Aswan Dam dam near Aswan was in the 11th century, when the Arab polymath and engineer Ibn al-Haytham (known as "Alhazen" in the West) was summoned to Egypt by the Fatimid Caliph, Al-Hakim bi-Amr Allah, to regulate the flooding of the Nile, a task requiring an early attempt at an Aswan Dam. His field work convinced him of the impracticality of this scheme. The British began construction of the first dam across the Nile in 1898. Construction lasted until 1902, and the dam was opened on 10 December 1902. The project was designed by Sir William Willcocks and involved several eminent engineers,
Aswan Dam year. The annual crop consumptive use of water is about . Hence, the overall irrigation efficiency is 38/46 = 0.82 or 82%. This is a relatively-high irrigation efficiency. The field irrigation efficiencies are much less, but the losses are reused downstream. This continuous reuse accounts for the high overall efficiency. The following table shows that the equal distribution of irrigation water over the branch canals taking off from the one main irrigation canal, the Mansuriya Canal near Giza, leaves much to be desired: The salt concentration of the water in the Aswan reservoir is about , a very low salinity