Rain Water Harvesting
Rainwater harvesting is the accumulating and storing, of rainwater. It has been used to provide drinking water, water for livestock, water for irrigation or to refill aquifers in a process called groundwater recharge. Rainwater collected from the roofs of houses, tents and local institutions, can make an important contribution to the availability of drinking water. Water collected from the ground, sometimes from areas which are especially prepared for this purpose, is called Stormwater harvesting. In some cases, rainwater may be the only available, or economical, water source. Rainwater harvesting systems can be simple to construct from inexpensive local materials, and are potentially successful in most habitable locations. Roof rainwater can be of good quality and may not require treatment before consumption. Although some rooftop materials may produce rainwater that is harmful to human health, it can be useful in flushing toilets, washing clothes, watering the garden and washing cars; these uses alone halve the amount of water used by a typical home. Household rainfall catchment systems are appropriate in areas with an average rainfall greater than 200 mm (7.9 in) per year, and no other accessible water sources (Skinner and Cotton, 1992).
There are a number of types of systems to harvest rainwater ranging from very simple to the complex industrial systems. The rate at which water can be collected from either system is dependent on the plan area of the system, its efficiency, and the intensity of rainfall (i.e annual precipitation (mm per annum) x square meter of catchment area = litres per annum yield) ... a 200 square meter roof catchment catching 1,000mm PA yields 200 kLPA.
Rainwater harvesting systems channel rainwater that falls on to a roof into storage via a system of gutters and pipes. The first flush of rainwater after a dry season should be allowed to run to waste as it will be contaminated with dust, bird droppings etc. Roof gutters should have sufficient incline to avoid standing water. They must be strong enough, and large enough to carry peak flows. Storage tanks should be covered to prevent mosquito breeding and to reduce evaporation losses, contamination and algal growth. Rainwater harvesting systems require regular maintenance and cleaning to keep the system hygienic.
A subsurface dyke is built in an aquifer to obstruct the natural flow of groundwater, thereby raising the groundwater level and increasing the amount of water stored in the aquifer.
The subsurface dyke at Krishi Vigyan Kendra, Kannur under Kerala Agricultural University with the support of ICAR, has become an effective method for ground water conservation by means of rain water harvesting technologies. The sub-surface dyke has demonstrated that it is a feasible method for conserving and exploiting the groundwater resources of the Kerala state of India. The dyke is now the largest rainwater harvesting system in that region.
Kerala leads the way!
There are good opportunities for Rainwater harvesting in Kerala because Kerala is blessed with two rainy seasons. Kerala faces severe water scarcity between February and mid May every year. During summer, there are drinking water shortages. During this period drinking water and other water purposes become unavailable. This is expected in the coming years. In spite of 44 rivers and world's largest water well density, per capita surface water and groundwater availability of the State is lower than that of arid States of India. Moreover, Kerala has one of the lowest per capita rainwater availability in the Indian sub-continent and it is still decreasing over the time, even though it receives 3000 mm of rainfall, which is around 3 times the Indian national average. The high variations in spatial and temporal rainfall add to the complexity of problems associated with water management faced by the State.
To learn the process of Rain Water Harvesting Watch the following very informative video on Rain Water Harvesting:
Disclaimer: EnviroSpectra has shown this video only for information purpose. We have no connection or link whatsowver with GRAF.
More Resoureces and useful information on Rain Water Harvesting visit:
- Rainwater Harvesting and Water Purification System.
- Kerala Wikipedia Article: Rainwater harvesting in Kerala
- Wikipedia : Rainwater Harvesting
Rainwater harvesting involves basement waterproofing and a whole house water filter, water filters, water storage barrels, water filtration, water purification and water softener to make it potable.
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