The Upper Kunene River

Geography

The headwaters of the Kunene River are located on the crest of the Angola highlands at elevations between 1 700 and 2 000 m, to the east of the town of Huambo. The northern water divide follows an east-west oriented uplifted geological belt (“the Lunda swell”) with drainage directed towards the Congo basin in the northern direction.
 

The Kunene River is characterised by a relatively steep slope for the first 330 km to Matala (altitude 1 255 m) with a gradient averaging 1:1 000. It presents several rapids, and flows within an approximately 100 m wide channel distinguished by a river bed of stones and sand, indicating a rapid runoff and little sediment storage within the river system. The steep river bed slope in this section also means that flows run relatively quickly to the coast, leaving the river almost dry at the end of the dry season. This section of the river has a number of permanent tributaries.

Climate

The Köppen Climate Classification for this river section is ‘temperate with dry winters’, with an average temperature of 18°C and a 4 to 5 month dry season from May to September. Along the western divide of the Upper Kunene lies an escarpment which drops steeply to the west, and which forms a barrier to humid air coming from the west and giving rise to typical relief rainfall over this northern part of the catchment. Annual rainfall throughout the upper catchment averages 1 300 mm (PJTC 1993), providing over 75 % of the volume of flow of the river.

Hydrology

The mean annual runoff of the Kunene River is 5.5 km³ at the river mouth. About 40 % of this runoff is generated in the Upper Kunene, upstream of Jamba-ia-Mina, and by the time it reaches Matala the river has a flow f over 75 % of the final flow into the Atlantic.  Catchment runoff decreases sharply from north to south as indicated by the table below. Gauging station data (records from 1962 to 1972) show an estimated runoff from 363 mm at Gove dam decreasing to 167 mm at the lowest section of the Upper Kunene in Matala (Pitman and Midgley 1974). 

Catchment Area and Long-term Mean Annual Runoff for Gauges on the Upper Kunene River (1961-1972)

Gauging Station	Area (km²)	MAR (Mm³/year)	MAR (mm)
Gove	4 900	1 777	363
Jamba-ia-oma	8 600	2 942	342
Jamba-ia-mina	11 800	3 622	307
Matala	29 300	4 884	167

Water Quality

The Kunene River on the whole is relatively unpolluted and water quality is considered to be good, with a low concentration of phosphorus and other nutrients. In addition, the Upper Kunene has a low sediment load.

However, there are concerns about deteriorating water quality, and the lack of any basin-level assessment of water quality means that conclusive statements on water quality are difficult to make. Localised pollution is likely due to poor sanitation or untreated sewage outfalls from riparian towns and villages. Deforestation, uncontrolled burning and the application of non-conservational agricultural techniques lead to nutrient and soil runoff into the river, thus impairing water quality. Water impoundments in huge dams along the Kunene River increase temperature, which impacts adversely on dissolved oxygen and nutrient concentrations.

Finally, the mining and industrial development opportunities of southern Angola have significant potential to cause harm to watercourses, including the Kunene, through uncontrolled discharges.

Habitats and Biodiversity