Wadi Erf Um Araka heads as a series of small wadis among the low hills south of Um Bisilla, and curves round westward between the high hills of Abu Shigelat and Erf el Gimal on the north, and Erf Um Araka or Gebel Belamhandeit on the south, to join Wadi Naam about five kilometres lower down than Wadi Um Bisilla. The hill country round the heads of Wadi Erf Um Araka is fairly open, so that one can proceed freely from the head of Wadi Arais, across those of Wadi Erf Um Araka, and on into the heads of Wadi Um Bisilla.
Wadi Arais originates by the union of many small feeders in the low hill country between Gebels Um Guruf and Hendusi, and courses for the first fourteen kilometres in a south-south-west direction. About nine kilometres below its head the Wadi Um Guruf, draining the hills round the conspicuous granite boss called Gebel Um Guruf, enters from the north-west. Some five kilometres further on, just beyond the place where Arais makes a sharp westward bend, Wadi Belamhandeit, draining the east face of the long gneiss range called Erf Um Araka or Gebel Belamhandeit, enters from the north. Wadi Arais now narrows into a winding gorge, cutting westward for about ten kilometres through the complex of high gneiss hills called Gebel Arais to join Wadi Naam. Its junction with Wadi Naam takes place in a small plain, with the sandstone plateaux of Gebel Um Sididad on the west and the gneiss hills of Gebel Arais on the east. The fall of Wadi Arais is from 464 metres above sea at the pass into Wadi Erf Um Araka, to 345 metres where it joins Wadi Naam after a course of twenty-five kilometres; so that its slope averages four and a half metres per kilometre.
Wadi Silsila[97] heads in high sandstone hills on the meridian of 34° 40′, north of Gebel Abraq, where at least one pass, steep and sandy, leads to the Wadi Arned. Its course is almost due east, over a plain with low sandstone banks, with a great deal of blown sand. Feeders enter it from the sandstone hills which bound the plain, the principal being the Wadi Um Sididad, draining the high sandstone hills, called Gebel Um Sididad, on the north. About seven kilometres before it joins Naam, Wadi Silsila cuts through the range of low sandstone hills which stretches southward from Gebel Um Sididad to near Abraq springs; in proceeding to Abraq from the pass at the head of Wadi Silsila, one bears off to the south before reaching this range, entering the drainage of Wadi Abraq over an open sandy plain.
Wadi Abraq is a rather ill-defined drainage line which originates on the north side of Gebel Abraq, and after skirting the high sandstone scarp, from which it receives small feeders, for about thirteen kilometres, turns eastward to join Wadi Naam, about nine kilometres above its junction with Hodein. Wadi Abraq is sandy and barren, and would be scarcely worthy of mention but for the fact that it contains some of the most important water sources of the entire Eastern Desert, the Abraq Springs. There are no less than five springs within a length of as many kilometres of the wadi, yielding perennial supplies of excellent water.
The first spring from the north, called Bir el Sunta, is a pool about two metres in diameter at the entrance to a little gully in the face of the high sandstone scarp; it is very easily accessible to camels, being practically on the plain, and fills as rapidly as it is emptied. The second and third springs, called together Bir Abu Dibesat, are about 1,500 metres south-east of Bir el Sunta, near the tomb of Sheikh Hamid; they form smaller pools at the foot of the scarp. The fourth spring, Bir Abraq, is situated a short distance up a stony gully which emerges from the scarp a little further south; the water lies in large pools under dipping sandstone beds on the south side of the gully. The fifth spring, Bir Gumbit, is said to be some three kilometres further south-east, and, like the others, at the foot of the sandstone scarp; it has not, however, been visited by the survey party.
Fig. 2.—Map of Abraq Springs. Scale: 5 centimetres to a kilometre.
The water at all the Abraq Springs is of excellent quality; it contains masses of green algæ, but these are easily avoided in baling out, and the water can be obtained quite clear. Of the four springs visited, the one called Bir Abraq is the chief; but Bir el Sunta is rather easier of access for camels. The springs are practically all at the same level, viz., 330 metres above sea, and all derive their water from the same sandstone beds. No camel food grows near the wells, and there are very few trees in the vicinity; consequently, the Arabs of the neighbourhood do not camp near the springs, but in Wadi Hodein and its tributaries, drawing water from Abraq or Abu Saafa at intervals. There are, however, ruins of a large ancient fort on a low hill east of Bir Abraq, and some Arab graves a little further north; among these latter is a large tomb said to be that of Sheikh Hamid.
Wadi Betan originates on the north side of Gebel Abu Dahr, where an easy pass, 610 metres above sea-level, connects its head with Wadi Um Karaba, and courses at first westward to near Gebel Hendusi; it then turns southward to join Wadi Naam a few kilometres only above its junction with Wadi Hodein. Its total length is over fifty kilometres, and its average slope is about seven metres per kilometre. Only the head of Wadi Betan has been surveyed in detail; but this is the most important part, as containing water sources and old mine workings; and the lower part of its course as shown on the map is probably substantially correct, being based on statements made near the spot by guides familiar with the district.
About five kilometres below its head, Wadi Betan contains the two wells called Bir Betan. These are excavations in the alluvium of the wadi. The lower one is at the mouth of the small Wadi Um Eleiga, while the other is about 600 metres further up Wadi Betan, close to a small tree. Both these wells were filled up by downwash when I visited them in February 1907, and their places were only recognisable by the clay “hôds” near them; at this time there was no necessity for the Arabs to open them, as a galt at the head of the wadi, just south of the pass into Wadi Um Karaba, was yielding a good supply of water.