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Sedimentation rhythms and hydrodynamics in two engineered environments in an open coast managed realignment site

Sedimentation rhythms and hydrodynamics in two engineered environments in an open coast managed realignment site
Sedimentation rhythms and hydrodynamics in two engineered environments in an open coast managed realignment site
Managed Realignment (MR) schemes are considered by many coastal managers and engineers to be a preferable method of coastal flood defence and compensating for habitat loss, by creating new areas of intertidal saltmarsh and mudflat habitat. Monitoring of MR sites has tended to focus on short term ecological factors, resulting in a shortage of high frequency, high resolution long term measurements of the evolution of the sediment erosion, transportation, deposition and consolidation cycle (ETDC) in newly breached sites. This is particularly true of analysis of the formation and preservation of sedimentary rhythmites and evaluations of sedimentation rates (and their variability) in newly inundated intertidal environments. This study provides an evaluation of sedimentation rhythms and hydrodynamics from two contrasting sites within the Medmerry Managed Realignment scheme, the largest open coast realignment in Europe (at the time of site inundation). Bed sediment altimeter data highlighted different sedimentation patterns at the two sites; near constant deposition of sediment occurred near the breach resulting in 15.2 cm of sediment being accreted over the one year monitoring period, whereas periodic accretion and erosion of sediment occurred inland leading to 2.7 cm of net accretion. Differences in the relationship between suspended sediment concentrations and site hydrodynamics were observed on a semi-diurnal to annual scale. This study highlights the need for further consideration of the sedimentation processes in MR schemes in order to enhance the design and construction of these sites. Advancements in the understanding of these processes will increase the success of MR schemes in terms of the evolution of the sediment regime and the ecosystem services provided, particularly as they are more widely accepted as a form of coastal flood defence and intertidal habitat creation method.
Managed realignment, Rhythmites, Altimeter, Hydrodynamics, Suspended sediment concentration (SSC), Intertidal mudflat morphology
0025-3227
120-131
Dale, Jonathan
f998e92c-cd34-45c2-bc2c-d38ff72b6edc
Burgess, Heidi M.
96772c7e-ab57-463f-8979-b70dd5a360c3
Cundy, Andrew B.
994fdc96-2dce-40f4-b74b-dc638286eb08
Dale, Jonathan
f998e92c-cd34-45c2-bc2c-d38ff72b6edc
Burgess, Heidi M.
96772c7e-ab57-463f-8979-b70dd5a360c3
Cundy, Andrew B.
994fdc96-2dce-40f4-b74b-dc638286eb08

Dale, Jonathan, Burgess, Heidi M. and Cundy, Andrew B. (2017) Sedimentation rhythms and hydrodynamics in two engineered environments in an open coast managed realignment site. Marine Geology, 383, 120-131. (doi:10.1016/j.margeo.2016.12.001).

Record type: Article

Abstract

Managed Realignment (MR) schemes are considered by many coastal managers and engineers to be a preferable method of coastal flood defence and compensating for habitat loss, by creating new areas of intertidal saltmarsh and mudflat habitat. Monitoring of MR sites has tended to focus on short term ecological factors, resulting in a shortage of high frequency, high resolution long term measurements of the evolution of the sediment erosion, transportation, deposition and consolidation cycle (ETDC) in newly breached sites. This is particularly true of analysis of the formation and preservation of sedimentary rhythmites and evaluations of sedimentation rates (and their variability) in newly inundated intertidal environments. This study provides an evaluation of sedimentation rhythms and hydrodynamics from two contrasting sites within the Medmerry Managed Realignment scheme, the largest open coast realignment in Europe (at the time of site inundation). Bed sediment altimeter data highlighted different sedimentation patterns at the two sites; near constant deposition of sediment occurred near the breach resulting in 15.2 cm of sediment being accreted over the one year monitoring period, whereas periodic accretion and erosion of sediment occurred inland leading to 2.7 cm of net accretion. Differences in the relationship between suspended sediment concentrations and site hydrodynamics were observed on a semi-diurnal to annual scale. This study highlights the need for further consideration of the sedimentation processes in MR schemes in order to enhance the design and construction of these sites. Advancements in the understanding of these processes will increase the success of MR schemes in terms of the evolution of the sediment regime and the ecosystem services provided, particularly as they are more widely accepted as a form of coastal flood defence and intertidal habitat creation method.

Text
Dale et al. 2017 Medmerry Sediment Rhythms_postprint.pdf - Accepted Manuscript
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More information

Accepted/In Press date: 1 December 2016
Published date: 1 January 2017
Keywords: Managed realignment, Rhythmites, Altimeter, Hydrodynamics, Suspended sediment concentration (SSC), Intertidal mudflat morphology
Organisations: Geochemistry

Identifiers

Local EPrints ID: 405042
URI: http://eprints.soton.ac.uk/id/eprint/405042
ISSN: 0025-3227
PURE UUID: 8bb83f9a-b9e9-4be5-a258-b73fda6a9f49
ORCID for Andrew B. Cundy: ORCID iD orcid.org/0000-0003-4368-2569

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Date deposited: 23 Jan 2017 14:10
Last modified: 17 Dec 2019 06:26

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Contributors

Author: Jonathan Dale
Author: Heidi M. Burgess
Author: Andrew B. Cundy ORCID iD

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