%0 Thesis
%9 Doctoral
%A Van Biervliet, Oliver Robin Malcolm
%B Geography
%D 2024
%F discovery:10192241
%I UCL (University College London)
%P 615
%T The hydrological effects of the Eurasian beaver (Castor fiber) in a UK headwater catchment
%U https://discovery.ucl.ac.uk/id/eprint/10192241/
%X Beavers (Genus: Castor) are ecosystem engineers that build dams, impounding  water and causing a cascade of interacting changes to water fluxes and storage.  Few studies have quantified site-scale effects of beaver dams on the water  balance. The effect of beaver dams on low-flows and high-flows have been  reported but results are sometimes contradictory and underlying mechanisms  remain unresolved. Little consideration has been given to the effects on average  flows. Numerical modelling could help to fill such knowledge gaps, but an  appropriately validated approach for representing beaver dams is currently  lacking. This thesis investigates the hydrological effects of beaver dams using  25-months of monitoring data from adjacent catchments in eastern Scotland, one  with 28 beaver dams (165ha) and another without beaver dams (58ha). Field data  were used to build, calibrate and validate coupled hydrological/hydraulic models  (MIKE SHE/MIKE 11) representing a 418m stream reach and 12.3ha of  associated floodplain containing five beaver dams. Model simulations  demonstrated that fluxes of stream water, mainly to floodplain soils, reduced  stream discharges downstream of beaver dams causing average-flow reductions  of approximately 29% and a median peak-flow reduction of 3% (range: +4% to -  11%). Beaver dams appeared to augment downstream discharges when they fell  below the leakage rate through the dams (estimated to be 0.5-2.0Ls-1  ), but  reduced low flows above this threshold. Subsequent model scenarios  demonstrated that soil permeability modulated the effect of beaver dams with  many of the hydrological effects of the dams decreasing in magnitude with  reduced soil permeability. Additionally, a commonly employed device used to    control beaver pond water levels was shown to substantially reduce beaver dam-  induced floodplain water levels. By changing the behaviour of artificially incised    streams from draining floodplains to partially irrigating them, beaver dams could  help to restore wetlands well beyond beaver ponds themselves.
%Z Copyright © The Author 2024.  Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/).  Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms.  Access may initially be restricted at the author’s request.