Hydrogeochemistry and Spatial–Temporal Groundwater Quality Assessment of the Alluvial Aquifer in the Guerrara Region (Algeria)

The assessment and careful utilization of groundwater resources are crucial in hyper-arid areas. In these regions, water demand continues to increase under the pressure of socioeconomic development. This research investigates the spatial–temporal evolution of groundwater quality and hydrogeochemical processes of the alluvial aquifer in the Guerrara region (Algeria). Data from field investigation was combined with historical data to study the spatial–temporal evolution in ten years from 2009 to 2019, covering both dry and wet seasons. Piper, Gibbs, and Wilcox diagrams have been selected to assess the water quality evolution in this study. The results revealed a large seasonal and temporal variation of groundwater physicochemical properties illustrated by the total dissolved solids (TDS) values ranging from 152 mg/l to 11400 mg/l during the dry season and from 147 mg/l to 9522 mg/l during the wet season and by the conductivity values increasing by 7120 μS, which reflected a deterioration of water quality from 2009 to 2019. Additionally, the notable change in TDS values from the dry to the wet season confirmed the groundwater sensitivity to surface seasonal flow. Moreover, Wilcox diagrams showed the alluvial groundwater adequacy for irrigation use during wet seasons but shifting to inadequate and bad during dry seasons. The alluvial groundwater quality deterioration highlighted here calls for further investigations and actions toward restoring and protecting this valuable groundwater resource.