Khor Makeir.About 8 miles east of the Pibor junction, Khor Makeir comes in on the right bank. This, near its mouth, is deep, with a sandy bed 30 yards wide. It has not been explored, but is believed by some to be the mouth of the Sonka, in which case it has its origin near Jebel Sonka in the Galla hills south of Kirin. Others say it is only a spill from the Baro.
Tributaries on left bank. Nigol or Aluro.The River Nigol (Nuer) or Aluro (Anuak) enters the Baro about 17 miles below Itang. It appears to have its origin on the Abyssinian plateau, and for some 25 miles before its junction with the Baro it flows parallel to that river, at a distance often of little more than a mile. In flood time it is a most formidable obstacle, as it forms large areas of swamp. Its entry into the Baro, near the border between Anuak and Nuer territory, is a very insignificant one, and barely discernible, as it spills out into a large swamp, near the village of Methok, before it reaches the actual river, and apparently the water gradually finds its way into the river through a thick forest-growth of trees by two small channels only a few feet wide. From the point where the Adura takes off from the Baro, the banks of the latter river are thickly wooded with sycamore and other trees as far as the eastern boundary of Nuer territory.
Pibor.The Pibor flows generally from south to north, and enters the Sobat river at a point about 25 miles above Nasser and about 200 miles from its (Sobat) mouth. It is by far the most important tributary of the Sobat. The Pibor was found (June, 1903) to be blocked by sudd immediately above the Akobo junction, and so its upper waters remained unexplored until September, 1904.[93] The greenish colour of its water would lead one to suppose that it receives its supply from vast marshes in the plain between the Akobo and the Nile, rather than from the Abyssinian plateau.[94]
The banks of the lower Pibor are, as a rule, swampy, especially at the season when the river is fullest. The adjoining country is flat and covered with grass, with but few trees, though, south of Koratong, the banks are firm and dry, and trees become general, especially on the right bank.
Width.The waterway of the Pibor in its lower reaches is exceedingly narrow, a steamer frequently touches the reeds of either bank simultaneously. About 40 miles from its mouth, however, it widens to from 40 to 100 yards.
Navigability.The Pibor river has not (1903) been navigated by steamer in the months of February, March, and April, during which period it appears probable navigation would be difficult, if not impossible. During the rest of the year the average depth of water is at least 10 feet.
Discharge.The discharge at the mouth of the Pibor, calculated by Captain H. H. Wilson in October, 1901, worked out at roughly 13,500 gallons per second. The width of the river here being about 80 yards, of which about 30 yards was blocked by sudd. The maximum depth was nearly 30 feet, and the current rather more than 1 mile an hour.
Route.There is a route over comparatively dry country from Nasser to Waratong (45 miles approximately).
Inhabitants.The inhabitants of the lower Pibor are Nuers, whose principal villages are a group at Koratong and another at Kur, both situated on the left bank. These appear to be the permanent homes of this section (Sheikh Jok’s) of Nuers, but in the dry season they occupy other villages both north and south along the Pibor, the most important of which is Bil (right bank) near the junction of the Gelo River; during this season Nuers from other districts visit the Pibor for fishing.
The Nuers of the Pibor do not differ in any essential degree from those of the Sobat and Baro, and are just as disinclined as their kinsmen to recognise the advantages of civilisation.