The University of Trás-os-Montes and Alto Douro (UTAD) recently released new research that mapped and characterized all of the barriers in the Duoro River basin. As a part of their research, they also identified the most harmful barriers. This basin is the largest in the Iberian Peninsula crossing parts of Spain and Portugal.
The UTAD research team found that the Duoro River basin is littered with barriers and the barriers are impacting this biodiverse area. Altogether, they found 1201 barriers – 57 dams, 40 mini-hydro, and 1105 medium and small barriers and dams. This number of small and medium-sized dams is in line with the recent estimations of the AMBER project, estimating 85% of in-stream barriers are small or medium-sized. The UTAD study estimates that about 25% of these barriers are abandoned.
The UTAD also developed a multi-criteria model for prioritizing the systematic removal of barriers. The model considers criteria for habitat, connectivity, water quality, socioeconomic and ecological. They applied the model to this study site and found 165 barriers as candidates for removal, and gave a ranking of the 20 most priority to be removed. Of these, 18 have no definite use and can be considered obsolete or abandoned.
Removing these barriers would be a great step forward to reaching the 25,000km of free-flowing rivers goal set out by the new EU Biodiversity Strategy.
Check out their website (in Portuguese) and download their studies for more information.