Irrigation in Egypt and S.A. 449 



upstream of the Barrage is allowed to rise till the head on the work 

 reaches the safe limit. This level is then maintained by gradually 

 opening the gates as the flood discharge increases until all the gates 

 are fully open ; the subsequent rise above this level follows the 

 natural rise of the Nile. It thus happened that, although the 

 demands for water increase greatly at this period, from about the 

 end of July until such time as the gates are fully open and the 

 upstream level at the Barrage begins to rise with the natural rise 

 of the river, which usually happens about the end of August, the 

 discharge into the canals cannot be increased, although a large 

 quantity of water is running to waste down both branches of the 

 Nile. It was obvious that, under these circumstances, the work 

 could not properly take advantage of the water stored in the Assouan 

 reservoir, unless that reservoir could supply enough water to bring 

 the Nile at Cairo into a condition of flood. This it could not do. 



Further expensive operations on the foundations of the work 

 were considered undesirable, and Sir Hanbury Brown conceived the 

 idea of constructing solid submergable weirs downstream of the 

 Barrage, which, by maintaining a constant back pressure of water 

 on it, would enable the upstream level of water to be raised above 

 what had been formerly possible, without imposing any increased 

 strain on the structure. This work was commenced in 1898, and 

 finished in 1901. By the completion of these weirs, whith enable 

 the old Barrage (originally projected in 1833) to take full advantage 

 of the arrival of the flood, and of the Assouan dam, which, to some 

 extent, supplies the deficiencies of the summer discharge of the 

 Nile, but cannot alter the date or character of its flood in any way, 

 the perennial irrigation of Lower Egypt may be said, after 100 

 years, to be more or less assured. 



During the construction of the large works above referred to, 

 a third Barrage was built across the Damietta branch of the Nile, 

 near the town of Zifta, about half-way between Cairo and the sea. 

 Although it is a work of considerable magnitude, its functions relate 

 more to the better distribution of water to the northern half of 

 Lower Egypt than to the general management of the Nile, and. 

 consequently, it is of comparatively little consequence in the general 

 question. 



The work of the Irrigation Engineers in Egypt is not, however, 

 confined to the preparation and construction of large projects. The 

 investigations of them occupied one or two of the senior officers of 

 the staff, while the construction was undertaken by a special staff 

 engaged temporarily under one of the senior officers of the 

 Department. 



The every-day duties of the staff were to improve and remodel 

 the canal system under their charge with due regard to the extra 

 supply of water which would be available eventually from the large 

 projects, to see that water was distributed fairly in proportion of 

 the areas under cultivation, and to advise the civil authorities 

 regarding disputes about water. A law was passed in 1894 defining 



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