Combination of Vertical Electrical Sounding (VES) and Electrical Resistivity Tomography (ERT) techniques for hydrogeological reconnaissance in the Guigou plain, Tabular Middle Atlas, Morocco

Abstract

The study site is located in the Guigou plain, which is situated on the south-eastern edge of the Tabular Middle Atlas and is characterised by a particular geology within the mountainous region. Unlike the Tabular Middle Atlas, which is generally covered by Lias carbonate formations, the Guigou plain is characterised by the presence of a different type of cover formed by basaltic flows of plioquaternary age, forming a surface layer that is used extensively for agricultural activities. The main objective of our study is to detect the different geoelectric levels both at the surface and at depth, thus providing indications of the specific aquifer formations in the region studied. The analysis of the results obtained highlighted the presence of a superficial resistant level, attributed to basalts of Plio-Quaternary age, with an estimated thickness of between 30 and 100 m, forming the superficial aquifer of the plain. Next, a conductive level was identified, associated with alternating marl and marl-limestone of Pliocene age, in keeping with the local geology. Finally, at a depth of 225 m, a very resistant level was identified, corresponding to Lias limestone, which becomes a deep aquifer on the Guigou plain. This study provides essential vertical hydrogeological reconnaissance and highlights the need to carry out numerous tomographic profiles as well as electrical boreholes. These combined approaches are crucial to enriching our understanding of the particular geological and hydrogeological characteristics of this region, which forms a transition zone between the MAT and the MAP.