Poorly planned Amazon dam project 'poses serious threat to life'
The biggest hydroelectric project in the Amazon rainforest has a design flaw that poses a “very serious” threat to human life and globally important ecosystems, according to documents and expert testimony received by the Guardian.
The studies suggest engineers failed to anticipate the impact of water shortages on the Pimental dam at Belo Monte, which has been closed and turned into a barrier. This is forcing the operators to choose between a structural weakening of the 14km-wide compacted-earth barrier and a reallocation of water in the reservoir or on the Xingu river, which is home to indigenous communities, fishing villages and some of the world’s most endangered species.
One analyst said there was risk of a rupture, and even before the report was issued federal prosecutors were preparing to call for the project to be suspended. They also intend to appeal to the Brazilian government for emergency humanitarian aid to support riverine populations that have experienced a devastating decline of fish on which they depend for nutrition and income.
After decades of resistance and 40bn reais (£8bn) of investment, the world’s fourth biggest hydropower plant is due to have the last of its 18 turbines installed this month, but lower-than-forecast water levels in the dam’s reservoirs have created an unforeseen structural problem in addition to longstanding environmental, social and economic concerns.
The Guardian and El País have seen a recent report by Norte Energia which warned that the fall in water levels in recent weeks has exposed a vulnerable section of the Pimental dam wall, which is separate from the barrier housing most of the turbines, to waves that sometimes form during tropical storms or strong winds blowing across the reservoir.
The 11 October document – Urgent action to control the level of the Belo Monte HPP Xingu Reservoir - is signed by Norte Energia’s CEO and addressed to the head of the national water agency. It says that water levels fell the previous day to a critical 95.2 metres, which posed a risk that waves “will reach areas of the dam not protected by rock” reinforcements. It asks permission for more water from the intermediate reservoir, a move which would put more pressure on an already strained hydrology.
Following two deadly tailings dam disasters in recent years at Brumadinho and Mariana, the uncertain situation has prompted experts to call on Brazilian authorities to increase monitoring of the dam, take remedial measures and clarify the magnitude of the risk to the public.
André Oliveira
Sawakuchi of the department of sedimentary and environmental geology at the University of São Paulo said it was unclear whether structural damage might occur within weeks, months or years, but the report’s call for immediate action suggested the threat was very serious.
His concerns were echoed by Francisco del Moral Hernandez, an energy science specialist who coordinated an expert panel on Belo Monte in 2009. “We’ve always known this project is inefficient from the standpoint of power generation. What we did not imagine is the weakness of the civil engineering,” he said. “If I were living downstream of the dam, I would move upriver … It is absurd this was not foreseen.”
The report says the problem arose as a result of unusually low water flows into the reservoir, with several days in early October when it dropped to 750 cubic metres a second. This is substantially below the minimum of 1,000 cubic metres a second that planning documents say is needed to guarantee water quality in the reservoirs and sufficient downstream discharge to ensure a healthy ecosystem, including for a turtle refuge, and indigenous and riverine communities’ navigation.
Hernandez and Sawakuchi said planners had been over-optimistic because historical data showed the Xingu river was lower on at least four occasions during the 50 years before construction started. Climate change is projected to cut water flows by about 30% by 2050. “It’s very strange these problems weren’t foreseen,” Sawakuchi said. “The structural risks are a surprise.”
The Belo Monte project has been beset with problems since its inception during the era of Brazil’s military dictatorship. Indigenous and riverine communities allied to oppose the dam system, which blocks one of the Amazon’s biggest tributaries with 2.1m tonnes of concrete and 79.2m cubic metres of earth.
Environmentalists and scientists warned this would devastate one of the world’s most unique biodiversity hotspots. Economists questioned the viability of a scheme paid for with pension funds and tax revenues, but which is designed to run at only 40% of its 11,200MW capacity. Prosecutors