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Ain Shams University (2021)

GEOENVIRONMENTAL ASSESSMENT OF SIWA OASIS, WESTERN DESERT

El Awady, Mohamed Ahmed Mohamed.

Titre : GEOENVIRONMENTAL ASSESSMENT OF SIWA OASIS, WESTERN DESERT

Auteur : El Awady, Mohamed Ahmed Mohamed.

Etablissement de soutenance : Ain Shams University

Grade : Doctor of Philosophy (PhD) in Environmental Science 2021

Résumé partiel
Siwa Oasis located across 29° 05´ and 29° 24´ latitudes and longitudes 25° 14´ and 26° 06´. It is located about 560 km west of Cairo and 300 km south of the Mediterranean Sea. Siwa depression total area of about 1000 km2 with 82 km long, 21 km wide with. It lies at about 18 m below the sea level being surrounded by the Desert. It is marked by the dominance of hyperarid climatic conditions with very low rainfall rates. The climate is somewhat warmer and more humid in the summer than most other Desert areas of similar latitudes and is slightly colder in the winter. Siwa Depression has an irregular elongated shape, about 75 km in the E-W direction. The lowest parts of the depression floor reach 18 m below sea level. Several major regions are distinguished in the depression, the most important of them from west to east are Bahe El Den, Al Maraky, Siwa, Aghurme, Abo Sharof, and Timeira- El Maasir regions. Recent and sub-recent alluvial and aeolian deposits are the main sediments characterizing the depression as they occur as thin deposits lying on the depression floor and as dune sand that bordering the depression on the south. Generally, the soils occupied the depression do not exceed 3 m in thickness in some localities, but they are very shallow in many places due to the high-water table level and/or rocky exposures. The most important landforms in Siwa Oasis are the saline lakes (Birket) e.g., Zeitun, Maraqi, Siwa, and Aghurmi. Around the saline lakes spread marshes, salinas, and sabkhas. The exposed sedimentary succession in Siwa Oasis belongs to the Miocene. This succession is overlain by Quaternary surficial deposits. The groundwater in Siwa Oasis is available at different depths and lithology. Based on the lithology and water characteristics, two main regional aquifer systems are distinguished ; they are the Tertiary Carbonate Aquifer System (TCAS) (Miocene and Eocene limestone and dolomite) and the Nubian Sandstone Aquifer System (NSAS) (Upper Cretaceous shale and marl layers).

Présentation étendue (EULC)

Page publiée le 27 février 2022