THE NILE RESERVOIR DAM AT ASSUAN 



FORMALLY DEDICATED DECEMBER 8. A NEW TYPE OF 

 STRUCTURE WHICH MAY MARK AN EPOCH IN IRRIGATION 

 ENGINEERING. PHOTOS FURNISHED BY THE AUTHOR 

 THROUGH COURTESY OF THE EGYPTIAN GOVERNMENT. 



BY 



THOMAS H. MEANS, 



IN CHARGE OF UNlTliD STATES SOILS SURVEYS, DEPARTMENT OF AGRICULTURE. 



EGYPT has probabh- been farmed 

 for over 7,000 years. Until the 

 present century practically all the farm- 

 ing done was by basin irrigation, which 

 S3'stem consists in flooding large areas 

 of land surrounded by dikes with water 

 taken from the Nile River during time 

 of flood. These basins vary in size from 

 less than 5 acres to over 50,000 acres, 

 and in a normal flood year are filled with 

 water to an average depth of 4 feet for 

 a period of about six weeks, after which 

 the water is drained away and the seed 

 sown in the newly deposited mud with- 

 out cultivation. Such a s^'stem of irri- 

 gation is very wasteful of water and 

 permits the growth of but one crop per 

 year. 



About 1820 Mohammed Ali, the reign- 

 ing viceroy, started a movement which 

 has almost revolutionized the agricul- 

 ture of Eg3'pt. He dug canals from 

 the Nile, so that water could be had 

 for irrigation throughout the year, per- 

 mitting the growing of such crops as 

 cotton, which would not mature under 

 basin irrigation, and, what is more im- 

 portant, enabling two and sometimes 

 three crops to be grown each year. To- 

 da3% of the 6,250,000 acres of arable 

 land in Egypt, less than 2,000,000 acres 

 are watered by the ancient basin system. 



While this change is more economical 

 of water it necessitates a more uniform 

 supph' throughout the season. The 

 Nile can alwa3's be depended upon to 

 supph' 8,000 cubic feet per second, but 

 for the complete development of the 

 modern or perennial S3'stem of irrigation 

 at least 30,000 cubic feet per second are 

 needed throughout the 3'ear. During 

 flood season the Nile frequently dis- 



charges from 300,000 to 500,000 cubic 

 feet per second. 



To conserve this flood supply for use 

 during seasons of low water, a system 

 of storage dams and regulators at vari- 

 ous points on the Nile has been planned. 

 As early as the time of Mohammed Ali 

 this plan was under consideration, but 

 it was not until Mr. W. Willcocks was 

 appointed director general of reservoirs 

 that the storage of water on the Nile was 

 thoroughly considered. 



In 1890 Mr. Willcocks presented a 

 report on the subject to the Egyptian 

 Government, in 1894 issued a second re- 

 port, and in 1895 a final report, with 

 plans and estimates. The central fea- 

 ture of this system of flood control pro- 

 vides for a dam across the Nile at the 

 head of the first cataract, or five miles 

 above the town of Assuan. In 1898, a 

 short time after Mr. Willcocks had left 

 the service of the Eg3'ptian Government, 

 contracts were signed by Sir John Aird 

 & Co. for the construction within five 

 years of the Assuan dam, upon the plans 

 prepared by Mr. Willcocks. Sir Benja- 

 min Baker acted as consulting engineer, 

 and Mr. Maurice Fitzmorris was ap- 

 pointed resident engineer. 



The dam as completed during the pres- 

 ent summer conforms almost through- 

 out to the plans of Mr. Willcocks. His 

 original plans provided for the construc- 

 tion of a dam following the line of sound- 

 est rock across the stream, with 60 under 

 sluices having an area of 21,500 square 

 feet, or sufficient to carr3' off the max- 

 imum floods of the river. In the plan 

 of 1 894 , 1 00 under sluices were provided , 

 of the same capacity. In the final de- 

 sign there are 140 under sluices, each 



(491) 



