1. Artificial recharge and Rain water harvesting –Case studies in Kerala
A.Subburaj,Scientist-D
Central Ground Water Board
Kerala Region,Trivandrum

2. Major causes for scarcity
Rainfall pattern
Geomorphological set up
Drainage
Sand mining
Hydro geological factors
Over exploitation
Reclamation of land for settlement

4. Definition
Augmentation of ground water reservoir by man made structures by using rain water.
Rain Water Harvesting is deliberate collection and storage of rain water

5. Methods of Artificial Recharge
a.Direct surface techniques
. Flooding
. Basins or percolation tanks
. Stream augmentation
. Ditch and furrow system
. Over irrigation
b.Direct subsurface techniques
. Injection wells or Recharge wells
. Recharge pits and shafts
. Dug well recharge
. Bore hole flooding
. Natural openings,cavity filling
c.Combination of Surface-Subsurface techniques
. Basin or percolation tanks with pit shaft or wells
d. Indirect Techniques
. Induced recharge from surface water source
.Aquifer modification

6. Rain water Harvesting
a.Storage of rain water on surface for future use
b.Recharge to ground water
Pits
Trenches
Dug wells
Hand pumps
Recharge wells
Recharge shafts
Lateral shafts with bore wells
Spreading techniques

7. Benifits
An ideal solution to water problems in areas having inadequate water resources
The ground water level will rise
Mitigates the effects of drought & achieves drought proofings
Reduces the runoff which chokes the storm water drains
Flooding of roads and low land areas are reduces
Quality of water improves
Soil erosion will be reduced
Saving of energy per well for lifting of ground water-a one meter rise in water level saves about 0.40 KWH of electricity.

8. Cost S.No Recharge structure Approximate cost (in Rs) 1 Recharge pit 2
Recharge trench 3
Recharge through hand pump 4
Recharge through dug well 5
Recharge well

9. Case studies

30. vallikavu

38. Chech dam

42. Check dam

53. Subsurface duke

58. Recharge pond