Travel web site: White Nile

The most historic and one of the greatest inland navigation waterways is the Nile, the river and its tributaries affording over 4,000 miles suitable for the passage of streamers and other craft between North and East Africa and Cairo.
The head of the navigable waterways may be said to be the town of Gondokoro, on the White Nile, about 1,000 miles above the city of Khartum, Gondokoro is the terminus of several caravan routes extending into the Congo, as well as Uganda and Unyoro. Small steamers ply upon the water-courses between Khartum and Gondokoro, connecting at the former city with steamers for Cairo. In recent years tourists have extended their trips from the Lower Nile as far as Gondokoro, but the rivers  are utilized principally for the transportation of products from the territory beyond Gondokoro and Khartum.
There is one very serious obstacle on the section of the Nile between Khartum and Gondokoro which has at times obstructed the channel so that continuous navigation ahs been delayed months at a time. This is the vegetation growth known as sudd, which is a translation from the Arabic term El Sett.
On one occasion the channel was blocked by a bar of sudd which actually measured 25 miles along the channel, while within a distance of 150 miles were three more growths aggregating no less than 60 miles. A fleet of vessels especially equipped and a large force of men were working continually for nearly six months before an opening large enough for the smallest river steamer could be made through the mass.
In studying the growth the investigators have found that it is more rapid under certain conditions. For example, it spreads very rapidly after an unusually extensive flood in the upper rivers, which carry down such an amount of sediment and vegetation, while when the rainy season is short the growth is checked considerably, and the current in the upper rivers is usually strong enough to carry out the young vegetation before it becomes dense enough to be able to resist the action of the water.
Since the obstruction of the Nile has such a serious effect in interrupting the transportation between upper and lower Egypt and in cutting off what is really a route between Cairo and Mombasa, the Egyptian government has built a fleet of steamers and barges especially constructed for removing the sudd and retains a large force of men in removing and destroying the vegetation. These vessels are stationed at different points on the Upper Nile, so that they may reach an obstruction without delay.
In clearing the river channel of sudd the engineers have devised several schemes. The top growth frequently becomes so dry that they can burn it over like so much grass. This removes much of the weight of the plants, but they are so matted together that saws are actually used to separate the growth ,as it cannot be removed in any other way. The vessels employed for sudd clearing, while light-draft boats, are strongly built and have blunt bows, so that they can be forced against the bank of vegetation. They are provided with steel cables or hawsers, saws, and axes, and carry crews of natives who are experts in working upon the sudd.
The way in which the channel is cleared is as follows: Often the water is so completely hidden that the first difficulty when you are encountered by a barrier of sudd is to discover where in this sudd the river bed runs. This is done by “sounding” through the sudd with long poles. The average depth of water in the sudd may be only a few feet, but when the actual river bed is reached this suddenly increases to a depth of 15 to 18 or 20 feet. Having found the real river bed, the first thing to do is to cut down or burn the top growth, consisting mostly of papyrus.
Having cleared the top of the sudd “block,” the men are landed with large saws to cut along the true river bank, which may be either submerged with a few feet of water over it and papyrus and sudd on it, or solid ground with ant heaps, the solid ground never being of any great extent and always surrounded by swamp. Cross and parallel cuts with the saws are then made through the sudd, diving it into blocks of a convenient size for the steamer to tear out, the size of these blocks, of course, depending on the consistency of the sudd and the power of the steamer.
Having cut the sudd into convenient blocks, the bow of the steamer is run into the block, a loop of steel hawser is placed around it, when the rods of the cable are passed over the bows of the steamer. Here it is taken by the men on board and placed in what is called the trench cut, and held down with their feet. The steamer then goes full speed astern, the men all standing on the hawser to keep it in position. In the case of tough sudd, as many as twenty trials may have to be made before the block of sudd eventually tears away.
When the block is torn out, the steamer goes slowly astern till the mass is pulled clear into the current, if there is one, when it is east adrift to float downstream, where it is gradually disintegrated. If there is no current, it is towed to a piece of open water, where as a temporary measure it can be tied by ropes to the bank, leaving a wide enough channel for the steamer, and on the appearance of a current to be cut adrift to float downstream.
While the composition of the sudd is usually the water papyrus, it is mixed with what is called elephant grass – a kind of bamboo growing to a height of 20 feet or more. To these climbs a creeper of a kind of convolvulus. Another portion of the sudd consists of am batch and a long sword grass that cuts like a knife.
Strange as it may seem, the sudd interferes but little with the flow of the river, and the Nile passes under it with little resistance. This is because the growth is principally near or on the surface. As the river is over a mile wide in some places and the deep channel may be only a hundred feet, it is often hard to tell where to find the channel to clear it, as all of the water may be hidden.
The density of the vegetation even in deep water is remarkable. The men can walk over it without sinking into the mass, such is its tenacity and strength. Animals such as the rhinoceros have been seen crossing the Nile upon this great ware carpet, which is woven as deftly and strongly as by the loom.