The Eastoke Peninsula - A Study in Coastal Defence

A case study of the management of the beach frontage at Eastoke, Hayling Island

To see a poster version of this information with more images, follow these links (PDF - Adobe Acrobat required):

Page 1a - Introduction (346kb)
Page 1b - Eastoke Facts (357kb)
Page 2 - Beach Replenishment (275kb)
Page 3 - The Future; Climate Change; CHIMET live data service (203kb)

PAST

Since the early 1920's the Eastoke Peninsula has been increasingly developed as a residential area. The building of beach huts and bungalows commenced in the 1930's along the backshore of the wide shingle beach. Natural erosion of the foreshore made it necessary to build defences to protect these properties.

By 1939 it was necessary to build a concrete seawall in front of the Beach Club, with a timber revetment (sloping surface) and groynes adjacent to it.

By 1974 these defences had extended to the east and west, for a total of 2.6 kilometres. It was this seawall which made the natural erosion of the foreshore worse. Beach levels continued to reduce and by 1978 repairs to the seawall were required.

Prior to the 1985 Beach Replenishment Scheme the southern Eastoke Peninsula frontage regularly overtopped, causing flooding damage. The ageing concrete seawall was also approaching the end of its serviceable life and a failure could have led to erosion of up to 3 metres per annum and subsequent loss of properties. The frequency and severity of overtopping (water carried over the top of a coastal defence) events was increasing annually. In an effort to reduce the damage, a rear splash wall was constructed along the entire length of the seawall. These measures did not adequately prevent regular overtopping or storm damage to properties.

FACT: Original 1920's beach was a mixtures of sand and shingle.
FACT: Residential development resulted in need for defences.
FACT: Defences caused erosion leading to a loss of Sand and Shingle beach, which led to a need for BIGGER not necessarily better defences.
FACT: Flood Damage = Structural damage, a common occurrence.

The Beach Replenishment Scheme (1985) has successfully alleviated further incidents of this nature by removing the waves energy before it is reflected by the concrete seawall. The scheme involved importing half a million cubic metres of shingle from the Owers Bank and placing it on the beach over a length of 2.2 kilometres. There is a requirement for ongoing maintenance to provide the necessary level of protection.

Such a large amount of material being injected into the sediment transport system, resulted in the rapid transport of material along the frontage. In 1987 timber groynes were built in order to try and control the transport rate along the replenished area and in 1990 a rock groyne was constructed to further reduce loss of material around Eastoke Point.

In 1992 it was necessary for emergency repairs to be carried out at Eastoke Point, these works involved the construction of 150 metres of rock revetment and rock stub groynes. These works proved to be successful and a stable beach was maintained.

A Beach Management Plan was adopted in 1992, although now expired, the objectives of this plan included:

Continuous monitoring of the beach.
Immediate reaction to any rapid drawdown (rate at which sea removes material) in a groyne bay (beach compartment between two groynes).
Carry out annual beach recycling.
Use of material accreting (accumulation of beach sediment) at Central Beachlands as a source of material.

PRESENT

The success of the Beach Management Plan (1992), led the Council to develop and approve recommendations contained within the Beach Management Strategy Plan for the southern frontage of the Eastoke Peninsula (1999). This Plan recommended defending the frontage against a storm event with a return period (average period of time between occurrences of a given event) of 1 in 200 years, which is achieved by adopting the following:

Annual shingle recycling operations, moving shingle from areas of accretion to depleted areas.
Annual Coastal Management Study.
Beach Nourishment operations. When appropriate, the nourishment material will be sourced from the navigational maintenance dredging of the approach channel to Chichester Harbour. Follow the links below to find out more about Beach Nourishment operation in 2008 and summer 2009.

Groynes and revetments are regularly monitored along the beach, with the profile of the groynes being adjusted by adding or reducing the number of planks to suit the changes in beach profile. Unfortunately there is a net loss of some 5,000 cubic metres per year of shingle from the Eastoke frontage, this is due to it not being possible to recycle all the shingle that is moved out of the area; the 5-yearly nourishment operations restore this material.

The most suitable time for undertaking the annual shingle recycling operation is around Easter; as this will avoid the severest winter storms and the summer period will allow the material to naturally sort and develop a resistance to storm events.

Monitoring and research is an important part of Beach Management. Surveys are carried out in order to identify sources of suitable material available for extraction and recycling to the Eastoke promenade area. The better our understanding of coastal processes allows Engineers to design sustainable schemes. The following are examples of the type of monitoring that the Council undertakes:

Surveys of beach profiles.
Surveys of seabed bathymetry.
Sediment Budget Analysis.
Recording wave heights.
Recording wind speed and direction.
Recording tidal data.
Measurements of current velocity and direction throughout tidal cycle.

BEACH NOURISHMENT OF THE EASTOKE FRONTAGE

Beach nourishment is the placing of material from offshore onto the beach, in order to maintain the required standard of protection along the frontage for the residents of Eastoke, Hayling Island.

In 1985 the beach nourishment scheme was implemented, creating a man made beach in front of the now redundant sea wall. Coastal processes are constantly eroding this frontage and without intervention the redundant concrete seawall would again be exposed. The result of this would be a return to regular serious flooding of Eastoke, through continuing erosion of the coastline.

The wave energy dissipation diagram shows how the beach profile created through nourishment will absorb the wave energy and help to prevent overtopping.

