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Coast Protection and Sea Defence

As a result of research commissioned by the Ministry of Agriculture, Fisheries and Food (MAFF) the coastline of England and Wales has been subdivided into major ‘sediment cells’. A sediment cell is defined as ‘a length of coastline which is relatively self-contained as far as the movement of sand or shingle is concerned and where interruption to such movement should not have a significant effect on adjacent sediment cells’. The Solent frontage is contained within sediment cell 5 and is subdivided into subcells 5a-5e (Map 20).

The coastal group for the Solent area is SCOPAC. Coastal groups provide a forum for considering the needs of the sediment cell and developing forward looking Shoreline Management Plans which take account of natural processes, coastal defence needs, environmental considerations, planning issues and current and future land use. Responsibility for development of the plans rests with the operating authorities (i.e. the district councils and the NRA).

The Solent coastline is included within three Shoreline Management Plans:

(i) Hurst Spit to Hamble River - lead authority New Forest District Council

(ii) Hamble River to Selsey Bill - lead authority Chichester District Council

(iii) Isle of Wight - lead authority Isle of Wight Council.

The preparation of the three plans is under way.

For the SCOPAC coastline the best estimate for sea level rise is 6mm per annum and this has been accepted by MAFF as an appropriate allowance to be made in the design of new coast protection works. The figure for Portsmouth Harbour area is 10mm.

Description of the Solent Coastline

Northern Shore

Section 1 Christchurch Bay

Although not part of the Solent as such, the bathymetry and the processes operating in Christchurch Bay have a major effect on the land forms and tidal regime of the Western Solent.

Hengistbury Head to Hurst Spit - Mainly characterised by narrow shingle beaches and soft cliffs which increase in height from Milford on Sea to Highcliffe. Extensive protection works have been built by New Forest District Council and Christchurch Borough Council leaving unprotected sections of eroding coast only at Naish and Hordle Cliffs. Most of the protection works, which cover above 60% of the Christchurch Bay shoreline, have been built or replaced over the last 20 years, and are generally in good condition.

Naish Cliffs are an internationally important geological SSSI and provide the only naturally occurring source of beach material in the eastern part of Christchurch Bay. The Barton clays exposed by erosion are the international yardstick for this type of geological formation.

The cliffs are eroding by up to two metres per year and there are concerns that the Barton and Highcliffe protection works may eventually become outflanked. Research is being carried out into developing methods of slowing the rate of cliff erosion without damaging the SSSI.

Section II - Hurst Spit to Lymington River

This is a low lying area, mainly within the Hurst Castle to Lymington River SSSI, and very susceptible to flooding.

Hurst Spit -A naturally formed shingle spit protecting the whole Western Solent from the prevailing south west winds and long fetch waves from the Atlantic. The shingle beach is fortified with rock at its north-western end, and with hardwood timber breastwork around the castle at its south-eastern end.

Protection works constructed at Milford, and further west, over the last 50 years have substantially reduced the natural shingle supply to the Spit in the littoral drift, and caused it to diminish in size. Breaching now occurs every winter under storm wave attack.

The Spit is in the joint ownership of New Forest District Council, Hampshire County Council and a private owner. The public authorities share the repair and maintenance costs, which are growing yearly as the Spit diminishes in size and becomes ever more vulnerable to wave attack. A proposal to re-nourish the Spit with 600,000 tonnes of shingle, possibly dredged from the Shingles Bank, has been submitted for government approval and financial assistance.

Keyhaven River - Unprotected except at its upstream end at Keyhaven. Salt marshes either side being lost by encroachment of Hurst Spit to the west and migration northwards of the river mouth. Parts of Keyhaven prone to flooding (flood door recently installed on the coastal road). Small ferry excursions and fishing excursions operate.

Keyhaven to Lymington - Extensive saltmarshes are backed by a seawall built in the early 1990s by the NRA. Very rural in character but with scattered development approaching Lymington. There is a major sewage works and sea outfall at Pennington.

The saltmarshes have been receding for many years, the current rate of recession being about six metres per year. Despite extensive investigation and monitoring the causes of saltmarsh recession in this area are still not well understood. Rising sea levels could hasten the decline of the marshes as the seawall will prevent them from retreating inland as the water level rises.

Section III - Lymington River

Following severe flooding in 1989/90 the river banks and quay walls were rebuilt to a higher level in conjunction with the new Lymington to Keyhaven seawall. Some of the work was carried out by private owners of river frontages, the remainder by the NRA. A timber wave screen was built across the river in 1993 to protect moored boats.

