Rivers are some of the most threatened ecosystems in the world and a major focus of restoration programmes in Europe and elsewhere. A major challenge to achieving good ecological status, as required under the EU Water Framework Directive, is the reduction of fragmentation of river habitats caused by many thousands of barriers. Strikingly, the real number and location of barriers in Europe is, currently, unknown. In that context the H2020 AMBER project addresses the issue of river fragmentation in European rivers and seeks to apply adaptive management of barriers at multiple scales to achieve more efficient restoration of river connectivity. AMBER is building the first pan-European database of stream barriers across Europe, collating and harmonising existing databases at national and regional scales.
We present here the most up-to-date database on the distribution, typology and drivers of river fragmentation at the pan-European scale. From the 48 national and regional barrier databases collated, >260,000 barriers were identified. Of these, 60% of barriers could be attributed to one of six common barrier types whilst the remaining 40% were of unknown type; 62% were without height attributes; c. 30% lacked river or basin name and only 7% included information about fish passage. We integrate this new information with pan-European datasets on climate, geography and socio-economic data to derive meaningful drivers of barrier density, from which barrier distribution can be inferred in countries and regions where data are scarce.
This approach allows the generation of a more realistic picture of river fragmentation at the national and European scale with regards to impacts on sediment, water and biota connectivity that can inform future barrier monitoring and management.