Modeling coastal aquifer dynamics in Qatar for long‑term water banking

Qatar relies almost entirely on desalination to meet its potable water needs due to the limited and deteriorating quality of
natural groundwater resources. To enhance long-term water security and complement surface reservoir infrastructure, this
study investigates the feasibility of managed aquifer recharge (MAR) as a strategy for large-scale water banking in Qatar’s
coastal aquifers. A three-dimensional, density-dependent SEAWAT model was developed and calibrated using historical
groundwater head and salinity data to simulate groundwater flow and solute transport in a 1480 km2 study area in Northeast
Qatar. The model incorporates regional hydrogeologic characteristics and karst features using an equivalent porous medium approach, supported by pilot point calibration. It is then used to assess multiple long-term MAR strategies under uncertainty
using Monte Carlo simulations driven by probabilistic precipitation and spatially variable hydraulic conductivity fields. Simulation results indicate that MAR is a viable and flexible strategy, with cyclic and delayed extraction approaches providing the best trade-offs between water quality and volume recovery. High-rate short-term extraction is effective for emergency supply but poses risks to aquifer health. This work represents the first 3D density-dependent MAR modeling effort in Qatar and provides critical insights into the design and management of sustainable water banking systems in arid coastal environments.