Chapter XII: The Sudd

If the White Nile carried its waters in a channel in any way resembling that of the Blue Nile, there would be small cause for anxiety over the summer supply of Egypt. As far as Lado, indeed, the Bahr el Gebel, or Mountain River, as it is called, does flow with as good a slope and as sound a rocky bed as any Egyptian could desire. Then it enters upon the great plain which extends practically as far as Khartoum, but until Bor is reached it has not to encounter more than the ordinary troubles of a flat country. The swamps are still well above the summer level of the river, and the loss of volume is not great. At Bor, however, the real difficulties begin, and the ‘shorn and parcelled river strains’ miserably along for some 350 miles through the real sudd country. The river that leaves Lado in April or March with a volume of 600 cubic metres per second is reduced to less than half this amount by the time it emerges from the maze on the further side, and that, too, although it has nominally received at Lake No through the Bahr el Ghazal the drainage of a vast province.

Lake No is the remains of an inland sea which once covered all this desolate region. Gradually this lake became silted up with peaty deposits, and formed a series of swamps and lagoons through which the Bahr el Gebel from the south and the Bahr el Ghazal from the west wander in a series of loops and curves without any certain banks. The smallest rise in the level of the river floods an immense tract of country, and at all times of the year the sudd region is one gigantic evaporating pan. The Bahr el Ghazal, so far as any active contribution to the volume of the Nile is concerned, is practically lost altogether, though by spreading out over the marshes it fills a space which the Bahr el Gebel would otherwise occupy, and so helps to form a sort of reservoir, which prevents any rapid fall in the level of the White Nile.

All these swamps are covered with a dense growth of reeds and water-weeds. Of these, the most important is the papyrus, which grows in great abundance, and often reaches a height of 10 to 16 feet. Once the papyrus was common in Egypt, but now it is not found north of Abu Zeid, 190 miles south of Khartoum. In Europe it is not found, except on the river Anapo in Sicily, where, however, it does not attain anything like the same luxuriant growth. There are also great stretches of the reed called in Arabic ‘um soof,’ or the mother of wool. It is no wonder that the party sent by Nero to explore the river was intimidated by these interminable forests of papyrus and reeds, and turned back. No travellers have a good word to say for this country, unless they only pass through it extremely quickly. It is monotonous and desolate in the extreme, the air is always hot and steamy, and after dark mosquitoes rage in countless myriads.

As far as Shambe the banks of the river are fairly well defined, but there are numbers of breaches in them, through which the water spills into the marshes. In a distance of seventy-five miles Sir W. Garstin counted 129 of these breaches, usually about 4 yards wide; nearly all of these were on the eastern side. These channels are deeply cut with vertical sides, as if dug by hand, and the loss of water through them is very great. The marshes on the eastern side drain off into the Bahr el Zeraf, which takes off near Shambe, and, cutting off the corner, rejoins the Nile below Lake No. Greatly diminished by this loss, the Bahr el Gebel continues on its way, its bank being often nothing more than a line of papyrus separating it from large lagoons or dense thickets of reeds. As long as the channel is clear, tortuous and winding though it is, a great deal of water is able to pass; but under certain circumstances the channel becomes blocked by bars of solid vegetable matter, called sudd. Upstream of the obstruction the level rises, and, spreading out over the marshes, more and more water is lost in evaporation.

Sudd occurs both in the Bahr el Ghazal and the Bahr el Gebel, but it is of different kinds. The Ghazal sudd is very much less substantial than that of the Gebel. It is chiefly composed of masses of the smaller swimming plants, which grow in Lake Ambadi and other shallow lagoons on that river and its affluents. But on the Gebel the principal constituents of the sudd are the papyrus and the ‘um soof’ reed. Both these plants grow with their roots bedded in the soil below the shallow water of the lagoons. Strong gales are prevalent in these latitudes, and these loosen the roots, so that, if the storms are accompanied by flood, large masses of the plants are set free, and begin drifting over the lagoons. Quantities of earth remain clinging to their drifting roots, and thus they are driven backwards and forwards by the wind. The storms come generally just before the flood, and thus there is plenty of water for the reeds to float in. Eventually they are driven, whole acres at a time, into the channel of the river, and are carried down the stream. But the channel being very narrow and winding, they soon get caught up, and a block occurs. New masses come down, and these are sucked by the stream under the original block, till a dense mass is formed, sometimes as much as over 20 feet thick, and so solid that a man can walk over it. If left to themselves, these blocks may last a very long time, and cause the river to change its course; or else by increased pressure the block is burst, and a great wave passes down the river, which sweeps all other blocks away. Years of high flood are generally followed by a great deal of sudd.

