76 — 
When the turbid flood has passed and the comparatively clear winter 
supply of the river has begun to arrive, the sluices are gradually closed 
and the reservoir filled. Beginning about the 1st December, the reser- 
voir is filled in 100 days. It will ordinarily be full on the 1st March. 
No additional water is needed for irrigation between March 1st and 
May 1st as the river naturally has enough for the requirements of the 
area at present under crop at this season. As the area under peren- 
nial irrigation will be gradually increased, the demand for water for 
the new lands will begin about the 1st of April. The demand in- 
creases through May and June, and the reservoir will then be aiding the 
river with its supplement. If the flood is very late, water may be 
required from the reservoir till the 10th July ; if the flood is early no 
water will be needed after the 20th of June, as in 1903, the first year 
of the reservoir. The earlier the flood the more effective the reservoir. 
By the time the flood has begun to get turbid, the under and upper 
sluices will all be open and the muddy waters of the Nile will sweep 
through the dam without impediment. 
The dam has worked for two years and given satisfaction. When the 
Nile was at its lowest in May 1903, the natural discharge of the river, 
supplemented by all the subsoil infiltration water which enters the 
river between Assouan and the sea, was 400 cubic metres per second. 
The reservoir was adding 200 cubic metres per second to the supply, 
raising the total supply available for irrigation to 600 cubic metres per 
second. The reservoir was supplying one-third of the water which 
was being utilized in Egypt. This water will suffice for an increase to 
the perennially irrigated area of \ million acres. 
At the time of designing the dam it was intended that it should be 
of such a section that it could be raised 6 metres in height and hold 
up another milliard of cubic metres of water. Such an operation, if 
performed to-day, would mean: the whole length of dam being raised 
6 metres, the winches working the sluice gates being raised 6 metres 
and provided with new wire ropes; and new copings being given to 
the parapets. It would necessitate two more locks and three more lock 
gates, and nothing else. The expenditure incurred would be about 
£ 500 , 000 . 
33. The Wady Rayan Reservoir Project.— When the 
Assouan dam will have been raised, we shall be standing on the 
threshold of what it will be able to do. The projected Wady Rayan reser- 
voir, or the modern Lake Moeris, will be well able to supply the two 
