Seawater intrusion (SWI) poses a significant threat to groundwater quality in coastal aquifers worldwide, impacting numerous regions across the globe. The objective of this study is to comprehensively evaluate the controlling factors of the Quaternary aquifer in the Sudr area of South Sinai, Egypt. The primary focus is to evaluate the suitability of groundwater quality for irrigation purposes by employing hydrochemical indicators and leveraging GIS technology. Accordingly, sixty groundwater samples were collected from the area to determine the physical and chemical parameters. The findings indicate that the high salinity values are reported in the west and north-west, while the values decrease towards the east near the main stream of Wadi Sudr. The Piper plot suggests that the main water types are Na-Cl, Ca-Cl, and CaMg-Cl. Based on the evaluation using Salinity Diagram (USSL) and Doneen's diagram, a majority of the collected samples exhibit suitability for supporting plant species characterized by high salt tolerance. This conclusion is further supported by the results obtained from SAR, Na%, PI, PS, KI, and MH analysis. Moreover, the findings regarding Residual Sodium Carbonate (RSC) indicate that all groundwater samples are considered safe for irrigation purposes. This study serves as a valuable contribution to the monitoring of coastal aquifer groundwater quality, offering a valuable resource for policymakers and stakeholders.