Agriculture Reference
In-Depth Information
Adverse Effect of Groundwater Overabstraction (or Groundwater Mining)
If the groundwater withdrawal is not based on safe yield or greater than the natural
recharge (for long-term consideration), groundwater mining (or overdraft) occurs,
which causes numerous adverse effects or environmental consequences:
•
Failure of suction-mode pumps
•
Reduction in stream flow
•
Drying up of natural water bodies (e.g., ditches, ponds, canals), thus affecting the
ecosystem
•
Shallow-rooted trees become endangered
•
Degradation of water quality
•
Intrusion of polluted water (brackish or saline water) in coastal areas
•
Disruption of ecosystem
•
Land subsidence
If the groundwater becomes contaminated (such as arsenic contamination in West
Bengal of India and Bangladesh), it will be a catastrophic event and troublesome
to purify. Environmental consequences of such exploitation may become slowly
critical in most cases. But the situation may be irreversible if care is not taken
beforehand.
Fresh-Water Aquifer Underlying Saline Groundwater
In most natural saline zones, a relatively fresh water aquifer underlay the saline
could be used as a source of irrigation supply. Other management practices may be
needed along with irrigation, depending on the salinity level of the water and the
salt tolerance of the desired crop.
Use of Nonconventional Water with Appropriate Measures
Poor quality water or saline surface/ground water may be used to irrigate crops with
some special measures (described below) and thus can be regarded as a vital source
of water in water scarce areas.
Mixing Saline Water with Fresh Water
Irrigable water can be increased by mixing highly saline water with fresh water
(good quality or low salinity water) to lower the salinity to acceptable/tolerable
limits. Mixing does not reduce the total solute content but reduces the solute
concentration due to dilution.
The salinity of the mixed water or the mixing ratio can be obtained by using the
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