The drainage systems of Ethiopia can be classified as follows:-
Drainage area A
This is an area which comprises four important river basins, the Mereb, Tekeze, Abay and Baro. Following the general slope of the land westward, all except the Mereb drain to the Nile and thus to the Mediterranean.
The best known Ethiopian river, the Abay (the Blue Nile) together with the Tekeze and Baro is also part of the Nile system. Among the river basins under drainage are A, the Abay has the largest catchment area and the Mereb the smallest.