Changing rainfall poses dilemma on dams
By Kieran Cooke
A changing climate usually means changing rainfall patterns. And that means a headache for dam builders.
For the builders of hydro-electric schemes – usually multi-billion dollar projects involving vast amounts of complex engineering work – changing rainfall is a serious problem.
With climate change either on the horizon or already happening in many regions of the world, rainfall patterns, on which hydro schemes ultimately depend, are becoming ever more unpredictable.
Christian Rynning-Tonnesen is CEO of Statkraft AS, Norway’s biggest power producer and a major player in the international hydro power business.
In an interview with the Bloomberg news agency, Rynning-Tonnesen says his company has had to double its spending over the last 10 years to reinforce dams in order to cope with heavier rains. He says climate change is hard to ignore when you’re in the hydro-electric business.
“Depending on water as the main source of power in future when we’ll have less of this natural resource looks like an unreliable strategy”
“The general trend all over the world is areas that are dry become more dry and areas that are wet become more wet.”
Norway has seen a 5% rise in rainfall over recent years, says Rynning-Tonnesen.
Others say planning processes behind dam building have to be revised in the face of climate change.
Emilio Moran, a visiting professor at the University of Campinas in São Paulo state in Brazil, says that in one of the world’s biggest hydro-electric building programmes, a total of 147 dams have been planned in the Amazon Basin, with 65 of them in Brazil.
In a study published in the Proceedings of the National Academy of Sciences journal, Moran and his co-authors say many of the dams in Brazil − either completed or still in the planning stages − are likely to produce far less power than anticipated, owing to climate variability.
The Amazon Basin is predicted to receive less rainfall and to be hit with higher temperatures in future.
“Depending on water as the main source of power in future when we’ll have less of this natural resource looks like an unreliable strategy”, says Moran.
“To reduce its vulnerability with regard to energy in the context of global climate change, Brazil must diversify its energy mix. It’s still too dependent on hydro-electricity. It needs to invest more in other renewable sources, such as solar, biomass and wind.”
Deforestation is expected to create further water shortage problems for hydro plants in the Amazon region. About half the area’s rainfall is due to recycling within the forest.
“Deforestation will, therefore, lead to less precipitation in the region aside from the expected decline due to global climate change”, say the study’s authors.
They say that if the building of large dams in developing countries is to continue, full consideration has to be given to their social impact, the overall cost to the environment and to climate change.
In many cases, this doesn’t seem to be happening. Turkey is spending billions on ambitious dam building projects on the Euphrates and Tigris rivers in the south-east of the country. Climate change is predicted to alter the amounts of water available to drive the operation of these dams.
The rivers flow onwards into Syria and Iraq: already water flows downstream are severely reduced at certain times of the year, creating regional tensions and putting in jeopardy the livelihoods of millions dependent on the rivers for drinking water and for agricultural production.
One of the world’s biggest dam projects is in East Africa − the Grand Ethiopian Renaissance Dam (GERD) on the Blue Nile, which flows into the Nile itself. Ethiopia wants to sell electricity generated by the dam to neighbouring countries.
Critics of the GERD project say climate change, including reduced rainfall in the Blue Nile’s catchment area, could seriously affect the dam’s generating capability.