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In this study, the geohydraulic parameters of aquifers in the Sahel Doukkala region, western Morocco were estimated using a geostatistical method to transform vertical electrical soundings (VES) data into electrical resistivity tomography (ERT) profiles. The resulting ERT profiles covered a larger area than the original VES data, allowing for a more comprehensive analysis. The obtained results indicated that the apparent and inverted resistivities range from 16 to 1558 Ohm.m and from 4 to 6980 Ohm.m, respectively, with a low inversion error (RMS) of 6.1–13.1%, demonstrating the reliability of the proposed approach. Using the inverted resistivities, the estimated hydraulic conductivity, effective porosity, and transmissivity ranged from 0.2 to > 103.7 m/day, 11.6% to > 45.8%, and 1.7 to > 2028.6 m2/day, respectively. These values reflect the sand, clayey sand, and limestone lithology prevalent in the study area, with medium to high aquifer potential. The validation of our results with pumping test data showed that the estimated geohydraulic parameters are representative of the geological formations in the study area. In addition to providing a rapid interpretation of the data, the present study offers fundamental insights for future research, contributing to better planning and management of groundwater resources. [ABSTRACT FROM AUTHOR]

This study aims to assess the evolution of seawater intrusion between 1992 and 2011 periods in the coastal aquifers of Oualidia. To achieve this objective, the combination of geoelectrical and hydrochemical methods was adopted. Apparent resistivity maps, using 74 Vertical Electrical Sounding (VES) performed on 1992, allowed to distinguish two different zones. The conductive one, with apparent resistivity ranging between 4 and 86 Ω·m, is limited to 1 km with respect to the ocean. Meanwhile, the resistant one is much farther from the coastline. Besides, results of Electrical Resistivity Tomography (ERT) profiles performed during 2011 are in good agreement with those obtained by apparent resistivity maps. The ERT profiles show a conductive level characterized by low resistivity below 30 Ω·m assigned to seawater intrusion effect. Moreover, hydrochemical analysis, performed on 19 wells during three different periods, on June, December 2010 and May 2011, indicates that the most affected part with marine waters was at that time localized in the first kilometer from the ocean, with high amounts of Na + and Cl − ions. Beyond this fringe, mineralization becomes very weak. Overall, the comparison of old VES with recent ERT coupled with hydrochemical results suggest no important evolution of the salt wedge since 1992. [ABSTRACT FROM AUTHOR]

This study aims to identify groundwater salinization origin and to determine seawater intrusion extension toward the inland in Chaouia, Morocco. To reach these objectives, firstly, 46 groundwater samples were analyzed for major chemical elements during January 2012 and, secondly, 10 electrical resistivity tomography (ERT) profiles were performed perpendicularly to the coastal fringe. Statistical analysis provided the distinction between three Clusters reflecting different hydrochemical processes. Cluster I and Cluster II-a showed a high water electrical conductivity (EC) (from 2.3 to 11.2 mS/cm) with the dominance of Na + (668 mg/L on average) and Cl − (1735 mg/L on average) ions as a consequence of seawater intrusion. However, Cluster II-b presented low ECs (from 0.5 to 1.7 mS/cm) and Ca 2 + (99.6 mg/L on average) and HCO 3 2 − (235.2 mg/L on average) ions dominance. Water chemistry in these wells was controlled by water-rock interaction, cation exchange, and anthropogenic activities. The Hydrochemical Facies Evolution Diagram highlighted the succession of different water facies developed between intrusion and freshening phases. The formation of Na-HCO 3 facies, which characterizes the last facies of freshening phase, followed the succession of Na-Cl, MixNa-MixCl, MixCa-MixCl, MixCa-MixHCO 3 , and Na-HCO 3 . In contrast, Na-Cl facies formation, which characterizes the last facies of intrusion phase, followed the evolution of Ca-HCO 3 , Ca-MixHCO 3 , Ca-MixCl, MixCa-MixCl, MixCa-Cl, and Na-Cl. Moreover, the obtained ERT results allowed determining the extent of different hydrochemical facies and provided more details about seawater intrusion extension. The conductive level assigned to seawater contamination showed a resistivity less than 36 Ω.m, which remains limited to 3000 m from the ocean, where Na-Cl water type dominates. The seawater intrusion depth varied between 5 and 40 m from the surface. Overall, this original study in Chaouia region demonstrated the effectiveness of combining hydrochemical and ERT methods to investigate seawater intrusion, particularly in areas with restrictive water chemistry data. [ABSTRACT FROM AUTHOR]

The coastal aquifer system of Chaouia is recognized as one of the most important aquifers in Morocco that is affected by salinization in the coastal fringe. The purpose of this study is to highlight the origin of salinization by sampling and analyzing groundwater from 44 wells for major elements. This study was carried out in May 2011. The results indicate that, in the central and downstream parts, the dominant facies are Mg 2+ , Na + and Cl − , while Ca 2+ and HCO 3 − dominate in the upstream zones. Ion exchange processes, under seawater intrusion, control the concentration of ions such as calcium, magnesium and sodium. Moreover, groundwater is oversaturated with respect to carbonate minerals (calcite and dolomite), and under-saturated with respect to evaporate minerals (gypsum, halite). The contribution of dissolved halite and gypsum in the groundwater mineralization is revealed by their positive correlation between (Na + Cl) and (Ca + SO 4 ), respectively. Furthermore, the comparison of the hydrochemical results to drinking water quality standards by World Health Organization (2008) shows that more than a half of the water sampled is not suitable for drinking purposes, especially with respect to high levels of EC, TDS, Cl − and NO 3 − . In addition, high mineralization is found to be a consequence of seawater intrusion and anthropogenic activities. [ABSTRACT FROM AUTHOR]