Assessing the Role of Infiltration Galleries to Enhance Groundwater Recharge in Model Town Lahore

Abstract

Lahore is the provincial capital of Punjab and second biggest city of Pakistan with respect to the population. Average annual population growth of Lahore is 4.14% from 1998-2018, which is much higher than the average population growth rate of Pakistan which is 2.4%. According to investigations average annual groundwater depletion rate of Lahore is 1.07 m/year. As with the growth of population new housing societies are being built to accommodate the burgeoning population. These societies enhance impermeable areas, moreover, pump huge amount of groundwater from the underground water source. There should be sustainability in water pumping and water recharging. Past studies show that groundwater exploitation in Lahore is not sustainable as abstraction rates are higher as compared to groundwater recharge rates. Therefore it is necessary of find out alternative means to recharge the groundwater aquifer of Lahore. There is a need to investigate the role of infiltration galleries to accelerate the groundwater recharge. In order to complete the research, temporal distribution was plotted on ArcMap. HEC-HMS was used for the calculation of discharges which were verified with analytical methods. Groundwater model prepared on Visual MODFLOW was calibrated and validated. The results indicate that due to groundwater overexploitation water levels continue to decrease with the passage of time. The average simulated water table decline is 1.1 meter per year in the study area. So in order to overcome this crisis, infiltration galleries were proposed and designed in the study area. It was seen that these infiltration galleries allow recharging the groundwater at better rate. As the model results showed that depletion rate of groundwater reduces and the groundwater level is about 0.3m higher when there are infiltration galleries. The study proposes that the Infiltration Galleries have a potential to recharge the groundwater at good rate, therefore its installation must be preferred according to the groundwater hydrological balance in the region.