|
AFTER an interval of nearly
twenty years since his visit to Alexandria, Mr. Abernethy designed a scheme
for the reclamation of Lake Aboukir, and acted as consulting engineer during
the execution of the work to an English Company, which had obtained a
concession from the Egyptian Government through the instrumentality of Mr.
William Grant to effect that object. While Mr. H. G. Sheppard, Assoc. M.
Inst. C.E., undertook the position of resident engineer at the scene of
operations.
Lake Aboukir was distant but
six miles from the city of Alexandria, and constituted one of a series of
salt lakes along the northern coast, between that city and Port Said. Its
area, as defined in the concession of March 12th, 1887, was 29,621 feddans,
or 30,717 acres (i feddan = 1.037 acre). In section it was shaped like a
saucer, flat in the centre and rising towards the edges, while the average
level of the centre was about 3.28 feet below mean sea level. None of the
land, even around the edges, was sufficiently high to admit of draining the
water into the sea, which was excluded by a stone sea wall.
The bed of the lake, like
those of the rest of the lakes in the district, being some feet below the
level of the sea, could only be drained by means of pumping and discharging
the water into the sea, which entails a heavy charge on lands reclaimed, or
by means of siphons or culverts under the Mahmoudieh Canal, running oft the
water to Lake Mareotis, the mean level of the water in the latter lake being
about 4*92 feet below the bed of Lake Aboukir.
The latter naturally
commended itself as being the cheaper and more efficient plan, but,
unfortunately, it failed to meet with the approval of the Egyptian Ministry,
and the system of pumping was specified as a sine qua non in the concession.
Even reclamation by the
system of pumping was, however, considered to be a profitable undertaking
from the facts of the lake being situated-on the outskirts of a rapidly
growing city of 250,000 inhabitants, with two railways and a large canal
encircling three sides, and the annual rent of land in the vicinity being £5
per acre.
From the month of May to
August in each year— the period of the hot season—the lake used to be
completely dry before the work of reclamation was begun, but during the high
Nile and winter months was covered with water to about nine inches in depth
over the bed, and there the water would remain till evaporated in the
following summer.
This water was partly rain
water and partly drainage water from the cultivated lands, bat there was
little or no infiltration from the sea. From this it will be gathered that
the lake was clearly a large salt-evaporating basin—the salt being almost
pure chloride of sodium- -the sale of which was a Government monopoly. Each
year this deposit of salt, probably increasing in quantity, was alternately
dissolved by the winter rains and dried by the summer heat, and this, and
this alone, prevented the successful cultivation of the bed of the lake.
The presence of the salt some
three or four inches thick in the depressions of the bed of the lake is
accounted for in various ways. Firstly, it is inherent in the whole of the
deltaic formation of Lower Egypt, while it is also stated that during a
great storm in the year 1715 the sea wall was breached by the sea, and that
for years after the breach remained open. Possibly also the sea being at a
higher level than the lake would tend to force any salts to the surface,
even if the salt water itself could not penetrate to an appreciable extent.
The site of the lake was
cultivated and populated in the days of the Pharoahs, as the buried remains
of ancient towns scattered over its surface made manifest.
The method of reclamation
adopted was by a complete system of drainage and fresh-water canals, which
derived their supply from the Mahmoudieh Canal, which bounded it on the west
and south. But the work of reclaiming the lake was of a more interesting
character than the mere pumping out of its water, for it included also the
deposition upon the land of a layer of rich alluvial matter held in
suspension in the waters of the Nile. In fact the irrigation was even of
more importance than the drainage. While the admission of the Nile water,
admitted and allowed to remain for a certain period, absorbed the salt in
the soil, it at the same time deposited the soil held in solution, which,
after the water had been pumped, became sweetened, and the clear water was
run off into drains, which conducted it to the pumps erected on the line of
railway to Rosetta, within 350 metres (383 yards) of the sea.
The engines and pumps of
immense power, supplied by Messrs. J. & H. Gwynne & Co., of London,
commenced working on March 8th, 1888, and on April 23rd a telegram was
received, announcing that Lake Aboukir was dry, the water having been pumped
off in the short space of 45 days, with a consumption of but 135 tons of
coal. To state the net result in figures, 2,900,000,000 gallons of water
were lifted to an average height of six feet, with the consumption of fuel
above-mentioned: equal to raising 21½ million gallons six feet high per ton
of coal, or 9,600 gallons of salt water the same height for each pound of
coal used: in other words, one pound of coal sufficed to raise 96,000 pounds
of water six feet.
The process of flooding and
pumping out the lake was repeated several times, and ultimately the soil was
rendered fertile. Steam ploughs were soon busy at work, and the Egyptian
Lakes Reclamation Company had numerous applications for leases of portions
of the area reclaimed, which in 1890 was described as “a waving sea of green
crop ”—Winetoa being presumably the green crop alluded to. |
