Demography and Pakistan

Demography, along with geography, has always figured in the making of nations and in inter-state relationships. But perhaps never so critically as in the case of Pakistan. Indeed, in all the annals of its proto-history and existential career, demography and Pakistan have been interminably entwined. This may sound incredible, even inexplicable.

Modeling the Effects of Groundwater Pumping on Watertable of a Faisalabad Water Supply Scheme

The Faisalabad city, resident of 2.6 million people, has brackish groundwater in its underlying aquifer. The water and sanitary agency (WASA) of Faisalabad Development Authority (FDA) installed a cluster of 29 tubewells in 1992, each of 114 lps capacity, at Chenab River bed well field aquifer, 30 km away from Faisalabad city in the North-West direction, to supply fresh groundwater for drinking. The continuous operation of all these tubewells resulted in lowering of groundwater level, from 5 m below the ground surface in 1992 to 22 m below the ground surface in 2010, in the study area and has started threatening sustainability of the system. Whereas WASA has installed 25 more tubewells for meeting drinking water demand. This study was undertaken to ascertain the effects of such large abstraction of groundwater on the aquifer while keeping in view the future scenarios. Prior to using a computer simulation model as a management tool, it requires its proper calibration and validation. A groundwater transient model was developed using MODFLOW to study the effect of groundwater pumping on the Chenab River bed well field area. The model was calibrated using water table data from 1992 to 2005 and was validated against independent data set of 2006 to 2010. The model simulation was reasonably acceptable based on model evaluation indicators such as residual mean, root mean square error, sum of squares, coefficient of correlation and coefficient of efficiency, which were within acceptable limits. Sensitivity of the model shows that the model was more sensitive to the hydraulic conductivity. The model simulations showed that major recharge was from the Jhang Branch canal in the range of 6,511 to 8,038 m3 day km-1. The recharge contribution varied from year to year as a function of rainfall and flows in the Chenab River. Moreover, the groundwater head contour showed steep gradient in southern part of the well field. This steep gradient indicates that a steady state condition has reached and the rate of declination will be less as compare to the earlier years. The calibrated model was used to simulate the effects of existing capacity of pumping continued to 2030 and 90% of the capacity, which showed a water table declined rate of 0.6 m year-1 to 1.3 m year-1, respectively. A groundwater recharge option was also simulated by considering a constant head boundary condition of 10 km length along the left side of Chenab River, which results a decline rate of 0.45 m year-1 till 2030. The model simulation showed that sustainability of the system can be achieved only if adequate recharge sites are established to control the falling water table.