Integrated Geochemistry, Isotopes, and Geostatistical Techniques to Investigate Groundwater Sources and Salinization Origin in the Sharm EL-Shiekh Area, South Sinia, Egypt

The Sharm El-Sheikh area is one of the most attractive touristic resorts in Egypt and in the world in general. The Sharm El-Shiekh area is located at the arid region of the South Sinai Peninsula, Egypt. Water desalination is considered the main freshwater supply for hotels and resorts. Scarcity of rainfall during the last decades, high pumping rates, disposal of reject brine water back into the aquifer, and seawater intrusion have resulted in the degradation of groundwater quality in the main aquifer. Water chemistry, stable isotopes, Seawater Mixing Index (SWMI), and factorial analyses were utilized to determine the main recharge and salinization sources as well as to estimate the mixing ratios between different end members affecting groundwater salinity in the aquifer. The groundwater of the Miocene aquifer is classified into two groups: group I represents 10 % of the total samples, has a moderately high saline groundwater, and is mostly affected by seawater intrusion. Group II represents 90 % of the total samples and has a high groundwater salinity due to the anthropological impact of the reject brine saline water deeper into the Miocene aquifer. The main groundwater recharge comes from the western watershed mountain and the elevated plateau while the seawater and reject brine are considering the main sources for groundwater salinization. The mixing ratios between groundwater recharge, seawater, and reject brine water were calculated using water chemistry and isotopes. The calculated mixing ratios of group I range between 25 and 84 % recharge groundwater to 75 and 16 % seawater, respectively, in groundwater located close to the western watershed mountain indicating further extension of seawater intrusion. However, the mixing percentages of group II range between 21 and 88 % reject brine water to 79 and 12 % seawater, respectively, in groundwater located close to the desalination plants. The outcomes and conclusion of this study highlight the importance of groundwater management to limit further groundwater deterioration of the Miocene groundwater aquifer and limit seawater intrusion along the coast.