The Hydrography of the Suez Canal
53
branch ofthe Delta. However, observations after the cessation ofthe Nile flow do
not support this assumption.
Spring tides at Suez are sometimes as high as 2.1 m (Wüst, 1934) or 1.8 m
(Tillier, 1902). Fox (1926) gives a main spring tidal range of 1.50 m. The "Red Sea
and Gulf of Aden Pilot" (1955) gives sea level rises of up to 2.7 m during southern
winds, which causes strong tidal currents to enter the southern part of the Canal.
Because the Bitter Lake acts as areservoir, the incoming current is stronger
than the outgoing one. Values for the incoming current are indicated as 1.38-2.00
rn/sec (Tillier, 1902) or maximum 1.40 rn/sec and average 0.82 rn/sec (Fox, 1926).
Miller and Munns (1974), on information supplied by Morcos, give for JulyAugust average current velocities of98.19 ern/sec at Shallufa.
The outgoing current is weaker. However, according to Morcos (1960) the
outgoing current becomes stronger during the summer than the incoming one,
perhaps in connection with the low summer levels in the Gulf ofSuez.
Since tides at Suez are semidiurnal, the tidal currents in the southern Canal
change directions four times a day. According to the "Red Sea and Gulf of Aden
Pilot", the onset of the northward tidal current is 2 h after the high tide at Suez
and continues till 5 h after high water. The returning current is similarly delayed.
The influence of the tidal currents is still feIt in the Little Bitter Lake and the
tidal friction reduces the current velocities by more than a quarter at Kabret
(Grace, 1931; after Miller and Munns, 1974). Gruvel (1936) gives interesting data
on the tidal fluctuations in the Bitter Lake. The high tide reaches the Deversoir at
the northern end of the Lake two to three hours after the tide at Suez. The tidal
span is, according to Gruvel, of 55 cm at Kabret, 55 cm at the Deversoir and 70
cm at Genefe in the South-Western corner of the Great Bitter Lake. This last
value is attributed by Gruvel to a concomitant piling up of the waters by the
N ortheast winds.
With the exception of the small tidal influence, little is known about the
current system in the Bitter Lake. Fox (1926) mentions several cases in which
changes in the direction of the wind caused inversion of the current in the Lake.
Miller and Munns (1974) suggest the presence of a counter-clockwise current in
the Lake. In their words "a northerly flow on the eastern side and a southerly flow
on the west seems to be borne out by the distortions of the salinity distributions".
For the sake of later discussion, it should be mentioned that no author ever
mentioned the existence of a throughgoing current in the Bitter Lake.
There is no precise knowledge as to what happens in the stretch of Canal
between the Bitter Lake and Lake Timsah. Usually it is assumed that here already
the 9-1O-months' regime of the northward currents prevails. However, Wüst
(1935) indicates an inverse current during July-October. In December 1973 Hecht
(personal communication) measured north of the Deversoir a wind-driven superficial southward current, a deeper and dominant northward current and along the
bottom, again, a southward flow.
Lake Timsah too, has no throughgoing currents and the water movements are
probably mainly wind-driven.
-
The currents in the northern stretch of the Canal have been much discussed. A
more detailed presentation is, therefore, necessary.
53
branch ofthe Delta. However, observations after the cessation ofthe Nile flow do
not support this assumption.
Spring tides at Suez are sometimes as high as 2.1 m (Wüst, 1934) or 1.8 m
(Tillier, 1902). Fox (1926) gives a main spring tidal range of 1.50 m. The "Red Sea
and Gulf of Aden Pilot" (1955) gives sea level rises of up to 2.7 m during southern
winds, which causes strong tidal currents to enter the southern part of the Canal.
Because the Bitter Lake acts as areservoir, the incoming current is stronger
than the outgoing one. Values for the incoming current are indicated as 1.38-2.00
rn/sec (Tillier, 1902) or maximum 1.40 rn/sec and average 0.82 rn/sec (Fox, 1926).
Miller and Munns (1974), on information supplied by Morcos, give for JulyAugust average current velocities of98.19 ern/sec at Shallufa.
The outgoing current is weaker. However, according to Morcos (1960) the
outgoing current becomes stronger during the summer than the incoming one,
perhaps in connection with the low summer levels in the Gulf ofSuez.
Since tides at Suez are semidiurnal, the tidal currents in the southern Canal
change directions four times a day. According to the "Red Sea and Gulf of Aden
Pilot", the onset of the northward tidal current is 2 h after the high tide at Suez
and continues till 5 h after high water. The returning current is similarly delayed.
The influence of the tidal currents is still feIt in the Little Bitter Lake and the
tidal friction reduces the current velocities by more than a quarter at Kabret
(Grace, 1931; after Miller and Munns, 1974). Gruvel (1936) gives interesting data
on the tidal fluctuations in the Bitter Lake. The high tide reaches the Deversoir at
the northern end of the Lake two to three hours after the tide at Suez. The tidal
span is, according to Gruvel, of 55 cm at Kabret, 55 cm at the Deversoir and 70
cm at Genefe in the South-Western corner of the Great Bitter Lake. This last
value is attributed by Gruvel to a concomitant piling up of the waters by the
N ortheast winds.
With the exception of the small tidal influence, little is known about the
current system in the Bitter Lake. Fox (1926) mentions several cases in which
changes in the direction of the wind caused inversion of the current in the Lake.
Miller and Munns (1974) suggest the presence of a counter-clockwise current in
the Lake. In their words "a northerly flow on the eastern side and a southerly flow
on the west seems to be borne out by the distortions of the salinity distributions".
For the sake of later discussion, it should be mentioned that no author ever
mentioned the existence of a throughgoing current in the Bitter Lake.
There is no precise knowledge as to what happens in the stretch of Canal
between the Bitter Lake and Lake Timsah. Usually it is assumed that here already
the 9-1O-months' regime of the northward currents prevails. However, Wüst
(1935) indicates an inverse current during July-October. In December 1973 Hecht
(personal communication) measured north of the Deversoir a wind-driven superficial southward current, a deeper and dominant northward current and along the
bottom, again, a southward flow.
Lake Timsah too, has no throughgoing currents and the water movements are
probably mainly wind-driven.
-
The currents in the northern stretch of the Canal have been much discussed. A
more detailed presentation is, therefore, necessary.