The environmental and social costs of hydroelectric mega-dams have been grossly underestimated, and will continue to grow further as climate change escalates, a new report finds. Dams have been linked to habitat degradation, harm to biodiversity and migrating aquatic species, and to negative changes in river ecology.
More problems: dams rarely live up to promoter pledges. Costs are often underestimated, and once built, big dams rarely generate the huge energy amounts promised. River sediment flow estimates are commonly downplayed in plans, and builders rarely take climate change, with its intensifying droughts, into consideration.
Despite evidence of harmful impacts and disappointing outputs, many more mega-dams are planned in developing nations in Asia, Africa and South America. But when mega-dam environmental and social impact assessments are conducted, they often underestimate harm, and their findings tend to be overlooked.
A re-vamp of an age-old technology – the water wheel – could offer a reliable energy supply to local communities. Instream Energy Generation (IEG) uses clusters of small turbines, enabling fish and sediments to pass freely while generating power. Wind and solar offer other alternatives to mega-dams.