This study aims to define sources and mechanism of salinization process of groundwater Quaternary aquifer in El Tur area
South Sinai. Groundwater samples were collected covering three provinces (Wadi El Wadi, El Qaa, and El Gobail) in
addition to Red Sea water sample (16 water samples). The hydrochemical results indicate that groundwater salinity is greatly
variable; it varies from (414-4307 mg/l) at Wadi El Wadi, (1208-4973 mg/l) at Sahal El Qaa and (2176-12000 mg/l) at El
Gobail area indicates that salinity increases in the direction of groundwater flow from the upstream the mountainous part in
the eastern side toward the downstream in southwest direction to the Gulf of Suez. Seawater Mixing Index (SWMI)
calculations divide groundwater samples into two groups; (Group I) has low groundwater salinity mainly at Wadi El Wadi
and El Qaa plan. (Group II) has highly saline groundwater mainly at El Gobail area which is affected by mixing with
seawater. Saturation Index calculations revealed that El Gobail samples are supersaturated in carbonate and sulphate
minerals. Environmental stable isotopes (δ18O and δD) showed that the precipitation is the major source of recharging
Quaternary aquifer in the area. However, the sources of increasing salinity due to the dissolution process have a significant
effect on the chemical composition of groundwater.