<P> By 1800, Egypt had a population of some 2.5 million inhabitants . </P> <P> Muhammad Ali Pasha, (1805--1848 Khedive of Egypt) modernized various aspects of Egypt . He endeavoured to extend arable land and achieve additional revenue by introducing cotton cultivation, a crop with a longer growing season and requiring sufficient water at all times . To this end, the Delta Barrages and wide systems of new canals were built, changing the irrigation system from the traditional basin irrigation to perennial irrigation whereby farmland could by irrigated throughout the year . Thereby, many crops could be harvested twice or even three times a year and agricultural output was increased dramatically . </P> <P> In 1873, Isma'il Pasha built the Ibrahimiya Canal, thereby greatly extending perennial irrigation . </P> <P> Although the British, during their first period in Egypt, improved and extended this system, it was not able to store large amounts of water and to fully retain the annual flooding . In order to further improve irrigation, Sir William Willcocks, in his role as director general of reservoirs for Egypt, planned and supervised the construction of the Aswan Low Dam, the first true storage reservoir, and the Assiut Barrage, both completed in 1902 . However, they were still not able to retain sufficient water to cope with the driest summers, despite the Aswan Low Dam being raised twice, in 1907--1912 and in 1929--1933 . </P>

Why doesn't the river nile flood anymore