Van Biervliet, Oliver Robin Malcolm;
(2024)
The hydrological effects of the Eurasian beaver (Castor fiber) in a UK headwater catchment.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
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.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | The hydrological effects of the Eurasian beaver (Castor fiber) in a UK headwater catchment |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | 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. |
| UCL classification: | UCL > Provost and Vice Provost Offices > UCL SLASH UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of S&HS UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of S&HS > Dept of Geography UCL |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10192241 |
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