Chapter V

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.

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.]