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Reduced fine sediment flux and channel change in response to the managed diversion of an upland river channel

Perks, M.J.; Warburton, J.

Reduced fine sediment flux and channel change in response to the managed diversion of an upland river channel Thumbnail


Authors

M.J. Perks



Abstract

This paper describes the implementation of a novel mitigation approach and subsequent adaptive management, designed to reduce the transfer of fine sediment (< 2 mm) in Glaisdale Beck, a small, predominantly upland catchment in the UK. Hydro-meteorological and suspended sediment data sets are collected over a 2-year period spanning pre- and post-diversion periods in order to assess the impact of the channel reconfiguration scheme on the fluvial suspended sediment dynamics. Analysis of the river response demonstrates that the fluvial sediment system has become more restrictive with reduced fine sediment transfer. This is characterized by reductions in flow-weighted mean suspended sediment concentrations from 77.93 mg L−1 prior to mitigation, to 74.36 mg L−1 following the diversion. A Mann–Whitney U test found statistically significant differences (p < 0.001) between the pre- and post-monitoring median suspended sediment concentrations (SSCs). Whilst application of one-way analysis of covariance (ANCOVA) on the coefficients of sediment rating curves developed before and after the diversion found statistically significant differences (p < 0.001), with both Loga and b coefficients becoming smaller following the diversion. Non-parametric analysis indicates a reduction in residuals through time (p < 0.001), with the developed LOWESS model over-predicting sediment concentrations as the channel stabilizes. However, the channel is continuing to adjust to the reconfigured morphology, with evidence of a headward propagating knickpoint which has migrated 120 m at an exponentially decreasing rate over the last 7 years since diversion. The study demonstrates that channel reconfiguration can be effective in mitigating fine sediment flux in headwater streams but the full value of this may take many years to achieve whilst the fluvial system slowly readjusts.

Citation

Perks, M., & Warburton, J. (2016). Reduced fine sediment flux and channel change in response to the managed diversion of an upland river channel. Earth Surface Dynamics, 4(3), 705-719. https://doi.org/10.5194/esurf-4-705-2016

Journal Article Type Article
Acceptance Date Aug 3, 2016
Online Publication Date Sep 2, 2016
Publication Date Sep 2, 2016
Deposit Date Oct 18, 2016
Publicly Available Date Mar 28, 2024
Journal Earth Surface Dynamics
Print ISSN 2196-6311
Publisher Copernicus Publications
Peer Reviewed Peer Reviewed
Volume 4
Issue 3
Pages 705-719
DOI https://doi.org/10.5194/esurf-4-705-2016

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