By hindering the free movement of water, organisms and sediment, artificial barriers on rivers constitute significant pressures for about 20% of European surface water bodies, according to a report by the European Environment Agency (EEA) that was published on 8 February.
According to this report, there are barriers on most European rivers in the form of large dams in particular, but especially small structures, the small individual effects of which accumulate along the course of the river and eventually result in a major impact on it.
Citing recent studies, the report points out that the cumulative impact of a large number of river barriers in Europe is one of the leading causes of the more than 80% decline in freshwater biodiversity and the loss of 55% of monitored migratory fish populations.
While a recent study mapping barriers on European rivers concluded that there are about 630,000 recorded barriers, field research estimates that this number could actually be well over 1 million, according to the EEA, while also noting that thousands of them are obsolete.
For the EEA it is therefore crucial that data available to the EU on river fragmentation is improved. In particular, this would make it possible for progress to be monitored regarding the EU's targets for restoring the continuity of watercourses, including that of restoring at least 25,000 km of free-flowing rivers by 2030, which forms part of the EU biodiversity strategy.
See the report: http://bit.ly/2MEqc5Q (Original version in French by Damien Genicot)