Structural Interpretation of the Essaouira Basin and Its Coastal Zone in Central-Western Morocco from Gravity Data: Hydrogeological Implications

Located in the central-western part of Morocco, where the climate is arid and semi-arid, the Essaouira basin is an area at high risk of water shortage due to the decrease in precipitation as a consequence of climate change on the one hand, and on the other hand to the incessant increase in the demand for this resource necessary for life. That is why, more and more underground water resources are used to meet the needs of the population, whether for domestic use or for irrigation. However, the mobilization of these resources requires a good knowledge of the aquifers of the Essaouira basin. The present study was undertaken with this perspective. Its main purpose is to achieve a better understanding of the deep structure of this basin. This study is based on the analysis of gravity data. The methodological approach involves, in addition to the qualitative interpretation of these data, the use of various filtering processes that help map hidden geological structures. The obtained results reveal the existence of a network of faults that complement the structural map of the study area. Some negative anomalies are clearly associated with evaporate deposits. However, most of them are in all probability related to structural lows and subsided depressions that represent favorable areas for groundwater accumulation and, consequently, favorable zones for drilling water exploitation boreholes.