Search

In a water-scarce country such as Pakistan, rainfall is the third-largest source of freshwater. In most of the urban cities of the country, rainwater is mixed with sewerage and is rendered useless for managed aquifer recharge purposes. Therefore, this study investigates the rainfall potential for managed aquifer recharge in Lahore (Pakistan). The present research was designed and conducted by the Irrigation Research Institute (IRI). Three different sites were selected for rainwater sample collection across the study area (Lahore), ranging from urban to rural areas. The rainwater samples were collected and divided into three categories (direct capture, rooftop runoff, street runoff). For longer rainfall events, the effect of time on the quality of the collected rainwater samples was also studied. Spatiotemporal trends of turbidity, pH, electrical conductivity, total dissolved solids, carbonates, bicarbonates, chloride, calcium, magnesium, and hardness in the collected rainwater samples were investigated. In terms of TDS, results indicated that directly captured rainwater is most suitable for managed aquifer recharge (TDS < 50 ppm), followed by rooftop runoff (TDS < 100 ppm). In addition, the quality of rainwater samples collected at the rural site was comparatively better. Moreover, the quality of rainwater samples improved after the initial ten minutes. All in all, this study concludes that direct capture of rainwater is the most suitable option for managed aquifer recharge.

The main objective of this study was to develop a procedure to evaluate various recharge components of a groundwater reservoir to estimate the long term average seasonal groundwater recharge in Rechna doab in the Punjab province of Pakistan. A regional lumped water balance model for the Rechna doab was developed and applied to estimate the long term a seasonal recharge to groundwater reservoir. For comparison, recharge was also estimated by a specific yield method from observed groundwater levels. A water balance study was conducted on seasonal basis (6 months) for a period of 31 years (1960–1990). Recharge estimated by the two methods was found to be in good agreement. The average value of net groundwater recharge during Kharif (April–September) season was found to be some 60 mm. No recharge occurred during Rabi (October–March), rather there was a depletion of the groundwater reservoir during the winter months. Long term average annual depletion of a groundwater reservoir was found to be greater than corresponding value of annual recharge. It was concluded that on a regional basis the groundwater reservoir was being depleted resulting in an average groundwater table of Rechna doab about 2.3 m fall over the 1960–1990 period.