geosciences Review Sand Seas and Dune Fields of Egypt Olaf Bubenzer 1,* , Nabil S. Embabi 2 and Mahmoud M. Ashour 2 1 Im Neuenheimer Feld 348, Institute of Geography and Heidelberg Center for the Environment, Heidelberg University, 69120 Heidelberg, Germany 2 Department of Geography, Faculty of Arts, Ain Shams University, Cairo, El-Khalyfa El-Ma’moun Street Abbasya, Egypt; [email protected] (N.S.E.); [email protected] (M.M.A.) * Correspondence: [email protected] Received: 22 August 2019; Accepted: 5 March 2020; Published: 10 March 2020 Abstract: The article reviews the state of knowledge about distribution, sizes, dynamics, and ages of all sand seas (N = 6) and dune fields (N = 10) in Egypt (1,001,450 km2). However, chronological data (Optically Stimulated Luminescence, Thermoluminescence), used in the INQUA (International Union for Quaternary Research) dune database, only exists from three of the five sand seas located in the Western Desert of Egypt. The North Sinai Sand Sea and four of the ten dune fields are located near the Nile Valley, the delta or the coast and therefore changed drastically due to land reclamation during the last decades. Here, but also in the oases, their sands pose a risk for settlements and farmland. Our comprehensive investigations of satellite images and our field measurements show that nearly all terrestrial dune forms can be observed in Egypt. Longitudinal dunes and barchans are dominant. Sand seas cover about 23.8% (with an average sand coverage of 74.8%), dune fields about 4.4% (with an average sand coverage of 31.7%) of its territory. For the Great Sand Sea and the Farafra Sand Sea, situated in the central and northern part of the Western Desert, a Late Glacial transformation by strong westerlies was found, but not for the Selima Sand Sea, situated in the south of Egypt. Regarding the sparse chronological data up to now, for a reasonable estimation of future sand mobility in the course of global climate change, further data are essential. Finally, further studies concerning sand mobility, local wind systems, and land use are needed. Keywords: Egypt; sand seas; dunes; sand accumulation; geomorphology; aeolian morphodynamics 1. Introduction Egypt covers an area of ~1,001,450 km2, taking the neat shape of a square. Geographically, Egypt can be divided into four regions: the Nile Valley, the Western Desert, the Eastern Desert, and Sinai Peninsula (Figure1). The Nile enters Egypt from the south, and runs northwards till it reaches the Mediterranean Sea for ~1200 km. It is bordered by a valley which widens northwards, reaching its widest section (~20 km) at the latitude of Beni Suef City. A few kilometers north of Cairo, the Nile Delta starts where the Nile branches into two distributaries (Rosetta and Damietta), representing what is left from several others. Because of the similarity between their triangular shape and the Greek letter D, Herodotus (450 BC) called it delta. Both the Nile Valley and the Delta covers ~3.5% of the total area of Egypt. Along the northern, western and eastern margins of the Nile Delta, and the western side of the Nile Valley, sand accumulated at several localities forming small dune accumulations. The Western Desert is the largest region in Egypt. It covers roughly two-thirds of its total area and is characterized by dunes, plateaus, depressions, and plains. Heights above 1000 m are present in the vicinity of the Gilf El-Kebir and Abu Ras plateaus and Uweinat Mountain, whereas areas below sea level can be found in the northern depressions (Qattara 145 m, Siwa 22 m, Wadi El-Natrun 20 m, Wadi − − − Geosciences 2020, 10, 101; doi:10.3390/geosciences10030101 www.mdpi.com/journal/geosciences Geosciences 2020, 10, 101 2 of 32 El-Rayan 65 m, El-Fayum 45 m). There are innumerable closed depressions in the Western Desert, Geosciences 2020− , 10, x FOR PEER REVIEW− 2 of 33 which vary in size from minute ones to huge basins such as the Qattara Depression (about 18,000 km2). DunesDesert, spreadwhich allvary over in size this regionfrom minute as sand ones seas, to dune huge fields, basins or such sand as sheets, the Qattara of which Depression the Great (about Sand Sea18,000 is thekm2 largest). Dunes and spread for which all over the this most region chronological as sand seas, data dune are fields, available or sand [1]. sheets, Vast plains of which occupy the theGreat southern Sand Sea part is ofthe this largest. desert, Vast extending plains intooccupy northern the southern Sudan, notablypart of thethis Selima desert, Sand extending Sheet [into2,3]. Anothernorthern plainSudan, lies notably between the the Selima northern Sand (El Sheet Diffa /Marmarica)[2,3]. Another Plateau plain andlies thebetween Mediterranean, the northern which, (El asDiffa/Marmarica) a coastal plain, Plateau is characterized and the byMediterranean, the presence which, of linear as limestone a