— 16 — 
Consequently from Lake Albert to Khartoum we have 43 days in flood 
and 53 days in low supply. 
From Khartoum to Assuan the Nile takes 11 days in flood and 22 
days in low supply, and consequently from Lake Albert to Assuan we 
have 54 days in flood and 7 5 days in low supply. 
From Assuan to Cairo we have 6 days in flood and 12 days in low 
supply. 
Table III is very interesting and well worth study. Through the Sudd 
region we have a velocity of *6 metres per second, but only of *35 metres 
per second in the White Nile. In Egypt the Nile in flood has a velocity 
of 1*75 metres per second, and in low supply of *85 metres per second. 
5. Catchment basins of the Nile and its tributaries. — 
Table I, of Appendix A gives the areas of the catchment basins of the 
Nile. The total area according to the table is 3,007,000 square kilometres. 
The limits of the basin are depicted on Plate I, and, with rare exceptions, 
they are now fairly well known everywhere. North of the 20th 
parallel of latitude the watershed on the west of the Nile is not far 
removed from the edge of the plateau skirting the Nile valley. The 
plateau falls away to the west, and occasional ravines find their way to 
the Nile down the reverse slope. On the east of the Nile the crest of 
the hills skirting the Red sea is the watershed. South of the 20th 
parallel of latitude the eastern watershed follows the crest of the 
hills on the west of the Red sea as far as Suakin. South of Suakin 
the watershed leaves the Red sea, to allow the Khor Barraka to flow 
into this sea. From the south east of Kassala, round by Addis Ababa, the 
watershed follows the crest of the high hills forming the eastern back- 
bone of Abyssinia, and dividing the waters of the Nile from those flowing 
into the Indian Ocean. South west of Abyssinia the watershed travels 
in a south-westerly direction to the east of Gondokoro, and divides the 
Sobat from the rivers draining into Lake Rudolf. The watershed 
then moves due south to the western escarpment east of Lake Victoria. 
Mounts Kenia and Kilmanjaro are not within the basin of the Nile. 
Sweeping in a rough curve round Lake Victoria and nearly touching 
Lake Tangangyika in 4° south latitude, the watershed keeps close to the 
western shores of Lakes Edward and Albert to nearly opposite Wad elai. 
All the slopes of the Ruenzori mountains drain into the Nile. 
From near Wadelai the watershed moves in a north- westerly direction 
along the hills dividing the waters of the tributaries of the Gazelle 
river from the Welle. Due west of the Sudd region the watershed has 
