. Alternate Thoughts on Raiwater Harvesting, July 2016
  7. 7. Water Demand by the Residents 7 If you consider water requirement by a person to be around 150 liters, all the residents need aroundbe around 150 liters, all the residents need around 7000 liter water. So water recharge (to ground) will compensate just 15 days or 4% of their water demand. In case of high rise buildings with more number of occupants, this figure would be much less.occupants, this figure would be much less. In case, they do not recharge the groundwater and use this directly, the figures would be much lesser. Alternate Thoughts on Raiwater Harvesting, July 2016
  8. 8. Huge Investments, Little Gains 8 Over the past couple of decades, there have been many RWH installations.many RWH installations. But, if we consider any city, have we quantified percentage of houses with RWH? Guess what could be this figure? 1%, 2%, 5%? We are working towards RWH aggressively for past decade, but why there exists so little installation base? Alternate Thoughts on Raiwater Harvesting, July 2016
  9. 9. Alternate Thoughts 9 A typical RWH system is in working condition for 365 days, 24 yours but is able to do its work only365 days, 24 yours but is able to do its work only 50-80 hours a year (during rainfall). For the remaining period of time, it remains idle. Does that mean its uptime is less than 1%. Can we do something else to get better uptime? Alternate Thoughts on Raiwater Harvesting, July 2016
  10. 10. Alternate Thoughts 10 If we are, somehow, able to increase recharge to groundwater (as being done by RWH) by 100groundwater (as being done by RWH) by 100 times, probably we’d be able to maintain groundwater levels. How can this be done? Alternate Thoughts on Raiwater Harvesting, July 2016
  11. 11. Think River Water Harvesting 11 River water harvesting uses a part of water flowing in the rivers to recharge the ground water.in the rivers to recharge the ground water. Since decades, rivers have been used to supply water for mankind. But, river water harvesting is something unusual. Alternate Thoughts on Raiwater Harvesting, July 2016
  12. 12. A River 12 A river originates from mountains and carries a lot of water.of water. A part of water from the river is taken off through canals etc., and is supplied to agricultural fields for irrigation. Some water is also taken off from it for industrial and domestic purposes.and domestic purposes. Remaining water goes to sea. Alternate Thoughts on Raiwater Harvesting, July 2016
  13. 13. River Water to Sea 13 Unutilized river water, which goes to the sea is actually the unused river water.actually the unused river water. Generally the river water is much cleaner and usable compared to sea water. By not utilizing the river water, are we not wasting this clean, usable form of water? Alternate Thoughts on Raiwater Harvesting, July 2016
  14. 14. Harvesting 14 The river water harvesting is simple. Just install a pump to withdraw river water, followed by apump to withdraw river water, followed by a clarifier to settle down settleable solids present, and have few recharge wells where the clarified water is recharged to ground. Water from most of the rivers is continuously available for this purpose, and we may run theseavailable for this purpose, and we may run these RiWaH systems for 10 months a year (excluding summers with reduced water in rivers). Alternate Thoughts on Raiwater Harvesting, July 2016
  15. 15. Advantages 15 Every year, we hear news about draught. Every year, we hear news about floods.Every year, we hear news about floods. By this we attack the problem in two directions- “Maintaining the groundwater level” and “Underground linking of the rivers.” If we are able to divert a significant fraction of river’s unused water going to sea for groundwater recharging, both problems may be reduced drastically. Alternate Thoughts on Raiwater Harvesting, July 2016
  16. 16. Byproducts 16 The clarifier sediments (sand) can be used for construction purposes.construction purposes. Alternate Thoughts on Raiwater Harvesting, July 2016
  17. 17. 17 Think. Alternate Thoughts on Raiwater Harvesting, July 2016
  18. 18. Thank You. If you agree with this thought, please do share it with others. 18 with others. Maybe, together, we are able to maintain our groundwater levels at affordable cost. D K Singhal deveshksinghal@gmail.com Alternate Thoughts on Raiwater Harvesting, July 2016

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