THE DAM AND THE NEW BARRAGES
Once the financial difficulty was settled, no time was lost in
setting to work. As soon as the flood of 1898 began to subside,
Messrs. Aird and Co., the contractors, were busy with the foundations
of the Dam. Five years was the period allowed by the contract,
but a succession of low Niles gave unusual facilities for the work,
and everything was completed before the flood of 1902, a year before
the specified time.
From its vast proportions, the Dam is infinitely more impressive to
the imagination than any other of the irrigation works in Egypt. But
from an engineering point of view its construction was a plain,
straightforward business compared with the difficulties of building
a Barrage, where the river-bed offered no more solid foundation than
shifting sands. Still, there was a moment, on the first uncovering
of the river-bed, when its fate seemed to hang in the balance. The
Assouan site had been selected principally because the outcrop of
granite, there running clean across the valley, would give, it was
thought, solid foundation at a convenient level. It was found that
in some places the rock was rotten to a depth of 40 feet. It was an
anxious moment, both from an engineering and a financial point of
view. Every foot of rotten rock meant a considerable addition to the
calculated expense, besides modifying the building plan. Once more
Lord Cromer’s strong will saved the situation. On the financial side
he stood on firm ground, and he proved as good an engineer as he had
been a financier. Solid rock was reached, and the work went steadily
forward. Ten thousand men was the usual sum of those employed, and
of these 800 were Italian stone-cutters specially brought over to
deal with the tough granite of which the Dam is built. Granite and
Portland cement are the two great materials used for welding the
fetters of the Nile.
The Dam is about one mile and a quarter in length, and at its
deepest point it is 126 feet high. Sixty-five feet of water can be
held up when the reservoir is full, and it is capable of storing
about 1,200,000,000 cubic metres of water—that is to say, about
the same amount of water as passes through Assouan in a single day
when the flood is at its height. The face of the wall is a slope
on the downstream side, and its width at the bottom corresponds
approximately to its height. Seven hundred and eighty thousand cubic
yards of masonry have been used. On the western side a ladder of
four locks gives passage to boat and steamer traffic at all seasons.
All parts of Egypt are to benefit in a greater or less degree from the
extra summer supply. The original calculation assumed an amount to be
distributed of 1,065,000,000 cubic metres. It was allotted as follows:
_Cubic Metres._
South of Assiout 170,000,000
Assiout to Cairo with the Fayoum 510,000,000
Gizeh Province 85,000,000
Lower Egypt 300,000,000
This division meant that 52,000 acres could be reclaimed to
cultivation in the Fayoum, and 120,000 acres in the Delta. Further,
south of Assiout 200,000 acres could be converted to perennial
irrigation by means of pumps upon the Nile banks. In Middle Egypt
458,000 acres could be converted to perennial irrigation, and in
Gizeh Province 106,000.
A low Nile on the average comes about once in five years, but
assuming that it happened every year, these results may be expressed
in terms of money on the basis that conversion to perennial irrigation
increases the yield per acre by £2 annually, and that reclaimed land
produces a yield valued at £5 annually. This gives an increase of
value in the annual yield:
£E
South of Assiout 420,000
Middle Egypt and Fayoum 1,176,000
Gizeh Province 212,000
Lower Egypt 600,000
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Total £E2,408,000
while the direct annual gain to the State Exchequer in rental and
taxation would amount to £E378,400.
This does not exhaust the full extent of the benefits of the
Reservoir on which a money value can be placed. For some time
Egypt had been living beyond her real resources in the matter of
water. Encouraged by a series of good years, the acreage of cotton
had been greatly extended. The cotton-plant is very hardy, and
can retain its vitality for a certain period on a very scanty and
irregular supply of water. Cultivators, especially in the Delta,
had taken advantage of this quality up to the very hilt, and the
annual crop had reached an amount of 6,000,000 kantars.
