Full text: Remote sensing for resources development and environmental management (Volume 2)

Symposium on Remote Sensing for Resources Development and Environmental Management / Enschede / August 1986 
Assessment of desertification in the lower Nile Valley (Egypt) by an 
interpretation of Landsat MSS colour composites and aerial 
A.Gad & L.Daels 
Laboratory for Regional Geography, State University of Ghent, Belgium 
ABSTRACT : The study area is situated in the lower part of the Nile Valley (Egypt) from the Giza- to the 
El-Menia province. The most important geomorphogenetic factors forming a threaten for the cultivated area 
are : wind action, especially in the Western Desert and the combined fluvial and wind action in the eastern 
desert. A visual interpretation of two satellite MSS colour composites was used to assess the desert en 
croachment. The interpretation has been verified by field work. Interpretation of Landsat MSS-images 
revealed the eolian deposits as bright coloured bands interupted by dark coloured patches of coarser erosional 
deposits coming from the mountains and hills in western desert. Aerial photo-interpretation had to be used 
to reveal the different orders of the hydrographic network and connection of drainage patterns and also the 
identification of the different types of erosional and depositional landforms. The combined interpretation 
of Landsat MSS images and aerial photographs made it .possible to identify the landforms which are considered 
to be good indicators of desertification and so it was possible to recognize the endangered areas along the 
Nile Valley. 
Desertificatiop, the extension of desert like con 
ditions, is a severe problem in the arid and semiv 
arid regions. It happens, by different processes:. 
(e.g. wind erosion, water erosion, vegetation degra-r 
dation, salinization, compaction and crust formation.) 
The United Nations environment program (UNEP) stated 
that 20. million square kilometers hays recently 
reyerted to desert or desert like conditions-. 
Desertification in Egypt is not a new phenomenon. 
Closer to the Nile Valley, farmers have been 
fighting a lost battle with the sand for centuries. 
The dunes submerge the roads to the oases and 
encroach upon fields and complete villages. 
The Eastern side of the valley is also not free 
from damage. The dense old drainage pattern in the 
Eastern desert accumulate a great amount of altera- 
ted material. Once a thunderstorm happens, it 
provides an enourmous amount of debris material 
down the slopes threatening the cultivated land and 
the villages. 
The problem of desert encroachement is best under 
stood by locating the associated features, studying 
the rates and direction of their movements. The 
purpose of the current investigation is to make a 
jriaximal use of remote sensing data to assess deser - 
tffi'cation in the study area. It was possible to 
minimrae the need of ground information by analysing 
stereo coverages of some sample areas on aerial 
photoninterpretation were extrapolated upon enlarged 
landsat images. 
The investigated area is situated in the Northern 
part of the Nile Valley (Egypt). It lies approxi^ 
mately between latitudes 27°52* and 30°6' N and 
longitudes 29°46' and 31°41' E.(Fig.l) 
It includes, the. goyernorates of Gj-za, Beni-S.ue.f and 
El-Menia and the surrounding desert fringes. The 
three governorates represent one sixth of the 
cultivated area in Egypt. 
The Western desert is a northern dipping plain of 
sedimentary rocks , composed mainly of sand stone 
in the South and limestone in the North (Said 1962). 
It occupies 681,000 Km^, or more than two thirds of 
F’'g. 1 - Localisation of the in 
vestigated arda 
the area of Egypt. This flat 
region is interrupted by low- 
situated oases, and by granitic 
mountains in the South-West 
intersection between Egypt, 
Libya and the Soudan. Nume 
rous sand dunes and sand sheet 
belts are crossing the rocky 
plateau of the desert. 
The Eastern desert borders 
the Nile Valley eastward. It 
extends from the Nile Valley 
to the Suez Canal and the Red 
Sea, and has an area of about 
223,000 KmA The Eastern de 
sert differs markedly from the 
western one. It is intensely 
dissected by valleys and ra 
vines. Murray(1951)and Butzer 
(1959)stated that although de 
sert climatic conditions are 
prevailling over Egypt, the 
mountainous areas of the Eastern desert have received 
a higher amount of precipitations. 
The flood plain is built up by alluvial deposits, 
formed from the sedimentation of mud which was carried 
by the annual floods during the most recent geologi 
cal period. The mud is the product of igneous rocks 
forming the Ethiopian plateau. 
The Western desert fringes of the study area are 
dominated by sand sheets and sand dune belts and 
varnished pebbles. El-Baz (1978) found, by using the 
Apollo-Soyuz photographs, that some longtudinal dunes 
are encroaching on fertile lands of the Nile Valley 
to the south. He confirmed that this process is ac 
tive in several places along the western borders of 
the Nile Valley, south of Cairo. Kishk (1977) warned 
for the increase of dune encroachment on fertile land 
along the Western borders of the Nile Valley, espe 
cially after the completion of the High Dam and hence 
the absence of Nile alluvium. Monir et al (1984) 
refered also to the failure of reclamation projects, 
situated on the Western border of the Nile Valley, 
(El-Menia governorate). 
On the Eastern side of the valley, the cultivated 
strip is exposed to the danger of occasional thunder 
storms. The United Nation report (1980-1982) reffers 
that thunderstorms became more frequent during the 
last years. The El-Menia province was exposed to the

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