Hydrogeological mapping and conceptual hydrogeological modeling in Takhar, northeastern Afghanistan

Systemic insecurity and a fragile economy have impeded research into northern Afghanistan’s major, high-potential aquifer systems, even as climate-induced groundwater depletion accelerates deep well drilling. Addressing this critical gap, our study pioneers a comprehensive methodology was applied to develop hydrogeological maps and conceptualize aquifer structures in the Northern Takhar Province (NTP). This approach integrated diverse datasets, including precipitation records, digital elevation model (DEM), geological maps, borehole logs, technical well reports, pumping test results, geological interpretations, and continuous groundwater-level monitoring. Hydrogeological modeling streamlined the assessment process and facilitated the integration of newly acquired data. The visualization of sedimentary structures, geological features, aquifer hydraulic gradients, groundwater quality, and pumping test results provided critical insights into aquifer dynamics, supporting the development of a robust Conceptual Hydrogeological Model (CHM). This model was translated into a steady-state numerical simulation calibrated using observed hydraulic heads, spring discharges, and pumping test results. The study delineated three major aquifer systems: The Panj Amu River Basin (PARB), the Rustaq Valley Aquifer (RVA), and the Chahab Aquifer (CA). The RVA, consisting of an upper unconfined unit and a lower semi-confined unit, was selected as the mine focus due to its structural complexity and strategic importance. Hydro-geochemistry results indicate mixed Ca-Mg-Na water facies, and groundwater quality index (GQI) classifies the water as generally poor. Overall, the CHM provides a robust basis for advanced numerical modeling and supports groundwater management (GM) planning.