Bulk transfer schemes involve the removal and transfer of water from its basin of origin using diversions, pipelines, tanker ships or trucks into a receiving basin to alleviate water shortages or to generate hydropower.
There is only one major bulk transfer scheme of water out of the Kunene basin occurring at the Calueque weir and supplying water to the Calueque-Oshakati Water Supply Scheme in the Cuvelai basin in northern Namibia. The canal and pipeline scheme was constructed in the 1960’s and has been continually extended ever since. The Calueque-Oshakati Water Scheme consists of an open channel of around 160 km from Calueque to Oshakati and a pipe network of more than 2000 km (Kluge et al. 2008).
An abstraction rate of 6 m³/s from the Kunene River at Calueque has been agreed between the Namibian and Angolan. To date abstractions have been much less than the agreed volume, but in the long term Namibia has indicated an intention to increase abstraction to 12 m³/s (Burmeister & Partners, 1996).
The water pumped from Calueque flows via a concrete lined, open canal over the border. Shortly after crossing the border the canal splits and water is diverted westward towards the Etunda Irrigation Scheme and the town of Ruacana, whilst the rest flows to the east and into the Calueque-Oshakati Water Scheme via the Olushandja Dam. The Olushandja Dam has a strategic storage volume of around 42 Mm³ which is maintained by diverting water from the canal.
The canal brings water to four drinking water treatment plants that serve settlements in northern Namibia; where over 700 000 people (40 % of the Namibian population) live.
Calueque-Oshakati Water Supply Scheme.
Source: NamWater 2006
( click to enlarge )
The water demand throughout the Calueque-Oshakati Water Scheme peaks in October, corresponding to the low flow period in the Kunene. The production capacities of the drinking water treatment plant are listed in the table below.
Production Capacities of Drinking Water Treatment Plants on the Calueque-Oshakati Water Supply Scheme
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Treatment plant location
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Drinking water production capacity (m³/hour)
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Comments
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Olushandja
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Around 100
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2 different parallel treatment processes used - a batch process and a slow sand filter
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Outapi
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66
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Serves Outapi town, Onakayale centre and three rural schemes
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|
Ogongo
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1 500
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Drinking water is distributed to the north, south and east of Ogongo
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Oshakati
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2 000
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Serves as far north as Oshikango, as far south as Omapale and as far east Omutsegwonime
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Source: adapted from NamWater 2009
 The open canal transporting water from Calueque to supply northern Namibia. Source: Tump 2006 ( click to enlarge ) |
 Water gauging at Calueque branch canal for rural water supply in northern Namibia. Source: NamWater 2006 ( click to enlarge ) |
The scheme is to be further developed in the medium term to provide water to Santa Clara, Namacunde, Omupanda and Ondjiva in Angola. Further details on this can be found in Development, Operation and Maintenance of Water Infrastructure.
