1. RAIN WATER HARVESTING AND
ARTIFICIAL RECHARGE TO GROUND
WATER
BALDEV CHUGH
RAINWATER HARVESTING EXPERT
2. WHAT IS RAIN WATER HARVESTING :
• The principle of collecting and using precipitation from
a catchments surface.
• An old technology is gaining popularity in a new way.
Rain water harvesting is enjoying a renaissance of sorts
in the world, but it traces its history to biblical times.
Extensive rain water harvesting apparatus existed 4000
years ago in the Palestine and Greece. In ancient Rome,
residences were built with individual cisterns and
paved courtyards to capture rain water to augment
water from city's aqueducts. As early as the third
millennium BC, farming communities in Baluchistan
and Kutch impounded rain water and used it for
irrigation dams.
3. ARTIFICAL RECHARGE TO GROUND
WATER :
• Artificial recharge to ground water is a process
by which the ground water reservoir is
augmented at a rate exceeding that obtaining
under natural conditions or replenishment.
Any man-made scheme or facility that adds
water to an aquifer may be considered to be
an artificial recharge system.
4. WHY RAIN WATER HARVESTING :
• Rain water harvesting is essential because :-
• Surface water is inadequate to meet our demand
and we have to depend on ground water.
• Due to rapid urbanization, infiltration of rain
water into the sub-soil has decreased drastically
and recharging of ground water has diminished.
• Consider conserving water by harvesting and
managing this natural resource by artificially
recharging the system.
5. 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 :-
6. RWH TECHNIQUES..(CONTD..)
• 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, 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.
7. RWH TECHNIQUES..(CONTD..)
• 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.
8. RWH TECHNIQUES..(CONTD..)
• 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 is back filled with
boulders, gravels & coarse sand.
• 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.
9. DIVERSION OF RUN OFF INTO
EXISTING SURFACE WATER BODIES
• Construction activity in and around the city is
resulting in the drying up of water bodies and
reclamation of these tanks for conversion into
plots for houses.
• Free flow of storm run off into these tanks and
water bodies must be ensured. The storm run
off may be diverted into the nearest tanks or
depression, which will create additional
recharge.
10. Urbanisation effects on Groundwater
Hydrology :
• Increase in water demand
• More dependence on ground water use
• Over exploitation of ground water
• Increase in run-off, decline in well yields and
fall in water levels
• Reduction in open soil surface area
• Reduction in infiltration and deterioration in
water quality
11. Methods of artificial recharge in
urban areas :
• Water spreading
• Recharge through pits, trenches, wells, shafts
• Rooftop collection of rainwater
• Roadtop collection of rainwater
• Induced recharge from surface water bodies.
12. Computation of artificial recharge
from Roof top rainwater collection :
• Factors taken for computation :
• Roof top area 100 sq.m. for individual house
and 500 sq.m. for multi-storied building.
• Average annual monsoon rainfall - 780 mm.
• Effective annual rainfall contributing to
recharge 70% - 550 mm.
13. Benefits of Artificial Recharge in
Urban Areas :
• Improvement in infiltration and reduction in run-
off.
• Improvement in groundwater levels and yields.
• Reduces strain on Special Village Panchayats/
Municipal / Municipal Corporation water supply
• Improvement in groundwater quality
• Estimated quantity of additional recharge from
100 sq. m. roof top area is 55.000 liters.
• Reduces waterlogging
14. HARVESTING RAINWATER
HARNESSING LIFE :
A NOBLE GOAL - A COMMON RESPONSIBILITY
• Ground water exploitation is inevitable is Urban areas.
But the groundwater potential is getting reduced due
to urbanisation resulting in over exploitation. Hence, a
strategy to implement the groundwater recharge, in a
major way need to be launched with concerted efforts
by various Governmental and Non-Governmental
Agencies and Public at large to build up the water table
and make the groundwater resource, a reliable and
sustainable source for supplementing water supply
needs of the urban dwellers.
15. ……CONTD
• Recharge of groundwater through storm run off and
roof top water collection, diversion and collection of
run off into dry tanks, play grounds, parks and other
vacant places are to be implemented by Special Village
Panchayats/ Municipalities /Municipal Corporations
and other Government Establishments with special
efforts.
• The Special Village Panchayats
/Municipalities/Municipal Corporations will help the
citizens and builders to adopt suitable recharge
method in one's own house or building through
demonstration and offering subsidies for materials and
incentives, if possible.
16. ATTRIBUTES OF GROUNDWATER :
• There is more ground water than surface water
• Ground water is less expensive and economic resource.
• Ground water is sustainable and reliable source of water supply.
• Ground water is relatively less vulnerable to pollution
• Ground water is usually of high bacteriological purity.
• Ground water is free of pathogenic organisms.
• Ground water needs little treatment before use.
• Ground water has no turbidity and colour.
• Ground water has distinct health advantage as art alternative for lower sanitary
quality surface water.
• Ground water is usually universally available.
• Ground water resource can be instantly developed and used.
• There is no conveyance losses in ground water based supplies.
• Ground water has low vulnerability to drought.
• Ground water is key to life in arid and semi-arid regions.
• Ground water is source of dry weather flow in rivers and streams.
