Groundwater salinization is an increasing global concern, particularly in arid and semi-arid regions where freshwater resources are scarce and heavily solicited for agriculture. In the Tadla plain central Morocco, agricultural intensification and drought have been increasing the pressure on available groundwater resources. This study aims to identify the dominant groundwater types and the main possible sources of salinity through detailed chemical analysis. It further evaluated stable water isotopic tracers (δ18O and δ2H) to distinguish between groundwater origins and assess the influence of evaporation and anthropogenic inputs. Findings reveal the predominance of calcium sulphate-chloride and sodium chloride water types, suggesting that the possible sources of salinity are primarily linked to the dissolution of evaporitic minerals. However chemical variability also reflects the influence of multiple recharge sources, including water from the Atlas Mountains, irrigation return flows from the Oum Er Rbia River, dam water, and local springs. Isotopic analysis identifies two main groundwater groups: (i) modern recharge with minimal evaporation (average δ18O = − 6.30‰) and (ii) isotopically enriched water (average δ18O = − 5.4‰), suggesting greater evaporative and anthropogenic influence. δ18O/δ2H and EC/evaporation diagrams confirm that salinization is primarily controlled at the local scale. The integration of hydrochemical and isotopic data has enabled the development of a conceptual model, providing a scientific basis for understanding groundwater dynamics and salinization processes in the study area.