Rain Water Harvesting - an imminent necessity

My mother remembers being able to feel the water in a well by just lowering her arm into it. This was the situation decades back in a water-well in my cousins’ place, right beside our house in Cuttack. Today, the well has water a few feet below; this being in a city surrounded by two rivers. Ground water depletion is not alien if you are living in bigger cities like Chennai, Bangalore, Delhi, etc. In Bangalore, 800-1000 feet depth is the norm of new bore wells in most areas. 20 years back, a 150 feet bore well was sufficient to get water in that area. Rampant usage and removal of rain water harvesting sites like lakes and ponds are the causes of this. Ponds being replaced with high rises are a common sight in every developing city. 

more than 200 days of free swach water considering Kejriwal’s 700 litre per day use. Imagine the amount of rainwater wasted every year.

What is ground water? 

Ground water is the rain water percolated in the earth’s porous surface. Consider the surface below us a huge water storage. The top soil layers (sand, silt, gravel) are porous. Rain water gets absorbed through these and moves down by gravity till it reaches an impermeable surface rock or cracks in such rocks. The rain water saturated in this region can be extracted for use by drilling a well. These water bearing rocks or unconsolidated materials (sand, silt, gravel) are referred to as an aquifer. The depth at which aquifers are found depends on the geology of the place and amount of rainfall it receives. In rocky high altitude Bangalore, the water table lies much lower than the riverbed city of Cuttack where bore wells of 100 feet can suffice. Bhubaneswar, the twin city of Cuttack, has a lower water table too owing to its slightly higher altitude and distance from big rivers. Apart from that, rampant construction has lead to ground water shrinkage in the capital city. New bore wells have average depths of more than 200 feet here. Well it is undeniable that dry aquifers can lead to catastrophic effects on human civilization; storm water off buildings and roads causing flash floods, or dry wells aiding water tanker mafias. 

The percolation pit and recharge well are functionally similar to a soak pit.

What can be done to recharge the ground water? 

Ground water has depleted because rain water has not been allowed to enter the aquifers. In urban areas, there are a few ways to recharge the ground water. One of the simplest ways is rain water harvesting off the surface of buildings instead of letting it run off in the storm water drains. Storing the rain water in underground tanks/sumps or drums is very effective. Rain water is one of the purest sources of water. However, the roof surface must be clean enough to ensure that this water is potable. A simple mesh filter is often enough to use this water for most purposes like cleaning, washing, bathing, etc. This directly reduces your water consumption. Rain water is water filtered to perfection by nature. When this water reaches polluted rivers or streams via storm water drains, it gets contaminated. Pumping and treating this water back to houses is wastage of huge amounts of energy. Soak-pits are another simple way of recharging ground aquifers. A soak-pit is essentially a small dug out pit lined and layered with permeable materials like sand, coal, gravel, etc where rain water is allowed to flow, get absorbed and filter into the aquifers. A small soak-pit of 4x4x4 (feet) dimension can do wonders to increasing your ground water level. Larger the soak-pit, greater is the water absorbed. 

Aquifer

Another important way is recharging your bore well directly with the rain water. This process involves adding filters to the rooftop storm water discharge pipe. Every defunct bore well should be fitted so. Alternatively, one can dig up a soak-pit near the bore well. This would filter the water better and prevent clogging but a lot of water would have to be diverted away as its capacity & filtration rates are low. 

How much water can be collected? 

Rain water collected = Area of catchment (roof) X Total rainfall in a year. For Bhubaneswar, which receives around 1500 mm of rain every year, the rain water that can be collected from 100 square meters roof is 150000 litres. This means more than 200 days of free swach water considering Kejriwal’s 700 litre per day use. Imagine the amount of rainwater wasted every year. 

Rain water harvesting needs to be implemented both on the individual and organizational level. The government needs to introduce laws which mandate rain water harvesting in every building and plot of land. Some states in India have laws for bigger buildings. Apart from that, community and public rain water harvesting projects can be undertaken to improve ground water levels. Soak-pits or recharge pits by the side of roads can immediately reduce chances of flash floods while recharging dried aquifers below. High rise buildings, where consumption is high per unit area, can greatly benefit from rain water to bore-well recharges. According to a recent report, 80% of surface water in India is contaminated. Water is extremely precious; we have to start caring immediately. 

Indian Railways experiments Solar Powered Train - but is it green enough?

Indian Railways is the single biggest consumer of diesel fuel in the country. In order to save of heavy oil imports, the railways have recently affixed a few solar panels on a non-ac coach of the Rewari-Sitapur passenger train. This ‘solar powered’ coach produces 17 units of electricity in a day. Though it is very less compared to the total energy requirement of a train, the Indian Railways claim that such a train is going to save them up to 90000 litres of diesel and 200 tonnes of CO2 every year. This is impressive. It is very important to note that powering an entire train with solar panels on top is currently not possible.

(stat courtesy: http://www.dailymail.co.uk/indiahome...pollution.html)

The electrical power (17 kWh) produced by these solar panels can only be used for lighting and may be mobile charging points in the coaches. A ‘Solar Powered’ Train is still a distant dream. It is important to note here that 17 units of electricity are minuscule considering a 3000 HP train. We are assuming that such train would be consuming 20 kWh per km, which is 20000 kWh for a 24 hour trip. Even if all the coaches are fitted with solar panels, it would still be a mere 1-2 % of the total energy needs for the train. The entire surface area (40 m2) of the roof is not covered yet. If covered, an extra few panels can be accommodated. The Railways say that in a 40 hours trip, 15 hours will be exposed to the Sun as the train keeps moving. This is inefficient compared to stationary installations. Further there are shades from trees, tunnels, platforms and more importantly angle of inclination which will reduce the power generated. In comparison, the Indian Railways could install massive solar panels on top of stations and feed it into the grid. This would offset the carbon produced. But the Indian Railways’ biggest problem is that only around 34% of the routes are electrified. There are practical problems like theft of copper, lack of adequate power supply, security, etc. Hence putting up solar panels on top of the trains is a safer choice and this will help in direct reduction of expensive diesel fuel imports. It costs the Railways Rs.20 per unit for power generated from diesel. Plus PR wise, a train with solar panels on top makes more impact than others.

Even if all the coaches are fitted with solar panels, it would still be a mere 1-2 % of the total energy needs for the train...It is very important to note that powering an entire train with solar panels on top is currently not possible.

It will cost Rs.3.96 lakhs per coach and the payback period is 3-4 years. Maintenance wise, though this will be exposed to harsher climatic conditions compared to stand alone units - they will undergo a wash at the sheds which is debatable for stations or other rooftops. The Indian Railways going green is a welcome move considering the resources they have and need. On the environment day, the East Coast Railways has installed a 50 kW solar power plant on one of their buildings in Bhubaneswar. There is news that the Indian Railways is chalking out a 1000 MW solar power plan for their network. We hope they becomes greener by installing LED lights, harvesting rain water from stations, utilize toilet waste, making bio diesel by planting near tracks, and other ways.