University of Worcester Worcester Research and Publications

Field-based monitoring of instream leaky barrier backwater and storage during storm events

Muhwenimana, V., Follett, E., Maddock, Ian ORCID: and Wilson, C.A.M.E (2023) Field-based monitoring of instream leaky barrier backwater and storage during storm events. Journal of Hydrology, 622 (Part A). p. 129744. ISSN 0022-1694

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Engineered leaky barriers are increasingly used as natural flood management methods providing ecosystem and water quality benefits in addition to flood attenuation, complementing hard engineering flood defences. Field-based monitoring of a natural flood management site, Wilde Brook in the Corvedale catchment, England (UK) studied the rainfall-runoff relationship for a 5.36 km reach with 105 leaky barriers over two years. Paired pressure transducers were placed upstream and downstream of three channel spanning leaky barriers, allowing evaluation of upstream backwater rise relative to rainfall intensity, storm magnitude, and frequency. By increasing backwater rise, the leaky barriers caused overbank flows, resulting in a reduction in the cross-sectional area velocity after the event. The incidence of overbank flow depended on the local stream cross-sectional profile, barrier properties, location in the reach, and storm magnitude. Barrier operational flow conditions were classified into five modes according to relative bank inundation and barrier submergence extent. The backwater rise magnitude depended on barrier physical properties and evolution over time through cycles of accretion and build-up of brash and leafy material in the barrier, in addition to local bedload sediment transport dynamics, where instances of scour around the barriers were observed. Backwater rise and net volume hydrographs showed rapid filling up behind the barriers on the rising limb and slower water release on the falling limb. For a ∼4 yr return period storm event, results indicated that one leaky barrier increased storage volume by up to 102 m3, which translates to an overall net volume increase of ∼10,700 m3 for the full reach. These new findings provide quantitative evidence of leaky barrier backwater and storage performance, and leaky barrier design recommendations for storms up to a 4 yr return period. This evidence can be used to develop and validate flood modelling generalised approaches for smaller, more frequent storms, and work towards the development of an approach for modelling leaky barriers for larger storm magnitudes.

Item Type: Article
Uncontrolled Discrete Keywords: Natural flood management, Leaky barrier, Flood attenuation, Backwater rise, Barrier storage
Subjects: G Geography. Anthropology. Recreation > G Geography (General)
G Geography. Anthropology. Recreation > GB Physical geography
G Geography. Anthropology. Recreation > GE Environmental Sciences
Q Science > Q Science (General)
T Technology > TC Hydraulic engineering. Ocean engineering
Divisions: College of Health, Life and Environmental Sciences > School of Science and the Environment
Related URLs:
Copyright Info: © 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (
Depositing User: Ian Maddock
Date Deposited: 08 Jun 2023 09:39
Last Modified: 27 Mar 2024 09:50

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