Possible failure of Kariba Dam raises concern as El Nino bites

Lusaka - Concerns surrounding the structural health of the Kariba Dam have risen following an announcement that the region could be facing a shutdown of its hydroelectric plants as water levels drop "dangerously" low.

According to Bloomberg Business, Zambian Energy Minister Dora Siliya raised the alarm last week when she announced that water levels in the dam had dropped to below 14%, prompting the shutdown of the dam's hydroelectric plants.

The situation was exacerbated by a 4.6 magnitude earthquake, which hit the Kariba area and parts of Zambia on January 12.

The incident, according to Zimbabwe's state-owned Herald newspaper, raised fears about the vulnerability of the dam wall, although no damages were recorded.

Lake Kariba, which straddles the border between Zambia and Zimbabwe, generates up to 40% of hydropower to the southern African region and could have catastrophic effects should its walls fail.

Water levels 'dangerously' low

According to a statement sent to News24, Chipilaika Mukofu, Director at the Geological Survey Department in Zambia, revealed that the possible effects of the earthquake were being investigated.

Mukofu also said that the epicentre of the quake was within sensitive reach of Lake Kariba and that the stability of the dam wall could be affected as a result.

A recent report by the Institute of Risk Management South Africa (IRMSA) detailed the implications of a failure at the Kariba Dam.

The report, titled Impact of the failure of the Kariba Dam, said the dam was in a dangerous state, with a gaping crater of eroded bedrock undercutting the its foundation.

"While water levels are dangerously low, which takes some pressure off the failing construction of the dam for now, the bigger picture of the state of Kariba Dam is critical.

"Climate change, high rainfall patterns impacting future dam levels and water inflows from other regions, and potential seismic activity, could all contribute to the likelihood of failure of the Kariba Dam. In December 2014, the critical period was defined as 'the next three years', while the rehabilitation project is only due for completion in 2025," explained Kay Darbourn, researcher and writer of the report.

A News24 report last year indicated that Zambia and Zimbabwe had signed a $294m to repair the dam, but efforts seemed to have been delayed by the Zambezi River Authority (ZRA) as tender processes continued.

With some countries in the southern region relying mainly on hydropower from the Zambezi, several economies would be severely affected should the dam collapse. South Africa alone will lose 1 500MW of imported power, the report said.

Source http://www.news24.com/Africa/News/possible-failure-of-kariba-dam-raises-...