Shoreline response of eroding soft cliffs due to hard defences
Shoreline response of eroding soft cliffs due to hard defences
Soft cliff retreat has often triggered a hard adaptation response by the building of seawalls and groynes. On adjacent undefended coasts erosion continues, resulting in set-backs. This paper examines the impact of coastal defences on the adjacent coast from historic records and present practices, and explores possible future response. Continued set-back often leads to outflanking of defences, making them ineffective at their extremities, particularly at the down-drift end where it is most severe. Solutions to outflanking usually involve extending defences, initiating a cycle of set-back, outflanking and further extensions. Multiple defence extensions and continued retreat of the unprotected adjacent coast results in artificial headland formation. Over several decades, headlands experience foreshore steepening and reduced sediment availability, making them more difficult and expensive to defend. Shoreline management plan policies of managed retreat advocate selective defence abandonment, which may change the nature of artificial headland formation. Defence abandonment and new engineering works must be planned, anticipating the processes described in this paper. This will reduce unexpected changes and reduce maintenance and emergency work costs.
3-14
Brown, S.
dd3c5852-78cc-435a-9846-4f3f540f2840
Barton, M.E.
eea85a67-8def-49a1-a48c-f332310388d9
Nicholls, R.J.
4ce1e355-cc5d-4702-8124-820932c57076
March 2014
Brown, S.
dd3c5852-78cc-435a-9846-4f3f540f2840
Barton, M.E.
eea85a67-8def-49a1-a48c-f332310388d9
Nicholls, R.J.
4ce1e355-cc5d-4702-8124-820932c57076
Brown, S., Barton, M.E. and Nicholls, R.J.
(2014)
Shoreline response of eroding soft cliffs due to hard defences.
Proceedings of the Institution of Civil Engineers - Maritime Engineering, 167 (1), .
(doi:10.1680/maen.11.00026).
Abstract
Soft cliff retreat has often triggered a hard adaptation response by the building of seawalls and groynes. On adjacent undefended coasts erosion continues, resulting in set-backs. This paper examines the impact of coastal defences on the adjacent coast from historic records and present practices, and explores possible future response. Continued set-back often leads to outflanking of defences, making them ineffective at their extremities, particularly at the down-drift end where it is most severe. Solutions to outflanking usually involve extending defences, initiating a cycle of set-back, outflanking and further extensions. Multiple defence extensions and continued retreat of the unprotected adjacent coast results in artificial headland formation. Over several decades, headlands experience foreshore steepening and reduced sediment availability, making them more difficult and expensive to defend. Shoreline management plan policies of managed retreat advocate selective defence abandonment, which may change the nature of artificial headland formation. Defence abandonment and new engineering works must be planned, anticipating the processes described in this paper. This will reduce unexpected changes and reduce maintenance and emergency work costs.
Text
maen.11
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Accepted/In Press date: 12 June 2013
Published date: March 2014
Organisations:
Energy & Climate Change Group
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Local EPrints ID: 359764
URI: http://eprints.soton.ac.uk/id/eprint/359764
ISSN: 1741-7597
PURE UUID: a8cdb535-aec9-4c86-b0b2-00c00c26aa32
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Date deposited: 12 Nov 2013 11:45
Last modified: 15 Mar 2024 03:31
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