London: An unprecedented global boom in the construction of hydropower dams, spearhead by developing and emerging economies, could reduce the number of rivers by about 20 percent and pose a serious threat to freshwater biodiversity, says a study.
The Ganges-Brahmaputra basin in India and the Yangtze basin in China will face the highest dam construction in Asia, the findings showed.
The researchers also noted that the future hydropower dams could double the global electricity production from hydropower, within the next two decades.
Renewables account for 20 percent of the global electricity production today, with hydropower contributing 80 percent of the total share. An expected 3,700 major dams may more than double the total electricity capacity of hydropower to 1,700 GW within the next two decades, the findings showed.
"Hydropower is an integrated part of transitioning to renewable energy and currently the largest contributor of renewable electricity," said Christiane Zarfl University of Tubingen in Germany.
"However, it is vital that hydropower dams do not create a new problem for the biodiversity in the world's freshwater systems, due to fragmentation and the expected changes in the flow and sediment regime," she cautioned.
Zarfl, together with her colleagues, performed the study at the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB) in Berlin.
The boom in dam construction occurs primarily in developing countries and emerging economies in South America, Southeast Asia and Africa, that also hold some of the world's most important sites for freshwater biodiversity.
Given that all planned dams are realized, China will remain the global leader in hydropower dam construction although their share of total future global hydropower production will decline from currently 31 to 25 percent, due to increases in other parts of the world.
The study is forthcoming in the journal Aquatic Sciences: Research across Boundaries.