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Lookup NU author(s): Mhari Barnes, Dr James Bathurst, Dr Elizabeth Lewis, Dr Paul Quinn
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
Despite calls for large-scale afforestation to alleviate flooding, the effectiveness of such action remains unclear. Simulations with the SHETRAN hydrological model are therefore carried out for the 335-km2 Irthing catchment and its 1-10-km2 headwater catchments in northwest England to determine: whether forests can reduce flood peak discharges in a large catchment; the proportion of the catchment that requires afforestation to be effective; and the extent to which a combination of afforestation and natural flood management features (leaky dams) improves upon afforestation on its own. Four-year simulations were run with a range of forest covers and extents of leaky dam installation, the latter modelled as a channel hydraulic resistance. Hydrograph, flood frequency and peak discharge magnitude responses to forest cover simulated (and observed) in the headwater catchments are replicated in simulations at the full scale. Afforestation on its own can reduce the frequency of given flood magnitudes but has a variable and limited impact on individual peak discharge magnitudes. For the Irthing, a 100% forest cover reduces the mean discharge of 20 peaks in a partial duration flood series by 17.7% relative to 100% grassland cover but reduces the largest peak by only 4.4%. Accompanying adverse effects include 33.5% reduction in long-term runoff and loss of agricultural land. By contrast, leaky dams are found to mitigate flood frequencies and peak discharges effectively, over a range of discharge magnitudes, with no reduction of annual runoff. For the Irthing, installation in streams with Strahler orders of 1-3 reduces the mean peak discharge by around 40% and reduces the largest peak by around 50%. The study quantifies the extent to which a dense network of leaky dams can augment the otherwise limited effectiveness of afforestation for flood mitigation, while minimizing adverse impacts on water resources and food security.1School of Engineering, Cassie Building, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
Author(s): Barnes MS, Bathurst JC, Lewis E, Quinn PF
Publication type: Article
Publication status: Published
Journal: Hydrological Processes
Year: 2023
Volume: 37
Issue: 6
Print publication date: 13/06/2023
Online publication date: 13/06/2023
Acceptance date: 26/05/2023
Date deposited: 01/06/2023
ISSN (print): 0885-6087
ISSN (electronic): 1099-1085
Publisher: John Wiley & Sons Ltd.
URL: https://doi.org/10.1002/hyp.14920
DOI: 10.1002/hyp.14920
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