The upper reaches of the river, north of the road bridge, are entirely fresh water due to the action of a one way tidal flap installed in the nineteenth century. In the lower reaches the saltmarshes are eroding at about the same rate as the Lymington to Keyhaven marshes. Trial works in 1994, designed to protect the saltmarsh edge from erosion, have proved largely unsuccessful. The marshes are jointly monitored by New Forest District Council and the Lymington Harbour Commissioners.

Significant lengths of frontage on the east side of the river are occupied by British Rail, and by the Wightlink ferry terminal. In 1991 proposals to increase the size of ferries operating between Lymington and the Isle of Wight ran into considerable opposition and have now been shelved.

Section IV - Lymington River to Calshot

Saltmarshes east of the Lymington River give way to natural shingle beaches, some with softwood timber groynes and revetment works. This is a low lying very rural area with isolated developments between Pitts Deep and Thorns Beach. Most of the shoreline is in the ownership of the Pylewell, Sowley, Beaulieu, Exbury and Cadland Estates.

Beaulieu River - No protection works except for a few jetties with extensive but eroding saltmarshes at the mouth. The high water river entrance separating Needs Ore Point from Gull Island was blocked up in the late 1980s for habitat conservation reasons, resulting in the eastward growth of Gull Island across the main river mouth.

Lepe - The shingle beach begins on the eastern side of the Beaulieu River mouth and continues to Stansore Point. Mixed softwood and hardwood timber protection works have been built in front of Lepe House and along the Country Park shoreline. About 70% of the coast is protected in this way; about 25% being in private ownership. The softwood erodes fairly rapidly and needs regular maintenance and replacement.

A rock revetment was constructed in 1994 by Hampshire County Council, between Lepe House and Lepe Point, to support the coastal road, and a mixed rock and concrete revetment, in reasonable condition, protects Lepe Point itself.

Stanswood Bay - A natural shingle barrier beach protects a low lying marshy nature reserve area at the south end, near Stansore Point, and continues through to Hillhead. There are rapidly eroding low sandy cliffs in the middle of the bay near Bourne Gap.

Softwood timber groynes and revetments constructed by Cadland Estate protect 50% of the shoreline, with a further 10% protected by stone walls. The condition of the protection works is variable but Cadland Estate is gradually renewing the old sections.

Calshot - Situated on a natural shingle spit with a large shoal area just offshore. Mixed softwood and hardwood groynes and revetments have been renewed by New Forest District Council over the last five years.

Calshot Activity Centre is operated by Hampshire County Council who maintain the concrete protection walls around it, whilst Calshot Castle and its surrounding stone revetment is in the hands of English Heritage.

Section V - Southampton Water and the River Hamble

Western Shore - Between Calshot Spit and Hythe a series of low walls of varying construction and condition line the shore in front of the refinery and petro-chemical complexes. Ashlett Creek contains saltmarshes, but the only protection works are around the sailing club.

Hythe Marina is well protected by recently built stone and concrete walls, whilst to the north Dibden Bay is an undeveloped area of reclaimed land owned by ABP. Hythe, Marchwood and Eling are mostly well protected by old stone and concrete seawalls, quays and promenades.

Extensive tracts of saltmarsh, offering valuable natural protection to the shoreline, still exist between Calshot and Hythe, and between Marchwood and Eling.

Eastern Shore - Southampton Docks to mouth of River Itchen - all well protected quay walls including Red Funnel terminal, Town Quay and Ocean Village marinas etc.

Netley to River Hamble (Eastleigh District Coastline) - 75% man-made defences, 13% natural defences, and 12% undefended. 5.14km of man-made defences require moderate works and 1.86km show some signs of wear. 3.26km of man-made defences and 1.18km natural defences partly or wholly responsibility of district council.

Policies with regard to development on Eastleigh District coastline are contained in Structure Plan Policy C.12 and Deposit District Plan Policies 17.CO and 18.CO and amendments 2.35/36.

Netley to Hamble Common - shingle beaches with muddy foreshore either unprotected or bounded by low stone or reinforced concrete/sheet pile retaining walls. Problem areas include Netley Cliff (sand and gravel cliffs up to 9m high) which are eroding at between 0.1 m and 0.35m/year and Hamble Common where low lying land is eroding at up to 0.5m/year. A number of important historical and archaeological features are at risk at this latter site. Eastleigh Borough Council is intending to carry out "soft engineered" schemes to halt or reduce further erosion at both of these locations.

