THE FAYÛM IN THE FUTURE, AND POSSIBLE UTILISATION OF THE WADI RAIÂN.
The subject of storage reservoirs for husbanding the flood or winter
surplus waters of the Nile with the object of supplementing the Low
Nile is now under consideration and _sub judice_. Mr. W. Willcocks,
M.I.C.E., has been appointed Director-General of Works for the study
of this subject, and his final report has not yet been made.
It has been calculated that the total of the Nile discharges for even
a minimum year is more than sufficient for all the needs of Egypt,
developed to its fullest extent, and the main question to decide is
where the reservoir is to be made and what form it is to take.
Portions of the Nile Valley itself could be made to store the water
by forming one or several masonry dams across the Nile, and the Wadi
Raiân could also be made to serve the same purpose by putting it
into communication with the Nile by means of a channel cut in the
range of hills which divides the depression from the Nile Valley.
The discussion of the advantages of the different methods of forming
Nile reservoirs does not belong to this paper, but there is a
probability that a reservoir in some form will be made, and that the
Fayûm will receive its share of the resulting increase of the summer
water supply. Its present summer supply would probably be doubled,
which would enable the province to increase the area under cotton
from about 50,000 to 100,000 feddans, but would otherwise have no
great effect on the province. The expansion of the present area
under cultivation in the Fayûm to the lands along the north-east
and south borders of the province does not depend so much on an
increase to the present supply as on the construction of canals
designed to carry sufficient water at a high enough level to command
the lands above the present limits of cultivation. There is no want
of water during Nile flood time outside the intake of the Fayûm,
but its present canals will not carry more than a total discharge
of 7,000,000 cubic metres a day, and therefore that is the maximum
allowed to pass through the Lahûn bridges.
If, however, the Wadi Raiân were to be made a reservoir, the
reclamation of the lands along the south and south-west borders of
the Fayûm would be made comparatively easy. What this area amounts
to is rather uncertain.
In Chapter III. the conclusion was arrived at, that the Wadi Raiân
depression had never hitherto acted as a regulator to control the
Nile floods and supplement the Low Nile, and that its past history
shows no record of useful work, so far as the irrigation of Egypt is
concerned. But this fact does not affect the question of its possible
uses in the future, for which its physical features and geographical
position may fit it. It is a depression, separated by a short width of
hill from the Nile Valley, and if filled with water up to R.L. 24·00,
would become a lake, having a surface area of about 600 million
square metres, and a greatest depth of 64 metres. There is no doubt
that the communication could be made; the only question is, would it
be worth the expense, and could not better results be obtained for
the same expenditure by the adoption of other rival projects. This
question is now being considered by the Ministry of Public Works.
There are four uses which the Wadi Raiân depression might be made
to serve, if a communication with the Nile Valley were established.
It might be used,
(1) As a reservoir of control for the Nile floods.
(2) As a reservoir of storage to supplement the Low Nile.
(3) As an area to be brought under cultivation.
(4) As a receptacle for the drainage of the Nile Valley during the
flood season.
(1) It would not make an efficient regulator for the control of the
Nile floods, unless it were to be expressly reserved for this object,
and its level kept low until all fear of the necessity of relief
arising had passed. If it were considered necessary to provide for
the relief of the Nile to the extent of 100 million cubic metres
per day for 30 days, the lake, having an area (at R.L. 24·00) of
600 million square metres, should be kept at such a level as would
allow of its receiving the 3000 million cubic metres without checking
the inflow in consequence of its surface level becoming too high. An
addition of 3000 million cubic metres to the reservoir would raise it
about 4¾ metres, allowing for evaporation for 30 days. This is about
the extreme duty the Wadi could perform as a reservoir of control,
if it were expressly reserved as such; but, if it is to serve this
object alone, the expenditure, which would be incurred in fitting
it to do so, would certainly be considered out of proportion to the
benefits to be obtained. An attempt to combine the two duties of
controller of Nile floods, and feeder to Low Niles would probably
result in failure, as the necessity of keeping the reservoir level
low to fit it to act as an escape-valve during September might make
it impossible to raise the level afterwards to a sufficient height
to render it an efficient feeder to the Low Nile.
