5. Groundwater recharge is divided into two
parts:
1) Natural recharge: The process of Recharge of
ground water naturally is called natural recharge.
2) Artificial recharge: The practice of artificially
obstructing the flowing rainwater and inducing its
infiltration to increase the ground water reservoir is
called artificial recharge. It is carried out when natural
recharge cannot fulfil the requirements throughout the
year.
Groundwater recharge or deep percolation is a
hydrologic process where water moves downward from surface
water to groundwater.
4
6. Natural Recharge
Rainwater enters inside the soil through voids
and the recharge is natural recharge.
The conditions favourable for natural recharge
are:
1)Sandy or permeable soil
2)Rocky strata with fractures
3)Perennial rivers
4)Streams
5)Forest land
6)Comparatively level land with less slope
5
7. 1) Development of urban areas which reduces
open land for recharge
2) Deforestation
3) Reduction in agricultural land
4) Insufficient and irregular rainfall
5) Overuse of water by industries situated on river
banks
6) Discharge of polluted water in natural flow of
water reduces infiltration capacity of soil as
pores of soil gets blocked with impurities
6
8. Artificial Recharge
Due to rapid industrialisation, population
increase, intensive agriculture, urbanization, etc.
the use of water has been considerably
increased. For these purpose water is pumped
from the ground water sources.
The aquifers are not recharged at the same
rate at which water is pumped out. Thus the
water table falls every year. To fulfil the needs
artificial recharge is carried out.
7
10. Spreading method
In this method water is spreads over the
surface of permeable open land and pits
from where it directly infiltrates to shallow
aquifer.
In this method water is stored in shallow
ditches and spread over open area by
constructing low earth dykes.
Rate of recharging depends on
permeability of spreaded area and depth of
water stored.
9
12. This method is suitable for artificial recharge
where the topography is relatively flat, without hills or
valley.
In this method, the area is to be recharged is not
given any treatment. The area is completely flooded
without removal of any vegetation or soil covering.
Water is diverted from stream to supply ditch,
then to field ditches to recharge the ground water.
This method is simple and cost of recharge is
very less.
11
15. In this method area is divided into small basin
by constructing small embankments.
For effective recharge, the depth of water in
the basins is kept about 1.25 m.
If water remains stable in the basin, the rate
of infiltration reduces. Therefore, for effective
recharge, water should remains flowing in the
basin and flow should be along the diagonal.
Water enter the basins through supply ditch
and returns to the stream through outlet.
13
17. This method is suitable where the topography
of area is highly uneven and construction of
basins is not practically possible.
In area with highly uneven topography, the
height of embankments would be either too high
or too small, which may affect the depth of water
in the basins.
In this method, small channels are excavated
in the area. The bed slope of channel is kept
minimum so that detention period of water is
more and infiltration rate of water is high.
15
18. In this method, semi - permeable earthen bunds
are constructed across the flowing stream or
river at suitable spacing to obstruct the flow of
water. The height and spacing of such bunds
depends upon:
- Discharged in the stream/river
- Velocity of flow
- Width of stream/flow
- Characteristics of catchment area
16
19. Khet-Talavadi is the easiest and simple method of
collecting the rain water for storage purpose. The low
lying area in the farm is used for collecting rain water with
very little treatment.
As the name “Khet-Talavadi”, it includes a small
talavadi (Lake) in the farm.
Due to storage of rain water, infiltration of stored rain
water is increased and artificial recharging takes place
and thus water table level of underground reservoir
around the farm is increased. So irrigation capacity is
increased and cost of electricity is reduces.
17
21. In this technique dry village ponds and
reservoir are dug before monsoon and
deepened and widened. The storage
capacity of such ponds increased due to
widening.
During monsoon, the runoff water is
stored in pond / reservoir for domestic and
irrigation uses. The water stored in the
reservoir gradually percolates down to
recharge the ground water
19
23. Recharge well method
In this method a well is dug into ground where
recharge is to be done. This well is called recharge
well. Water is filled filled in the wells which is
percolated to the ground.
This method is suitable where,
1. Spreading method is not applicable
2. The area of recharge is small
3. The aquifer is located at great depth
o Advantage:
1. The recharge rate is high
2. Small area required for recharge
3. Deep aquifers can also be recharged
21
25. Injection method
This method of artificial recharge is more
effective where aquifer to be recharged is
located very deep. In this method water is
directly injected into the aquifer by means of
horizontal wells, gallery or shaft.
The spacing of wells depends upon :
1. The rate of recharge
2. The capacity of well
3. Capecity of aquifer to accept water
23
27. Induced recharge method
In this method the water table around the
natural sources of water such as stream, pond or
lake is brought down by pumping out of water
before monsoon season. The lowering of water
table will increase the rate of infiltration of water
during monsoon.
In this method wells or galleries are
constructed parallel to the river or around the
lake or pond. From these wells or galleries water
is pumped out before rainy season, and water
table is lowered.
25
