The Sudd region is unmistakably, as Lombardini pointed out years ago, an old lake which has silted up and become full of peat and sand deposits. At one time the lake must have had an extreme length of 400 kilometres and width of 400 kilometres and been a larger sheet of water than lake Victoria. The Sobat river flowed into it, and the Blue Nile may have flowed backwards up the bed of the present White Nile for tens of thousands of years. The north-east corner has been better filled with deposit than any other part.
The dense masses of papyrus and water-grasses which shut out the horizon in every direction intimidated the expedition sent up the Nile by Nero, and it returned northwards without having accomplished anything. From Nero’s time to that of Mehemet Ali little was known of these regions. Mehemet Ali made a determined effort to discover what lay beyond these inhospitable regions, and sent up a well-equipped expedition under D’Arnaud.
One of the earliest descriptions of the Nile between the fifth and tenth parallels of latitude is by Werne, who accompanied D’Arnaud’s expedition sent by Mehemet Ali in 1840-1841. The expedition found the channel of the White Nile and Albert Nile easily navigable between December and March. The Albert Nile between 7° and 9° N. lat. had apparently a mean width of 120 metres, depth of 5 metres, and velocity of about 60 centimetres per second, giving a discharge of some 400 cubic metres per second. In this first description of the river the fact that strikes one most forcibly is the omission of the Bahr Zeraf. Neither the inlet nor the outlet are mentioned, though the Sobat, the Gazelle, and numerous insignificant streams are minutely recorded. Practically the whole of the water was confined to one stream, and that a good one. The water level in winter was found to be some 50 centimetres below the general level of the berm, and about 60 centimetres above this level in flood. The swamps contained offensive and fetid water, which mixed with the waters of the rising flood and helped to pollute the stream on the first rise of the river. Between the river and the swamps in its southern reaches were numerous cuts and openings, some natural and some artificial, made by the aborigines for fishing purposes. While traversing the swamps, the waters of the river in flood lost their silt and became quite clear. On page 100 of Vol. II of Werne’s work there is this significant sentence: “The report that the natives below (i.e. in latitude 5° to 7°) had blocked the river to cut off our retreat, turned out to be unfounded.” From the above it will be noticed that the aborigines in 1840-1841 spoke of their ability to block the course of the river, while the training works in the side channels and spills for fishing purposes were described as solid works regulated by rows of strong stakes driven into the ground.
Between 1841 and 1863 the expeditions up the Nile considerably increased, while the aborigines were being brutally treated by the slave traders. What could be more natural than that, as a measure of protection, the aborigines should have widened and deepened the side channels and spills which took off from the river between latitudes 51⁄2° and 71⁄2°, so that they might escape from the traders. Subsequently, when the main river was patrolled by Government boats, the slave-traders themselves used these side channels for prosecuting their traffic. All the channels and spills tailed into the Bahr Zeraf, which now began to form an appreciable stream, and which was navigated over the lower part of its course by Petherick between 1853 and 1862. The Bahr Zeraf was however always described as sudded, while the Albert Nile was open to navigation. This action of dissipating the waters of the river went on increasing till 1863, when there occurred a very high flood indeed; the floating weeds brought down from the south were excessive, the waters escaped everywhere from the main stream, while the floating masses of creepers were confined by the grasses and papyrus to the main channel, and sudded it downstream of Lake No.
On ascending the White Nile and Albert Nile in January 1863, Sir Samuel Baker found the passage clear to the south. On returning in April 1865, he found the sudd of the flood of 1863 still in the Albert Nile downstream of Lake No. The sudd was 1000 metres long and had a passage 3 metres wide cut through the middle of it, down which the river ran like a mill race.
In February 1869, Dr. Schweinfurth and his party, on their way to the Gazelle, took six days to get through this sudd, though the main obstruction was now only 200 metres long. In July 1872, Dr. Schweinfurth on his way back found the sudd to the downstream of Lake No as before, and described the opening through it as “a narrow stream of water which rushed along as a wild brook. The depth of the fairway varied from 2 to 3 metres, and the boat nowhere touched the bottom.”
In February 1870 Sir Samuel Baker found the sudd in the Albert Nile impossible for his expedition of heavily laden boats and steamers. He found the Zeraf sudded in its southern 100 kilometres, and tried to cut his way through but failed. And yet the slave traders had means of getting slave boats down the Bahr Zeraf (“Ismailia” pages 61, 62 and 29). Baker returned in January 1871 to the Zeriba Kutchuk Ali on the Bahr Zeraf and had before him the 100 kilometres of sudded channel. With the aid of 1200 men he completed the work by March 13. The final operation was a canal through stiff clay 600 metres long (known to-day as Baker’s cut). The fall from the Albert Nile into the Bahr Zeraf was so great that, in order to get the boats and steamers across the final distance, Baker made a dam 120 metres long across the Zeraf by means of a double row of piles, sand bags and fascines of the tall grasses. He thus secured the necessary depth of water, and the flotilla sailed into the Albert Nile. On his way back in June 1873, he thus describes the appearance of the head of the Ziraf river where he had made the cut in March 1871:—
“On arrival at the Bahr Zeraf cut, we found that the canals which we had formerly cut were much improved by the force of the stream. Although these passages were narrow, they had become deep and we progressed with comparatively little trouble.” The rest of the journey down the Bahr Zeraf was easily performed.
In January 1874, when the river was low, the sudd in the Albert Nile was removed by Ismail Pacha Ayoub, Governor General of the Soudan.
From 1874 to 1878, while Gordon was Governor General, the Albert Nile was clear of sudd, but the wide stream of 1840 had dwindled down to a clear waterway free of weeds on a width of 6 metres over long reaches. The escape of water down numerous spills had deprived the Albert Nile of the power of keeping its channel clear and when the heavy flood of 1878 came down, the river was sudded.