Taking the not very high price of 175 piastres per kantar (1 kantar =
nearly 100 pounds), the annual value reached £10,000,000. A season
like that of 1889, when the summer supply was very low, and not the
lowest on record, would mean the loss of at least one-tenth of this
amount, and even more, in spite of the most successful working of
the Barrage, and the most careful system of rotations. Against such
a loss the Reservoir is a complete insurance, and, as a low year
cannot safely be reckoned as occurring less than once in five years,
the annual value of such insurance must be set down as £200,000. The
figures give some idea of the value of the new supply. The estimate
does not err on the side of exaggeration. It was framed in the most
cautious and conservative manner possible, and, in fact, it would
be by no means rash to put the total annual value a good deal higher.
According to the financial arrangement, the first payment towards
defraying the cost of the works was included in the budget for 1903,
but no fresh taxation for the purpose was to be imposed till 1904,
and even then the full amount of direct benefit to the Exchequer will
not be realized till 1910. Time is thus given for the full effects
of the change to be felt, and the Reservoir will be paid for out
of its own profits. The alteration of the basin lands to the new
system must take some time, and their cultivators will thus be given
full opportunity to familiarize themselves with the new methods of
agriculture which they will have to employ.
The scheme of distribution allotted nearly 50 per cent. of the
Reservoir supply to the Fayoum and the province between Assiout and
Cairo. Just south of Assiout is the head of the great Ibrahimiyah
Canal, which not only supplies these provinces, but also feeds the
Bahr Yusuf, which waters the Fayoum. It was necessary, in view of
the increased discharge, to widen the upper reaches of this canal,
and to provide it with a new regulating head. But more than this
was required to insure its receiving the proper proportion of water
whenever the sluice-gates of the Dam were opened. Accordingly, at
the same time that the foundations of the Dam at Assouan were laid,
a new Barrage was begun at Assiout just downstream of the head of
the Ibrahimiyah Canal.
In principle the Assiout Barrage is exactly the same as that at
the point of the Delta, and the difficulties of construction were
also exactly similar, for in both cases the foundations had to be
laid on the same shifting sands, and as each section of the work
was undertaken a portion of the river had to be diverted from its
course by means of temporary earthen dams. The shifting nature
of the river-bed, the almost personal malignity of the water,
constantly bursting through in countless springs, each of which had
to be separately dealt with and suppressed, called forth the highest
exercise of engineering skill. But the experience gained in the long
struggle with the imperfections of the earlier Barrage infallibly
told its tale. Every difficulty was successfully encountered, and
the Assiout Barrage was completed by the summer of 1902, and was able
to hold up the 10 feet of water required of it, without any failure,
at the first attempt.
The visible part of this Barrage, which is just over half a mile
in length, consists of a viaduct or bridge with 111 archways, each
16 feet 5 inches in width, closed by strong iron gates, working in
grooves made in the supporting piers, and raised or lowered from
above. In contrast to the Delta Barrage, it is built throughout of
stone, and not of brick. At the western end is a lock, the largest
in Egypt, through which the largest of the boats that ply upon
the Nile can easily pass. Below the water lies the strength of the
structure. The viaduct rests upon a solid platform of granite and
cement, 10 feet deep and 87 feet wide, set at a suitable depth below
the bed of the river. As a further precaution against the action of
the water, there are also below the platform two continuous lines
of iron sheet-piles, with hermetically sealed joints. With such a
series of obstacles to encounter, the danger of the water forcing
its way through underneath the Barrage is small indeed. The whole
amount of masonry used in this Barrage is 220,000 cubic yards.
The prosecution of these great works in Upper Egypt by no means
exhausted the activity of the Irrigation Department; indeed, it
would almost seem that the building of Barrages has become part of
its ordinary routine, for a third remains to be chronicled. This
is the Zifta Barrage on the Damietta branch of the Nile, halfway
between the point of the Delta and the sea. Because it lies in a
district unvisited by tourists, though very important commercially,
its construction has not been heralded by any blowing of trumpets. Yet
it is a work of the very first class, and deserves to be reckoned
among the greatest of the triumphs of the department. Built on the
same plan as the Assiout Barrage, and, like it, capable of holding up
10 feet of water, it is designed to secure a better distribution of
the supply north of the Delta Barrage. As the area of the cultivated
land extended gradually northward, it became apparent that the canal
system taking off from above the original Barrage was becoming
too long to admit of the water in times of pressure reaching the
northernmost parts of the country. There were some who held that a
second Barrage, with a new system of canals taking off from it, should
have been erected on the Damietta branch, even in preference to the
new stone weirs, which have increased the strength and distributing
power of the old one. The dispute has been happily settled by the
adoption of both projects, and with the Zifta Barrage completed
in time for the summer of 1903, and the new supply from Assouan,
the reclamation of the northern lands will go steadily forward.
