Rebecca Haw and Michael Underwood, Hydrologists in our dedicated surface water team, attended the River Restoration Conference in Liverpool this week, and enjoyed listening to thought-provoking talks as well as sharing their expertise by presenting academic posters.
Here, Rebecca shares her key learnings from the conference:
The day started with the concept of reconnecting floodplains to the rivers by giving the rivers space. The presenters, based out in Oregon in the USA, showed compelling evidence for the ‘Stage 0’ restoration phase, where channels are returned back to the floor of the valley. Their results, although not yet quantified, have shown good initial responses with flow being slowed, as it is allowed to spread across the valley bottom coming into contact with rough areas such as fallen wood on the valley floor. The results of giving water space and returning it to valley floor level from a previously deeply incised channel is the spread of the power per unit area, this spread results in no flushing of the system so vegetation can survive, and nutrients are not lost downstream.
Engagement with communities and landowners was another hot topic, with this being a known barrier to implementing restoration projects. Whilst many recognise the issue, a single solution for all situations was elusive with different approaches working in different scenarios. There was a move towards showing landowners and the communities the benefits of the projects and restoration methods rather than imposing the methods. Engagement with industry and developers was also identified as important and currently lacking. As funding for restoration is currently limited, restoring rivers in the UK and around the world may ultimately fall to industry and developers. There was a keen interest to see this done through education of the benefits of including restoration as part of a development project or industrial enterprise, as well as the need for policy to guide and enforce restoration requirements.
Biology, not a topic often considered within river restoration was given centre stage in two interesting talks in the morphology and physical processes session. A key consideration here was the ability of a river to naturally evolve back to a more natural state if given the space to do so. This was shown in Janine Castro’s (US Fish and Wildlife Service) talk, where the large scale restoration project in Oregon was initially controlled by geology due to the deep incision into the clayey soils which confined the river to a single high power channel. This geological control is typically only seen in upland areas, not lower valleys like this case study. Once the channel was returned to the natural level of the valley floor the hydrology became the most important factor, with transport and depositional areas being created and moved with high and low flows. Finally, as the was no longer a high powered system in a small space, but a lower power system spread over a larger area, biology had the chance to develop and contribute to the factors controlling rivers with vegetation returning to banks and bars. This causes sediment entrapment and deposition increasing the channel diversity and habitat variation within the reach.
The conference provided a great debate on the hot topics of river restoration. The main take-aways were:
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