Rain Water Harvesting System
The problem of water scarcity is one that is affecting a great many number of cities and villages around the world. The main reason for this is that even though most regions get adequate amount of rainfall, there is no set pattern for the monsoon rains. This means that if there is adequate amount of rain one year, or even excess, the next year could always prove disastrous because of drought like conditions. Such a problem has only one solution: collection of rain water for future use. This is known as the rain water harvesting system.
The rain water harvesting system is one of primal importance to all human beings because surface water is not enough to meet man’s ever growing demands and the dependence automatically goes to groundwater. Since urbanization has increased so greatly, there is a decrease in the absorption of rainwater into the soil. Also, the consequent exploitation of groundwater sources leads to drought conditions in the surroundings. Rain water harvesting system is vital also to the growth of vegetation cover. The collection of rainwater also leads to the increase of water in the otherwise drying up bore wells.
- Rain Water Harvesting Process
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There are two main techniques that can be employed in order to carry out the Rainwater Harvesting Process. The first one is the rainwater being stored on surface, and being used later, when needed. The second method is the recharge to groundwater. The more popular and simpler method among the two is the storage of rainwater on surface, which is done by the creation of underground tanks, dams, weirs,
etc.
The technique of recharge to the groundwater is a relatively new process and can be carried out using the following structures.
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Pits:-
Recharge pits are built in order to recharge the underground aquifers. They may also be used to recharge a bore well. As it is backfilled with stones, it is also less dangerous, than an open well.
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Trenches:-
A trench is dug around 1 meter deep and can can be many meters in length and is a good option for percolation of water. They are filled with filter material.
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Dug wells:-
A dug well can be used as a recharge structure. However, water should be filtered before letting it into the dug well.
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Hand pumps:-
If the availability of water is limited. The existing hand pumps may be used for the rechage of shallow / deep aquifers. As in the case of dug wells, Water in the hand pumps must first be filtered.
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Recharge wells:-
Also called injection wells, they are used to recharge other sources of water. They are used to store water in the subsurface.
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Lateral shafts with bore wells:-
For recharging the upper aswell as deeper aquifers, lateral shafts with one or two bore wells are constructed. These lateral shafts are back filled with boulders, gravels & coarse sand.
Spreading techniques:-
When permeable water starts from top then this technique is used. Spread the water in streams by making check dams, cement plugs, and gabion structures. Percolation ponds may also be built.
It is of utmost importance that we employ methods of rain water harvesting as our water resources are few and they are of vital use to us.