It appears that the conditions on the river between Lake No and Shambe are much more favourable to blocking by sudd than they used to be. In 1840 Mehemet Ali sent a scientific expedition under D’Arnaud to explore the White Nile. At that time the main stream through the sudd country was much bigger and stronger. No mention is made of the Bahr el Zeraf at all, which looks as though it was of much less importance, at any rate. They noticed, however, a number of openings in the banks between the river and the swamps, some natural, but some artificial, made by the natives for fishing purposes. It is plausibly argued by Sir W. Willcocks that these openings were later widened by the natives to enable them to escape in their canoes from the slave-dealers, and then by the slave-dealers themselves, escaping in their turn from Government patrol boats. All these spills would drain into the Bahr el Zeraf, which gradually became a navigable stream in its lower part. In 1863 Sir Samuel Baker ascended the Bahr el Gebel without any difficulty; but in that year there was a very high flood and a great deal of sudd. Returning in 1865, Baker found the river north of Lake No considerably blocked. In 1870 Baker was unable to ascend the Bahr el Gebel with his expedition to Equatoria, and went by the Bahr el Zeraf. He cut through the sudd in that stream with prodigious labour, and had finally to cut a ditch through 2,000 feet of solid clay. Even then the Bahr Zeraf level was so much below that of the Bahr el Gebel that he could not get his boats through until he had dammed the Zeraf behind them so as to lift them up. In 1873 he says he found the canals much improved by the force of the stream. All this naturally contributed to weaken the power of the main stream and render it very liable to sudding.

In 1874, when the river was low, the sudd was cleared away by Ismail Pasha Ayoub, then Governor-General of the Soudan, and all through Gordon’s time in Equatoria there was free passage, but the channel had dwindled very much. The heavy flood of 1878 brought the sudd down again worse than ever, where it remained until cleared by Marno in 1880. It was in that year that Gessi, on his way back from his province, was caught and suffered such hardships in the sudd on the Bahr el Ghazal. He was only rescued by the appearance of Marno. Unfortunately, no record has been left of the methods which Marno employed in the work, but he spoke of it as quite an easy matter.

Little is known of the state of the sudd during the years of the Mahdi and the Khalifa; but in 1898 Lord Kitchener found the Bahr el Gebel blocked by sudd immediately above Lake No; and about the same time Colonel Martyr, coming from Uganda, was unable to penetrate more than 20 miles north of Shambe for the same reason. As soon as the Khalifa had been finally crushed, operations to clear the channel were immediately undertaken. In the first three months a length of 80 miles of river had been cleared, including 5 miles of actual sudd in eleven blocks, besides three more blocks which broke away of themselves. The blocks that came away of themselves represented a very large amount of sudd. After one of them had burst, the floating weed took thirty-six hours to pass a given point. The effect produced by the sudd in damming up the river is illustrated by the fact that when the third block, which was nearly 20 feet thick, was removed, the upstream level fell 5 feet in four days, and all the swamps and lagoons began to drain into the river.

