The two strips of land outside the main drainage lines have a different character, and considerably less Nile deposit (see [Map]).
Medineh, the chief town of the Fayûm, from which most of its canals and roads radiate, stands on ground (R.L. 22·50) three to four metres lower than the land of the Nile Valley in the neighbourhood of Lahûn, where the Bahr Yûsuf turns westward to enter the Fayûm.
From Medineh for 8 kilometres the country surface slope is 1 in 1400, for the next 4 kilometres 1 in 666, and then 1 in 150, till the Birket-el-Qurûn (Lake of the Horns) is reached. This lake occupies the lowest part of the Fayûm, and at the beginning of 1892 its water surface level was 43·30 metres below mean sea; while the bed of the lake is 5 metres lower at least.[1]
The Fayûm and Wadi Raiân together are everywhere encircled by a continuous range of hills, except where the Bahr Yûsuf enters through the gap in the Libyan Hills, and also towards the north of the Fayûm, where the height of the hills becomes less, but where there is probably no gap lower than R.L. 30, though this has not been actually established by levelling.
The Birket-el-Qurûn and Evaporation.—Such being the physical features of the Fayûm, it is evident that there is no outflow for the drainage of the province. All the drainage (except that of the Gharaq Basin) finds its way into the Birket-el-Qurûn and there evaporates. The present surface area of the lake is not accurately known, but being about 40 kilometres long by 5 broad, the area is about 200 square kilometres (78 square miles).
Notwithstanding the considerable quantity of water that drains into the lake during the twelve months of the year, its level has fallen steadily of late years. The following table gives the measure of the fall from the first of March of one year to the first of March of the next.
Level on 1st March.
| Year. | Metres below Sea. | Fall. | |
|---|---|---|---|
| 1885 | 39·80 | ||
| 1886 | 40·00 | ·20 | |
| 1887 | 40·38 | ·38 | |
| 1888 | 40·73 | ·35 | |
| 1889 | 41·17 | ·44 | |
| 1890 | 42·00 | ·83 | |
| 1891 | 42·78 | ·78 | |
| 1892 | 43·32 | ·54 | |
| Total fall from 1stMarch, 1885, to 1st March, 1892 | 3·52 | metres | |
| Yearly average | ·50 | nearly. | |
There are no records of the level of the lake previous to 1885. Linant Pasha states in his ‘Mémoires’ that Vansleb, who was in the Fayûm in 1673, said that one embarked at Sanhûr to pass to the other side of the lake. Dead tamarisk bushes standing in the water seem to prove that the lake has in the past been lower by a metre or more than it is at present, for these tamarisks grow along the margin of the lake above the water edge, but not in it.
The fall of the lake is not continuous throughout the year, but generally takes place from the 1st March to the 31st October; the level rises from the 1st November to the end of January, and remains stationary during February.