Just above the wells, Betan receives from the south the feeder called Wadi Mistura, draining the west side of Gebel Abu Dahr. The little Wadi Um Eleiga, which drains into Betan close to the south well, is of importance as leading to some extensive ruins and old workings about two kilometres up from its mouth. The ruins are mostly rubble hovels, while the workings, which were evidently for gold, vary from mere scratchings to pits ten metres deep in the rock. A diorite mill-stone is to be seen near the ruins.
The Wadi Abu Debebi lil Betan, which joins Betan on the north about three kilometres below the wells, leads by an easy pass into Wadi Abu Debebi lil Khoda, one of the heads of Wadi Khoda, and forms the nearest way to the coast from Bir Betan. Wadi Abu Sieiyil is a small feeder entering Betan from the south, three kilometres further down. The principal remaining tributaries of Betan are the Wadis Hefeiri, Abu Beid, and Egat. Wadi Hefeiri runs westward from near the Abu Debebi pass, and turning south near Gebel Hendusi, receives the Rod el Hendusi just before entering Betan. Wadi Abu Beid el Azrak originates near Gebel Abu Sieiyil west of Abu Dahr, and flows southwards to join Wadi Abu Beid el Abiad, which in turn flows into Wadi Betan. A well, Bir Abu Beid, is situated near the junction of Wadi Abu Beid el Abiad and Wadi Abu Beid el Azrak, where there are numerous seyal trees; it was yielding a fair quantity of good water in 1906. Of the Wadi Egat, nothing has been seen; it is, however, stated by the Arabs to originate in the rugged hilly tract south of Gebel Abu Dahr, and to join Wadi Betan lower down its course than Abu Beid.
Wadi Dif originates in the sandstone hills round Bir Dif, and pursues a very sinuous north-easterly course, cutting through the high sandstone plateau which is named Gebel Hodein to the north, and Gebel Dif to the south of it. For the major part of its length of twenty-nine kilometres it is very narrow, with very high steep sandstone scarps on either side, but it is a little more open near its origin, where Wadi Feqoh joins it, and in its lower part it winds as a broad sandy valley through the low hills which separate the Wadi Hodein from the high sandstone plateaux; it joins Wadi Hodein close to the meridian of 35°. Except the Wadi Feqoh, which is of immense length, and drains a very large area, Wadi Dif has only a few insignificant feeders. Of these, Talet Um Karaba and Wadi Enqireidia enter from the south plateau near the place where Wadi Dif leaves the high sandstone hills; and Wadi Gelabat Shabai, coursing north-east through the low hill country flanking the plateau, joins Wadi Dif just above its junction with Hodein.
Bir Dif is situated in a small gully forming the head of Wadi Dif, in latitude 23° 12′ 42″. To a traveller coming up Wadi Dif, Wadi Feqoh forms the main continuation of Wadi Dif, and the gully containing Bir Dif appears to be a lateral tributary coming in from the west; but the Arabs restrict the name Dif to the drainage line below the spring, and apply the name Feqoh to all the upper main channel. Bir Dif is a spring forming two pools of good water, situated about a kilometre up the gully, at the junction of sandstone and schists. The approach to the pools is very stony, but camels can easily reach the water; the spring is 290 metres above sea-level.
Wadi Feqoh, a tributary of Wadi Dif, is many times longer than Wadi Dif itself, and even longer than the Wadi Hodein of which Wadi Dif is a tributary, having a length along its main channel of 150 kilometres, with feeders totalling several times that length. Though only portions of Wadi Feqoh have been surveyed in detail, the position of its entire course is known with tolerable accuracy from the statements of guides at various stations from which portions of it could be pointed out. It is for the most part a very barren wadi, forming an ill-defined drainage line through a dreary waterless sandy waste. Its very name, which means “devoid of nourishment,” indicates its character. It originates near the west side of Gebel Soaorib, only some twenty kilometres north of the 22nd parallel of latitude, where the main watershed separates it from the feeders of the Wadi Alaqi. From here it follows a north-westerly course, passing between the mountains of Eir Arib and Hadal Derqa. Curving slightly to the north, it crosses the great sandy plain west of Gebel Korabkansi, and passes close west of the isolated mountain called Gebel Shabih. Further on, it enters a country of low hills with sandy interspaces, passing close west of the low range called Gebel Um el Kalala, and then sweeps round in a great curve towards the east to join the Wadi Dif close to Bir Dif. The fall of its bed from near Gebel Shabih to its junction with Wadi Dif, that is, in a length of seventy-two kilometres, is from 470 metres to 280 metres above sea, giving an average slope of only about 2·6 metres per kilometre; Wadi Feqoh has in fact the most gentle gradient of all the great seawards-draining wadis.