(2) It would, however, make an efficient feeder for supplementing
the Low Nile, if the control of the flood Nile were neglected. If
connected with the Nile about Beni Suef, and also with the Bahr
Yûsuf (which could continue to flow into it after the Nile
ceased to do so), the reservoir could easily be filled to R.L. +
26·00. Assuming R.L. 21·00 as the level to which the water in
the reservoir would fall in summer, and allowing one metre for
evaporation for six months, the volume required to fill the lake
from R.L. 21 to 26 would be 600,000,000 square metres × (5 + 1) =
3600 million cubic metres. From November to January, say 90 days,
the Bahr Yûsuf could supply an average of 12 million cubic metres
a day at least, or 1080 million cubic metres, leaving 2520 million
cubic metres for the direct Nile feeder during the 90 days of flood,
or an average of 28 million cubic metres a day.
The reservoir would return to the Nile Valley 600,000,000 × (5 - 1)
= 2400 million cubic metres. Allowing for a loss of 10 per cent. in
the distributing canals outside the reservoir, we get a supply of
(2400 - 240 =) 2160 million cubic metres available for irrigation.
Now 60 days is given as the critical period in Lower Egypt, when
the Nile supply is generally insufficient. Subtracting 160 million
cubic metres for the Fayûm, the 2000 million cubic metres remaining
would therefore give an average discharge of 33 million cubic metres
a day to supplement the Low Nile, and, if distributed in increasing
quantities in proportion as the Nile fell, it might be so arranged as
to prevent the Nile minimum discharge ever falling below 50 million
cubic metres a day in the very lowest years of summer Nile.
But calculating with a period of 100 days, which is the length of
the critical period for Upper Egypt, we obtain a mean discharge of
20 million cubic metres a day, which might be so distributed as to
prevent the minimum Nile falling at any rate below 45 million cubic
metres a day, as for instance below:—
--+---------------+-----------------------+------------+----------+--
| |Minimum Nile Discharge |Supplied by | Total |
| Month. | without Reservoir. | Reservoir. |Increased |
| | Monthly Average. | |Discharge.|
+---------------+-----------------------+------------+----------+
|March | 40,000,000 | 5,000,000 |45,000,000|
| | | | |
|April | 35,000,000 | 10,000,000 |45,000,000|
| | | | |
|May | 25,000,000 | 20,000,000 |45,000,000|
| | | | |
|June | 20,000,000 | 25,000,000 |45,000,000|
| | | | |
|10 days of July| 30,000,000 | 15,000,000 |45,000,000|
--+---------------+-----------------------+------------+----------+--
This disposes of 1975 millions, whereas 2000 millions was the quantity
calculated as being available after loss by evaporation in the lake,
and by absorption and evaporation in the distributing canals outside
the lake. I think, therefore, I have not overstated the capabilities
of the reservoir as a feeder to supplement the Low Nile.
I have said nothing about the first filling of the lake, which is a
question of no small difficulty. To fill it to R.L. 21·00, its low
summer level when once in working order, would require a volume of
15,000 million cubic metres plus the quantity required to meet loss
by evaporation during the time of filling.
(3) The idea that the depression might be converted into a cultivated
basin is, I think, not likely to get beyond the stage of suggestion,
as, with the object only of extending cultivation, the expense
of connecting the Wadi Raiân with the Nile will not be incurred,
since there are so many other projects of reclamation, which would
need less expenditure and give a better return.
(4) The last use to which the Wadi Raiân might be put, and which
has lately been suggested, is to adapt it for the reception of the
drainage waters of the Nile Valley, after the basin area of at least
Middle Egypt has been converted into Sêfi (summer) irrigation by
means of the increased supply provided by the assumed existence of
reservoirs in the Upper Nile Valley and a regulating dam at Asyût.