coastal ridgesplain, is that characterized extend parallel by the to thepresence coastline. of linear limestone ridges that extend parallel to the coastline. Figure 1. Relief map of Egypt. The Eastern Desert is the second largest region in Egypt and covers roughly one quarter of the country’s totaltotal area. area. It isIt theis the region region of mountains, of mounta plateaus,ins, plateaus, and large and wadi large nets. wadi The nets. RedSea The Mountains Red Sea divideMountains the wadisdivide into the wadis two groups: into tw easterno groups: ones eastern that goones to that the Redgo to Sea, the andRed westernSea, and wadiswestern that wadis run towardsthat run thetowards Nile Valley.the Nile Examples Valley. Examples are the Wadi are the Araba, Wadi which Araba, run which towards run the towards Red Sea the and Red separates Sea and theseparates two mountain the two ridgesmountain (Galalahs), ridges whereas(Galalahs), Wadi wh Qenaereas runs Wadi towards Qena theruns Nile towards Valley. the Altitudes Nile Valley. above 1000Altitudes m above above sea 1000 level m (m above asl) are sea present level (m on asl) both are the present plateaus on and both mountains. the plateaus Several and peaksmountains. in the RedSeveral Sea peaks Mountains in the riseRed to Sea altitudes Mountains of 2000 rise m to or alti more,tudes such of 2000 as Gabal m or more, El-Shayeb such (2187 as Gabal m asl, El-Shayeb latitude 27(2187◦ N). m Low-lying asl, latitude areas 27° are N). present Low-lying firstly areas in the are El-Mallaha present firstly Basin in as the part El-Mallaha of the coastal Basin plain as part of the ofRed the Seacoastal south plain of Ras of the Ghareb Red andSea aresouth occupied of Ras by Ghareb a sabkha and and are salina. occupied Here, by heights a sabkha are onlyand salina. a few meters Here, aboveheights sea are level. only Thea few second meters low-lying above sea area level. is situated The second at the low-lying northern area margin is situated of this Desertat the northern between Sinaimargin and of the this Delta. Desert Here, between heights Sinai decrease and the gradually Delta. Here, from 200heights m asl decrease at the latitude gradually Cairo-Suez from 200 to m a few asl metersat the latitude above seaCairo-Suez level around to a few El-Manzalah meters above Lake. sea It level is covered around by El-Manzalah fluvial materials Lake. deposited It is covered by theby wadisfluvial comingmaterials from deposited the south. by the Apart wadis from coming the El-Khanka from the south. dune fieldApart that from lies the just El-Khanka to the east dune of Cairo, field sandthat lies accumulations just to the east are of concentrated Cairo, sand accumulati in the extremeons are southeast concentrated of this in desert, the extreme where southeast four small of dune this fieldsdesert, are where developed. four small dune fields are developed. The Sinai Peninsula has a triangular shape, bounded by the Mediterranean Mediterranean coast from from the the north, north, the Gulf of Aqaba and the border to Israel from thethe east, and the Gulf of Suez and the Suez Isthmus from the west. It It covers covers about about 6% 6% of of the the total total area area of of Egypt. Egypt. Nearly Nearly all all geologic geologic formations, formations, structures, structures, and landforms of Egypt are represented here. High mountains with igneous and metamorphic rocks dominate the landscape in the south, whereas vast limestone plateaus (El-Tih and El-Egma) cover its central parts (Figure 1). The northern section is divided into two subregions, where domal/anticlinal mountains and hills dominate the landscape in the south, while a sandy plain covers its northern parts up to the Mediterranean coast. Bardawil Lake presents a unique form in the coastal plain. Several sabkhas spread around this lake, and extend eastwards, westwards and inland. Geosciences 2020, 10, 101 3 of 32 central parts (Figure1). The northern section is divided into two subregions, where domal /anticlinal mountains and hills dominate the landscape in the south, while a sandy plain covers its northern parts upGeosciences to the Mediterranean2020, 10, x FOR PEER coast. REVIEW Bardawil Lake presents a unique form in the coastal plain. Several3 of 33 sabkhas spread around this lake, and extend eastwards, westwards and inland. SandSand accumulations accumulations are are presentpresent inin nearlynearly allall regionsregions of Egypt. They They cover cover parts parts of of variable variable areas areas (from(from a fewa few hundred hundred square square kilometers kilometers to more to more than hundredthan hundred thousand thousand kilometers). kilometers). In dune literature,In dune theseliterature, sand coveredthese sand areas covered are called areas sand seasare orcalled dune sand fields seas [4–7 ]).or Several dune geomorphologistsfields [4–7]).