Climate change threatens Zambezi dam projects

Source: Thomson Reuters Foundation - Wed, 3 Oct 2012 10:07 GMT
Author: Madalitso Mwando
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BULAWAYO, Zimbabwe (AlertNet) – Ambitious multi-billion dollar dam projects along the Zambezi River, carried out by southern African countries seeking to boost hydropower generation, could turn out to be white elephants because of growing climate challenges, experts say.

Concerns that some African countries are responding inadequately to climate change forecasts are highlighted in a new report that warns that governments have failed to appreciate the effects of poor rainfall and of potentially devastating floods – both linked to climate change - on long-term dam projects.

The report by International Rivers, a non-profit organisation involved in the protection of rivers and the rights of communities that depend on them, says that the Zambezi Basin is liable to suffer most from climate change among 11 major sub-Saharan African river basins and will experience the greatest reduction in rainfall and runoff in the coming years.

According to the report, increasing extreme rainfall patterns could result in “uneconomic dams that under-perform in the face of more extreme drought, and more dangerous dams that have not been designed to handle increasingly damaging floods.”

The 3,540 km (2,200 mile) Zambezi, Africa’s fourth longest river, runs through nine southern African countries and an increasing number of them are exploring dam building on it, especially since the ratification of the Zambezi Watercourse Commission paved the way for member states to harness the transboundary river.

Rudo Sanyanga, Africa programme director for International Rivers, says any future dam projects face huge adaptation risks in the face of shifting rainfall patterns and urges governments to adopt fresh ideas to deal with the region’s water problems.

“Large-dam hydro [power] poses not just economic risks, but also adaptation risks. Africa has been called the continent ‘most at risk’ of climate change,” Sanyanga said.

There are currently 13,000 megawatts (MW) of new large-dam hydro power proposed for the Zambezi and its tributaries as energy needs grow in the region, with countries like Zimbabwe facing huge demand and turning to regional neighbours for their energy needs.

Already, two major dam projects are planned that will be fed by the Zambezi – the $4 billion Zimbabwe-Zambia Batoka Gorge dam, which will generate 1,600 MW, and the Mphanda Nkuwa dam, whose construction was approved by the Mozambique government in 2010 at the cost of $2.3 billion.


But Sanyanga says any large reservoirs for hydropower production conflict with flood management efforts because of the large amount of water they must store to produce power. That may be particularly important in countries like Mozambique that in the past have suffered dramatic floods.

The International Rivers report says that the dam projects are “based on historical hydrological records and have not been evaluated for the risks associated with reduced … annual flows and more extreme flood and drought cycles”.

Concerns have previously been raised about poor integrated water management efforts in countries along the Zambezi. The South African Development Community’s water division has noted a regional lack of technical expertise and understanding of the basin’s resources.

“The region’s energy planners and governments must acknowledge these hydrological risks, and take steps to improve planning and management of large dams in the basin,” urged hydrologist Richard Beilfuss, lead author of the report.

“At (a) minimum, existing and future dams should undergo a thorough analysis of climate risks,” he added.

Southern African countries have recently experienced a mix of prolonged droughts and devastating floods during the same season, raising the spectre of a continuous cycle of weather-related disasters that could affect people and dams, and hit energy production in a region with huge energy deficits.

In particular, if dams reach capacity during periods of heavy rain and must release water to protect the integrity of the dam, communities could be at risk, Sanyanga said.

“Community based emergency preparedness is critical but is compromised by presence of large dams,” she said. “Sudden release of large water quantities often exceeds the natural floods, thus bringing devastating impacts on communities.”

Experts believe the problem could better be avoided with new ways of thinking, including better managing floodplains.

“Flood storage can be achieved by managing the vast Zambezi floodplains as active floodplains … and ensuring that people do not resettle in areas that are already highly flood-prone,” Beilfuss said.

Development in the region in general needs to become more sustainable, Sanyanga said.

 “We need to act now to protect our rivers as sources of livelihoods and food security,” she said.

Madalitso Mwando is a journalist based in Harare, Zimbabwe.