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Leaky dams augment afforestation to mitigate catchment scale flooding

Lookup NU author(s): Mhari Barnes, Dr James Bathurst, Dr Elizabeth Lewis, Dr Paul Quinn



This is the authors' accepted manuscript of an article that has been published in its final definitive form by John Wiley & Sons Ltd., 2023.

For re-use rights please refer to the publisher's terms and conditions.


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

Publication metadata

Author(s): Barnes MS, Bathurst JC, Lewis E, Quinn PF

Publication type: Article

Publication status: Published

Journal: Hydrological Processes

Year: 2023

Volume: 6

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.


DOI: 10.1002/hyp.14920

Notes: This version of the paper is the original submitted version, before peer review and journal acceptance. Under the Wiley licence agreement, the accepted version of the paper (revised following peer review and accepted by the journal) will be posted 12 months after the final journal publication.


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