THE NILE RESERVOIR DAM AT ASSUAN." 



1)V 'I'lio.MAs II. Means. 



Ill cliiinir iij I'liitfd SIdtfx /Soil iSiirnii, Drpurtmnil nf Ai/ricii/lnre. 



K<^y\)t has ])r()l)a])ly boon fanned for ovoi- seven thonsand years, 

 liitil the present eentury practically all the fanning- done was by basin 

 irriii'ation. which system consists in fioodino- lai'o-e areas of land snr- 

 ronnded by dikes with water taken from the Nile River dnrino- time 

 of Hood. These l)asins vary in size from less than 5 acres to over 

 oO.iMio acres, and in a noi-mal flood year are tilled with water to an 

 a\erao-e depth of 4 feet for a period of about six weeks, after which 

 th(^ water is drained away and the seed sown in the newly (h^posited 

 nnid withont culti\ation. Such a system of irrioation is very waste- 

 ful of water and pcn-niits the oTOwth of but one crop per year. 



About lsi!(i Moliammed Ali, the reioninii' vicin'oy, started a movc- 

 nicnt which has almost re\oluti()ni/ed the agriculture t)f Eo-ypt. He 

 duu' canals from the Nile, so that wjijtei" could be had for irrio-ation 

 (hrouohout the year, permittino- the growino- of such crops as cotton, 

 which would not mature under l>asin irri^'ation, and, what is more 

 important, enablinu- two and sometimes three crops to be o-iown each 

 year. To-day, of the (5, t^;")*), 0(H) acres of arable land in E_oyj)t, Ic.ss than 

 2, 000, (1(10 acres are watei'cd by the ancient basin system. 



\\'hile this chano-e is more economical of water it necessitates a 

 more uniform supply throughout the>eas()n. Th(^ Nile can alwavs bo 

 depended upon to supply S,0()(i cubic feet per second, but for the 

 complete development of the modern or peremiial >y<tem of iri'ioation 

 at least 30, 000 cubic feet per second are needed throuohout the year. 

 Durino- Mood season the Nil(> freciuently di^charycs from ;>00,000 to 

 500,000 cubic feet p(>r second. 



To conserve this tlood supply for use durinu- seasons of low water, a 

 system of storage dams and regulators at various points on the Nile 



"Reprinted, by perinissKni, liom lM)restr\- and Irrigation, Washins^ton, D. C, 

 Vol. VlII, No. 12, Decembei, li)02. [Formally dedicated Decembers — A new type 

 of Htructure which may marlc an epoch in irri<ration engineering— Photos furnished 

 l)y the author througli courtesy of tlie ligvi)tian Government.] 



531 



