Asyut Barrage

The Assiut Barrage is a dam on the Nile River in the city of Assiut in Upper Egypt (250 miles to the south of Cairo). It was completed in 1903.

Background

It was designed by the famous British engineer Sir William Willcocks who also concurrently designed and built the Aswan Low Dam, the first Nile reservoir, about 350 miles (560 km) up-stream. The Assiut dam was constructed between 1898 and 1903, and in conjunction with the reservoir, provided for the diversion of river water into Egypt's largest irrigation canal, the Ibrahimiya Canal, during the low water season. The dam was estimated to cost £525,000 but by the time of its completion it actually cost £870,000. The main contractor for the project was the British contractor John Aird & Co. The project's massive size involved 2,400,000 cubic yards of earthwork, 125,000 cubic yards of concrete, 85,000 cubic yards of masonry, 125,000 cubic yards of pitching and more than 4,000 tons of cast iron pipes.

The dam consists of a masonry dam about 2,769 feet (844 m) long extended on both sides by earthen banks, making a total length of about 3,937 feet (1,200 m). There are 111 arched openings of 5 metres (16 feet 5 inches) span in the masonry dam. They can be closed by steel sluice-gates 16 feet (4.9 m) high. The piers and arches are founded upon a masonry platform 87 feet (27 m) wide by 10 feet (3.0 m) thick. This platform is protected on its up-stream and down-stream sides by a continuous and impermeable line of cast iron tongued and grooved sheet-piling with cemented joints. This piling extends into the sand bed of the river to a depth of 23 feet (7.0 m) below the upper surface of the platform and prevents it from being undermined. The river bed is protected against erosion for a width of 67 feet (20 m) upstream by a stone paving laid on a puddle clay blanket to check infiltration, and on the downstream side for the same width by a stone paving having an inverted filter bed underneath, so that any springs that may be caused by the water above the sluices shall not carry sand with them from beneath the paving.

The piers between the openings have a length of 51 feet (16 m) up and down stream and are 6.56 feet (2.00 m) wide with the exception of every thirtieth pier, which has double this width. The roadway is 41 feet (12 m) above the top of the masonry platform. The dam has a maximum height of about 48 feet (15 m), the maximum head of water retained being about 33.5 feet (10.2 m). It is constructed of granite, the foundation platform mentioned above being of concrete. A lock 262.5 feet (80.0 m) long by 52.8 feet (16.1 m) wide and capable of passing the largest Nile cargo ships and barges was constructed at the dam.

The Ibrahimiya head regulator structure, which was built at the same time when the Assiut Barrage was being constructed, was of similar design to the barrage except having only nine 5 m wide sluices, and a 9 m wide lock.