ABSTRACT
August. In April the heavy rains near Lado force down the green water of the swamps, and about April 15 the Nile has begun to rise at this place; this rise is felt at Kbartum about May 20, and at Aswan about June 10, and the green water announcing this rise is seen at Cairo about June 20. About June 5 the Blue Nile begins to rise quickly, and it reaches its ordinary maximum by August 25; its red, muddy water reaches Aswan about July 15. and Cairo 10 days later. When once the red water has appeared the rise of the Nile is rapid, for the Atbara is in flood shortly after the Blue Nile; the Atbara flood begins early in July and is at its highest about August 20. The Nile continues to rise until the middle of September, when it remains stationary for a period of about three weeks, sometimes a little less. In October it rises again, and attains its highest level. From this period it begins to subside, and, though it rises yet once more, and reaches occasionally its former highest point, it sinks steadily until the month of June, when it is again at its lowest level. Thus it is clear that the Sobat, Blue Nile, and Atbara rivers supply the waters of the inundation, and that the White Nile supplies Egypt for the rest of the year. The ordinary maximum discharge of the Nile at Aswan is 10,000 cubic metres per second, and the ordinary minimum discharge 410 cubic metres per second; the ordinary maximum discharge at Cairo is 7,600 cubic metres per second, and the ordinary minimum discharge 380 cubic metres per second.
