Symposium on Remote Sensing for Resources Development and Environmental Management / Enschede / August 1986
599
Assessment of desertification in the lower Nile Valley (Egypt) by an
interpretation of Landsat MSS colour composites and aerial
photographs
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.
1 INTRODUCTION
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.
2 LOCALIZATION AND ENVIRONMENT OF THE STUDY AREA
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
