— 99 — 
at present, that they will not rise higher, and that they will fall 15 
days earlier than what they do now. With low floods there will be no 
appreciable difference as to date, but the floods will be slightly higher 
at Cairo. In ordinary floods, there will be an advance of from 20 to 25 
days in the date of the maximum flood, and a maximum gauge at Cairo 
50 or 60 centimetres under the maximum gauge at Assuan. We have 
so far considered Cairo only, as the Delta proper depends on the Cairo 
gauge. We now turn to the Nile in Upper Egypt itself : south of 
Sohag, there will be no serious change in levels, but the Sohagia and 
Ibrahimia canals between them carry at present 7 50 cubic metres per 
second in excess of what they would carry if there were perennial 
irrigation in Egypt, and the greater part of this water is not returned 
to the Nile until the Kushesha escape is reached. The reach of the 
Nile from Sohag to Kushesha is the one which will experience the 
greatest changes, and I calculate that there will be a rise of 40 centimetres 
as compared with the maximum gauges under basin irrigation. 
It will be noted that at the beginning of this paragraph I stated that 
“the perfection of the perennial irrigation of the Delta north of Cairo 
will in no way affect the Nile in flood.” This had reference only to the 
quantity of water taken from the Nile in high floods. There is however 
one very serious aspect of this quescion. The regulation on the Bar- 
rage in low floods, which has gone on steadily since 1899 when Sir 
Hanbury Brown used the Barrages in flood for the first time, has 
enormously increased the value of the works, but it has certainly 
caused the Main Nile to silt, and probably also the branches, owing to 
a reduced discharge and velocity of the silt-bearing water, whose 
capacity to carry on that quantity of silt depends on its velocity. It 
seems to me that unless steps are taken to insure the scouring out of 
this silt by the clear water of November, December and January the 
conseqnences will be very serious. High floods scour out their beds, 
but if a very high flood were to come early before the silt had been 
scoured out, it might overflow the banks near Cairo or in the middle 
reaches of the Nile branches in the Delta. 
Sir William Garstin has estimated the cost of converting the existing 
basins of Upper Egypt into perennially irrigated hand at £7,000,000, 
thus made up : — 
Conversion of Upper Egypt basins . * * £5,000,000 
Two barrages between Assyut and Kena . , . . . . . . . . * * „ 2,000,000 
Total £7,000,000 
