The Aswan High Dam in Egypt, built across the Nile during the 1960s, caused severe erosion downstream. Sediment that would normally have replenished the area remained trapped behind the dam, and salt water from the Mediterranean eventually inundated parts of the delta.
Few recent hydropower projects have been as controversial as China's Three Gorges Dam (pictured). The US$25-billion dam, which will create a lake 600 kilometres long and is due for completion at the end of the decade, drew particular criticism over the forcible resettlement of more than half a million people.
The author Arundhati Roy has led a high-profile campaign against dam building in India, in particular the Narmada Dam Project in central India. The Indian government has several major dams under construction and in planning, but Roy and others say previous projects caused severe damage to local ecosystems and communities.
Large scale
But although several national governments and the World Bank have earned praise for implementing some of these ideas, experts say China has not followed suit. At Merowe, for example, where commercial electricity production is scheduled to begin next year, a 7-kilometre-long, 65-metre-high wall will trap more than 10 million cubic metres of water. Land belonging to 10,000 families will be affected, and four resettlement schemes are under way. A project of this scale in Europe or North America would have required years of independent study before being given the go-ahead, say dam experts. But the first environmental-impact assessment was completed in 2002, just a year before construction began.
Contrary to rules for dam projects adhered to by other big funders such as the World Bank, the assessment was conducted, not by independent experts, but by Lahmeyer International, the German company acting as engineering consultants for the project. The assessment, which was never formally published in Sudan, also fails to tackle key issues. It falls well short of international standards, say researchers at the Swiss Federal Institute of Aquatic Science and Technology in Kastanienbaum, who will publish their review of the assessment on 23 March.
Sediment accumulating behind the dam is one such issue, says Cristian Teodoru, a geologist at the institute who produced the review. This will affect farmers downstream who rely on nutrients in the sediment to fertilize their fields during the annual floods. “This issue is not even mentioned in the report,” says Teodoru. The future of downstream ecosystems gets similarly short shrift. Teodoru says that the water column at the front of the dam will contain layers of anoxic water, which, if sent through the turbines and released, could harm aquatic life below the dam — another point the assessment fails to acknowledge.
Egon Failer, an executive director at Lahmeyer in Bad Vilbel, defends the report, saying that it was an early-stage document and that the final design addresses some of the problems that Teodoru identified. Dam gates will, for example, be opened to flush out sediment in July when the floods arrive and stir up water in the reservoir. He adds that the centre of the turbine inlet is just 12 metres below the dam surface, so that oxygen levels will be high enough not to harm downstream ecosystems.
Inaccessible
If African governments don’t care, or are corrupt, why will the Chinese engineers worry?
But details of the final design have never been published, and scientists working for Lahmeyer were required to sign confidentiality agreements that prevent them from talking to the media, making it impossible for researchers and environmental groups to assess Failer's assertions. Teodoru points out that even 12 metres below the surface oxygen levels could be dangerously low. Water levels will also fluctuate during the year, and could leave the base of the turbine twice as deep as Failer indicated. Many modern projects minimize the problem of anoxic water by using designs that extract water from different depths, or incorporate devices that mix the water to prevent anoxic areas forming, says Karin Seelos, a senior environmental adviser at Hydro-Québec, an energy company in Montreal, Canada.
Critics of Merowe say the project also looks set to repeat perhaps the most severe social mistake of previous dam schemes, which have seen the livelihoods of hundreds of thousands of resettled people suffer. Mutaz Musa Abdalla Salim, director of financing at the Merowe Dam Project Implementation Unit in Khartoum, denies this. He points out that 35% of the 10,000 affected families have been resettled and US$700 million will eventually be spent on new homes, clinics and other facilities. But when staff at the International Rivers Network, an environmental group in Berkeley, California, which part-funded the Swiss study, visited the resettlement sites in February 2005, they catalogued many problems. The group say sanitation was already poor owing to cramped conditions in the new towns, and that soil quality was in some places too low to support agriculture. Salim angrily denied these assertions when Nature put them to him.
Experts are concerned that the problems identified at Merowe will affect other Chinese-built dams. Press reports suggest that China is considering, or has already started work on, at least a dozen dam projects in Africa. These projects tie in with investments in many other African projects, some in countries with poor human-rights records, in a strategy that Western political commentators say is designed to secure access to the continent's oil and other natural resources.
Chinese government officials did not return requests for comment on their country's involvement with Merowe or other African dams. But Jia JinSheng, vice-president of the China Institute of Water Resources and Hydropower Research in Beijing, confirms that his country is winning contracts in the region. He says Chinese firms can undercut rivals in Europe and North America by around a third, and finish construction more quickly. He adds that environmental and social issues have become more important in China in the past five years, but that ultimately responsibility rests with the host nation: “It's the business of the owners and local government,” he says.
Local responsibility
Those parties are often ill-equipped to provide the necessary safeguards, says Ute Collier, an expert on dams at the WWF in Godalming, near London. Collier published a report on hydropower in Africa on 6 March in association with UK charities WaterAid and Oxfam. She backs the potential of hydropower, pointing out that around a third of the continent has no access to electricity. But she says that only a few African countries, such as Zambia and South Africa, have the political will and infrastructure to ensure that hydropower is implemented responsibly. Elsewhere, she says, funders with low environmental standards, such as China, or the Arab banks that are also contributing to the Merowe project, can operate almost unchecked.
Pressure could potentially come from the third group involved in dam building: the commercial firms that run the projects. But Collier says that some Western companies seem happy to work on such projects. As well as Lahmeyer, two other European firms are involved in Merowe: the Swiss company ABB, which sells equipment for electricity sub- stations, and Alstom in France, which is supplying turbines and generators. “Companies should operate in the same way as they do at home,” says Collier. “But that is often not the case.”
On the issue of resettlement, for example, Lahmeyer seems to have set aside its own reservations about the project. The company's 2002 assessment acknowledged that, with just over a year to go before construction, there was no agreed plan on how to resettle the 50,000 people involved and that prospects of “smoothly” resettling at least one group — members of the Shaigiya tribe — were “doubtful”.
“Maybe the assessment should have been done earlier,” says Failer. “But the country didn't have the time. They need electricity. The water is there and they're pushing for it. I'm deeply convinced this is good for the country.”
