Hydropower dams may conjure images of the massive Grand Coulee Dam in Washington state or the Three Gorges Dam in Hubei, China — the world’s largest electricity-generating facility. But not all dams are the stuff of documentaries. Tens of thousands of smaller hydroelectric dams exist around the world, and all indications suggest that the number could substantially increase in the future.
These structures are small enough to avoid the many regulations large dams face, and are built more quickly and in much higher densities. As streams, rivers and watersheds absorb more small dams, however, surprisingly few scientific studies have considered their environmental impact, and policies or regulations are lacking or largely inconsistent.
University of Washington researchers have published the first major assessment of small hydropower dams around the world — including their potential for growth — and highlight the incredibly variability in how dams of varying sizes are categorized, regulated and studied. Their paper, the first to provide a global synthesis of the science and policy of small hydropower, appears this month in the journal Frontiers in Ecology and the Environment.
“As we started exploring this topic of small hydropower development, we realized we’re facing a proliferation of this kind of facility, but we don’t know exactly how their environmental impacts scale up in a watershed,” said lead author Thiago Couto, a UW doctoral student in the School of Aquatic and Fishery Sciences.
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Image via Rylee Murray, University of Washington