Hamble Common to Bursledon Bridge (River Hamble) - Recreational, commercial and residential uses with banks mostly well protected by quays and walls of either sheet piling and/or concrete as well concrete/stone/revetments.

Section VI - Southampton Water to Portsmouth Harbour

Solent Breezes - Shingle beach in front of low cliffs protected by stone filled gabions and timber breastwork with broken concrete behind.

Hill Head - Shingle beach with concrete sea wall/esplanade behind; timber groynes.

Lee on Solent - Shingle beach with sea wall/esplanade behind and timber groynes (car park and other development behind). Serious erosion along 2 kilometres of the Lee on Solent frontage is being investigated with a view to undertaking shingle beach nourishment in the near future.

Browndown Ranges (MOD) - Shingle beach with old timber groynes and low wall of broken concrete.

Stokes Bay - Wide shingle beach unprotected in places but otherwise with low sea wall/promenade behind - no groynes.

Gilkicker - Shingle beach with timber groynes and concrete sea wall/esplanade in places only.

Fort Monckton (MOD) - Broken rock revetment protecting stone wall of fort.

HMS Haslar (MOD) - Very substantial sloping stone slabbed revetment with level stone paved "esplanade" at the top.

HMS Dolphin (MOD) - Very substantial sloping stone slabbed revetment or stepped wall with level "esplanade" extending to entrance to Portsmouth Harbour. Similar, very well protected frontage continues into harbour with wharves, sea walls, sheet piling sections etc., to whole of HMS Dolphin frontage.

Section VII - Portsmouth Harbour

Creek Behind HMS Dolphin - Partly unprotected (mudflats) but with miscellaneous protection to development at Seafield and Haslar Road.

Haslar Marina, Gosport Ferry and Camper and Nicholson Marina - Well protected with stone armouring quay walls and revetments in good condition.

Forton and Camber Basin (MOD) - Miscellaneous concrete and timber sea walls, some in poor condition.

Priory Road and Elson - Miscellaneous stone/concrete walls and revetments - variable condition.

Bedenham and Fleetlands (MOD) - Protected by embankments and groynes only.

Fareham Creek - Miscellaneous low sea walls with low open ground behind with quays at Town Quay and Upper Quay.

Portchester - Low lying areas protected by low concrete/timber/stone walls - height increases at Portchester Castle.

Paulsgrove and Port Solent Marina - Protected by fairly recently constructed and sound sea walls/revetments.

Horsea Island, Tipner and Whale Island (MOD) - Protected by revetments and or gabions/sea walls to a reasonably good standard and with beaches below.

Rotten Row, Albert Johnson and Flathouse Quays to Common Hard - Low sea walls with beaches below and quays/promenades on top.

HMS Vernon, The Camber, Old Portsmouth Dock and Town Quay - All quay walls with hard area behind.

Section VIII - Portsmouth, Southsea, Eastney

The Point, Weeks Wharf, Portsmouth Sailing Club and Point Battery - All well defended with sea walls and rock armouring at base, slipways, stone walls or steel sheet piling. Large shingle beach below "castle" construction of Point Battery.

Sally Port to "Long Curtain" - "Castle" type stone sea wall with beach or stone revetment below with some timber groynes at the eastern end.

Clarence Pier to Southsea Castle - Wide shingle beach below a sound concrete sea wall with promenade behind. Hovercraft terminal of extensive concrete apron.

Eastney and Fort Cumberland (MOD) - Wide shingle beach backed by raked concrete sea wall or embankment.

Section IX - Langstone Harbour

(Description of Portsmouth coastline not included)

Farlington Marshes to Hermitage River - Clay/chalk bund wall faced with concrete revetment.

Hermitage River to Langstone - Reclaimed land protected by various different styles of sea wall.

Creek Point - Rapidly deteriorating bund walls of concrete rubble tipped in the 1980s.

West Coast of Hayling Island - Mainly natural shingle coastline, localised areas protected by the NRA or private landowners.

Section X - South Hayling (Hayling Bay)

Ferry Point/Gunner Point to Eastoke Corner - Mainly natural shingle beach with individual properties protected by sheet steel piles. Concrete wave return wall or groynes and sloping timber breastworks.

