— 23 
per second, while the Albert Nile at its head was at its highest in 
December with 1,060 cubic metres per second. Lake Albert took 5 
months to fill up. At Gondokoro the Albert Nile was at its lowest in 
April when it discharged 700 cubic metres per second as against 550 
cubic metres in the previous year. Swollen by timely and good rains 
south of Gondokoro the discharge at Gondokoro rose to 2,100 cubic 
metres per second in September after the river had scoured out its bed 
over a metre in depth. The mean discharge for the year at Gondokoro 
was 1,200 cubic metres per second. 
The Gazelle river gave no discharge in the first half of the year and 
about 30 cubic metres per second in the latter half. Its mean discharge 
was 10 cubic metres per second for the year. 
The Albert Nile at its tail above the Sobat junction gave as a 
minimum 350 cubic metres per second in March, which discharge rose 
to 430 cubic metres per second in September, but could not rise higher 
as the Saubat river was then in flood and the White Nile could not 
carry off much more than the discharge of the Sobat without putting 
the northern part of the Sudd region under 2 metres of water. This 
held back water helped later to maintain the discharge of the White 
Nile in January and February. 
The Sobat river gave as a minimum a discharge of 40 cubic metres 
per second in April, and then rose to a maximum in November of 1,080 
cubic metres per second. 
At its tail, the Albert Nile gave a mean discharge for the year of 
390 cubic metres per second and the Sobat of 550. 
The White Nile at its head was at its lowest in April with 400 cubic 
metres per second and at its highest in December with 1,460 cubic 
metres per second, with a mean discharge of 940 cubic metres per 
second. At its tail near Khartoum the White Nile was at its lowest 
in May with 420 cubic metres per second and at its highest in October 
with about 1,700 cubic metres per second. As this latter figure was 
about 400 cubic metres per second more than it was receiving at its 
head, the additional water represented Blue Nile water which had run 
up the valley of the White Nile, been stored there while the Blue Nile 
was high and then been discharged into the Main Nile when the Blue 
Nile had fallen. The mean discharge at the tail of the White Nile was 
830 cubic metres per second. This figure was much below that at the 
head and was due to the fact that in July, August and September the 
Blue Nile water was flowing up the White Nile. 
