The Wadi Um Saha drains the hills south-west of Bir Baaneit, and after coursing southwards among the mountains turns the corner and runs north-east across the plain to Wadi Shab.
Wadi Sherefa el Sharqi, which drains the south portion of the Gerf massif and the north-east flanks of Gebel Dreb, heads in the important Sherefa pass, 807 metres above sea-level, and forming the direct route from Gebel Hamra Dom and Gebel Um Rasein to Bir Sararat Seyet by way of Wadi Sherefa el Gharbi. The pass is a fairly easy one, though the fall is rapid, especially on the east side, where Wadi Sherefa el Sharqi falls no less than one hundred metres in the first two kilometres of its course. A feeder which enters Wadi Sherefa el Sharqi from the south about two kilometres below the pass is said to lead by another pass to a well called Bir Bint el Dreb, situated at the head of Wadi Dreb, a tributary of Wadi Feqoh. For the first seven kilometres of its east-south-easterly course below the pass, Sherefa el Sharqi is shut in by very high hills, from which numerous feeders join it; it then divides just before reaching the great white granite hills called Eir Arib, part of its drainage going southward to join Kwat Hewah, and part continuing its course on the north side of the granite hills to join Diqdib near the granite cones of Tibashoi and thence turning northwards over a large sandy plain to enter Wadi Shab.
Kwat Hewah drains the eastern flanks of Gebel Dreb and the north flanks of G. Medarai. Its heads unite to form a series of channels in a small plain south-west of Eir Arib, and here it receives a contribution from Wadi Sherefa el Sharqi as mentioned above. As it passes Eir Arib, Kwat Hewah divides, part of its drainage curving round to the north to join that of Wadi Diqdib and Wadi Sherefa el Sharqi on its way to Wadi Shab, and the remainder going south-west to join the Wadi Medarai. From the head of Kwat Hewah there is said to be an easy pass into the Wadi el Krim, a tributary of Wadi Feqoh.
Wadi Ibib, which drains the eastern slopes of Gebels Medarai, Abu Hireiq, and Abu Hodeid, and the eastern and northern faces of Gebels Soaorib, Adar Qaqa, Leqaq, Um Seleim, Qidmib, Orgem, and Um Bishtit, as well as Gebel Hamra Dom and the smaller hills south of it, is formed by the union of the Wadis Hasium and Medarai, a little east of Gebel Um Rasein, and enters the sea at Mersa Shab. It has a drainage basin of about 1,800 square kilometres. Including Wadi Hasium, which is simply the upper portion of Ibib, its total length along its main channel is slightly over one hundred kilometres. Its principal tributaries are the Wadis Shinai, Abu Hodeid, Abu Hireiq, Medarai, Soaorib, and Um Bishtit.
Wadi Hasium, which forms the upper portion of Wadi Ibib, originates on the main watershed in about latitude 22° 10′ and longitude 35° 15′; a pass leads from its head on to a stony plain, whence a track leads to Miti Kwan, a tributary of Wadi Alaqi. Near its head, Wadi Hasium contains a small well called Bir Kagog. A few kilometres further down, the short Wadi Mantil Hasium, draining the western face of Gebel Adar Qaqa, enters from the east, while the Wadi Hilwit Hasium, draining the mountain of the same name and containing a galt near its head, joins Wadi Hasium from the west. Continuing its course northward past the mountains of Adar Qaqa and Leqaq, Wadi Hasium enters an extensive sandy plain, open to the north, bounded on the west by the mountains of Abu Hodeid and Um Rasein, on the south by those of Leqaq and Um Seleim, and on the east by those of Qidmib and Orgem. This plain, which averages fifteen kilometres in width, is broken by low hills, the principal of which, Gebel Hamra Tit, Kulet Meiqrum, and Kulet Tinasal, rise to considerable heights. Hasium courses slightly east of north near the western edge of this plain to near Gebel Um Rasein, then curves to the east across it, receiving the Wadi Medarai and becoming Wadi Ibib. In its northward course through the plain, Wadi Hasium receives a number of important tributaries from the western mountains, besides a few smaller feeders from the mountains to the south and from the hills on the plain. These may be briefly described in order.
Wadi Shinai, draining the hills south of Gebel Abu Hodeid, courses a little south of east and enters Wadi Hasium about latitude 22° 19′; it has not been surveyed in detail, but it contains a well known water source, Bir Shinai, which is said to be about seven kilometres from its junction with Hasium.
Wadi Delawet, another small feeder which likewise drains the hills south of Abu Hodeid, and enters Wadi Hasium about three kilometres below Wadi Shinai, is of importance as leading to a camel track over hills which forms the means of access to Bir Odis Maaleq, I have not visited this water source, but it is said to yield immense quantities of good water, and to be situated at a rather high level in the head of a small wadi called Wadi Odis, a tributary of Abu Hodeid. It appears to be a spring fed by the rainfall on the surrounding high mountains, the overflow filling large rock basins. The reason why it is approached by the Wadi Delawet and the track over the mountains, instead of by ascending Wadi Abu Hodeid and the Wadi Odis directly, is that the latter route is very difficult for camels owing to the steep and stony nature of the wadi floor; it is, however, possible to use this route on foot. As nearly as I could make out from my guides’ statements, the total distance of Bir Odis Maaleq from the mouth of Wadi Delawet is about nine kilometres, of which the first four are in the Wadi Delawet and the remaining five on the hill track. The distance by the other route from Bir Abu Hodeid is about four kilometres, some of which is climbing. My native assistant, who was sent to erect the beacon on Gebel Abu Hodeid, took two and a half hours to go on foot from Bir Abu Hodeid to Bir Odis Maaleq, and estimated the latter spring to be some 150 metres higher than Bir Abu Hodeid.
Wadi Abu Hodeid, which drains the mountain mass of the same name, lies to the east of the highest peaks of Gebel Abu Hodeid and is shut in between them and another high range further east. It has a general south-south-easterly direction, and a very rapid fall. Its principal feeder is the short Wadi Odis above referred to, which falls into it from the west about six kilometres below its head. About one and a half kilometres below the point of influx of Wadi Odis, there is a large and important spring of good water in the wadi, called Bir Abu Hodeid. Though I have not visited this spring, its situation is shown on the map with tolerable accuracy, as its position with regard to neighbouring triangulated points was indicated by the guides. My native assistant, who passed the spring on his way to erect the beacon on Gebel Abu Hodeid, reported it to be very similar to the springs of Abu Saafa in appearance, though the latter are in a different rock. From its position in the midst of high mountains, Wadi Abu Hodeid must at times of rainfall collect a great deal of water, and this explains the constant supplies yielded by the spring. Above the spring, the steepness of the wadi renders its ascent very difficult for loaded camels, and there is no road through its head, but guides state that there is good grazing at certain seasons in its upper parts, and animals are taken there to feed. Below the spring, the wadi opens out and curves eastward round the foot of the remarkable rounded peak of Abu Hodeid Oqla to join Wadi Hasium on the plain.
The Rod Anut Berer, which joins Wadi Hasium about the same point as Wadi Abu Hodeid but from the opposite side, drains the mountains of Leqaq and Um Seleim which bound the plain to the south.
Wadi Tikraneib, a small wadi full of trees, drains a jagged range north of Abu Hodeid Oqla, and joins Wadi Hasium on the plain by several channels.