Wadi Feqoh has many tributaries. Those near its head, and others coming in from the western mountains through the low hill country north of Gebel Mishbih, have not been traced; but those draining Gebel Korabkansi and Gebel Niqrub, which are probably the most important, have been mapped in detail. Most of the drainage from these localities eventually finds its way into the great trunk feeder of Wadi Feqoh, called the Wadi Gimal,[98] which joins Wadi Feqoh about sixteen kilometres before its junction with Wadi Dif. The tributaries of Wadi Feqoh are of much more interest than Wadi Feqoh itself, as they contain in many places a fair or even relatively rich assemblage of trees and bushes, and at least one good well, Bir Sararat Seyet.
The most southern tributaries of Wadi Feqoh which have been mapped are Wadi Kamoyib, draining eastward from Gebel Wadhait, and Wadi Tawayib, draining the east face of Gebel Korabkansi. These are for the most part barren wadis each coursing for about sixteen kilometres across a sandy plain to join Feqoh.
The main head of Wadi Gimal is called Wadi Seyet. It originates between Gebel Wadhait and Gebel Dreb about latitude 22° 35′, and by means of many feeders drains the east face of Gebels Dreb and Gerf. The principal feeder of Wadi Seyet from the south-west is Wadi Wadhait, collecting the south drainage of Gebel Korabkansi, while on the east the Wadi Sherefa el Gharbi, which leads to the important Sherefa pass, contributes the drainage from the northern parts of Gebel Dreb and the south-west parts of Gebel Gerf. These both join Wadi Seyet a little south of latitude 22° 40′, while a little further down there enter from the east two small feeders called Wadi Delawet and Wadi Buyet. The name Seyet is given to this wadi only down to where it passes through a narrow gap between high hills in latitude 22° 42′; below that point it is called Wadi Gemal. Wadi Seyet is remarkably well wooded, containing an immense number of fine large acacia trees, and presented an almost park-like appearance at the end of 1907. It also contains a deep well, Bir Sararat Seyet, excavated in the wadi floor just above the gap between the hills above referred to. This well was full of downwash in the winter of 1907. It is said to be twenty metres deep and to yield plenty of good water, but at that time there was plenty of water in galts in the mountains, and the Arabs said they preferred to derive their supplies from these so long as they lasted, only digging out the well when further supplies were necessary.[99] An unnamed feeder from the west, joining Wadi Seyet just below the well, leads by an easy pass into the head of Wadi Hushenab, which drains through Wadi Sortdau into the Wadi Gemal lower down its course.
The country between Gebel Korabkansi and Gebel Niqrub Foqani, through which the course of Wadi Gemal lies, is a gently sloping plain with mere low banks, among which the drainage lines branch out forming numerous loops. The main channel runs fairly straight in a north-westerly direction, receiving Wadis Sortdau and Remalib, draining the hills north-west of Gebel Korabkansi as tributaries on its west side; but a sort of loop line runs off eastward and reaches the main channel again by the Wadi Haletiai, which also collects the drainage from the south parts of Gebel Niqrub Foqani. After passing west of this last-named mountain, Wadi Gemal takes a more northerly course; it receives an immense number of feeders from the west and north of Gebel Niqrub Foqani, of which the principal is called Wadi Umeiatib. Other feeders enter from among the low hills on the west, the principal being Wadi Hadelshisheib, coming from the neighbourhood of the dark cone called Gebel Mismih. From Bir Sararat Seyet to its junction with Wadi Feqoh the length of the main channel of Wadi Gemal is fifty-seven kilometres, and its fall is from 560 metres above sea to about 310 metres, or on the average about four and a half metres per kilometre; its slope is thus much more rapid than that of Wadi Feqoh, though in its lower parts, where it passes over what is almost a plain, its gradient is less than half this average amount. The upper parts of the Wadi Gemal and its tributaries contain as a rule a fair abundance of trees and bushes.
Wadi Abu Hashim, which joins Wadi Feqoh about three kilometres above Bir Dif, commences its course near Gebel Butitelib, where an easy pass, broad and sandy, 405 metres above sea-level, divides it from the heads of Rod Mukrayib, a tributary of Wadi Madi. Wadi Abu Hashim follows a north-westerly course, nearly in a straight line, collecting principally the drainage from the western slopes of the range of high schist hills which flank the sandstone plateau of Gebel Anfeib. It has a length of seventeen kilometres, and an average slope of about six metres per kilometre. It is a fairly open wadi, without much vegetation; on its west side are only very low hills.