Eastoke Corner to Sandy Point - Renourished shingle beach and groynes in front of a vertical concrete sea wall.

Sandy Point to Black Point - Natural shingle beach, rock revetment and timber or rock groynes protecting low lying nature reserve and residential development.

Section XI - Chichester Harbour

East Coast of Hayling Island - Mainly reclaimed land protected by earth bund walls with individual properties protected by concrete brick or gabion sea walls.

Langstone to Wade Court - Vertical sea wall in brick or stone.

Wade Court to Emsworth - Vertical revetment of railway sleeper, sloping concrete revetment, gunite sprayed clay cliffs and revetted earth banks.

Western Avenue - Rip rap revetment.

Emsworth - Principally concrete or masonry faced vertical sea walls (including mill pond wall).

Southern Shore

Isle of Wight

Section I - Foreland - Bembridge

Partly defended coastline of shingle/sandy beaches backed by low vegetated cliffs, with seawalls in good condition, beach nourishment and groynes. A £180,000 groyne and beach nourishment scheme east of Bembridge Point is being considered by MAFF. All this frontage is private. At Bembridge Harbour an earth and stone embankment supports the main road which divides the harbour from the marshes behind.

Section II - Bembridge to Ryde Pier

A mixture of Victorian to modern defences in varying condition. St Helens beach has a groyne system (installed 1992) and beach will be nourished shortly. Priory Bay is virtually undefended although some minor works have been completed recently by the National Trust. Seagrove Bay and Seaview walls are private in poor to fair condition. Puckpool toll road frontage is private and in average-poor condition. Springvale seawall was completely refurbished in 1994. Springvale to Ryde Pier seawalls are masonry or concrete in fair to good condition. Most of the frontage is private except Ryde. The beaches consist of shingle and sand with increasing presence of sand towards Ryde. Immediately east of Ryde Pier a marina was reconstructed in concrete with rock armour in about 1991. Ryde beach comprises extensive sands/flats.

Section III - Ryde Pier to River Medina

Masonry and concrete walls for 1km west of Ryde Pier thereafter the whole frontage is undefended to Old Castle Point at East Cowes. Investigations are in progress at Fishbourne regarding the scour effect of ferries on adjacent beaches. The seawall at East Cowes is in average condition. West of Ryde all this frontage is private or Crown land. The sandy foreshore diminishes as one moves westwards and becomes a rocky/clay foreshore backed by low wooded clay cliffs for the rest of this frontage.

Section IV - River Medina to Western Yar

Masonry and concrete walls on West Cowes frontage in good condition. The beach at West Cowes is shingle which forms a bank up to road level. New seawall completed in 1995 at Egypt Esplanade, Cowes. Gurnard frontage has limited private defences and is being considered for a grant aided scheme. No defences until Newtown Estuary (National Trust). There is the possibility of a scheme here to defend an important archaeological site, in consultation with English Nature/National Trust. The character of the coastline is wooded cliffs on coastal mudslides decreasing in height where the coast is broken by estuaries, extensive salterns at Newtown Creek.

Undefended coast to Bouldnor where a concrete sea wall in good to fair condition and gabions support the coastal slope and A3054. Various private frontages through Yarmouth village in average condition. Yarmouth Harbour breakwater is in average condition; the frontage is owned by Yarmouth Harbour Commissioners. Wightlink Car Ferry terminal together with the east quay of the harbour provides good protection at the harbour entrance as does the South Quay. Upstream of the swing bridge which carries the A3054 over the river the banks are protected for a short distance only.

Section V - River Yar to The Needles

A sand and shingle spit to the west of Yarmouth Harbour and the breakwater forms a small beach. A low timber breastwork prevents landward migration of spit onto marshes. Seawall west of River Yar was reconstructed in the 1980s beyond which is Fort Victoria (Victorian structure) with sandy beach frontage. Undefended coast moving westwards until Fort Albert where a rock revetment was completed in 1993. Brambles Chine frontage at Colwell has two new groynes and beach nourishment (completed 1993). At Colwell Bay a timber cribwork runs into a concrete promenade which extends to beyond Totland. This wall is in fair condition but the coping and rear cliff drainage is poor. The Totland seawall was reconstructed in 1993. Beyond Totland to Alum Bay the coast is undefended. Apart from short sections at Colwell the whole frontage is private.

Source: Towards Strategic Guidance for the Solent, March 1996

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