Ruacana Falls now the scene of a stunning natural spectacle - News - Gondwana Collection


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Ruacana Falls now the scene of a stunning natural spectacle

Avatar of inke inke - 01. mai 2018 - Environment, Tourism

Dirk Heinrich

The same quantity of water that 40 households in Windhoek use in one month is currently gushing down Ruacana Falls every second. On 13 April the Kunene River reached its fastest flow rate this year when 1654 cubic metres per second plunged over the falls to a depth of 107 to 120 metres. The Kunene started to rise after heavy rains in south-western Angola and masses of water pushed south on their long way to the border with Namibia, where the river turns west to the Atlantic Ocean for its final stretch of 352 km. Below Ruacana Falls it burst its banks and flooded or isolated quite a few lodges on the Namibian side as access roads disappeared under the brown deluge. Local downpours also helped to wash out roads and added even more water to the Kunene. Temporarily the flow rate at Ruacana dropped to a little over 900 m³/s but on 21 April the river rushed over the falls and through the four turbines of the hydroelectric power plant at 1480 m³/s again. The next day the flow rate increased to 1604 m³/s, but had dropped to 1469 m³/s by Monday (23 April) when we took our photos. Now the rate is back to a little over 900 m³/s.

In the late seventies a conversion weir with five sluice gates (flap gates) was built into the Kunene less than one kilometre upstream from Ruacana Falls on Angolan territory. Since then it never became necessary to open all five of the sluices. The fastest flow rate that NamPower’s predecessor SWAWEK measured at the falls was far over 3000 m³/s in April 1984. The exact data could not be recorded at the time because the measuring station was flooded for over a week. So far, the second fastest flow rate of the Kunene at Ruacana Falls was 1844 m³/s in 2011.  

Apart from flood regulation, the purpose of the conversion weir is to direct water into a pressure tunnel with a diameter of eight metres and lead it over a length of 1500 metres to the four turbines in the power station’s machine hall 140 metres underground. The turbines have a total capacity of 347 MW. Despite several dams in Angola, which were partly financed by SWAWEK and built in the 1970s together with the hydroelectric power station, the water supply to Ruacana is still insufficient for optimum electricity generation throughout the year. 

The weir upstream from the falls is in a very shallow dam with a maximum depth of only 23 metres. Some 40 km further upstream in Angola is the Calueque Dam. It was repaired only recently after being badly damaged during the last years of the bush war before Namibia gained independence. This dam as well as Gove Dam (75 km south of Huambo in Angola and 430 km upstream from Ruacana), built in the seventies with South African funds, was intended to regulate the water supply for full utilisation of the hydroelectric power station throughout the year. At a certain time of year the falls are dry because the water level is so low that the Kunene River is channelled right through the power station.           

The pictures were taken on 23 and 24 April this year.

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