Contribution to the study of water resources in the coastal region of Essaouira, using vertical electrical soundings (VES), electrical resistivity tomography (ERT) and GIS (Essaouira, Morocco)

Abstract The geophysical study using the VES and the ERT, carried out in the coastal area of Essaouira (Morocco), for the purpose of mapping the aquifers by combining the two geo-electrical methods, the results allowed us to determine the lateral and vertical distribution of the geological formations in the study region. Thereafter the exploitation of these results by the decision makers in the choice of the sites likely to be hydrogeologically fertile to answer the need for the inhabitants in resource in water. The synthesis on the evolution of the geological layers, the variations of thickness and to highlight the anomalies which could affect them, the GIS tool makes it possible to draw up maps (VES) and electrical imagery (ERT ) at a depth chosen by data interpolated by Kriging. The analysis of the results shows that the Qsob zone is of paramount hydrogeological interest, it is represented by a very important layer given the great extension of the resistant formations of Plio-Plioctecene and Cretaceous age with significant thicknesses. The area is crossed by the Qsob River which is the main source of supply for these two aquifers. With the communication of the two aquifers by the very abundant and dense electric discontinuities of general directions E-W, NE-SW and NNE-SSW.