Vertical Electrical Sounding (VES) Technique to Map Potential Aquifers of the Guigou Plain (Middle Atlas, Morocco): Hydrogeological Implications

Abstract

Vertical electrical sounding (VES) as a geoelectrical method has proven its effectiveness throughout the history of groundwater geophysical investigation. In this sense, VES was carried out 47 in the study area with the aim of determining the geometry and limits of Quaternary basaltic aquifer formations and, above all, the location of electrical discontinuities in the area located in the north of Morocco, between the center of Almis Guigou and the city of Timahdite. This area is experiencing an overexploitation of the groundwater due to excessive pumping and the development of intensive agriculture activities, resulting in a continuous decrease in piezometric levels. The processing of the diagrams by WINSEV software showed the presence of an electrically resistant surface level, attributed to basaltic formations, of the Quaternary age, whose thicknesses reach at least 150 m to the SW of the area. This level is superimposed on a moderately conductive horizon which, according to local geology, corresponds to Pliocene marl and limestone alternations. The correlation of VES interpretation models allowed us to elaborate thematic maps and geoelectrical sections which illustrate the vertical and lateral extension of the basaltic reservoir as well as its thickness, which decreases in general from the south-west to the north-east; however, the main electrical discontinuities also correspond to faults and fractures, and they show a NE–SW direction sub-parallel to the major accidents of the Middle Atlas. A prospectivity map of the local aquifer was generated, coinciding with regional fault lines and confirmed by the alignment of very good flowing water boreholes. This geophysical study by electrical sounding shed light on the geometry and extension of the aquifer and opened avenues to draw further conclusions on its physical and hydrodynamic characteristics, as well as to optimize the future siting of groundwater exploitation boreholes through the elaboration of the local aquifer prospectivity map.

Direct Detection of Groundwater Accumulation Zones in Saprock Aquifers in Tectono-Thermal Environments

“…Careful data management practices implemented during the data conversion, modelling and interpretational phases are normally adopted to either edit the affected data point (or segments) or completely delete (remove) them so long as such action will not compromise the data quality. Curve smoothening is one such data management practices usually performed to reduce noisy points or segments to their normal equivalent [72][73][74][75][76]. This procedure involves the careful removal of any outliers from the datasets to reduce their impacts, particularly on modelling and interpretational errors.…”

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

“…The Guigou plain is an intra-mountainous plain stretching in a NE-SW direction over a distance of around 32 km, covering an area of around 1,313 km². Unlike the rest of the Tabular Middle Atlas, which is generally covered by carbonate formations forming a main reservoir hosting a free water table, the Guigou plain is characterised by the presence of a cover formed by plio-quaternary basaltic flows of very heterogeneous thicknesses [1], [3], [5], [6].…”

“…The Tabular Middle Atlas (TMA), located in the north of Morocco, is essentially made up of carbonate formations of the Lias, forming the main reservoir where an unconfined groundwater table is located, characterised by groundwater of very high potential in terms of quantity and quality [1]- [6]. However, at its south-eastern limit, the limestones of the Lias are quite deep and covered, at the level of the Guigou plain, by a cover of basalts dating from the Plio-Quaternary [3], [7]. This cover plays a key hydrogeological role, hosting a fairly limited, free water table that is used for agricultural purposes in the region.…”

Geotechnical Characterization for Territorial Planning of a Special Economic Zone at a University Campus in Ecuador

“…The VESs allowed the detection of the variation in resistivity as a function of depth and analysis of the structure of the subsoil [37,38]. The Terrameter SAS 1000 resistivity instrument was used in the field to carry out the VESs.…”