627
the ERTS imag-
eatures west
ine and mainly
NW-SE faults,
along the weste
y occupy the
resent the up-
ion in the gu-
tterns
and hydrograp-
are examined,
ted and the
e defined by
e drainage pa-
els and tribu-
In. A combine-
fter the exam-
ave a trend
est of the gu
elfi uence of
structural
are defined
y in the pres-
re differenti-
d on some cri-
tegration, the
ty, the orien
tile angularit-
Ray,1960; Tho
L-Etr & Yousi-
examined (No-
-basins are
defined from north to south of the area resp
ectively. They all shared together with the
outlets along the coastal plain. The main chr-
annels issuing from the high basement plateau.
The following features are concerned when
dealing with the drainage sub-basins in the
studied area( Fig. 3 and Table, 1) :
2.1. The surface area of the drainage sub
basins varies between 123.5 sq. Km. and 962
sq. Km.
2.2. The total length of the main stream
varies between 27 Km and 82 Km. It increases
from north to south of the area. The main st
ream changes into meander one in the southern
sub-basins.
2.3. The stream order assumes the fourth
to the fifth order in all the drainage sub
basins. This reflects the same slope trend
and magnitude and lithologic characters alon-
g the present sub-basins.
2.4« The drainage density has an average
value changing from 5*7 to 8.7 one per sq.Km.
This reflects moderate density in the high
plateau. While in the coastal plain the drai
nage density assumes the minimum value and ra
nges between 2 and 5 one per sq.Km. This ind
icates more or less homogeneous lithology and
slopes, where the porous and permeable rocks
are exposed on the surface.
2.5. The dominant types of drainage patter
ns in each of the nine sub-basins vary great
ly. The common types along the high plateau
are the dendritic and the sub-parallel types
of drainage. While the dominant types in the
coastal plain area are the braided and dicho
tomic types. This variation reflects the cha
nging in surface facies and local slopes in
the same sub-basin from west to east and bet
ween the nine sub-basins. The dominant struc
ture plays an important role in the developm
ent of certain assortment of drainage patter
ns in the area. The trillis, the pinnate and
the barbed types of drainage patterns reflec-
t the influence of the dominant trends of fa
ulting and folding in the area.
The drainage network which developed in the
area of study is an outcome product of the 1-
ast fluvial periods of the Pleistocene and
Recent times. The present dry vallies and tr
ibutaries were already engraved during that
fluvial periods. They are now filled with su-
rficial deposits of gravels, sands and clays
having high infiltration capacities( 0.5 to
1.5 mm/ sec.). The occassional showers during
winter times at present along the high plate
au and slopes maintain short-period floods
where great amount of water infiltrate dowen-
ward at the foots of the plateau and in the
coastal plain to contribute the groundwater
in the Miocene aquifer. The drainage sub-bas
ins shedding water almostly to the east, whi
le other local trends of northeast are present,
3. Geomorphologie units
The area of study is built of three geomorph-
ic units. These units are distinguished as
based on the relief criteria and drainage pa
tterns. The system proposed by Verstappen
(1977) is considered. The structural deforma
tion of the area plays an important role in
the development of these units. While the li
thologic variation along the surface reflects
the chief events of the géomorphologie histo
ry of the area( Figs. 4 and 5 ).
3.1. The coastal plain
It occupies the eastern part of the area. It
forms a longitudinal strip of land running
parallel to the gulf of Suez in the NW direc
tion. It has a width varies between 2.5 Km
and 9.5 Km. It increases in width from north
to south. The surface elevation ranges betwe
en zero level and 70 m above sea level. It li
as gentle slope which assumes 5.9 m/ Km aver-
agely( slope angle of less than 1/2 degree).
It includes lowlying marsh lands (El-Maiah-
at) which occupies a longitudinal area paral
lel to the coast.
The surface of the coastal plain is built
of Middle Miocene facies, exposed in parts
and covered in others by Recent surficial de-
positsC Fig. 5). It is built of a great syn
cline running in the NW-SE direction and dev
eloped along the graben parallel to the gulf
of Suez.
It represents the area of the water collec
tor west of the gulf of Suez, where it recie-
ves water either by surface runoff through t
the drainage basins or by subsurface flow in
Miocene aquifer.
3.2. The pediment
It occupies the gentle inclined plain at the
foot of the higher plateau and represents the
transitional zone between the coastal plain
and the high plateau. It has a width ranges
between 18 and 24 Km. The surface elevation
attains the maximum of about 300 m above sea
level. It has the gradient of about 10m/ Km
averagely.
The surface of the pediment is built of the
Middle Miocene facies. It is dissected by dry
vallies and tributaries issued from the high
plateau in the direction of the coastal plai-
n. The channels are filled by surficial depo-
sities of high infiltration capacities.
The pediment plain is formed by degradation
and retreat of the mountain front in arid or
semiarid regions across rocks of varying lit
hology (Easterbrook,1969). A break in slope
Table 1. Drainage analysis and hydrographic network of nine sub-basins in the studied area.
Ser.no
Name
Area(sq.Km)
Length(Km)
Order
Drainage
density(one/sq.Km)
Mosaics
mm
max
aver
no.
I.
Northern
296.0
27.0
4 th
4
17
8.7
25,26
II.
Wadi Abu-Haad
296.5
4O.5
4 th
5
9
6.7
25,26,29
III.
W. El-Darb
125.5
33.0
4 th
4
11
7.3
25,26,29
IV.
W. Khreim
188.5
46.0
4 th
2
14
7.3
25,26,28
V.
W. Um-Yasar
188.0
3O.O
4 th
2
11
5.7
28,29
VI.
W. Khurm ElUyun
333.5
42.7
4 th
5
11
7.7
28,29
V.
W. Dara
672.5
51.5
5 th
4
7
5.7
28,29,42
43
VI.
W. Dip
539.0
53.5
4 th
4
12
7.3
42,43,44
48
42,43,44
VII.
W. Abu-Had
962.0
82.0
5 th
4
11
8.7
48,49
