At Assuân the Nile has a mean range of 7.90 metres between high and low supply, with a maximum of 9·80 metres and a minimum of 6.40 metres. The high supply varies between 13,200 and 6,500 cubic metres per second, with a mean of 10,000 cubic metres per second, while the low supply varies between 350 and 1400 cubic metres per second with a mean of 590 cubic metres per second. September is generally the highest month and May the lowest. The mean low water level is R. L. 85.00.

At Cairo the Nile has a mean range of 7·00 metres with a maximum of 9·6 metres and a minimum of 5·3 metres. The high supply varies between 12,000 and 4,800 cubic metres per second with a mean of 7,600 cubic metres per second, while the low supply varies between 1,300 and 250 cubic metres per second, with a mean of 500 cubic metres per second. October is the highest month and June the lowest. The mean low water level is at R. L. 12·25.

PLATE XI.

CROSS SECTIONS of the NILE & its TRIBUTARIES
Horizontal Scale 1 : 2.000
Vertical Scale 1 : 500

Lith. Sur. Dep. Cairo.

[Larger cross sections] (140 kB)

No.19.River Rahad at Khor Abou Seghire 20 km. above the Nile junction
No.20.Atbara River at Khashim al Girba 410 km. from Nile
No.21.Atbara River at Khor Abadar 25 km. from Nile
No.22.Nile at Manfalout
No.23.Rosetta Branch at Khatatba
No.24.Damietta Branch at Benha

[Tables 41] to [52] refer to the Nile between Assuân and the Barrage at the head of the Delta proper.

[Table 46] gives the Reduced Level of the mean low water level of the Nile at various points between Assuân and Cairo. If, for example, it is known that the water surface at any time of the year at Assiout is R. L. 50.80, we know the mean low water by the Irrigation Department levels is 45.05. The gauge is therefore 5.75, and by turning to [Table 37] we know the discharge.