Hydrogeochemical study of groundwater in arid and semi-arid regions of the Infracenomanian aquifers (Cretaceous Errachidia basin, Southeastern Morocco). Using hydrochemical modeling and multivariate statistical analysis

Abstract

Groundwater in the Cretaceous Errachidia basin, located in the southern part of Morocco, is crucial in supporting the region's main economic activities, such as farming. This arid region faces multiple challenges, including an average annual rainfall of less than 80 mm/year, intense agricultural activities, high evaporation, and extremely high evapotranspiration rates up to 1580 mm/year. Therefore, the hydrogeochemical study focuses on the Infracenomanian aquifers in the Cretaceous Errachidia basin. The goal is to evaluate the sustainable use of saline lands and brackish water, particularly assessing water resources and sustainable socioeconomic development in southeastern Morocco. In June 2021, 20 samples were collected and analyzed for pH, electrical conductivity (EC), total dissolved solids (TDS) and major ions. The hydrogeochemical parameters were analyzed using multivariate statistical methods. Statistical techniques such as Piper's trilinear diagram analysis of hydrochemistry types, Gibbs diagram analysis, The HFE diagram and ion correlation analysis were used to examine the origins of the main ions in the groundwater and to determine the source of the salinization processes in the groundwater.The findings revealed a strong positive correlation between TDS and the spatial distribution of major ions (Na+, Ca2+, Mg2+, Cl−) and EC, revealing high mineralization in the study area. The main cations in groundwater are Na+ and Ca2+, while the main anions are Cl−. The elevated concentrations of Cl− and Na+ are due to the evapotranspiration of irrigation water. Furthermore, the hydrochemical facies types are predominantly sodium chloride (Na–Cl), followed by calcium chloride (Ca–Cl) and a mix of calcium and magnesium chloride facies (Ca–Mg–Cl). These analyses indicate that the hydrochemistry of groundwater in the study area is primarily influenced by water-rock interactions, such as the dissolution of sedimentary rocks, soil leaching through gravity irrigation, and evaporation in the region. Moreover, the analysis using the Gibbs diagram indicates that evaporation is the primary hydrogeochemical process that shapes the chemical composition of the groundwater in the area under study.