Hydraulic Modelling of Eurasian Beaver Structural Modifications: Implications for Evaluating their Contributions to Natural Flood Management in Scotland

Sammanfattning: The concurrent climate and biodiversity crises in Scotland necessitate the exploration of ecosystem-based adaptation to simultaneously address increased flood risk and the loss of native species. This research investigated the contributions of Eurasian beaver reintroductions to natural flood management in Scotland. It did this by reviewing the relevant literature on the primary structural modifications built by beavers and translating them into modellable features. A 1D hydraulic model of a small Scottish river system was then built and the presence of these structures simulated to analyse their effects on flooded areas during a 1 in 10-year event. Several key findings emerged that suggest these structures can have a marginal net attenuative effect on a hyper-local scale, but with significant uncertainty dependent on dam size and channel morphology. There were divergent upstream and downstream effects that were not reflected in total flood extent calculations. The modelling process brought about a critical examination of the utility models in assessing the contributions of beaver reintroductions to the field of natural flood management, concluding that models are inherently limited in their ability to capture the complexity of natural systems. Insights from the theories of complex adaptive systems and deep ecology further complicate what it means to evaluate the contributions of non-human species to flood risk management, and whether their ecosystem services should be the sole justification for their reintroduction.