The shingle beach along the southern frontage of the Eastoke peninsula is the first line of defence against the threat of coastal erosion and flooding. The Council is the Coast Protection Authority that enables the use of permissive powers to manage these risks when it is considered in the Public interest. The Council developed and approved a Beach Management Strategy Plan that identified the most effective approach to managing this frontage; this decision was made after considering all economic, environmental and technical criteria. The beach nourishment works are one element of this preferred approach to managing this frontage and will restore beach material that is moved out of the area by natural coastal processes.

Council Officers have been monitoring the coastal processes around the Eastoke area over many years and have determined that wave and tidal action moves shingle in both directions along the beach from a drift divide around the middle of the frontage. Part of this material therefore moves eastwards along the frontage and into the entrance to Chichester Harbour. This material is then moved by strong ebb tidal currents at the entrance to the Harbour and comes to rest approximately a kilometre offshore.

The diagram to the right shows how the natural coastal processes move beach material around the Eastoke area.

The diagram to the right shows the areas of accretion within the safe passage of navigation that can be a hazard to mariners navigating the approach channel to Chichester Harbour. Havant Borough Council work in partnership with Chichester Harbour Conservancy to reduce the hazards identified, where possible, through the beneficial use of arisings for Beach Nourishment operations. This ensures the material is not removed from the local sediment transport system.

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Nourishment Works Summer 2009

In September 2008, Havant Borough Council successfully completed phase one of the Beach Nourishment scheme placing 25,000m³ of material on the frontage of Eastoke. After securing funding from the Environment Agency, Havant Borough Council now intends to carry out the second phase of the operation this summer. This involves placing a further 65,000m³ of material on the frontage to raise the beach to the recommended 1 in 200 year Standard of Protection. The works took approximately 1.5 months to complete.

Work started on the 19th June 2009 and was completed on 2nd Aug 2009.

For further information on the 2009 Beach Nourishment scheme please follow the link below:

More about the September 2009 Beach Nourishment works >>

FUTURE

Eastoke Point Coastal Defence Scheme

Development Stage

Following the successful completion of the study as described above Havant Borough Council applied to the Environment Agency for funding to take the scheme forward.

This proposal was adopted after HR Wallingford was commissioned to develop the Eastoke Point Coastal Defence Study 2009 on behalf of Havant Borough Council. If work is not undertaken up to 1,700 properties on the south east of Hayling could be at risk of flooding over the next 100 years.

The Environment Agency gave technical approval on the 5^th August 2010 to commence detailed design of the scheme and to obtain the necessary planning and other consents to enable the main scheme to be constructed. The construction of the main scheme however is dependant on there being sufficient funds from central government available.

The development stage commenced in September 2010 and it is hoped that the design will be completed and the necessary consents obtained by early 2012 dependant on the amount of funds made available by the Environment Agency.

The new project includes:

A rock revetment buried at the top of the beach along the whole frontage to protect residents and their properties plus the Sandy Point Nature Reserve.
New rock groynes to reduce the movement of beach material and long shore drift.
Upgrading the existing revetment and groynes near the Lifeboat station.
Improving the ‘Splash Wall’ to the rear of the eastern end of the promenade which will reduce the risk of flooding to homes in the area.
Continued beach management with nourishment, recycling and monitoring of material. This activity will maintain the beach as the primary defence at Eastoke.

Preliminary site works were carried out in Winter 2010 to determine the current condition and positions of the defences, works on the detailed design started in the New Year. Once our Coastal Engineer develops the key specifications for the scheme to ensure it provides adequate coastal protection, we will be holding further public exhibitions to determine your views on the designs. Follow the link below for current updates of the project.

For any questions or more information please contact Clive Evans on 02392 446 617 or clive.evans@havant.gov.uk

Click here to see Current Updates of the Eastoke Point Coastal Defences Works>>

Adequate protection at Eastoke Point, around the Nature Reserve, is of crucial importance to the prevention of flooding. Upon approval of the Eastoke Strategy, Council Officers will be carefully considering all options available to improve the present standard of protection.

Advances in technology will enable improvements in the delivery of the coastal defence service, the following are some of these opportunities:

Use of Global Positioning Systems (' GPS ') satellites to monitor changes in beach levels.
Use of the Internet to make information available.

The Council has published the East Solent Shoreline Management Plan 1997. This document contains a wealth of information on our existing knowledge of the coastline from Pagham Harbour through to the River Hamble and also recommends the preferred approach to future coastal management.

Another popular web site is CHIMET, which provides actual measurements of:

Tidal Heights.
Wind Speed.
Wave Heights.
Temperature.
Barometric Pressure.

The provision of this service has been undertaken in partnership with Havant Borough Council, the Chichester Harbour Conservancy, the RNLI and the Chichester Harbour Federation.

CLIMATE CHANGE

The predicted effects of climate change and sea level rise present a significant challenge for future coastal management. It is anticipated that there will be increased risk to many coastal assets. Key pressures are identified as follows:

Increased problems of overtopping of existing defence structures due to sea level rise.
Increased beach volatility and increasing sea levels will mean beach recharge schemes may require increased material volumes.
Diminishing beaches and marshes in front of defences reducing both support and protection of structures.
Higher sea levels will result in greater wave heights at the shoreline, resulting in increased wave forces on structures.
Potential changes in patterns of longshore drift could result in altered patterns of erosion and deposition.
Increased potential for 'flash flooding' of low-lying areas by intense rainfall events.
Erosion and 'squeeze' of inter tidal habitats between rising sea levels and existing or new coastal defences.

Havant Borough Council, Civic Centre Road, Havant, Hampshire PO9 2AX