When all these basin lands are converted into tracts under perennial
irrigation, there will be a great difficulty in the disposal of
their drainage water during the time of high flood, and the Wadi
Raiân affords a possible means of solving this problem. Even though
the drainage might gain on evaporation and the Wadi Raiân become
eventually full, its water surface could be annually so far lowered
by allowing a flow out into the Nile during the summer months, as
to prepare the basin for the reception of all the drainage it would
be called upon to receive during the next flood season.
It would further be possible to combine the uses Nos. 2 and 4,
and make the depression serve both as a receptacle of the drainage
during the floods and a reservoir to supplement the Low Nile during
summer. But it might be objected that the admixture of drainage
with the reservoir waters, returned to the Nile in summer, might
render the river water unfit for irrigation. Supposing the drainage
discharge, which must be received into the reservoir, amounts to 15
million cubic metres a day for 80 days (probably a high estimate),
the total volume of drainage water would amount to 1200 million
cubic metres, or one-third of the quantity of water (3600 million
cubic metres) required to fill the lake from R.L. 21 to 26, or half
of the 2400 million cubic metres returned to the Nile Valley. This
would be further diluted by the summer discharge of the Nile itself,
to which it would be added.
If the reservoir were filled to R.L. 25 during the flood months by
the drainage and flood waters together, the remaining metre could
be added by a canal discharging 7 million cubic metres a day for
100 days in winter, and fed from the Ibrahimîyah Canal, or a new
branch of it, which would replace the Bahr Yûsuf, when the latter
was converted into the main drainage line consequent on the basin
lands being brought under perennial irrigation.
If then the drainage water should not be found salt enough to
seriously affect the quality of the reservoir water, the Wadi Raiân
might be made to serve both the purposes stated.
It has been assumed in previous notes on the subject, that such
a reservoir alongside the Fayûm would be capable of giving that
province its summer supply, but there would be a difficulty in
the way of doing this. Under present arrangements the water-level
at the end of the Bahr Yûsuf at Medineh is maintained throughout
the summer at R.L. 21·70. If the level were to be lowered, lands
now commanded by the water would cease to be so. The Wadi Raiân
reservoir, whose level has been assumed to fall to R.L. 21·00,
while a length of canal of at least 40 kilometres would be required
to convey the water to Medineh, could not, during part of the summer
(after its water surface had fallen below R.L. 23·50) deliver water
at the level at present maintained.
It would, probably, therefore be necessary, in spite of the adjacent
reservoir, to supply the Fayûm during summer by a branch from the
Ibrahimîyah Canal, but the reservoir could assist by providing
for the irrigation of all the lands, now cultivated or capable of
being reclaimed, on the left of the main south drainage line, and
the part of the province watered by the Qalamshah Canal; that is,
it would feed the Gharaq, Qalamshah, and Nezlah Canals, and so far
assist in the summer irrigation of the province.
No doubt the proximity of a lake of 600 million square metres (280
square miles), filled to a high level with reference to the greater
part of the Fayûm, would affect the climate of the province, and
at any rate take some of the heat out of the south winds, which blow
at intervals in March and April.
INDEX.
