51 



the critical months. During the remainder of the year the river always 

 furnishes more water than is needed. 



Mean discharge of the Nile, 1S7S-1892. 



Month. 



January. 

 February 

 March . . 



April 



May 



June 



July 



Acre-feet. 



4, 192, 050 

 3, 116, 728 

 2, 210, 85S 

 1,538,460 

 1,335,114 

 1,538,400 

 5,484,600 



Month. 



August 



September. 

 October . . . 

 November 

 December . 



Total 



Acre-feet. 



17,684,568 



20, 620, 106 



19, 650, 906 



9, 329, 7C0 



5, 899, 014 



92,001,224 



The reservoir system would, during average 3'ears, have to supply 

 126,000 acre-feet in March, 799,000 acre-feet in April, 1,002,000 acre- 

 feet in May, 799,000 acre-feet in June, and probably 120,000 acre-feet 

 during the first few days of July. The reservoirs would have to store 

 a total volume of 2,852,000 acre-feet in order to furnish water for the 

 irrigation of this land. Even in low-water years the Nile supplies 

 plenty of water to till a reservoir system of nmch larger cay)acity. If 

 the reservoir system could be made large enough to maintain a uniform 

 flosv in the river throughout the year, it would at all times discharge 

 about 257,230 acre-feet per day, or about 130,000 cubic feet per second. 

 The Nile furnishes an average volume of 92,600,000 acre-feet annuall3^ 

 Disregardinglosses in storage and transit, it is estimated that 27,521,000 

 acre-feet of water would irrigate all of the agricultural land. Under 

 this assumption the land would be covered to a depth of 1.27 feet. 

 This would leave 65,200,000 acre-feet of water unused when Egypt 

 was fully supplied. It will be seen that the building of the Assuan 

 reservoir, with an estimated capacity of 863,100 acre-feet, is only the 

 first step in the construction of storage works. The Wady Ryan site 

 alone could probably store about 3,000,000 acre-feet, enough water to 

 supply Egypt, but it could be used only in Lower Egypt; but the nat- 

 ural flow of the Nile furnishes more water than is needed for Upper 

 Egypt. If this site w^ere improved, the Assuan reservoir would not 

 be needed; hence, it will very likely be the policy of the government 

 to build* a number of storage works similar to the Assuan reservoir 

 farther up the river. That the expense of maintaining these and the 

 difficulty of controlling the discharge of water from them will be much 

 greater than for one large reservoir, can not be doubted. 



If reservoirs are constructed farther up the Nile, they must be 

 farther from Egyptian territory, and consequently more difficult to 

 control. Much discussion has occurred as to the feasibility of utilizing 

 lakes Victoria and Albert in central Africa as reservoirs. But little 

 has been done toward making surveys in that locality and no figures 

 are available as to the cost of converting the lakes into storage works. 



