Hydrochemistry and environmental isotopes of spring water and their relation to structure and lithology identified with remote sensing methods in Wadi Araba, Egypt | Hydrogéochimie et isotopes environnementaux des eaux de sources et leurs relations avec la structure et lithologie identifiées par télédétection dans le Wadi Araba en Egypte Hidroquímica e isótopos ambientales de aguas de manantiales y su relación con la estructura y litología identificadas con métodos de teledetección en Wadi Araba, Egipto 埃及Wadi Araba泉水水化学和环境同位素及其基于遥感方法指示的与结构和岩性关系 Isótopos hidroquímicos e ambientais de águas de nascente e a relação deles com a estrutura e litologia identificadas com métodos de sensoriamento remoto em Wadi Araba, Egito
2021
Wannous, Manal | Theilen-Willige, Barbara | Troeger, Uwe | Falk, Marianne | Siebert, Christian | Bauer, Florian
Springs located at the historical sites of Wadi Araba (Eastern Desert of Egypt) and emerging from the escarpments of the Northern and Southern Galala Plateaus were investigated. A combination of methods, including hydrochemistry, stable and radioisotope composition, and structural analyses based on satellite data, provided information about the structure of the subsurface and the derived groundwater flow paths. Satellite images reveal karst features within the northern plateau, e.g. conical landforms. Karstic caves were documented along both escarpments. Chemical analysis of floodwater from Wadi Araba indicates higher concentrations of terrestrial salts compared to floodwaters from central and southern parts of the desert. δ¹⁸O and δ²H signatures in spring waters resemble those of floodwater and fall on the global meteoric water line, confirming their fast infiltration with minor influence of evaporation. The aquifer feeding the springs of the Northern Galala Plateau has low retention and the springs dry out quickly, even after heavy rainfall. Contrastingly, ³H activities in springs emerging from the Southern Galala Plateau refer to much slower subsurface passage. With respect to ³H content (3.8 TU) in recent flood waters, the spring water at Southern Galala Plateau contains about 40% recently recharged groundwater. However, its largest spring—the St. Antony spring—discharges water with a radiocarbon age of about 15,000 years. In combination with this spring’s constant and high discharge over a period of several months, that age estimate suggests a large reservoir with moderate to high retention.
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