Kariba Dam wall in a stable state

The Zambezi River Authority has allayed fears that the Kariba Dam wall is facing imminent collapse indicating that the structure was in a stable state while a series of rehabilitation works are required to avoid gradual degradation.

In a statement on Monday, ZRA spokesperson Elizabeth Karonga expressed regret over the misrepresentation of facts about the impending collapse of the dam wall.

"While the situation at the Kariba Dam wall is cause for grave concern, the engineers on the ground have the situation under control. This does not translate to an immediate calamity. However, all urgency is expected in order to avert as such catastrophe as dam failure," she said.

ZRA is a corporate body jointly owned by Zimbabwe and Zambia through bilateral agreements to co-manage the shared stretch of the Zambezi River and it has been managing Lake Kariba and its attendant infrastructure to facilitate and support hydropower generation through the country's power utility companies.

Karonga attributed stories on the dam collapse to the co-operating partners' conference held early this year in Livingstone, Zambia to mobilise funds for the Kariba Dam wall rehabilitation.

She said the information denoted scenarios that could occur should ZRA fail to carry out maintenance and monitoring on the dam wall.

"ZRA carries out inspections and surveys twice a year on the Kariba Dam. In addition, every five years, a special safety inspection is undertaken with experts from France who were involved in the original design of the dam, with the last inspection having been undertaken in 2010. Other ad hoc inspections are conducted from time to time when required," she said.

Karonga said several other instruments in the dam wall measure stress, changes or movement in the wall, water pressure and drainage.

"These are continually inspected and have remained intact over the last 54 year," she said.

She added: "In recent years, concern has been raised over the safety of the Kariba Dam wall, which was built over 50 years ago (and) the dam wall now requires a series of rehabilitation works in order to avoid gradual degradation of key dam safety features while maintaining operation levels acceptable in accordance with international operating standards."

Karonga said ZRA had also identified undertaking critical dam maintenance programmes in its five year strategic plan (2010-2014) and these were being implemented while a lasting solution is sought.

She identified these as the plunge pool re-shaping, requiring stabiliastion to limit scouring and erosion that could undermine the dam foundation, leading to dam failure.

There is also the spillway refurbishment that involves designing, fabrication and installation of an emergency gate and a new gantry to prevent uncontrolled loss of water in the event of floodgate failure, which would result in dropping water levels below minimum operational levels and interrupting power production.

The programme, according Karonga, would also include the refurbishment of the upstream stop-beam guides and replacement of secondary concrete to prevent failure during operation of stop-beams.

She said Zimbabwe and Zambia had appointed a resource mobilization committee to ensure concerted resource mobilisation efforts for the critical works and other projects.

"It is with this background that the co-operating partners took a keen interest in the project and agreed to identify financial options, including timelines," she said.

The Kariba Complex, according to the World Bank Report 2010, is central to the Southern Africa Power Pool with 3 200 MW of the 50 000MW capacity translating to 15 percent of the total power output.

ZRA is currently updating its Emergency Preparedness Plan for the Lower Zambezi and also enhancing internal processes and procedures for preparedness.