Contribution of hydrochemistry and stable isotopes of water to the study of the functioning of the Gharb surface water table

Abstract

The Gharb plain is located in the northern part of Morocco. This plain was formed during the Alpine orogenic phase. Its evolution is the result of the succession of several tectonic phases staggered over geological time. The Gharb groundwater table is the subject of our hydrochemical and isotopic study. The main aim is to understand how the table functions and to assess the state of contamination by anthropogenic elements. The hydrochemical characterization of the aquifer revealed that the groundwater is actually contaminated by anthropogenic elements whose concentrations exceed the most marked drinking standards are sulfates and nitrates. This contamination is mainly attributed to the intensive agricultural practices that take place in the region; there is also waste that plays an important role in raising the concentration of these elements. The isotopic diagnosis of groundwater was based on analyses of water isotopes, in particular oxygen-18 and deuterium, which can provide information on the origin of groundwater, recharge processes and residence times in the aquifer. The contribution of isotopes combined with the results obtained by the hydrogeological and hydro study chemical allows us to say that the Gharb aquifer is mainly fed by infiltration of precipitation water and groundwater has a permanent potability between the quality (good admissible and poor.