The Nile flows for 6,700 kilometres through ten countries in north-eastern Africa – Rwanda, Burundi, Zaïre/Congo, Tanzania, Kenya, Uganda, Eritrea, Ethiopia, the Sudan, and Egypt – before reaching the Mediterranean, and is the longest international river system in the world – see Map 1. Its two main tributaries converge at Khartoum: the White Nile, which originates from Burundi and flows through the Equatorial Lakes, provides a small but steady flow that is fed by the eternal snows of the Ruwenzori (the ‘rain giver’) mountains, while the Blue Nile, which suffers from high seasonal fluctuations, descends from the lofty Ethiopian ‘water tower’ highlands. They provide 86 per cent of the waters of the Nile – Blue Nile 59 per cent, Baro-Akobo (Sobat) 14 per cent, Tekesse (Atbara) 13 per cent – while the contribution from the Equatorial Lakes region is only 14 per cent.