Groundwater hydrochemistry of Aflou syncline, Central Saharan Atlas of Algeria

The current paper sheds light on geochemical methods used to characterize water-rocks interaction. The concern is to assess the vulnerability of groundwater resources to contamination in Aflou, an area in central Saharan Atlas of Algeria. This study of hydrochemistry reveals lithological impact on hydrochemistry in Aflou syncline. Our study region is like a basin meaning that the important groundwater resources are located in the sandstones of the Intercalary Continental Aquifer (Barremian-Albian). This study marks a noticeable influence of evaporated minerals and ascents of Triassic materials, which are widely propagated along with different levels for several wells of Djebel Amour. Lithology influence on the hydrochemistry of this aquifer is very visible by evaporation contained essentially in the Triassic and in the marly intercalations of the Portlandian, the Barremian-Aptian-Albian and those of the Mio-Pliocene. For Aflou region, the lower Cretaceous (Portlandian) and Upper Jurassic (limestone) formations, the calcium sulfated facies, have very high levels of SO4–, Cl–, Ca2+, and Na+. Integration of both graphical and Piper diagram, saturation index values (estimated by Phreeq-C method) and geographic information system tool was helpful not only to create the database for analysis of spatial variation in respective water quality parameters but also to decipher the hydrogeochemical process occurring in our study area. This study utilized the inverse distance weighted (IDW) interpolation method to interpolate and estimate cell values in Aflou syncline by averaging the values of sample data points in the neighborhood of each processing cell. IDW method has been used in establishing maps. The examination of iso-contents maps and the principal component analysis results show that the water composition was very closely related to the lithological nature of the different formations.