Before the 1960’s, the discharge from the Nile largely varied throughout the year, although the source from the White Nile remained fairly constant (being based in an equatorial climate). The majority of the discharge came from the Blue Nile which is located in a tropical climate with seasonal rainfall between April and October, followed by a drought in the dry season which caused a high peak followed by a dip in the discharge.
During the seasonal fluctuations, the land would experience floods which found to leave silt behind on the land which was inevitably good for the agriculture of the land. However, during the 1950’s the Egyptian government had to face a very high population growth rate. Given its limited resources of arable land in the Nile valley, Egypt was looking for opportunities to expand its agriculture, energy and associated manufacturing production. The easiest alternative was to expand the irrigated areas and to increase the number of crops per year. In 1960, constructions for an additional dam; the high dam at Aswan began.. The main aims of the dam were: to control the river’s discharge, to store water from each annual flood achieving regulated releases of water for irrigation, and to generate hydroelectric power.
The high dam successfully controlled the flow of the Nile: floods were prevented and the seasonal fluctuations were minimised. As a result, many lives and damage to the Egyptian economy were saved and crops could be grown all year round. An additional economical benefit was the electricity generation by the released water from the dam. Also, the formation of the big upstream reservoir – lakes Nasser and Nubia had several positive effects as well: The existence of such a large freshwater reservoir in an arid climate was a major advantage for the Egyptian economy and population.
However, the dam was not all good news and caused some detrimental effects: The dam had a role as a sediment trap – as a result the sediment load was filling the reservoir instead of reaching the land which required it for good fertility. In addition, because of the increase in dissolved solids in the Nile water, more salts reached the soils and ground water. The stronger affinity of the salty water to the sediments decreased future agricultural land and water resources and also increasing coastal erosion of the delta.
Overall, the dam has been a success in terms of regulating the flow of the river to produce a more evenly spread discharge and to reduce flooding risks, but has not however helped the agricultural economy in terms of producing more crops for the growing population.
