Hydrochemistry and environmental isotopes (18O, 2H, 3H, 3He/4He) of groundwater and floodwater in the great area of Hurghada, Eastern Desert of Egypt

U Troeger,M Wannous,C Jahnke,F Bauer,M Falk

doi:10.1007/s12665-021-09487-9

Abstract

Porous and fractured aquifers exist in the area of Hurghada, Eastern Desert of Egypt, whose recharge processes through the common flash floods are not identified. Hydrochemical parameters, stable isotopes 18O, 2H and tritium in floodwater and groundwater were applied in the area subject to study. Additionally, He isotopes were investigated in the deep wells in the faulted zone at the Abu Shaar Plateau. 3H activity in all sampled points lies below the detection limit excluding a recent recharge component in groundwater. However, the hydrochemical ratios and the stable isotope signature confirm that the shallow wells and springs (Red Sea Hills group) are being recharged from modern precipitation. The hydrochemical parameters of the deep wells at the Abu Shaar Plateau (coastal plain group) confirm another origin for the ions rather than the modern precipitation. Together with the 18O and 2H values, the Br/Cl ratio of this group confirms the absence of seawater intrusion component and the role of the fault as a hydraulic barrier. These 18O and 2H values deviate from the GMWL confirming an evaporation effect and colder infiltration conditions and reveal strongly a possible mixing with the Nubian Sandstone in the region. The 3He/4He ratio confirms a mantle contribution of 2% from the total He components.

Highlights

Groundwater is the only available freshwater resource in areas far from the River Nile valley
The purpose of this study is to investigate the processes which influence the hydrochemistry of groundwater and their stable isotopes values in the area and weather the flash floods which are common in the region contribute to the groundwater recharge
The Red Sea water shows a deviation from the SMOW (Table 1: S1: δ18O: 2.3‰; δ2H: 11.6‰), which is typical for the northern part of the Red Sea, compare e.g. (Andrié and Merlivat 1989), (Table 1, Sect. 4.2.1, the northern red Sea)

Summary

Introduction

Groundwater is the only available freshwater resource in areas far from the River Nile valley. The investigation area is located between Hurghada city in the south and Wadi Melaha Oasis in the north at the Red Sea coast of Egypt (Fig. 1). Abu Shaar Plateau exists around 22 km south of Wadi Melaha Oasis and 5 km west of El Gouna (Fig. 1). At the fault zone which separates this plateau from the coastal plain (Klitzsch and Linke 1983) several wells were drilled between 1994 and 2000 (Kleinendorst 2004) to pump brackish water to supply El Gouna area. Moving southwards to the area extended between El Gouna to 36 km SW of Hurghada city, several springs and shallow wells (Fig. 1) provide small communities in the Eastern Desert with water. In Wadi Melaha Oasis north of El Gouna (Fig. 1) a permanent spring and a stream could be detected

Objectives

Results

Discussion

Conclusion