The amount of labour was prodigious. At one place, owing to the enormous masses of um soof and papyrus that kept pressing into the river, no less than eleven clearances had to be made in one year. Five gunboats and 800 dervish prisoners, besides officers and guards, were employed. Sir W. Garstin gives an interesting description of the methods by which the sudd was removed:

‘In the first place, the papyrus and reeds on its surface were burnt (curious to relate, these green reeds burn readily when the marsh is dry), and in a few hours’ time the surface of the sudd was an expanse of blackened stalks and ashes. As soon as the fire had died down, gangs of men were landed from the steamer and employed in cutting trenches on the surface of the sudd. These trenches averaged from 0·60 to 0·80 metre in width, and from 1 to 1·25 metres in depth—_i.e._, as deep as the men could work. The surface was thus divided into a number of rectangular blocks some 3 metres by 4 metres. To these blocks were attached, one by one, steel hawsers and chains. This done, the steamer downstream went full speed astern. It invariably took several pulls to detach a block, and in some instances as many as nine were necessary. Both hawsers and chains kept constantly breaking, although the former were calculated to stand a strain of 35 tons per square inch, and the latter as much as 60 tons. As soon as a block was detached from the mass, it was allowed to float downstream. It was curious to see the green reeds and papyrus which had been confined beneath it reappear on the surface of the water. A horrible stench prevailed from the rotting vegetation.’

In 1900-1901 four more blocks were removed. An experiment was made to break up one of the blocks by means of explosives, but it was found that the sudd, though very solid, was too elastic, and the only effect was to make large holes in it and no more. The old method had to be once more resorted to. By the end of 1901 only 23 miles of the channel remained uncleared, but this proved to be the most difficult of all. One block was actually 7 miles in length. Portions of the sudd had rotted, and, sinking to the bottom, completely filled up the channel, so that there was no stream at all, and it was impossible to tow pieces away and float them downstream by the usual process. To get up the river it is still necessary to go round by a series of lagoons, in which navigation is difficult, and operations have been suspended for the present.

The sudd in the Bahr el Ghazal was much easier to remove, and great progress has been made, so that now the whole of that river is free, and boats can even ascend the Jur River to Wau.

It is very difficult to ascertain the precise effect of the removal of the sudd on the water-level in Egypt. But it is certain that as each block was removed a quantity of water drained off the marshes and helped to diminish the fall of the river in summers of very small supply. Most of this water, spread out over a large surface, must otherwise have been evaporated and lost altogether. There can be no doubt that the improvement of the channel has been a permanent gain to Egypt of a very substantial kind, to say nothing of the advantage to the Soudan from the opening up of such an important line of communication. Those who laboured at the task deserve the highest praise. The river was so low that all communication with Khartoum was cut off for several months, and transport of supplies was always difficult. Besides this, the climate is always unhealthy, and the mosquitoes at night are almost beyond endurance.

Under present conditions it will require constant care and watchfulness, especially in years of high flood, to prevent the sudd from frequently obstructing the river. But if the danger is to be permanently removed, the main channel must be so much improved by widening and deepening it that it will carry a greater volume. This will at the same time prevent the water from being dissipated in the marshes, and diminish the chances of any obstruction. The necessity for some work of this kind, if there is to be a reservoir at Lake Albert or Lake Victoria, has already been referred to. The clearing of the sudd is only the essential preliminary to the greater scheme.

One point remains to be noticed. Under the old basin system in Egypt there could hardly be too high a flood, nor did a low summer Nile create any extraordinary difficulties when there was so little summer cultivation. But with perennial irrigation a high flood becomes a matter of supreme anxiety, and the preservation of its dykes is the anxious care of every village. On the other hand, all the schemes for reservoirs aim at increasing the summer supply. If the Bahr el Gebel was trained so as to bring down more water in summer, it would also bring down more in flood, though the swamps would still act as an escape for the waters beyond a certain rise. It might therefore become a matter of great importance to Egypt to actually diminish the supply during the flood, especially as year by year more of the basin land is converted to perennial irrigation. Regulators at Lakes Victoria and Albert would serve in some degree for flood protection as well as for storage against summer use. It is calculated that the complete closing of the outlet of Lake Victoria at the Ripon Falls would only raise the surface of the lake 20 inches in a year. But it would be far more effective if some of the flood-waters of the rivers—_e.g._, the Blue Nile and the Atbara—which are fed by the rains of Abyssinia could be intercepted before they reached Egypt. A large irrigation during the flood and early winter along the Blue Nile might indeed actually lengthen out the flood in Egypt, whilst depriving it of danger through excess at any one period.