Oct 12, 2012
Proposed Zambezi hydropower dams pose some risks, expert warnsBack
Construction|Africa|Flow|Hydropower|Projects|Resources|Safety|SECURITY|System|Water|Africa|Energy|Flow|Power Generation|Power-generation|Services|Batoka Gorge|Zambezi|Zambezi River|Power|Richard Beilfuss|Rudo Sanyanga|Water
© Reuse this
Existing and proposed hydropower dams are not properly evaluated for the risks of natural hydrological variability, which is extremely high in the Zambezi river, not to mention the risks posed by climate change, says US State of Wisconsin Department of Safety and Professional Services hydrologist Dr Richard Beilfuss.
“The result could be that uneconomic dams underperform in the face of more extreme drought and more dangerous dams that have not been designed to handle increasingly damaging floods,” he notes.
Overall, Africa’s fourth-largest river will experience worse droughts and more extreme floods. Dams currently being proposed and built will be negatively affected, yet energy planning in the basin does not include the necessary steps to address these significant hydrological uncertainties, he warns.
The basin exhibits the worst potential effects of climate change among 11 major sub-Saharan African river basins. It will also experience the most substantial reduction in rainfall and runoff, according to the International Panel on Climate Change. Multiple studies estimate that rainfall across the basin will decrease by 10% to 15%.
“The basin is likely to experience significant warming and higher evaporation rates in the next century. Because large reservoirs evaporate more water than natural rivers, big dams could worsen local water deficits, resulting in less water for hydropower. Currently, more than 11% of the Zambezi’s mean annual flow is lost to evapora- tion from large hydropower dam reservoirs, which increases the risk of shortfalls in power generation and significantly impacts on downstream ecosystem functions,” he explains.
The designs for two of the larger dam projects proposed for the Zambezi, the Batoka Gorge and Mphanda Nkuwa dams, are based on historical hydrological records and have not been evalu- ated for the risks associated with reduced mean annual flows and more extreme flood and drought cycles. Under future climate scenarios, these hydropower stations, which are based on records of flows, are unlikely to deliver the expected services, says Beilfuss.
The occurrence of more frequent extreme floods threatens the stability and safe operation of large dams. Extreme flooding events, a natural feature of the Zambezi river system, have become more costly downstream since the construction of large dams. If dams are ‘underdesigned’ for larger floods, the result could be serious safety risks to millions of people living in the basin.
The Zambezi river is already highly modified by large hydropower dams, which have profoundly altered the hydrological conditions that are most important for downstream livelihoods and the preservation of biodiversity. The ecological goods and services provided by the river, which are key to enabling societies to adapt to climate change, are under grave threat.
Large-dam hydropower poses economic and adaptation risks. Africa has been referred to as the continent most at risk of being nega- tively affected by climate change. Successful adaptation will require new ways of thinking about water resources. We need to act now to protect our rivers as sources of livelihoods and food security,” says International Rivers Africa programme director Rudo Sanyanga.
“The region’s energy planners and governments must acknowledge these hydrological risks and take steps to improve planning and manage- ment of large dams in the basin. Existing and future dams should, at least, undergo a thorough analysis of climate risks,” notes Beilfuss.
Edited by: Martin Zhuwakinyu© Reuse this Comment Guidelines (150 word limit)
Other Environment News
Updated 25 minutes ago Paper and packaging group Mpact has concluded a broad-based black-economic empowerment (BBBEE) deal that will see a purpose-formed trust subscribing for 10% of the ordinary issued shares in group subsidiary Mpact Operations, which holds its South African businesses....
Updated 30 minutes ago With South African business and consumer confidence being negatively affected by the unfavourable exchange rates and ongoing power cuts, JSE-listed Nampak said the performance of its local businesses, particularly its home business division, was under pressure. The...
Updated 32 minutes ago Throwing open a process often criticised for its lack of transparency and frequent irregularities, the Gauteng Provincial Government (GPG) for the first time on Wednesday opened the adjudication of a tender to the public, describing it as an effort to improve...
Recent Research Reports
Steel 2015: A review of South Africa's steel sector (PDF Report)
Creamer Media’s Steel 2015 report provides an overview of the key developments in the global steel industry and particularly of South Africa’s steel sector over the past year, including details of production and consumption, as well as the country's primary carbon...
Projects in Progress 2015 - First Edition (PDF Report)
In fact, this edition of Creamer Media’s Projects in Progress 2015 supplement tracks developments taking place under the Renewable Energy Independent Power Producer Procurement Programme, which has had four bidding rounds. It appears to remain a shining light on the...
Electricity 2015: A review of South Africa's electricity sector (PDF Report)
Creamer Media’s Electricity 2015 report provides an overview of State-owned power utility Eskom and independent power producers, as well as electricity planning, transmission, distribution and the theft thereof, besides other issues.
Construction 2015: A review of South Africa’s construction sector (PDF Report)
Creamer Media’s Construction 2015 Report examines South Africa’s construction industry over the past 12 months. The report provides insight into the business environment; the key participants in the sector; local construction demand; geographic diversification;...
Liquid Fuels 2014 - A review of South Africa's Liquid Fuels sector (PDF Report)
Creamer Media’s Liquid Fuels 2014 Report examines these issues, focusing on the business environment, oil and gas exploration, the country’s feedstock supplies, the development of South Africa’s biofuels industry, fuel pricing, competition in the sector, the...
Water 2014: A review of South Africa's water sector (PDF Report)
Creamer Media’s Water 2014 report considers the aforementioned issues, not only in the South African context, but also in the African and global context, and examines the issues of water and sanitation, water quality and the demand for water, among others.
This Week's Magazine
Projected capital expenditure (capex) in the South African automotive assembly industry should reach a record R7.48-billion this year, says the National Association of Automobile Manufacturers of South Africa (Naamsa) in its 2014 fourth quarter business review. Capex...
After several years of navigating project-threatening red tape and currency fluctuations, the 4.4 MW Bronkhorstspruit biogas power plant, which will supply clean energy to a leading automotive manufacturer in Gauteng, is expected to enter production before June....
South African paper and pulp producer Sappi reported earlier this month that it would build a pilot plant for the production of low-cost Cellulose NanoFibrils, or CNF (nanocellulose) at the Brightlands Chemelot Campus in Sittard-Geleen in the Netherlands.
The long-term outlook for Nigeria is a country that has the potential to be very strong. So affirmed International Monetary Fund (IMF) Nigeria Mission Chief and Senior Resident Representative Dr Gene Leon on recently. "But we are starting from a point of huge...
Poor infrastructure planning and inadequate maintenance are becoming increasingly problematic for new developments and the associated infrastructure required to support such developments. In many urban and rural municipalities, the state of infrastructure has been...