You may have seen Tweed Forum at a local event this year, using their miniature river catchment model to demonstrate a very big idea on a very small scale. As Luke Comins, Director of Tweed Forum, explains, “using our unique catchment model to show how Natural Flood Management works has been a big success for us at various events throughout Scotland this last year. People really get to grips with Natural Flood Management, something quite theoretical, when they can see it working right in front of their eyes.”
Tweed Forum’s innovative catchment model is a tangible demonstration of Natural Flood Management (NFM), using 2 miniature river catchments to explore how NFM works. One catchment features various NFM measures, whereas the other reflects a more typical rural landscape. ‘Rain’ is introduced into the catchment via a number of nozzles and the resulting flow of water through the river channel and across the wider landscape can be easily seen. More importantly, the volume of water being “retained” by the two catchments can be measured, showing very clearly that the catchment with various NFM measures retains far more water than its counterpart. This natural capacity of the landscape to retain water is what NFM relies on, slowing flood flows so that flood events are more manageable for the communities impacted by them.
More specifically, NFM uses a catchment-based approach, looking at the total river catchment from source to sea. Even if flooding is only an issue at one single point within the river system, it recognises that the river exists and reacts as a single unit within the boundaries of its catchment. NFM harnesses the power of natural river processes, such as meandering channels, floodplain storage and the presence of large woody debris, and carefully deploys these measures within the river system instead of relying on ‘hard’ engineering, such as concrete flood barriers. These NFM measures, when correctly deployed, work together to sustainably reduce the impact of flooding at key sites.
Handily, NFM measures usually provide other benefits too, such as creating additional or improved spawning habitat for fish. For example, NFM measures on the Eddleston Water are being put to very good use by spawning salmon, barely a year and half after the meandering channels were created. Another potential benefit for the salmon angler, in areas with NFM measures, is an increase in favourable river levels. This is due to NFM measures “slowing the flow” of water such that a return to unfavourably low water conditions is considerably delayed. Getting as many benefits as possible from a single project is a key aspect of much of Tweed Forum’s work in the catchment.
The catchment model will continue to be showcased at various local shows and events so keep an eye out for the Tweed Forum banner at an event near you. If you would like to read more or request the catchment model at your event click.
Words by Nicola Bissett Project Officer.