The presentation shows rain water harvesting techniques in rural area.

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

2. What is Rain Water Harvesting (RWH)?
• 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
◦ water availability in wells/ tube-wells
◦ the quality of ground water through dilution
◦ living conditions in rural areas
 Saving energy in lifting ground water – one
meter rise in level saves 0.40 KWH
 Reduction in soil erosion due to reduced
surface water runoff
 Prevention of sea water ingress in coastal
areas

4. Aspects to be considered for designing RWH
system
• Hydrogeology of the area including
• nature & extent of aquifer,
•soil cover,
•topography,
•depth to water level,
• ground water quality
• Availability of source i.e. surplus runoff
• Hydro-meteorological characters
– rainfall duration, pattern, intensity
• Area contributing runoff like roof top area, etc

5. CATCH RAIN WHERE IT FALLS
What are the Rain water Harvesting techniques for Rural
areas?
Recharge Shaft
-- 2 meter diameter or
more, ends in permeable
strata
- If unlined, backfilled with
filter medium
- If lined, small conductor
pipe leads recharge water to
• Useful for village ponds having top impermeable clay
filter
• Shaft top projects above bed-level of pond and is taken
upto half the full water depth
• Top one or two m done with brick masonry for stability
of shaft
• Half of water collected in pond recharges groundwater.
The other half used for domestic purposes.

6. DUG WELLS
•Abandoned and existing dug wells can be put to use
after removing silt
• Periodic chlorination required
• Recharge water taken through delivery pipe via silt
chamber to well bottom to avoid scouring.

7. CHECKDAMS/NALA PLUGGING
• Constructed across streams with gentle slopes.
• Should have sufficient thickness of permeable bed
• Water confined within the bank of stream
• Height not to exceed 1.5 to 2 meter in general
• Excess water flows above wall
• May be constructed with masonry/ concrete
• Downstream water cushion chamber required to
prevent scouring.

8. Underground Checkdam/ Subsurface dyke
• Constructed below ground
to retard movement of water.
• Site to have shallow
impervious layer with wide
valley, narrow outlet
• One or two meter wide
trench dug across streambed
with depth extending to
impervious layer.
• Trench can be filled with clay or concrete wall upto 0.5
meter below ground level
• PVC sheet of 3000 psi tearing strength at 400 to 600
gauge or LDPE film 200 gauge can also be used along
excavated face of the trench

9. Percolation Tanks
• Located on highly permeable
soil so as to allow water
stored above to percolate and
effect recharge
• Normal storage capacity 0.1
to 0.5 million cubic meter
• Tanks created by earthen
bund with masonry spillway
 Built along hilly slopes Gully Plug
across gullies/ small
streams using locally
available stones, clay
etc.
 Better selection where
slope breaks so as to
have some storage
behind
 Prevents soil erosion and
conserves soil moisture

10. Contour Bunds
• Suited for lands with
moderate slopes without
involving terracing
• Suited for low rainfall area
where runoff can be stored on
slope all along contour of equal
elevation.
• Prevents soil erosion and conserves soil moisture
• Spacing between two contour bunds depends upon
slope and soil permeability.