8 NOTES ON EGYPTIAN AGRICULTURE. 



up, over and above the natural level of the river, and the amount of 

 water discharged into the various distributing canals is enormously 

 increased. The bed of the river below the Barrage is to all intents 

 and j)urposes drj^ This provision of water during the summer months 

 permitted the cultivation of cotton, which from this date gradually 

 increased. At the present time the whole of lower Egypt is under a 

 perennial system of irrigation, while ujjper Egypt, though largely 

 under basin irrigation, is in a transition stage. 



The ancient s^^stem of basin irrigation, whereby the land received 

 annually a deposit of rich mud, will soon be, comijaratively speaking, 

 a thing of the past. It is unnecessar}- here to enter into any details 

 regarding this ancient type of irrigation, but merely to state that 

 under this system the land is divided by means of banks into basins 

 (of which there are 212), whose areas range from as few as 500 to as 

 many as 75,000 acres. For convenience in the regulation of the flood 

 water, these basins are divided into various sections, 11 of which are 

 on the left bank of the river, while 13 are on the right. During flood 

 time, when these basins are filled, tlie water is charged with suspended 

 matter, which during its sojourn in the basin is to a great extent 

 dejDOsited on the land. The filling of the basins generally begins 

 about mid- August and is comi)leted in the southern basins by the end 

 of SeiJtember. The escapes are oj)ened and the water discharged into 

 the river by the middle of October. The more northerlj- basins are 

 filled and emptied later, the last basin north of the Delta Barrage not 

 becoming dr^' until the end of November. 



When the time for emptying the basins has arrived, the escapes are 

 opened and the water discharged. In some years, when the flood is 

 low and the basins are not full, the upper series of basins are drawn 

 upon to complete the ojieration; the water passes, that is to say, 

 through the lower series and is then discharged. The water remains 

 in the basins for a period of about sixty days. 



The water of the Nile at the time of flood contains from 150 to 200 

 parts per 100,000 of suspended matter. If 170 parts are assumed to 

 be an average, about 130 parts are actually deposited in the basins, 

 while the remaining 40 parts are returned to the river in the water of 

 discharge. These figures can only be regarded as approximations, the 

 amount of mud deposited on any given area depending to a certain 

 extent on the position of that area in the basin. Again, the water 

 entering all the basins is not equally rich in sediment. Further, 

 water is continually i)assing through the basins, even though thej^ are 

 full, and consequently the actual quantity which passes through them 

 and deposits its mud is not equivalent to the capacity of the basin 

 itself. The nature of the sediment also varies, being more valuable, 

 relativelj' sjieaking, in a low flood, and more sandy and consequently 

 less valuable during a high flood. It is calculated that when the 

 basins are full they contain on an average between 3 and 4 feet of 

 water and the deposit is equal to between 14,000 and 15,000 pounds of 