It has been already pointed out that it is almost as important to
get the water off the land as to get it on, and the proper drainage
of the Delta lands has been the necessary complement of all the new
schemes. Though eclipsed by the splendour of the Reservoir and other
creations more taking to the eye, the performance of the engineers
in this direction during the last few years has been sufficient
to make them very memorable in irrigation annals. Since 1896 about
1,000 kilometres of new drains have been dug, and nearly as great
a length of existing drains remodelled. It has cost the Egyptian
Government close upon a million of money, but that this expenditure
has not been thrown away is proved by the great rise in the value
of all the lands affected.
The Zifta Barrage cost about £500,000, the Assouan Dam and the
Assiout Barrage £3,200,000. Apart from the ordinary expenditure on
maintenance and the suppression of the corvée, the twenty years ended
1902 have seen an expenditure of £9,000,000 devoted to irrigation
and drainage. There could be no greater proof of the wisdom of those
who have directed Egyptian policy during that period. However pressed
they have been at different times by demands for immediate expenditure
on other objects when resources were low, they have always adhered
steadily to a policy of liberality towards public works likely to be
of a remunerative character. In no other country do economic laws work
out their results with greater directness and certainty. Reproductive
expenditure is really worthy of its name, and brings its visible
and tangible fruit almost without a moment’s delay. As they have
sown, so have they reaped. There can be no comparison between this
expenditure and the benefits it has conferred upon Egypt. Three
salient examples may be given to point the force of these remarks.
First, the works undertaken by Colonel Ross to improve the system
of basin irrigation in Upper Egypt. 1877 was a year of very low
flood, and nearly 1,000,000 acres were sharaki—that is, entirely
exempted from taxation owing to absence of irrigation. In 1899, a
worse year—in fact, the lowest flood of the century—the sharaki
lands were no more than 250,000 acres, a result mainly due to the
successful reforms carried out by Colonel Ross in 1888-89. 1902 was
a year very similar to 1899, and the sharaki acreage was no more
than 140,000 acres.
Second, the case of the Assiout Barrage. The work was finished a
year before the time named in the contract. On August 15, 1902, the
usual date of filling the basins, the flood was exceptionally low,
and it was decided to lower the gates of the Barrage. By so doing
the water-level of the canals was raised by 1½ metres, an increase
which was more than sufficient to avert the threatened disaster. The
money value of the crops thus secured to the land-owners of the
Fayoum and Middle Egypt is estimated at not less than £600,000. The
cost of the new works at Assiout, including the new regulator on the
Ibrahimiyah Canal, was about £875,000. Thus, in the first year of
their existence they nearly repaid their whole cost, and that, too,
as it were, by a sidewind; for the Barrage’s real function is to
hold up the river in the low summer season, and not in the flood.
Third, the case of the Assouan Reservoir itself. The summer supply
in 1903 has been the lowest on record; the discharge at Assouan has
fallen to 200 cubic metres per second. By means of the Reservoir
this supply has been actually doubled. Had the flood been late
in coming down, it would have been impossible to distribute the
water at so liberal a rate. The Soudan gauges gave warning that
an early flood was to be expected, and thus the authorities were
able to calculate with certainty, and open the sluice-gates with
much greater freedom. But the calculation would have been a useless
exercise unless there had been a store to draw upon. At the lowest
computation the loss avoided may be reckoned at a couple of millions.
The administrators of Egypt have had many difficulties and obstacles
in their path, but to be able to point to such results is a great
compensation; their efforts need no formal monument.