On the east side of the hills the valleys are narrower and have a steeper fall, and possess well-defined and clean-swept watercourses, which, in the narrower valleys, cover the whole bed of the valley.
The most important of the khors draining west are Khors Garar, Arbat, Okwat, and Adit.
The general course of Khors Garar and Okwat is at right angles to the watershed, and the upper parts of these khors are therefore steep and stony. Khors Arbat and Adit lie parallel to the watershed for a considerable part of their length.
Khor Arbat is the largest of these khors, and, from its watershed, opens out almost immediately into the broad Odrus plain, which the Berber-Suakin caravan road crosses.
Entering the Akareirirba hills, it narrows in, and in the lower part of its course it becomes a defile shut in by steep hills, which rise directly from the sandy and stony bed of the watercourse.
Khor Adit also has its maximum width in its upper part between Sinkat and Jebel Erba, and, narrowing as it descends, joins Khor Okwat through Khor Totali, a winding defile shut in by steep hills, and in places only 200 yards wide.
The minor khors which drain eastward from the hills bounding Khors Adit and Arbat, are steep stony valleys, ending in agabas, strewn with boulders and difficult of passage by loaded camels.
Such are Khors Adaia and Bengar, leading from Khors Arbat and Khors Teiutelri and Abent from Khor Adit.
The khors become ill-defined on leaving the hills, and what vegetation they possess gives place to the low scrub and coarse grass of the maritime plain.
Climate.The higher parts of the watershed on the eastern side have a perfect winter climate, and the extreme ranges of the temperature are less than those of the higher plains of the northern Atbai.