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

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.

Hydrochemical Characteristics and the Relationship between Surface and Groundwater in a Typical ‘Mountain–Oasis’ Ecosystem in Central Asia

“…Therefore, hydrochemical information for various water bodies can reflect the basic characteristics of inland river basins, which is of great significance for maintaining regional water security, the rational utilization of water resources and sustainable development [11]. In the past several decades, hydrochemical information on inland river systems in Central Asia [11][12][13], North Africa [14] and arid inland areas of China [15][16][17][18] has been fully recorded and analyzed. The projection of temporal and spatial distribution characteristics of river water chemistry provides unique insights into the protection of the ecological environment, the rational utilization of water resources and the hydrological function of inland river basins.…”