<P> Nile cities include Khartoum, Aswan, Luxor (Thebes), and the Giza--Cairo conurbation . The first cataract, the closest to the mouth of the river, is at Aswan, north of the Aswan Dam . This part of the river is a regular tourist route, with cruise ships and traditional wooden sailing boats known as feluccas . Many cruise ships ply the route between Luxor and Aswan, stopping at Edfu and Kom Ombo along the way . Security concerns have limited cruising on the northernmost portion for many years . </P> <P> A computer simulation study to plan the economic development of the Nile was directed by H.A.W. Morrice and W.N. Allan, for the Ministry of Hydro - power of the Republic of the Sudan, during 1955--1957 Morrice was their Hydrological Adviser, and Allan his predecessor . M.P. Barnett directed the software development and computer operations . The calculations were enabled by accurate monthly inflow data collected for 50 years . The underlying principle was the use of over-year storage, to conserve water from rainy years for use in dry years . Irrigation, navigation and other needs were considered . Each computer run postulated a set of reservoirs and operating equations for the release of water as a function of the month and the levels upstream . The behavior that would have resulted given the inflow data was modeled . Over 600 models were run . Recommendations were made to the Sudanese authorities . The calculations were run on an IBM 650 computer . Simulation studies to design water resources are discussed further in the article on hydrology transport models, that have been used since the 1980s to analyze water quality . </P> <P> Despite the development of many reservoirs, drought during the 1980s led to widespread starvation in Ethiopia and Sudan, but Egypt was nourished by water impounded in Lake Nasser . Drought has proven to be a major cause of fatality in the Nile river basin . According to a report by the Strategic Foresight Group around 170 million people have been affected by droughts in the last century with half a million lives lost . From the 70 incidents of drought which took place between 1900 and 2012, 55 incidents took place in Ethiopia, Sudan, South Sudan, Kenya and Tanzania . </P> <P> The Nile's water has affected the politics of East Africa and the Horn of Africa for many decades . Countries including Uganda, Sudan, Ethiopia and Kenya have complained about Egyptian domination of its water resources . The Nile Basin Initiative promotes a peaceful cooperation among those states . </P>

When did the nile river valley civilization begin and end