Aug 2, 2014

Idea for Better Life - Recharging Ground Water

I live in Mumbai, India. That part of the world which gets heavy to very heavy rains. Where flooding is a norm from June till late August each year. This TIFR page states that the annual cumulative rainfall of about 70 inches or 1800 mm.

Now the paradox of my city is that every year, despite this phenomenal natural gift of pure rainwater, the water supply from the MCGM dwindles after February. People face water shortages, each year, the supply is cut by 10% first, then 20% and so on. One of the example is this report on dependence of rainfall in catchment areas, scarcity of which means water supply cuts.

Now, think about other places, which are not naturally endowed with such monsoon. Aurangabad, an industrial town only about 375 kms from Mumbai, where I studied engineering, faces acute water crisis every year. And this one problem leads to several other crises such industries facing power supply cuts, power plants being shut down, rise in water-borne diseases like dengue, diarrhoea, etc.

These water shortages get acute year over year. Each year the reservoirs, lakes tend to dry earlier than last year. This is an empirical observation. I leave it to the experts to prove me wrong.

I believe that one of the reasons responsible for such water shortages is the drying ground water level. And the reason for receding ground level is that we have cut the connection between the water falling from the sky and that of the ground. How, you ask?

My dear friends, with a very amicable set of chemicals such as concrete and asphalt, we have waterproofed our grounds, forever. And waterproof surfaces do not leak. We all know leakages. It is horrible when our roofs leak. But the really horrible thing is that our grounds no longer leak. The rains fall, we have tea and pakodas in the lovely balconies, and the water flows away in the sewers.

I have a small incremental idea to improve this situation. And it is inexpensive one for sure. Here it is:

1. All apartment complexes have separate pipes to allow water to flow away.
2. These pipes are taken to the ground level and then discharged into sewers.
3. Instead, during monsoons, connect these pipes to another set of pipes that go at least 15-20 feet deep below the ground level.
4. During monsoons connect the terrace pipes to these new pipes and divert rainwater from terraces of  buildings into the soil under the top concrete layer.

Something I have tried to depict in this slide here:

Ground is a large single reservoir. I believe this will reduce the load and dependence on the rainfall in catchment areas. This is similar to rain-water harvesting with a small change that we recharge the ground water.

I invite comments if this idea is correct. We need to reconnect the natural cycle of events, only then can we live in harmony with nature.

I invite all readers to comment. Thanks!


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