<P> The Nile has long been used to transport goods along its length . Winter winds blow south, up river, so ships could sail up river, and down river using the flow of the river . While most Egyptians still live in the Nile valley, the 1970 completion of the Aswan High Dam ended the summer floods and their renewal of the fertile soil, fundamentally changing farming practices . The Nile supports much of the population living along its banks, enabling Egyptians to live in otherwise inhospitable regions of the Sahara . The rivers's flow is disturbed at several points by the Cataracts of the Nile, which are sections of faster - flowing water with many small islands, shallow water, and rocks, which form an obstacle to navigation by boats . The Sudd wetlands in Sudan also forms a formidable navigation obstacle and impede water flow, to the extent that Sudan had once attempted to canalize (the Jonglei Canal) to bypass the swamps . </P> <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>

What is the elevation of the banks of the nile river in egypt