Sustainable Phosphate Mining: Hydrogeological Insights and Numerical Modeling of the Beni Amir Phosphate Deposit, Morocco

The phosphate mining from the Beni Amir deposit, located in the southern part of Central Morocco, presents many difficulties, due to the presence of groundwater, which can either partially or completely submerge the phosphate layers. This challenge becomes particularly pronounced in the context of climate change conditions and water scarcity.

To address these issues, a hydrogeological study has been conducted aiming to understand the aquifer’s function and ensure sustainable phosphate extraction from the deposit. Initially, geological, and hydrogeological information from 692 boreholes were collected and analyzed to develop a 3D hydro-stratigraphic conceptual model, which indicate that approximately 73% of the deposit is at least partially submerged by the groundwater, while the remaining 27% constitutes the dry zone.

Additionally, a numerical model was developed and calibrated using the MODFLOW code. Calibration was accomplished under both steady-state and transient conditions by adjusting model parameters until the model's solution aligns with known data, utilizing 580 observed groundwater levels measured in 2023 and 7 pumping wells. The model’s performance was evaluated using R², RMSE, and NRMSE coefficients, showing high accuracy and consistent model performance.

The hydrogeological model was executed to evaluate the effects of the dewatering process in the surrounding mining areas, revealing a high impact on groundwater resources and the water table level. These findings will be employed to strategize well-considered plans for optimal groundwater pumping and mine dewatering strategies, ensuring the safety of mining operations throughout different stages of mine development.