This presentation shows various methods of rain water harvesying in urban area

1. WATER MANAGEMENT FORUM
The Institution of Engineers (India)
http://www.wmf-iei.org/index.php/

2. • Process of arresting and storing rain water for
efficient application and conservation
• An effective way of utilising large quantum of
water which otherwise goes as surface runoff.
• RWH has 2 components:
1) Rain water collection for storage
2) Recharging groundwater
What is artificial recharge to ground
water?
• Process of enhancing ground water storage artificially
at a rate exceeding natural rate of recharge
• Possible by putting up small structure enabling storage
and infiltration

3. What are the advantages of RWH & recharge?
 Improvement in ground water levels
 Enhancement of water availability in wells/ tube-wells
 Improvement in the quality of ground water through
dilution
 Saving energy in lifting ground water – one meter rise
in level saves 0.40 KWH of electricity
 Reduction in soil erosion due to reduced surface water
runoff

4. What are the Rain Water Harvesting techniques for urban
areas?
• Suitable for buildings having roof
area of 100 square meters
Constructed for recharging shallow
aquifers
Pit width 1 to 2 meter, depth 2 to 3
meter
Pits to be backfilled with
boulders at bottom --5 to 20 cm
size,
gravel in between 5-10 mm size
and
coarse sand at the top --1.5 to 2
mm size in graded form.

5. • Backfill pits for smaller roofs with brickbats/ cobbles.
- Mesh to be provided at top to prevent leaves etc from falling &
choking
- Top sand to be cleaned periodically.
- Bye-pass arrangements to be provided before collection
chamber to reject first showers
Abandoned Tube –wells
 Can be utilised for recharging as shallow aquifers have dried
up
 Water channelized for recharging, after silt removal from
such wells
 10 cm diameter PVC pipes connected to roof drains. First
rains allowed to pass through bottom of drain pipe, which is
closed thereafter.

7. Recharge Trench
• Suitable for buildings having roof area of 200 square meters
or more
• Suited at places where shallow permeable strata exists
• Half to one meter wide, one to one and a half meter deep
and 10 to 15 meter long trenches

8.  Backfilled with boulders at
bottom --5 to 20 cm
size, gravel in between 5-10
mm size and coarse sand at
the top --1.5 to 2 mm size in
graded form.
 Mesh to be provided at top
to prevent leaves etc from
falling & choking
 Top sand to be cleaned
periodically.
 Bye-pass arrangements to
be provided before
collection chamber to reject
first showers

9. RECHARGE WELLS/ SHAFTS
Suited at places, where deeper permeable strata exists.
100 to 300 mm diameter recharge well, constructed 3 to 5
meter below water level.
Trench for channelizing
water to well – 1.5 to 3 m
wide, 10 to 30 m in length
constructed.
Shaft of 2 to 5 m
diameter, 3 to 5 m depth is
constructed if aquifer is
located at greater depth.
Recharge well mentioned
above, is to be constructed
within this shaft.

10. Inputs : Courtesy Central Ground Water Board