The development of small hydropower dams is widespread throughout Brazil and elsewhere in the world, vastly overshadowing large hydropower projects. The proliferation of these smaller dams is a response to growing energy and security needs. Their expansion, however, threatens many of the remaining free-flowing rivers and biodiverse tropical regions of the world — interrupting the migrations of freshwater fishes, on which millions of peoples’ livelihoods depend. The findings confirm that small hydropower plants are far more responsible for river fragmentation than their larger counterparts due to their prevalence and distribution. small hydropower dams greatly outnumber large hydropower dams, but their combined energy output is much less.
In Brazil, small hydropower plants only account for only 7% of total generation capacity even though they represent more than 85% of hydropower plants in the country. It is projected that river fragmentation will increase by 21% in the future, and two-thirds of the 191 migratory species assessed in the study occupy river basins that will experience greater connectivity losses.
— source University of Washington | Jan 27, 2021
