The Hydrography of the Suez Canal
55
First of all, the tidal differences, an eventual driving force, are minimal in the
Eastern Mediterranean. Gohar (1954) indicates a tidal range of 15-40 cm at Port
Said. Fox (1926) gives a maximum spring tide value of 40 cm. It follows that there
are practically no tidal currents in the northern Canal section. Fox indicates tidegauge amplitudes of 3.0-3.5 cm at EI Qantara (Km 46). In July 1963, during the
transit of the "Atlantis II" through the Canal, the influence of the Mediterranean
tide extended as far as Ras el Esh-about 30 km (Miller and Munns, 1974;
Fig.22).
The current in the northern Canal is, therefore, influenced by the seasonal
water level differences. Starting with Tillier, all the authors concerned agree that
there is a prevailing northward current in the northern Canal for three quarters of
the year, between October and June. For this, current velocities of 0.5 to 2 knots
are given. In June 1967, the current was so strong that SCUBA divers working at
EI Qantara had to attach themselves to the piers. In November-December 1967
the current flowed a constant north, despite the permanent strong winds in the
opposite direction (Ben Yami, personal communication).
It is curious that the older authors and especially Lesseps (1876) made different observations. He wrote: "L'evaporation etant plus active dans le centre de
l'isthme qu'aux deux entrees de Suez et de Port Said, le courant vient presque
toujours du sud au nord a partir de Suez jusqu'aux Lacs Amers et du nord au sud
a partir de Port Said". Keller (1882) even indicates a speed of 0.3 cm/sec for this
southward current in the northern Canal. Wehave to consider that Keller visited
the Canal in January, i.e. in the season in which the current is reversed. That
Keller was keen in observing the currents is evident from the very accurate
description he gives for the diurnal changes in the tidal currents of the southern
Canal.
It would be interesting to suppose that the current regime in the Canal
changed after the first few decades-eventually owing to the deepening of the
Cana1. 1
From J uly throughout September there is a southward current in the northern
Canal. Gruvel (1936) is the only author who mentions that this current starts
already in June. During these summer months the level of the Mediterranean
waters becomes equal to those ofthe Gulf of Suez. It is reasonable to assume that
under such circumstances the wind, permanently northerly, becomes the driving
force of the current. The equalization of the sea levels is due to the loss by
evaporation in the summer heat of the Gulf of Suez. This is however, even much
more severe in the Bitter Lake, which according to Wüst (1935) lies some 10 cm
below the level of the Gulf of Suez.
Morcos (1960) reports on continuous current measurements at two pointssouth and north of the Bitter Lakes during 1933-35. However, according to
Morcos (discussion with Miller and Munns, 1974) there is "a net flow towards the
north in the summer and a net flow towards the south in winter". The winter flow
1 Note added in proof: More recently Morcos and Messieh (1973a) and Morcos and Gerges
(1974) following Baussan (1938) speak of a transitional stage in ilie currents in ilie summer,
when water flows both from the Mediterranean and from Red Sea into the Bitter Lakes.
55
First of all, the tidal differences, an eventual driving force, are minimal in the
Eastern Mediterranean. Gohar (1954) indicates a tidal range of 15-40 cm at Port
Said. Fox (1926) gives a maximum spring tide value of 40 cm. It follows that there
are practically no tidal currents in the northern Canal section. Fox indicates tidegauge amplitudes of 3.0-3.5 cm at EI Qantara (Km 46). In July 1963, during the
transit of the "Atlantis II" through the Canal, the influence of the Mediterranean
tide extended as far as Ras el Esh-about 30 km (Miller and Munns, 1974;
Fig.22).
The current in the northern Canal is, therefore, influenced by the seasonal
water level differences. Starting with Tillier, all the authors concerned agree that
there is a prevailing northward current in the northern Canal for three quarters of
the year, between October and June. For this, current velocities of 0.5 to 2 knots
are given. In June 1967, the current was so strong that SCUBA divers working at
EI Qantara had to attach themselves to the piers. In November-December 1967
the current flowed a constant north, despite the permanent strong winds in the
opposite direction (Ben Yami, personal communication).
It is curious that the older authors and especially Lesseps (1876) made different observations. He wrote: "L'evaporation etant plus active dans le centre de
l'isthme qu'aux deux entrees de Suez et de Port Said, le courant vient presque
toujours du sud au nord a partir de Suez jusqu'aux Lacs Amers et du nord au sud
a partir de Port Said". Keller (1882) even indicates a speed of 0.3 cm/sec for this
southward current in the northern Canal. Wehave to consider that Keller visited
the Canal in January, i.e. in the season in which the current is reversed. That
Keller was keen in observing the currents is evident from the very accurate
description he gives for the diurnal changes in the tidal currents of the southern
Canal.
It would be interesting to suppose that the current regime in the Canal
changed after the first few decades-eventually owing to the deepening of the
Cana1. 1
From J uly throughout September there is a southward current in the northern
Canal. Gruvel (1936) is the only author who mentions that this current starts
already in June. During these summer months the level of the Mediterranean
waters becomes equal to those ofthe Gulf of Suez. It is reasonable to assume that
under such circumstances the wind, permanently northerly, becomes the driving
force of the current. The equalization of the sea levels is due to the loss by
evaporation in the summer heat of the Gulf of Suez. This is however, even much
more severe in the Bitter Lake, which according to Wüst (1935) lies some 10 cm
below the level of the Gulf of Suez.
Morcos (1960) reports on continuous current measurements at two pointssouth and north of the Bitter Lakes during 1933-35. However, according to
Morcos (discussion with Miller and Munns, 1974) there is "a net flow towards the
north in the summer and a net flow towards the south in winter". The winter flow
1 Note added in proof: More recently Morcos and Messieh (1973a) and Morcos and Gerges
(1974) following Baussan (1938) speak of a transitional stage in ilie currents in ilie summer,
when water flows both from the Mediterranean and from Red Sea into the Bitter Lakes.