Destabilisation and Accelerated Roll-Back of a Mixed Sediment Barrier in Response to a Managed Breach
Sea level rise increases the pressure on many coastlines to retreat landwards which will lead to coastlines previously held in position through management, being allowed to retreat where this is no longer affordable or sustainable. Barrier beaches have historically rolled back in response to differe...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-04-01
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| Series: | Journal of Marine Science and Engineering |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2077-1312/9/4/374 |
| _version_ | 1797539127721197568 |
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| author | Uwe Dornbusch |
| author_facet | Uwe Dornbusch |
| author_sort | Uwe Dornbusch |
| collection | DOAJ |
| description | Sea level rise increases the pressure on many coastlines to retreat landwards which will lead to coastlines previously held in position through management, being allowed to retreat where this is no longer affordable or sustainable. Barrier beaches have historically rolled back in response to different hydrodynamic events and sea level rise, but very little is known as to how quickly and how far roll-back is going to occur once management has ceased. Data from more than 40 topographical surveys collected over 7 years along the 1.5 km long, almost swash-aligned shingle barrier at Medmerry (southern England) are used together with hydrodynamic data in a wide-ranging assessment of barrier roll-back. This study shows that roll-back is progressing through time along the barrier in downdrift direction in response to a gradual reduction in cross-sectional area through longshore transport. The Barrier Inertia concept provides a practical means to assess stability/instability for events experienced, but also a tool to assess the short- to medium term risk to the coast downdrift of the immediate study area where flood risk still needs to be managed. Roll-back is influenced particularly by the creation of an artificial tidal breach and removal of its sediment, the elevation of the underlying marsh and clay sediments, the number and severity of storms experienced and the presence of legacy groynes; roll-back has exceeded modelled predictions and expert judgement by an order of magnitude. |
| first_indexed | 2024-03-10T12:41:51Z |
| format | Article |
| id | doaj.art-ac4559c8ad454e1a8c6966d4b74f690a |
| institution | Directory Open Access Journal |
| issn | 2077-1312 |
| language | English |
| last_indexed | 2024-03-10T12:41:51Z |
| publishDate | 2021-04-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Journal of Marine Science and Engineering |
| spelling | doaj.art-ac4559c8ad454e1a8c6966d4b74f690a2023-11-21T13:52:34ZengMDPI AGJournal of Marine Science and Engineering2077-13122021-04-019437410.3390/jmse9040374Destabilisation and Accelerated Roll-Back of a Mixed Sediment Barrier in Response to a Managed BreachUwe Dornbusch0Environment Agency, Worthing BN11 1LD, UKSea level rise increases the pressure on many coastlines to retreat landwards which will lead to coastlines previously held in position through management, being allowed to retreat where this is no longer affordable or sustainable. Barrier beaches have historically rolled back in response to different hydrodynamic events and sea level rise, but very little is known as to how quickly and how far roll-back is going to occur once management has ceased. Data from more than 40 topographical surveys collected over 7 years along the 1.5 km long, almost swash-aligned shingle barrier at Medmerry (southern England) are used together with hydrodynamic data in a wide-ranging assessment of barrier roll-back. This study shows that roll-back is progressing through time along the barrier in downdrift direction in response to a gradual reduction in cross-sectional area through longshore transport. The Barrier Inertia concept provides a practical means to assess stability/instability for events experienced, but also a tool to assess the short- to medium term risk to the coast downdrift of the immediate study area where flood risk still needs to be managed. Roll-back is influenced particularly by the creation of an artificial tidal breach and removal of its sediment, the elevation of the underlying marsh and clay sediments, the number and severity of storms experienced and the presence of legacy groynes; roll-back has exceeded modelled predictions and expert judgement by an order of magnitude.https://www.mdpi.com/2077-1312/9/4/374shingle beachcoastal catch-uplongshore transportmarsh cliff erosionoverwashovertopping |
| spellingShingle | Uwe Dornbusch Destabilisation and Accelerated Roll-Back of a Mixed Sediment Barrier in Response to a Managed Breach Journal of Marine Science and Engineering shingle beach coastal catch-up longshore transport marsh cliff erosion overwash overtopping |
| title | Destabilisation and Accelerated Roll-Back of a Mixed Sediment Barrier in Response to a Managed Breach |
| title_full | Destabilisation and Accelerated Roll-Back of a Mixed Sediment Barrier in Response to a Managed Breach |
| title_fullStr | Destabilisation and Accelerated Roll-Back of a Mixed Sediment Barrier in Response to a Managed Breach |
| title_full_unstemmed | Destabilisation and Accelerated Roll-Back of a Mixed Sediment Barrier in Response to a Managed Breach |
| title_short | Destabilisation and Accelerated Roll-Back of a Mixed Sediment Barrier in Response to a Managed Breach |
| title_sort | destabilisation and accelerated roll back of a mixed sediment barrier in response to a managed breach |
| topic | shingle beach coastal catch-up longshore transport marsh cliff erosion overwash overtopping |
| url | https://www.mdpi.com/2077-1312/9/4/374 |
| work_keys_str_mv | AT uwedornbusch destabilisationandacceleratedrollbackofamixedsedimentbarrierinresponsetoamanagedbreach |