* * * * *
Arsinoë, 25
Arsinoite Nome, 48, 82
Bahr Yûsuf, 9 _et seq._
Biahmu, ruins of, 76, 83; supposed quay at, 85
Birket-el-Qurûn, 6-9, 49, 96; area of, 7; evaporation, 9
Brugsch Pasha, 39, 93
Canal, the Ibrahimîyah, 10; ruins of two ancient canals, 99
Crocodilopolis, 25, 72
Crops in the Fayûm, 17
Diodorus, 21, 27
Fayûm, the, 5 _et seq._; area of the Lake Fayûm, 67; derivation of
name, 24; fisheries in the, 18; geological history of, 61; situation
of, 5
Hawârah, the pyramid of, 25
Hawârat-el-Maqta, 97, 102
Helouan, 72
Herodotus, 19
Labyrinth, the, 25, 81
Levels:—Lowest summer levels at Wâstah, 78; between Dimay and
Schweinfurth’s Temple, 55
_Reduced Levels_:—Bahr Yûsuf, 12; Birket-el-Qurûn, 7; the Fayûm, 30;
Gharaq Basin, 5; “Hêt Rozma,” 101; Lake Mœris (_max._ and _min._)
79, 88; Lahûn Bridge, 103; Medineh, 6, 65; of Nile deposit at
Hawârah, 48, 65; Nile deposit at Lahûn, 48; at Wâstah in April, 66;
rock sill at Hawârah, 48; ruins of Dimay, 51; Temple of
Schweinfurth, 52; Wadi Raiân, 5, 42
Linant Pasha, theories of, 28 _et seq._; difficulties of his theory,
30; inaccuracies of his theory, 34
Medineh, the town of, 6, 92
Mœris, the Lake, 19 _et seq._; Arabic tradition concerning, 22;
identical with Fayûm depression, 48; in the time of Herodotus, 88;
decline of, 95; inflow and outflow of, 77; levels of Nile and lake,
79; supposed regulators of, 73, 89; supposed maker of, 69; volume of
water required to fill, 79; Cope Whitehouse’s theory concerning, 5,
37, 40; objections to his theory, 42 _et seq._; Petrie’s theory, 56-60
Nile, the, gradual rise of water-level, 87, 92; the river in the days
of Herodotus, 87
Petrie, W. M. F., 77, 85, 94
Pliny, 22
Ptolemy, Cl., 41, 44
Reservoirs, different methods suggested, 105 Ruins at Dimay, 51, 52
Schweinfurth, Dr., 38, 43; temple of, 51, 52
“Shad,” the town of, 92
Strabo, 21
Wadi Raiân never in direct communication with Nile, 43, 48; position
of, 5; possible reservoir, 106; Western’s official description of, 42
Water-wheels, different kinds of, 14-16
LONDON:
PRINTED BY EDWARD STANFORD, 26 & 27, COCKSPUR STREET,
CHARING CROSS, S.W.
[Illustration: FAYÛM PROVINCE
London: Edward Stanford, 26 & 27, Cockspur St, Charing Cross, S.W.
_London: Stanford’s Geogl. Estabt._]
FOOTNOTES:
[Footnote 1: A maximum of 20 metres is obtained from statements made
by the fishermen. Crossing to Dimay, the greatest depth I obtained
was 4·85 metres, but the fishermen said that at a point towards the
south-west four times that depth was to be found, but I have not yet
been able to verify this statement.]
[Footnote 2: Its actual height is under 6 metres as a maximum.]
[Footnote 3: I believe the ridge east of Edwah and running parallel
to the railway along its south side is natural. Its crest has a
decided inclination downwards from the hills on the east of Edwah. The
artificial bank begins at Edwah and runs west, but it is joined at
Edwah to this natural ridge.]
[Footnote 4: Dr. Schweinfurth includes the Edwah-Biahmu bank and the
Minia wall under the expression “dams.”]
[Footnote 5: Probably that of Fra Mauro, of 1459 A.D., which, as Mr.
Cope Whitehouse states, in a paper published in Paris, represents two
small lakes unnamed, of which that on the south is larger than that on
the north.]
[Footnote 6: See map at end.]
[Footnote 7: Mr. Petrie’s information is incorrect on this point. The
quay at its upper end is at R.L. 25·438, as ascertained by careful
levelling and check-levelling in May 1892, made by Mr. W. O. Joseph and
M. Pini, under my directions.]
[Footnote 8: A feddan = 4200 square metres.]