Vikas C. Sharma
Next to air, it is water which is of paramount importance for living beings. It is possible to survive without food and shelter for some days, but without water it is not possible to survive for much of time. It is gift of the Nature to human race. If we analyse the past civilizations, all the major ancient civilization developed along the river banks because water was available for drinking and domestic uses and also for irrigation puposes. Beside water required for domestic purpose which includes Drinking, cooking ,bathing, washing etc ,it is required for other activities like agricultural, industrial, recreational and hydropower generation .Due to increase in development activities and continuous rise in population the dependency on water has increased considerably
In our country especially in our state people depends on Government system to meet out their Daily requirement of water. But the fact is, it is not an easy task for government to supply water to each nook and corner because of its hilly topography and scattered population. So there is dire need of reform in water management system and revival of traditional old system for collection of Rain water, it requires people initiative and active public participation too.
The term rain water harvesting is being frequently used now days, however the concept of water harvesting is not new in India, it has been evolved and developed ago. Rain water harvesting is simply the storage of rain water or it is a conscious collection and storage of rain water to cater the demand of water for domestic, irrigation etc. If water is collected by using Roof, slab, terrace of building it is called as Rooftop Rain Water Harvesting (RTRWH).
Although water can also be harvested by collecting the surface runoff and that is known as “Surface Runoff Harvesting”. In this article our focus is on Rooftop Rain water Harvesting system (RTRWH). Beside its use Rain Water Harvesting also helps in checking of soil Erosion, to consume surface water runoff during rainy season and to check ground water decline.
Components: Rooftop rainwater Harvesting (RTRWH) system mainly constitutes the following sub components:
* Catchment
* Transportation
* First flush
* Filter
* Storage Tank
Method: In Rooftop Rain Harvesting system (RTRWH) roof act as catchment area as it receives direct rainfall. In rural areas people have constructed their house by using CGI roofing, whereas in semi urban and urban areas houses are constructed with flat R.C.C slab, second step is to transport water down and it can be easily done by using PVC pipes of required capacity. At terraces, mouth of the each drain should have wire mesh to restrict floating material and .In third step “First flush” required to be installed, basically it is device to flush water received in first shower, the first shower of rain needs to be flushed off to avoid contaminating storable/ rechargeable water by the probable contaminants of the atmosphere and the catchment roof, it also helps in cleaning silt and other material deposited on roof during dry season, provision of first flush should be made at outlet of each drain pipe.
In fourth step water is forced to pass through commonly used filters constructed by using brick masonry filled with pebbles, gravels, sand and charcoal each layer separated by wire mesh. Sponge filter is the easiest and cheapest and suitable for residential buildings. Thereafter water can be easily transported to storage tank by using PVC pipe. Multiple storage tanks in series is also advisable with water overflow system at the end, excess water can also be diverted to Recharge wells. Harvested rain water can easily be used for all purposes including drinking if treated with chlorination.
Rooftop rainwater harvesting is the most effective way of rainwater harvesting. Main advantage of this method is not to save water from conventional sources, but it also helps to save energy including in transportation and distribution of water at the door step .In our state especially those villages which are situated in and around Shivalik Range and receives enough rainfall during south west Monsoon and western disturbance, water can be stored during these peak months and same can be used later on during non peak months, secondly most of the sources of water are situated at lower level and to supply water from lower level to the villages situated at higher level ,lot of energy is required in term of pumping water. If people starts adopting this method at every panchayat level dependency on Government machinery will automatically get decreased.
As per data available on the website of India meteorological Department, on an average in the year 2015 and 2016 Districts of Jammu province received 1433MM and 1100MM of rainfall respectively across the year. If we assume an slab area of 126 sqm (5 Marla) and 1200MM of rainfall then we can easily trap 1.50Lac Litre of Water annually for our own use.
Regarding facts and its utilization, Tamil Nadu was the first state to make Rainwater Harvesting compulsory for every Building to avoid Ground water depletion, in Bangalore (Karnataka) adopting Rainwater harvesting is mandatory for every new as well old building having area measuring 1200 Sqft and 2400 Sqft respectively. In Rajasthan rainwater harvesting traditionally practiced by the people, in Pune (Maharashtra) Rainwater harvesting is compulsory for new society. Countries like Israel, New Zealand, Srilanka, U.K, Canada etc are already using this traditional method of conserving water.
(The author is AE (Civil) PHE)
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