Evaluation of Changes in the Nile Water Composition Resulting from The Asswan High Dam

Abstract

AbstractThe composition of Nile River water has been examined to show the effect of the Asswan High Dam on the fertility and salinity of the water for irrigation.The Nile water contains about 110 × 106 metric tons/year of suspended materials as it crosses the Egyptian border. Before the Asswan High Dam was constructed, 24 × 106 metric tons/year of solids were deposited, mainly on the Egyptian flood plains. After the dam was finished, only 2.1 × 106 metric tons/year of solids were present in the Nile water to be deposited on the Egyptian soils; the remainder, 21.9 × 106 metric tons/year of solids, settled out in Lake Nasser.The loss of nutrients in the sediments which settled out in Lake Nasser, and the gain in soluble cations which resulted from construction of the Dam, were calculated from sediments and water analyses. The loss of 12,000 metric tons/year of sediment N is probably not significant for Egyptian agriculture. The loss of P, including a maximum of 6,000 metric tons/year of soluble P, will probably require a significant increase in the use of P fertilizers.The quality of the Nile water for irrigation, as determined by values for electrical conductivity, sodium adsorption ratio, adjusted sodium adsorption ratio, residual carbouate, and pHc, did not change significantly after construction of the dam.