1.5 – Drainage system

All of Uganda drains into the Nile. Within the Albertine graben, there are three main lakes: Lake Albert, Lake Edward and Lake George. Most of the rivers and streams originating from the highlands surrounding this area drain into the lakes which, in turn, drain into the Nile via Lake Albert. Most significant of these rivers is River Semliki which comes from Lake Edward through the western edge of the great Ituri rain forest in DR Congo, and enters Uganda at a point close to the northern end of the Rwenzori range. The other, is the Victoria Nile which enters Lake Albert at its northern most tip before draining out of the lake as Albert Nile on its way to Nimule and onward to Sudan. Both rivers have built deltas into Lake Albert with that of the Semliki being larger. Ninety percent of the delta is created in Uganda. Although the Victoria Nile carries more water than the Semliki, it has little influence on the ecology of the lake, other than to maintain water levels. The Semliki on the other hand provides the primary supply of water into the lake system. The lake also has a large sedimentation potential from the Victoria Nile. There are other numerous small streams entering the lake from both Uganda and DR Congo, some of which are highly seasonal and of only minor importance to the hydrology of the lake.

Sensitivity of the rivers is in regard to their proximity to the oil wells; The closer the wells are to the river, the more sensitive the river is and vice versa. Several drainage classes are, therefore, formed based on the proximity of the wells to the rivers, as indicated in Map 5:

Map 5: Albertine graben Drainage (Source: DEM - from UNEP. Drainage - from the Directorate of Water Resources Management, Entebbe)

Map 5: Albertine graben Drainage (Source: DEM – from UNEP. Drainage – from the Directorate of Water Resources Management, Entebbe)