The Kunene River Scheme

In the Third Water Use Agreement of 1969 the Governments of Portugal and South Africa outlined the first phase of their joint development of the water resources of the Kunene River. The agreement outlined a plan to manage the river as an integrated system enabling the development of a hydropower project at Ruacana. This resulted in the construction of three major structures on the river in the 1970s comprising the Kunene River Scheme, in addition to the already existing Weir and Power Plant at Matala. These three structures, built on the Upper, Middle and Lower Kunene, were to function as an integrated system, ensuring regular flow conditions for constant electricity generation. The three structures are the Gove dam, the incomplete Calueque weir (which also facilitates drinking water supply to the northern parts of Namibia as well as water supply to irrigation projects) and the Ruacana weir and hydropower plant 170 km upstream of the proposed Baynes Site (ERM 2009).

The elements of the Kunene River Scheme are:

The Gove Dam

Located in the upper reaches of the catchment, 120 km south of Huambo, the Gove dam was the first component of the Kunene River Scheme to be completed in 1975, and thus facilitated the construction of the weirs at Calueque and Ruacana. The reservoir behind the dam has a storage capacity of around 2 570 Mm³ although the dam was seriously damaged during the war. The average annual flow of the river at Gove is about 1 600 Mm³ / year.

The primary design function of the Gove dam was to:

• Accommodate flood waters during the rainy season and thus regulate the Flow along the entire Kunene throughout the year to enable optimal power generation downstream at the Ruacana power station.

In addition to this, the Gove dam was also intended to:

• Generate hydroelectric power for local consumption, particularly for the provinces of Huambo and Bié. An installed capacity of 60 MW will finally be available from February 2011; and
• store water and supply irrigation needs along the middle Kunene River in Angola.

The war in Angola prevented the Gove dam from being used to regulate the flow of the Kunene as planned, and the structure was damaged in two attacks, with the second attack in 1990 causing particular damage. The Gove dam and associated infrastructure is currently under Rehabilitation to guarantee it functions as foreseen.

A regulated flow in the Kunene will not only benefit the Ruacana power station but also useful for example for the planned power stations at Jamba Ia Mina and Jamba Ia Oma.

Calueque Dam

The dam at Calueque lies at the lower end of the Middle Kunene around 540 km downstream from the Gove dam. Work on the dam started in 1972 and was 70 % complete when work was abandoned in 1976 due to the war although it is partially functional, serving to store considerably less than the original design volume of 475 Mm³. In 1988 the weir was severely damaged during an attack. The Calueque dam was designed with two main functions in mind:

• To provide further regulation of the flow of the Kunene and enable optimal electricity generation downstream at Ruacana; and
• To store water for bulk transfer for human and animal requirements and for irrigation in northern Namibia

In addition to this, the dam serves to store water for domestic water supply and local development in Angola.

The existing agreement between the governments of Angola and Namibia allows for a maximum abstraction rate of 6 m³ / s for uses in northern Namibia in this Bulk Transfer Scheme. The Calueque dam is currently being repaired in order to fully function as foreseen, with an extension in its function planned with the addition of hydroelectric generators.

Ruacana Diversion Weir

The Ruacana diversion weir is some 40 km downstream from the Calueque weir in the Lower Kunene. The weir was completed in 1978 but only came into use in January 1980 when the sluice gates were closed for the first time. The main objective of the Ruacana diversion weir is:

• to provide a constant head of water in the river and divert water through an 8m diameter pipe for hydroelectric power generation for Namibia.

Whilst the weir and inlet structures for the hydropower plant are in Angola, the power plant itself is in Namibia. The plant has a capacity of 240 MW, with three 80 MW turbines installed, and is Namibia’s main source of power generation. NamPower are planning to increase production capacity by adding a fourth turbine.

The Ruacana hydropower plant is NamPower’s main source or power generation, despite the fact that Ruacana's contribution to Namibia's electrical energy demands varies from year to year - in 1991 Ruacana contributed 69 %, while in 1997 this had dropped to 31 % due to run of river conditions.

Due to the war the Kunene River Scheme has yet to function in the planned integrated manner. The flow of the river has so far been poorly regulated by the Gove dam and Calueque weir, meaning power generation at Ruacana has been open to huge seasonal fluctuations, with spills during the wet season and very little generation during drought spells, as well as annual fluctuations. However, the Work Currently Underway at both Gove and Calueque will ensure that the entire Ruacana scheme finally functions as foreseen.