Groundwater investigations were carried out along two transects (S1 and S2) perpendicular to the shoreline in Korba coastal aquifer in northern Tunisia from 2006 to 2013. They involved groundwater sampling (for Na, K, Ca, Mg, Cl and SO4), stable isotopes (for 2013 campaign), piezometric measurements and Electrical Resistvity Tomography imaging. The objective was to identify the potential origin of groundwater salinization (ie high TDS and NO3) and to study associated processes. Historical data, set up since 1962, were also collected and analysed to evaluate time and space evolution of the salinization spread. Ionic ratios (ie, Br/Cl, Na/Cl, Mg/Ca, HCO3/Cl, Ca/(SO4+HCO3) and SO4/Cl) and ionic deltas, conventional diagrams and geochemical modelling using PHREEQC were also used. Besides, multivariate statistics techniques, Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were performed. The nature of prevailing flow systems may also be proposed, as there are flows of different salinity that were detected at different depths. The piezometric survey confirmed the inversion of the groundwater flow in transect S1 where a piezometric depression of 5 m was observed at 4,000 m from the shoreline. PCA reveals that two main processes are contributing to groundwater mineralization and thus salinization: seawater intrusion and agricultural contamination mainly through N-fertilizers. The geochemical impacted area of seawater intrusion was estimated to 4,000 and 1,500 m respectively along transect S1 and transect S2. Inversely, agricultural contamination is rather acting in internal areas beginning at 2,000 m and 1,500 m from the shoreline for S1 and S2, respectively. This suggests that the vertical components of flow are to be given consideration in the evaluation of the response to abstraction as the inducement of irrigation return flow to production wells.