A Risky Climate for Big Dams in Africa
Climate change is bringing many uncertainties, especially to the world
of water. No continent will be harder hit by climate change than Africa. The
Intergovernmental Panel on Climate Change has stated that African river basins
will be especially affected by climate change, and are expected to face worse
droughts and more extreme floods as a result.
Yet across the continent, large dams are being planned with no
understanding of how a changing climate will affect them - and little attention
to the related problem of how dams will hurt river-based communities' ability
to adapt to climatic changes. Governments and dam-lenders aren't taking the
lead on these critically important issues.
To fill this gap, International Rivers commissioned an eminent
hydrologist to examine the risks to dams in Africa's fourth largest river
basin, which is slated for dozens of new large hydropower dams. His study
warns that new and proposed dams on the Zambezi River are ill-prepared to
withstand the shocks of a changing climate. The result could be 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.
Dr. Richard Beilfuss, a hydrologist with 20 years' experience on the
Zambezi River, evaluated the hydrological risks to hydropower dams in the
basin. Overall, he says, the river will experience worse droughts and more
extreme floods. Dams being proposed and built now will be negatively affected,
yet energy planning in the basin is not addressing these huge hydrological
uncertainties.
The report's key findings describe a region moving toward the edge of a
hydrological precipice:
• The basin is likely to experience significant reductions in rainfall,
and higher evaporation rates in the next century. Because large reservoirs
evaporate more water than natural rivers, big dams could worsen local water
shortages (and reduce water available for hydropower).
• The designs for two of the most advanced dam projects are based on
the now-outdated historical hydrological record, and have not been evaluated
for hydrological risks. Under future climate scenarios, they are unlikely to
deliver the expected services over their lifetimes, resulting in wasted
investments.
• The occurrence of more frequent extreme floods threatens the
stability and safe operation of large dams. If dams are
"under-designed" for larger floods, the result could be serious
safety risks to millions of people living in the basin.
• The Zambezi is already heavily dammed, and these projects have caused
profound harm to livelihoods and biodiversity. The ecological goods and
services provided by the river, which are key to helping societies adapt to
climate change, are not being properly valued in planning for large dams in the
basin.
"Ensuring energy and water security for the future will require
new ways of thinking about river basin development," notes Dr. Beilfuss.
"We must avoid investing billions of dollars into projects that could
become white elephants."
Dr Beilfuss makes a number of recommendations to help African nations weather the coming storm. First and foremost, he calls for incorporating climate change scenarios into dam design, to avoid the hazards of over- or under-designed infrastructure.
Dr Beilfuss makes a number of recommendations to help African nations weather the coming storm. First and foremost, he calls for incorporating climate change scenarios into dam design, to avoid the hazards of over- or under-designed infrastructure.
Africa faces numerous risks from climate change, including serious
water stress. Successful adaptation will require radical new ways of thinking
about water resources. The report notes: "While more water storage will be
needed, decentralized solutions that preserve river-based ecosystem services are
better suited to the needs of the rural majority, who face the greatest
adaptation challenges."
Dr. Beilfuss also recommends big-picture for energy planning.
"Planners need to carefully consider dams in the context of how climate
change will shape water supply, and how future river flows must meet competing
demands for power, conservation, and water for domestic use, agriculture,
industry, and other services. A strategy aimed at empowering people to adapt to
climate change must be central to these planning efforts."
He also calls for a full accounting of the values of ecosystem services
supported by river flows, and changing dam design and operation to allow more
natural flows to help restore ecosystem services on dammed rivers. The report
also recommends more diversified investments in energy supply projects to
"avoid putting all eggs into one basket" in a time of increasing
hydrological uncertainty - an especially critical step for Africa's most hydropower-dependent
nations. Many African countries have a huge untapped potential for solar,
wind, geothermal, and other renewable energy technologies that are well-suited
for both urban and rural energy development.
The situation on the Zambezi is hardly unique. On nearly every
continent, in many of the world's major watersheds, large dams are at risk of
becoming white elephants due to drought, and weapons of mass destruction during
extreme floods. Africa especially cannot afford to take a head-in-the-sand
approach to the climate risks of large dams. The time is now to prioritize
climate-smart investments that explicitly factor in economic risk and the
values of river systems.
