The Hydrography of the Suez Canal
61
1969 (Por and Ferber, 1972). Fox (1926) mentions seven brine pools near Kabret-within about 200 m from the shore. The pools had a wide range of salinities,
from 52%0 to near saturation (density 1176). All these lagoons and pools are
formed by spilling-over of the lake waters during the winter storms. Their highly
saline water, as well as that ofthe surrounding salt wetlands, probably contributes
a sizeable share to the increased salinity of the Bitter Lakes, either through direct
leaching out by waves or through percolation in the sediment.
Lake Timsah is characterized by a marked saline stratification. It receives
salty bottom waters from the south and these are overlain by a layer of diluted
water coming from the Nile. The fresh water comes from the Nile through a canal
which supplies drinking and irrigation water.
Until1891 this canal flowed out freely into Lake Timsah and therefore during
the Nile floods huge amounts of fresh water reached the lake. Tillier (1902) even
considers that some preexistent marine species were exterminated by these floods.
After 1891 the fresh-water canal was extended northward to Port Said. However,
even after this date the waters of the fresh-water canal ("Abassa Canal") still
reached the lake either from the sewers of the town of Ismailiya or as agricultural
runofffrom the lush fields ofthe western bank. 1
Since Lake Timsah has many shallow lateral lagoons, these carry almost
exclusively fresh-to-brackish waters to a depth of 30 cm (Fox, 1926). While the
deep center of the Lake is occupied by a saline bottom layer, the stratification
sometimes reaches a considerable amplitude. In December 1924 Fox reports a
difference of 9%0 between surface and bottom. W. Steinitz (1929) indicates that at
the surface the salinity may fluctuate between 7.86%0 to 47.6%0. Morcos (1960)
found less than 30%0 at the surface and 45%0 at the bottom. In June 1967, surface
salinity in the lake opposite Isma'iliya was 29.3%0 (por and Ferber, 1972). EI Sabh
(1969) gives surface salinities of 35%0. Miller and Munns (1974) report strong
differences between surface and bottom: in October 1966 from 36%0 to 41%0, and
in November 1966 from 37%0 to 42%0. They speak of a "strong intrusion of fresh
water" and "extra volumes of Nile water entering at Lake Timsah". In February
1965 Lake Timsah was almost homogenous and of the same salinity as the Bitter
Lake, i.e. ± 43 %0.
Thus the stratification of Lake Timsah is still considerable and is a seasonal
phenomenon with a peak in the late summer.
The northern stretch of the Canal between Lake Timsah and the Mediterranean is exposed to an inflow of low salinity Mediterranean water from
August-October. The inflow is mainly caused by the equalization of levels of the
two seas--or even a decrease of the Red Sea level below that of the Mediterranean, in late summer (see above). Before the building of the Aswan High
Dam, this period also coincided with the seasonal opening of the Nile barrages
and the flow of large amounts of fresh water into the sea not far from Port Said.
The salinity decrease in the northern Canal was first observed in the salinity
data of Durand-Claye in 1872. In the harbor of Port Said the salinity was 23.1 %0
while at Km 60 it was 45.5%0. In the rest of the Canal the concomitant salinities
1 Note added in proof: Morcos (1975) puts the influx of agricultural freshwater runoff at
210 million cubic meters per year and expects this influx to increase in the near future.
61
1969 (Por and Ferber, 1972). Fox (1926) mentions seven brine pools near Kabret-within about 200 m from the shore. The pools had a wide range of salinities,
from 52%0 to near saturation (density 1176). All these lagoons and pools are
formed by spilling-over of the lake waters during the winter storms. Their highly
saline water, as well as that ofthe surrounding salt wetlands, probably contributes
a sizeable share to the increased salinity of the Bitter Lakes, either through direct
leaching out by waves or through percolation in the sediment.
Lake Timsah is characterized by a marked saline stratification. It receives
salty bottom waters from the south and these are overlain by a layer of diluted
water coming from the Nile. The fresh water comes from the Nile through a canal
which supplies drinking and irrigation water.
Until1891 this canal flowed out freely into Lake Timsah and therefore during
the Nile floods huge amounts of fresh water reached the lake. Tillier (1902) even
considers that some preexistent marine species were exterminated by these floods.
After 1891 the fresh-water canal was extended northward to Port Said. However,
even after this date the waters of the fresh-water canal ("Abassa Canal") still
reached the lake either from the sewers of the town of Ismailiya or as agricultural
runofffrom the lush fields ofthe western bank. 1
Since Lake Timsah has many shallow lateral lagoons, these carry almost
exclusively fresh-to-brackish waters to a depth of 30 cm (Fox, 1926). While the
deep center of the Lake is occupied by a saline bottom layer, the stratification
sometimes reaches a considerable amplitude. In December 1924 Fox reports a
difference of 9%0 between surface and bottom. W. Steinitz (1929) indicates that at
the surface the salinity may fluctuate between 7.86%0 to 47.6%0. Morcos (1960)
found less than 30%0 at the surface and 45%0 at the bottom. In June 1967, surface
salinity in the lake opposite Isma'iliya was 29.3%0 (por and Ferber, 1972). EI Sabh
(1969) gives surface salinities of 35%0. Miller and Munns (1974) report strong
differences between surface and bottom: in October 1966 from 36%0 to 41%0, and
in November 1966 from 37%0 to 42%0. They speak of a "strong intrusion of fresh
water" and "extra volumes of Nile water entering at Lake Timsah". In February
1965 Lake Timsah was almost homogenous and of the same salinity as the Bitter
Lake, i.e. ± 43 %0.
Thus the stratification of Lake Timsah is still considerable and is a seasonal
phenomenon with a peak in the late summer.
The northern stretch of the Canal between Lake Timsah and the Mediterranean is exposed to an inflow of low salinity Mediterranean water from
August-October. The inflow is mainly caused by the equalization of levels of the
two seas--or even a decrease of the Red Sea level below that of the Mediterranean, in late summer (see above). Before the building of the Aswan High
Dam, this period also coincided with the seasonal opening of the Nile barrages
and the flow of large amounts of fresh water into the sea not far from Port Said.
The salinity decrease in the northern Canal was first observed in the salinity
data of Durand-Claye in 1872. In the harbor of Port Said the salinity was 23.1 %0
while at Km 60 it was 45.5%0. In the rest of the Canal the concomitant salinities
1 Note added in proof: Morcos (1975) puts the influx of agricultural freshwater runoff at
210 million cubic meters per year and expects this influx to increase in the near future.