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The past, present and future evolution of Hurst Castle spit, Hampshire

The past, present and future evolution of Hurst Castle spit, Hampshire
The past, present and future evolution of Hurst Castle spit, Hampshire
Previous models of the evolution of Hurst Castle Spit over-emphasised longshore growth at the expense of other processes, particularly rise in sea-level. Initially, a Pleistocene valley system was submerged creating a tidal strait, the West Solent, between Christchurch Bay and the East Solent. This almost certainly caused a major hydrodynamic change, transforming much of Christchurch Bay and the West Solent from a low to a high tidal energy environment. Hurst Castle Spit and the Shingles Bank then began to form due to a combination of an easterly littoral drift, offshore gravel movement due to the high tidal energy, a rising sea-level, the transgression of Hurst Beach due to overwashing and the formation of recurves due to waves in the West Solent. The growth of the Shingles Bank due to offshore sediment movement from Hurst Castle Spit was of particular importance because of its influence on the wave energy along Hurst Beach. Significant local supplies of shingle in the vicinity of Hurst Castle Spit, reworked from Quatenary deposits, were also of importance. Thus, it is not a classic multi-recurved spit and the transgressive segment, Hurst Beach, has much in common with barrier coastlines.

The same processes are continuing to shape Hurst Castle Spit at present, with the additional effects of human interference in the coastal sediment system. The construction of sea defences at Milford-on-Sea in the period 1936 to 1968 has modified the sediment budget and Hurst Castle Spit is experiencing a phase of rapid evolution: maximum recession rates have increased from 1.5m a?1 (1867–1968) to 3.5m a?1 (1968–1982). It is difficult to quantify the exact role of sea-level rise in the present evolution of Hurst Castle Spit.

The future evolution of Hurst Castle Spit will depend largely on man. If there is no further interference, which is highly unlikely, the beach volume will continue to decline, resulting in a further increase in the rate of recession. Ultimately, a true tidal breach will probably form, marking a new phase in the evolution of Hurst Castle Spit and its environs. However, shingle renourishment, or another coastal engineering solution will probably be undertaken. The future rate of sea-level rise will have important long-term influences on all these options.
0079-6611
119-137
Nicholls, R.J.
4ce1e355-cc5d-4702-8124-820932c57076
Webber, N.B.
35b67b22-86ae-45ee-a79e-7b8c220b8838
Nicholls, R.J.
4ce1e355-cc5d-4702-8124-820932c57076
Webber, N.B.
35b67b22-86ae-45ee-a79e-7b8c220b8838

Nicholls, R.J. and Webber, N.B. (1987) The past, present and future evolution of Hurst Castle spit, Hampshire. Progress in Oceanography, 18 (1-4), 119-137. (doi:10.1016/0079-6611(87)90029-2).

Record type: Article

Abstract

Previous models of the evolution of Hurst Castle Spit over-emphasised longshore growth at the expense of other processes, particularly rise in sea-level. Initially, a Pleistocene valley system was submerged creating a tidal strait, the West Solent, between Christchurch Bay and the East Solent. This almost certainly caused a major hydrodynamic change, transforming much of Christchurch Bay and the West Solent from a low to a high tidal energy environment. Hurst Castle Spit and the Shingles Bank then began to form due to a combination of an easterly littoral drift, offshore gravel movement due to the high tidal energy, a rising sea-level, the transgression of Hurst Beach due to overwashing and the formation of recurves due to waves in the West Solent. The growth of the Shingles Bank due to offshore sediment movement from Hurst Castle Spit was of particular importance because of its influence on the wave energy along Hurst Beach. Significant local supplies of shingle in the vicinity of Hurst Castle Spit, reworked from Quatenary deposits, were also of importance. Thus, it is not a classic multi-recurved spit and the transgressive segment, Hurst Beach, has much in common with barrier coastlines.

The same processes are continuing to shape Hurst Castle Spit at present, with the additional effects of human interference in the coastal sediment system. The construction of sea defences at Milford-on-Sea in the period 1936 to 1968 has modified the sediment budget and Hurst Castle Spit is experiencing a phase of rapid evolution: maximum recession rates have increased from 1.5m a?1 (1867–1968) to 3.5m a?1 (1968–1982). It is difficult to quantify the exact role of sea-level rise in the present evolution of Hurst Castle Spit.

The future evolution of Hurst Castle Spit will depend largely on man. If there is no further interference, which is highly unlikely, the beach volume will continue to decline, resulting in a further increase in the rate of recession. Ultimately, a true tidal breach will probably form, marking a new phase in the evolution of Hurst Castle Spit and its environs. However, shingle renourishment, or another coastal engineering solution will probably be undertaken. The future rate of sea-level rise will have important long-term influences on all these options.

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Published date: 1987
Organisations: Energy & Climate Change Group

Identifiers

Local EPrints ID: 353140
URI: https://eprints.soton.ac.uk/id/eprint/353140
ISSN: 0079-6611
PURE UUID: 2ddaf761-5d3a-4027-b973-5358552bbb7d
ORCID for R.J. Nicholls: ORCID iD orcid.org/0000-0002-9715-1109

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Date deposited: 18 Jun 2013 13:16
Last modified: 06 Jun 2018 12:44

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Author: R.J. Nicholls ORCID iD
Author: N.B. Webber

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