Dam construction involves higher environmental and social costs than previously estimated, a new study has suggested.
The study, cited by Phys.org, was carried out by researchers from Michigan State University and found that "When a large dam is built, the result is a downstream loss of a great many fish species that are important to riverine populations. These communities will have to continue somehow making a living despite dwindling fish stocks for 15 or 20 years, for example, and the costs of these projects don't take such economic and social losses into account," as explained by the lead author of the study, Emilio Moran.
A lot of developed countries have stopped building large-scale dams and have switched to smaller hydropower installations but developing countries such as Brazil are still investing in large dam construction.
"We argue that if the construction of large dams in developing countries is to continue, it must always be preceded by a painstaking assessment of their real cost, including the environmental and social impact they have," Moran noted. The lead author of the study is visiting professor at the University of Campinas in Sau Paulo state in Brazil.
The environmental costs of large-scale hydropower installations are not new but they don’t seem to get as much attention as other forms of power generation. The Union of Concerned Scientists, for example, cites an article on the environmental and social impacts of the world’s biggest dam, the Three Gorges, in China.
Its construction involved the flooding of a huge region, destroying ecosystems, affecting wildlife habitats and necessitating the relocation of entire communities. The total number of people displaced because of the project was 1.13 million.
What’s more, dams don’t last forever. They need to be retired and dismantled and this bears a high financial cost, too. "The cost of removing a dam once its useful life is over is extremely high, and should be taken into account when computing the total cost of a new hydro development," Moran notes. "If the cost of removal had to be included, many dams wouldn't be built. It would be far more expensive to produce a kilowatt-hour of electricity via a hydro complex with a useful life of 30 to 50 years, like those under construction in Brazil."