Assessing groundwater abstraction and salt accumulation in the unconfined aquifer of Rachna Doab, Pakistan: a modeling approach

ABSTRACT Groundwater is a critical resource facing growing threats from overuse and contamination globally. This study examines uncontrolled groundwater extraction and salt accumulation in the Rachna Doab region using ArcGIS, MODFLOW, and MT3DMS algorithms combined with a finite-difference numerical technique. Geological, hydrological, and hydrogeological data were analysed to assess groundwater level decline and total dissolved solids (TDS) concentration. The model was calibrated using piezometric data and TDS concentrations (2009–2016) and validated with data from 2017–2021, showing strong correlations between estimated and observed values. Two pumping scenarios for 2027 were considered: maintaining current pumping rates (Scenario I) and increasing rates based on future trends (Scenario II). Simulations indicated that water samples near Samundri Drain had the highest TDS concentrations, highlighting the impact of wastewater drains and saline groundwater. Groundwater samples revealed that higher pumping rates and poor-quality deeper groundwater are primary causes of saline intrusion.