Option 1Abstract
The length of coastline covered by this Consultation Brief extends from Cooden to Langney Point in East Sussex. For the purposes of this brief, this coastline and adjacent sea area is referred to as Pevensey Bay. This coastline acts as an important defence against flooding and storm damage from the sea for a large area of very low-lying land immediately behind the beach. Situated in this area are a large number of properties, recreational interests, transport links, grazing pastures and two important nature reserves. These are all at risk from flooding if a breach of the defences occurs.
The sea defences of this area are the responsibility of the National Rivers Authority, Southern Region (NRA). Despite their regular maintenance efforts the sea defences are deteriorating. To restore an appropriate standard of defence the NRA are proposing to undertake major capital works. The Babtie Group, which is an engineering consultancy, has examined the coast in detail over the past two years, and have devised three options for new defences.
One of these options will be chosen when all factors have been taken into account and duly considered. These factors include engineering, economic and environmental considerations. The environmental factors are being examined using a procedure known as an Environmental Assessment.
Option 1
Option 2
Option 3
Introduction
The beach between Langney Point and Cooden provides an important defence against flooding from the sea - it protects the developed areas of Pevensey Bay, Norman's Bay, Langney, Westham and Pevensey itself as well as the adjacent low-lying Levels. This area covers approximately 50 km2, and is known as the High Risk Flood Zone (HRFZ). If there was a permanent breach of the existing defences, then this area would be flooded.
The coastline is extremely important from a great many viewpoints. The foreshore has a large number of uses, such as sailing, bathing and fishing and is an important recreational and commercial area. There are a large number of properties both along the beach crest and immediately behind it which would be at risk of damage if further deterioration of the sea defences is not prevented.
The low-lying land behind the coast also contains major vital transport links. The most important of these are the A259/A27 roads and the British Railways mainline between Hastings and Eastbourne. The HRFZ is also important for its agriculture and ecological value. All of these uses and infrastructure links would be lost or severely disrupted if a permanent breach of the sea defences were allowed to develop.
The National Rivers Authority (was in 1992), Southern Region (NRA) is responsible for the sea defences of Pevensey Bay. The capital assets represented by the groyned beach and associated structures are now deteriorating at a faster rate than can be prevented by normal maintenance expenditure. The NRA must therefore either abandon the sea defences or make an economic argument for major capital expenditure on their improvement. Abandonment of the defences is not considered an appropriate option at this location.
The purpose of this Consultation Brief is to:
Your replies to this Consultation Brief will contribute towards an Environmental Assessment. The purpose of this assessment will be to ensure that the adverse impacts of the sea defence options are minimised as far as practicable and beneficial impacts are identified. The results of the Environmental Assessment will be set alongside economic and engineering appraisals to identify the optimum sea defence option for Pevensey Bay.
History of the bay
Pevensey Bay was originally a far deeper bay including the low-lying levels and flats behind. Natural processes gradually formed the existing beach which caused siltation of the area behind. This siltation formed saltwater marshes which have been gradually reclaimed and defended against the sea to form the present agricultural and developed areas.
The natural shingle supplies which built up the beach have now diminished and, to retain the beach material, groynes have been constructed.
In the absence of improved defences, the beach will continue to erode, which in turn will reduce the strength of the sea defences. In the immediate term, the properties on the beach crest will be subject to a growing danger of subsidence and storm damage. In the medium to long term, or under particularly severe storm conditions, the greatest threat is from a breach of the sea defences. This could cause damage to several thousand properties. Grazing pastures and wildlife habitats in the Hooe Flats and Pevensey Levels would be lost and the roads and railway would be harmed and possibly closed. Some of the damage could be permanent.
The cost of the damage from flooding would amount to several tens of millions of pounds (1992 figures) and in past cases of breaches and flooding at other locations there has been a loss of life.
Strategy choices and their overall impacts
There are three strategies that the NRA may adopt regarding sea defences. Briefly, these are:
Do nothing: If the sea defences were effectively abandoned, the groynes would continue to deteriorate. Beach material would be lost from the frontage and some of the properties on the beach crest would be undermined and eventually lost. The beach would continue to recede until a breach occurred. Such a breach would initially flood only part of the area behind the defences but would gradually be opened up by the sea until all the levels were regularly inundated by the tide and reverted to saltmarsh.
Maintain as at present: A programme of maintenance and emergency maintenance would continue to defend the coast in the short term. However, it would not reduce the chances of a breach to an acceptable level, nor would it be able to offer an acceptable standard of sea defence against flooding for this important area. Both the risks of flooding and breaching would be increased by future anticipated sea level rises which this strategy could not accommodate.
Major capital investments: These would involve substantial improvements to the sea defences. New structures would be added to the coast and the beach would be enlarged. This is the only strategy which the NRA considers will provide appropriate long term sea defences for this area.
The NRA will be seeking to embark on major capital investment in the sea defences of Pevensey Bay since this is the only one of these strategies which provides an appropriate long term standard of sea defence protection for this area.
From the wide range of sea defence options that were considered, three have been developed as being practicable and affordable.
Major capital investment - sea defence options
In the absence of a cliff, the final barrier to the sea is a beach. A natural beach is a very effective means of dissipating the energy of the sea. In the past when natural beaches diminished they were traditionally reinforced by seawalls of concrete, masonry, timber and other materials. Recognising the effectiveness of beaches of natural material, coastal engineers have concentrated in recent years on methods for stabilising and enhancing natural beaches. These methods are generally far less environmentally intrusive than the construction of large rigid seawalls. For the Pevensey Bay frontage the option of constructing a large rigid seawall along the whole length of the beach has not been considered to be appropriate and the options that have been developed are based around the creation and stabilisation of a beach of natural material. The figures attached for each option show the approximate extent and positions of the works. The exact locations and sizing of these structures will be finalised during the detailed design.
