By Jawwad Rizvi
THE aquifer of Lahore is quickly depleting and during the last three decades it registered decline of over 300 percent which poses serious threat about availability of water to the City in the future.
The rapid increase in population, migration of people to Lahore and industrialisation had increased the water supply demand manifold, especially in the last two decades. On the other hand, the urbanisation and industrialisation have reduced the recharge as a significant portion of the land has become impermeable.
According to a study conducted by the Water and Sanitation Agency (Wasa), the public water supply to the City is totally dependent on groundwater abstraction by sinking tubewell mostly of 4.00cfs and some 2.00cfs capacity.
In 1980, the minimum level of aquifer in Lahore was 5.70 meter and the maximum 19.83 meter which lowered down to 8.18 meter and 25.25 meter in 1990 and 10.67 meter and 32 meter in 2000.
In 2010, the minimum aquifer level in Lahore reached minimum 21.55 meter and maximum 43.90 meter, registering a total decline of 15.85 meter and 24.07 meter respectively in just three decades
At present, 460 tubewells are in operation to supply water to the Lahorites and the extraction of the tubewell is about 400mgd. The tubewells belonging to Pakistan Railways, M.E.S., Cantonment Board, DHA, Hospitals, PHA, government buildings, private societies and industry and for irrigation purposes are also extracting water from the aquifer of Lahore.
As Wasa is continuously adding new tubewells to meet the public demand of the Lahore area, the aquifer of the City is under stress and the rate of lowering of groundwater table is increasing day by day but since last five years, the situation has become worrisome which can be clearly understood from the following table.
The study of water quality with the help of the Pakistan Institute of Nuclear Science and Technology (PINSTECH) of Pakistan Atomic Energy Commission has also indicated the presence of toxic metal in water. Arsenic was detected in most of the samples with the concentration range of 4-129 ppb. Hence, there is the possibility of facing the serious problems relating to the quantity and quality of groundwater in the provincial metropolis in near future. Therefore, in order to overcome the problem, there is the need to study the aquifer of Lahore both quantitatively and qualitatively, which may include but may not be limited to the following, identification of the groundwater flow pattern, potential and recharge mechanism, determination of sustainability from deep aquifer in case of large scale exploitation, setting of tubewells, in order to arrest the lowering of water table.
The study also suggests the assessment of potable water quality with special reference to the toxic elements, which may include but not be limited to the following: determination of interaction/hydraulic linkage between fresh water and contaminated water, especially with reference to toxic elements, determination of source of toxic elements (especially arsenic) in different zones (aquifer system) and mobilization of toxic elements (especially arsenic) in deep aquifer and identification of toxic elements (especially arsenic) free areas of production wells, for future exploitations.
It has suggested that no department/agency should be allowed to install tubewells without prior permission and the aquifer charges also be imposed depending upon the capacity of tubewell. (This issue is addressed in the draft Punjab Municipal Water Act).
The figure of supplying 80 gpcd may be reduced to 50 gpcd. This will go a long way for conservation of groundwater resources of Lahore (Long-term remedy proposed under Lahore Wasa Business Plan).