Design and numerical analysis of inverted well technique for aquifer recharge estimation

Abstract

The seasonal polarization due to climate change and population explosion in developing countries is translating into rapid groundwater depletion. In the populous cities relying on groundwater for their water requirements, aquifers are turning into exiguity due to much higher depletion corresponding to recharge rate. Therefore, it is imperative to model the aquifer conditions for extrapolating the future scenario and adopting efficient and safe groundwater recharge techniques based on simulation results to counter the proliferating depletion rate. In this study, an efficient inverted well design with effective multiple filtration compartments is proposed for ground water recharge at natural runoff collection points having high conductivity and effective filtration. The current depletion rate and design recharge capability was assessed by simulating the aquifer conditions along with boundary conditions confined to model town area, groundwater table data of extraction and observation wells in study area from year 2014–2020, precipitation data 2008 to 2020, and other spatial and temporal variations in model town area of Lahore in VISUAL MODFLOW program. The model results exhibited that the depletion rate of Lahore (model town area having a land area of 5.9 km2 approximately) was 0.96 m per year (investigating year 2014–2020), this concurred with the depletion rate recorded by water table observations of extraction and observations wells from year 2014–2020. The depressions in model town park area of Lahore were simulated as recharge points, and 4 inverted wells with their calculated conductivity were simulated in model. The precipitation data with peak runoff generations for 7 years (2014–2020) was intercalated in the model. The results explicated that the simulation of inverted wells recharge technique at natural rainfed depressions of model town park area significantly reduced the depletion rate from 0.93 m per year (2014–2020) to 0.76 m per year (2021–2023) in MODFLOW visual water table contours. Therefore, this inverted well design-based recharge technique can effectively be used for efficient groundwater recharge, and its application at natural depressions in the groundwater dependent cities can effectively hinder and stabilize the depleting ground water resources.