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 | Rain Water Harvesting - Check list | |
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Does your apartment have rainwater harvesting done? If you haven’t done it
yet – Read this section!
WHAT IS RAIN WATER HARVESTING ?
 The
principle of collecting and directing rainwater to a tank so that the water
does not evaporate / goes wasted is called rainwater harvesting. An old
technology, this is gaining popularity in a new way.
WHY RAIN WATER HARVESTING ?
Rainwater harvesting is essential because: -
1. Surface water is inadequate to meet our demand and we have to depend on
ground water.
2. Due to rapid urbanization, infiltration of rainwater into the sub-soil
has decreased drastically and recharging of ground water has diminished.
As you read this guide, seriously consider conserving water by harvesting
and managing this natural resource by artificially recharging the system.
RAIN WATER HARVESTING TECHNIQUES:
There are two main techniques of harvesting rainwater.
a. Storage of rainwater on surface for future use.
b. Recharge to ground water.
The storage of rainwater on surface is a traditional technique and
structures used were underground tanks, ponds, check dams, weirs etc.
Recharge to ground water is a new concept of rainwater harvesting and the
structures generally used are: -
Pits :- Recharge pits are constructed for recharging the shallow
aquifer. These are constructed 1 to 2 m, wide and to 3 m. deep which are
back filled with boulders, gravels, and coarse sand.
Trenches :- These are constructed when the permeable stram is
available at shallow
depth. Trench may be 0.5 to 1 m. wide, 1 to 1.5m deep and 10 to 20 m. long
depending up availability of water. These are back filled with filter
materials
Dug wells :- Existing dug wells may be utilised as recharge structure
and water should pass through filter media before putting into dug well.
Hand pumps :- The existing hand pumps may be used for recharging the
shallow/deep aquifers, if the availability of water is limited. Water should
pass through filter media before diverting it into hand pumps.
Recharge wells :- Recharge wells of 100 to 300 mm. diameter are
generally constructed for recharging the deeper aquifers and water is passed
through filter media to avoid choking of recharge wells.
Recharge Shafts :- For recharging the shallow aquifer which are
located below clayey surface, recharge shafts of 0.5 to 3 m. diameter and 10
to 15 m. deep are constructed and back filled with boulders, gravels &
coarse sand.
Lateral shafts with bore wells :- For recharging the upper as well as
deeper aquifers lateral shafts of 1.5 to 2 m. wide & 10 to 30 m. long
depending upon availability of water with one or two bore wells are
constructed. The lateral shafts are back filled with boulders, gravels &
coarse sand.
Spreading techniques :- When permeable strata start from top then
this technique is used. Spread the water in streams/Nalas by making check
dams, nala bunds, cement plugs, gabion structures or a percolation pond may
be constructed.
At present rainwater harvesting is made compulsory by every government.
During these times when water is scarce, it is the duty of every household
to have this in place.
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