RAIN WATER HARVESTING WITH RAINY FILTERS
RAIN WATER HARVESTING TECHNIQUES :
There are two main techniques of rain water harvestings:
1. Storage of rainwater on surface for future use.
The storage of rain water on surface is a traditional techniques and structures used were underground tanks, ponds, check dams, weirs etc.
2. Recharge to ground water.
Recharge to ground water is a new concept of rain water harvesting
and the structures generally used are - Pits, Trenches, Dug wells, Hand pumps, Recharge wells, Recharge Shafts , Lateral shafts with bore wells.
Spreading techniques :-
When permeable strata starts 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.
Urbanisation effects on Groundwater Hydrology :
1. Increase in water demand
2. More dependence on ground water use
3. Over exploitation of ground water
4. Increase in run-off, decline in well yields and fall in water levels
5. Reduction in open soil surface area
6. Reduction in infiltration and deterioration in water quality
Methods of artificial recharge in urban areas :
1 .Water spreading
2. Recharge through pits, trenches, wells, shafts
3. Rooftop collection of rainwater
4. Roadtop collection of rainwater
5. Induced recharge from surface water bodies.
Benefits of Artificial Recharge in Urban Areas :
1. Improvement in infiltration and reduction in run-off.
2. Improvement in groundwater levels and yields.
3. Reduces strain on Special Village Panchayats/ Municipal / Municipal Corporation water supply
4. Improvement in groundwater quality
5. Estimated quantity of additional recharge from 100 sq. m. roof top area is 55.000 liters.
