Engineering Wonders of the World
Volume I

THE NILE DAMS AND THE ASSOUAN RESERVOIR. 399 construction, and 7,000 labourers were at one time engaged upon this work, which was completed successfully in 1906. Although a description of the Assiout Bar- rage may be said to follow naturally upon that of the great reservoir, it should not be for- gotten that both works were constructed practically at the Barrage. . . J same time. This barrage was designed to hold up the river level at the inflow of the Ibrahimiyeh Canal, thereby in- creasing the area of land under perennial irri- gation in Middle Egypt and the Fayoum, and consequently assisting in the utilization of the water stored in the Assouan Reservoir. A word or two first as to the canal. Broader than most canals—it is 180 feet wide on the bed and 30 feet deep in flood, and carries 900 tons of water per second—the ^’'canal^6’1 Ibrahimiyeh Canal is certainly the longest in Egypt. It starts about a mile north of Assiout, the largest town of Upper Egypt, and runs parallel to the river for over 170 miles, to a point 711 miles south of Cairo. Its importance, always great, has been vastly increased by the new barrage. In selecting the site for the barrage, con- sideration was given rather to the river and the formation of its bed than to the position of the canal inlet. Fortunately, a site just below the latter proved the most suitable. Here the river has a straight reach, although the deeper channels are subject to great variations. These channels shifted repeatedly, the fine and mobile silt of the river bottom resembling quicksand. In form and principle, but in nothing else, the Assiout Barrage resembles the Delta Bar- rage. The former is built entirely of limestone, and the methods employed in its construction were far unlike those used in founding the older structure. Between the Assiout Barrage and the Assouan Dam there is this important differ- ence. The latter is bonded into the rocky foundations on which it stands, and in a sense Fig. 18.—LOCK AND REGULATOR OF IBRAHIMIYEH CANAL, ASSIOUT BARRAGE. {Photo, by courtesy of Sir John Aird and Co.) is made a part of them ; while the Assiout Bar- rage is laid across a river bed of shifting sand and silt, and depends for its stability—as in the case of many weirs—on its great weight compared with the opposing force of the dammed-up river, and on the special measures taken to prevent water passing underneath, it. Its total length is 2,750 feet. A roadway is carried across the river along its top. There are 111 sluice openings, 16 feet 5 inches wide, between masonry piers 6 feet 6 inches thick ; and the same number of steel sluice gates, each composed of two leaves, which together mea- sure 16 feet high. These sluice gates* are provided with friction wheels, and are raised and lowered by means of movable hand winches travelling on rails, which run the whole length of the barrage. There are altogether four of these winches, but one only is required for a gate. When needed, a winch is brought immediately over the sluice to be raised or lowered. The barrage can hold up the water level 8 feet to 12’5 feet higher than the river level down-stream. One lock, 262 feet 6 inches long by 52 feet 6 inches wide, serves for the passage of boats past the west abutment. * These and other iron, and steel work were supplied' by Messrs. P. and W. Maclellan and Co.