Water quality caracterization of Drean-Annaba aquifer (NE Algeria): using hydrochemical and isotopic tools

In the Drean-Annaba alluvial aquifer, the water quality often fluctuates. Water-rock interactions cannot be the main cause of the observed changes, but the country’s dryness during the last two decades has played a significant role in water quality changes. During this time, abnormalities in the timing and distribution of rainfall events were detected. As a result, hydrochemical changes in groundwater and surface water, such as wadis, have a predictable pattern. To demonstrate these chemical effects statistically, principal component analysis (PCA) tools and a nickel diagram were used. The findings corroborate seasonal fluctuations in water quality between 1999 and 2000. The competition between alkaline and alkaline earths can be seen from a cationic standpoint. On the other hand, there is a shift from chlorides to sulfates and possibly to bicarbonates from an anionic standpoint. The isotopic technique revealed neo-salinity whose source was unknown. The current study was conducted in a small area, which was beneficial for demonstrating the relationship between dryness and water quality in both the aquifer system and surface water. This study investigated the complex dynamics of water salinity within the Seybouse Basin, offering insights into its distribution, origins, and implications for groundwater management. Through a multidisciplinary approach encompassing hydrochemical analyses, mineralization mapping, and isotopic investigations, we elucidate significant patterns governing groundwater quality in the region. Our findings reveal the intricate interplay of factors such as marine intrusion, evaporation, and geological formations in shaping salinity levels across various water sources. The spatial variations highlighted through mineralization mapping and Br/Cl ratio analysis underscore the nuanced nature of marine intrusion along the coast, which is influenced by hydrodynamic factors and geological features. The identification of distinct salinity families based on conductivity and isotopic signatures underscores the diverse mechanisms contributing to water salinity, from evaporation-induced conductivity changes to the effects of recent heating. This research underscores the importance of interdisciplinary approaches in understanding groundwater systems and informs critical considerations for water resource management and sustainability efforts in the Seybouse basin and similar regions. By leveraging the insights gleaned from our study, stakeholders can develop targeted strategies to mitigate salinity-related risks and ensure the sustainable utilization of water resources.