This study presents a decadal, multi-seasonal evaluation of groundwater quality evolution in the Zegrir alluvial aquifer, located in the hyper-arid Guerrara region of Algeria. A total of 16 groundwater samples were collected during dry and wet seasons across three time points (2009, 2013, and 2019), enabling a comprehensive assessment of temporal and spatial hydrogeochemical trends. Analytical parameters included major ions, physico-chemical indicators, Water Quality Index (WQI), and Sodium Adsorption Ratio (SAR), supported by multivariate statistical methods such as Principal Component Analysis (PCA). Findings reveal progressive groundwater salinization, with over 60% of samples classified as poor to unsuitable for drinking and more than 70% falling into moderate to high SAR categories, indicating serious irrigation constraints. Spatial analysis highlights those areas with shallow static levels and low recharge potential are particularly vulnerable. The dominance of Na+, Cl-, and SO42-, along with Na-Cl and mixed-type hydrochemical facies, indicates the persistent influence of evapoconcentration, evaporite dissolution, and cation exchange processes. The adopted multi-year, multi-seasonal framework proved essential for distinguishing between transient recharge-driven dilution events and long-term degradation trends, offering a more nuanced understanding of aquifer evolution under arid conditions. This integrative approach provides valuable insight into de-signing adaptive groundwater management strategies and underscores the critical need for continuous monitoring and distributed recharge interventions in climate-stressed regions.