Calibration of a groundwater flow model in a karst aquifer using EPM approach: Case of Elhajeb-Ifrane aquifer, Morocco

Abstract

Numerical models constitute a powerful tool for groundwater resources management, as they can provide information about flow path, water balance, and effects of future actions. In karst aquifers, groundwater modelling may be challenging because of the heterogeneity of the system. Indeed, karst aquifers have concentrated recharge in sinkholes and preferential flow patterns through fractures and conduits. Modellers used several approaches to simulate karst aquifers. The equivalent porous media approach was used by many researchers and showed an acceptable performance of the application of MODFLOW in regional and sub-regional aquifers. The objective of this study is to simulate the sub-regional aquifer of Elhajeb-Ifrane. The groundwater flow model was constructed using a Python package and was calibrated using the parameter estimation code. The results show a good fit between simulated and observed heads. The model reduced RMSE values to 0.49, 0.56, and 0.58 for piezometers 1098/22, 1448/22, and 1830/22, respectively. The annual water balance results show that the aquifer meanly discharges to the springs with 71.8% and 80.8% in 2016 and 2017, respectively, followed by streams with 5.9% AND 5% in 2016 and 2017, respectively, then discharges to Sais aquifers with 2.6% and 3.8% in 2016 and 2017, respectively.