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.

The coastal aquifer of the Essaouira syncline (Morocco) was studied to identify the main processes at the origin of the salinization of groundwater. In fact, a multicriteria analysis approach on hydrochemical data and physicochemical parameters of the Plio-Quaternary aquifer was used to understand their spatio-temporal variation and their origins. Currently, integrated water resources management has become paramount to both local, regional, national and international. This management is favored by extreme hydrological events (droughts or floods) which can have direct influences on human, economic and political aspects. Appropriate management of a resource requires its evaluation. The statistical study by Kohonen's self-organized classification (SOM) of hydrochemical data for the years 1995 and 2009 is used to process 47 samples distributed over the entire study area; it showed an evolution of the values of the parameters. Physico-chemical as a function of time and space with an increase in the values of the parameters, from the center of the study area towards the southwest.

In coastal areas, groundwater is the main source of consumption for drinking water, industry and agriculture. The Essaouira syncline is part of the Moroccan Atlantic coast, it is an area which is given a heavy responsibility in the socio-economic development of Morocco. The study area is limited to the north by the Jbeb Hadid, to the south by the Tidzi river, to the east by the reliefs of the South Chiadma, the reliefs of the North Haha and the diapir of the Tidzi, and to the West by the 'Atlantic Ocean. In this article, we have tried to study the quality of groundwater by applying multi-criteria methods and to validate the pollution vulnerability map established by the DRASTIC method. The combination of GIS and multi-criteria analysis confirms the validity of the DRASTIC map with a better correlation between areas with high concentrations of chemical elements in groundwater and areas of very high vulnerability to pollution.