The importance of removing obsolete barriers from our rivers
Rivers around the world have been heavily modified for many years now, for a variety of reasons and purposes. There are over 1 million barriers such as culverts, dams, and weirs in European rivers, impacting river health and ecology. In the UK, 23,000 barriers affect more than 99% of our rivers. While these played a vital role in the past in providing energy, drinking water, and enabling navigation, a great number of these have now become obsolete – up to 20% of recorded barriers in Britain are no longer in use.
Our rivers suffer enormous pressures from pollution, water abstraction, and channelisation, to name a few, which negatively affect their health and their resilience capacity to cope with extreme weather conditions posed by a changing climate. Outdated, needless barriers amount to these issues and put even more strain on local wildlife. An increase in pollution concentrations and changes in the movement of nutrients, sediments and water levels are some of the impacts.
These barriers also affect the availability and diversity of habitats for wildlife, leading to a loss of biodiversity. Migratory fish species, such as the European eel, the Atlantic Salmon, sturgeon, and others, are heavily impacted by these obstacles which prevent them from swimming to spawning grounds. From an ecosystem perspective, barriers can alter flow patterns that are vital for the productivity of downstream floodplains and wetlands.
Removing obsolete barriers can benefit both people and nature. Degraded and outdated barriers can pose risks to local communities and properties in the event of increased river flows resulting from changing weather patterns and conditions in times of climate change. As many concrete dams were built between 1930-1970, they’re nearing their 100-year lifespan and were not designed to cope with sudden flood events. The removal of these barriers is not only a cost-effective way to prevent expensive maintenance and repair works but also to decrease flood risks by reinstating natural processes and reconnecting a river to its floodplain.
River continuity is key to a healthy river. Around 674 rivers in England don’t achieve good ecological status due to “barriers to fish migration and impoundments”, and they are also one of the main reasons for European rivers failing to reach good ecological status.
At Thames21 we know the importance of natural, healthy, and resilient rivers for communities and biodiversity. Our river restoration projects use a variety of techniques and nature-based solutions to boost river health and water quality such as constructing wetlands, installing woody deflectors, removing toe-boarding, managing vegetation, and others. In our recently completed Glassmill Pond and River Ravensbourne restoration project, for example, we installed cobbles and gravel on the riverbed to enhance fish passage within the site.
If you want to learn more about our work and current projects, you can do so here. Also, you can check out our social media, where we’re constantly posting updates and opportunities to get involved in our work.