— 45 — 
mer. The Dinder has a bed width of about 120 metres, depth 4 metres 
in good flood and a velocity of 2 metres per second, which gives a 
discharge of about 1000 cubic metres per second in a high flood. The 
Rahad has a bed width of 60 metres, depth of 3 metres in a good flood 
and a velocity of 2 metres per second, which gives a discharge of 400 
cubic metres per second in a good flood. The deltas of the Blue Nile, 
the Dinder and the Rahad are formed of the richest Nile mud. Such 
soil is rich in lime, potash and phosphates, but is poor in nitrates. 
The velocity of the Blue Nile may be taken as 75 centimetres per 
second in low supply and 3 metres per second in high flood. 
20. The Atbara. — The Atbara river flows into the Nile at El-Damer, 
south of Berber. It is essentially a torrent fed by the rains of north- 
eastern Abyssinia. The rains here begin early and end early, so that 
the Atbara is in high flood in August and falls quickly through Sep- 
tember. Its floods last from June to October and the river is dry for 
the remaining months of the year. By dry it is meant that there is 
no running water, for the bed of the river contains numerous pools of 
water, which are nearly always deep and often very extensive. 
Mr. Dupuis has given a rough longitudinal section of the Atbara 
river. Rising within 16 kilometres of Lake Tsana, at a height of 
about 2000 metres above sea level, in its first 300 kilometres it falls 
1500 metres to 530 metres above sea level, where it is met by the Sa- 
laam river. In the next hundred kilometres it falls 40 metres and is 
joined by the Settit river, a larger and more permanent stream than 
the Atbara itself. Sixty kilometres lower down is the Khasm-el-Girba 
gauge, just upstream of Fasher and about 420 kilometres from the 
Nile. Two hundred kilometres below the Settit junction and about 
280 kilometres from the Nile is Gosrejeb, and 150 kilometres lower 
down Adarma. Finally, after a total length of about 880 kilometres, 
the Atbara flows into the Nile. 
The Settit junction is about 490 metres above sea level, Fasher 470 
metres, Gosrejeb 410, Adarma 380, and El-Damer about 365 metres 
above sea level. In the last 280 kilometres there is therefore a fall 
of 45 metres or about -6 o'* I n this reach the river has a width of 
about 330 metres and depth in flood of 6 metres. 
Tables 24 and 25 give the behaviour of the river. In 1902 and 
1904, two very low years, the maximum discharge was about 2000 
cubic metres per second, and in 1903 about 3000 cubic metres. In high 
floods the Atbara can discharge 5000 cubic metres per second. 
