Coastal Case Studies: Sussex Coast

• Fundamental coastal processes at Pevensey Bay


  South Westerly prevailing winds, longshore drift moving sediment to the North East (creates beaches that are parallel to the waves).

  During major storm events, the beaches become flatter, creating beach profiles that reduce wave energy and prevent waves from reaching the top of the shingle bank (reduces flood risk).

  Movement of sediment is irregular and there is a net loss of 25,000m^3 of beach every year.
• Landscape at Pevensey Bay


  9km long shingle bank from Eastbourne to Bexhill.

  Shingle beach stretches the length of Pevensey Bay, crest height is 6m and the shingle bank extends 45m seawards on average.
• Risks facing Pevensey Bay


  Coastal flooding is the greatest risk to this area due to its low lying relief.

  Sea levels continue to rise, wave action and longshore drift continue to move sediment.

  Storm frequency appears to be increasing.

  A 1 in 20 storm event could breach the shingle beach.
• What is protected at Pevensey Bay


  10000 properties

  Recreational sites

  Commerical sites

  A259 coast road and railway line from Hastings to Portsmouth

  Two nature reserves and a SSSI wetland site

  Livestock farms

  Arable farms
• Stakeholders at Pevensey Bay


  Local council

  Residents of 10000 properties protected by the management

  Local farmers

  Natural England

  Environment Agency

  DEFRA

  Pevensey Coastal Defence Ltd - consortium who manage the coastal defences

  Westminster Dredging Company.
• Management Strategies at Pevensey Bay

  Hold the line through soft engineering strategies

  Beach renourishment

  Beach Surveys

  Experimental use of tyres to build up shingle bank
• Previous Management at Pevensey Bay


  150 groynes, but these are being allowed to fail. Around 10 groynes are being retained and repaired. Despite this small element of hard engineering,the overall strategy for this stretch of coastline is soft engineering.
• Challenges in Sustainable Management at Pevensey Bay


  The delivery of 2000 tonnes of shingle at high tide, by the barge, is socially economically and environmentally sustainable.

  Socially it reduces congestion on small roads caused by large lorries.

  Economically, the small country roads will become damaged so they would've had to be repaired.

  Environmentally, not as many carbon dioxide is emitted from the boat.

  It is also environmentally sustainable as the old tyres are used to secure the single, instead of ending up in landfill.

  Unsustainable in the long term.

  Soft engineering preserves the beach as they can still use it for leisure.
• Fundamental coastal processes at Bognor Regis


  Dominated by waves from the South-west, resulting in a west to east drift of beach material.

  Waves from the south-west are more frequent.

  Bognor Regis is at risk of coastal flooding for a 1 in 200 year event.

  At risk of overtopping.

  Clays, silts and fine sands dominate the Geology.

  Much of this coastline is unconsolidated material.
• Landscape outcomes at Bognor Regis


  Beaches along this coast are typical of those found throughout the South-east of England, compromising mixed sand and shingle sediment.

  The beach at Bognor Regis is shingle-sand composite at a 1 in 9 slope with a sandy foreshore (shallow).
• Volume of sediment at Bognor Regis


  The volume of sediment is steadily increasing at Bognor Regis.

  Positive sediment budget.

  Since 2007, the total volume of beach sediment has increased by approximately 90,000m^3.

  More accretion.
• What is protected at Bognor Regis


  A seaside resort town with a population of ~24,000.

  Butlins holiday camp, East of the town centre.

  The town hosts the International Bognor Birdman for human-powered 'flying'.

  A259 Coast Road between Chichester and Worthing.

  Around 80-90 listed properties within 1km of the coastline.

  5034 properties are at risk, with a combined value of ~£1.552 billion.
• Stakeholders at Bognor Regis


  Arun District council

  Environment Agency

  Butlins

  Bognor Regis council

  Local residents

  Tourists
• What management is in place at Bognor Regis


  Concrete sea walls

  92 timber groynes and 8 rock groynes
• Challenges in management at Bognor Regis


  High input of time and money required

  Longshore drift

  Risk of overtopping

  Unresistant, unconsolidated beach material.

  Effective coastal management.

  - Positive sediment budget

  - Lots of monitoring of current beach profile

  - Risk of 1 in 200 year storm event.

  Adequately funded.
• Fundamental coastal processes at West Wittering


  Chichester harbour was formed by sea level rise (lowland Ria)

  There are no rivers flowing into the harbour any more.

  Small chalk streams such as the Fishbourne Stream enter from the North East.

  Harbour contains brackish water, where seawater mixes with the freshwater from streams.

  Depositional environment; low energy.

  Sediment moved along the spit from south to north by longshore drift.

  Longshore drift occurs along the beaches at West Wittering.

  The neck, and the spit, can be threatened by erosion during storms.
• Landscape outcomes at West Wittering


  'East Head' spit, situated on the West of the beach, at the eastern entrance to Chichester harbour.

  Sand dunes formed on the spit.

  The spit is roughly 1km long and 400 metres wide.

  It is joined to the mainland by a thin strip, known as 'the hinge'.
• Stakeholders at West Wittering


  East Head Coastal Issues Advisory Group

  Natural England

  Environment Agency

  Chichester District Council

  Chichester Harbour Conservancy

  The National Trust

  West Wittering Parish Council

  The Woodger Trust

  West Wittering Estates

  Cakeham Manor Estate

  Local Residents

  Visitors to the Area.
• Previous management at West Wittering


  A rock berm was put on the inside of the Hinge.

  in 2005 & 2009 a huge quantity of sand was transported from the northern tip and a huge bank built over the top of the surviving rock berm.

  Planting of Marram Grass
• Management at West Wittering


  Adapative management under the North Solent Shoreline Management Plan.

  A form of managed realignment, but is reviewed frequently and action taken in order to protect the hinge.

  The Adaptive Management Plan will monitor the spit but will not try to lock it into its current size, shape or orientation.

  Hard engineering is used along West Wittering Beach, but East Head spit is protected by Soft Engineering.

  The existing timber breastworks had reached the end of their lives.
• Challenges in Management at West Wittering


  Climate change - sea level rise

  - Increased storminess

  Limited supply of sediment

  Legal and regulatory obligations

  Sustainability

  Public opinion/acceptance

  Availability of funding

  Complexity of coastal processes.
• Summary of Pevensey Bay


  An example of hold the line that uses soft engineering including Beach Nourishment.

  - Flat bottomed barge (2000 tonnes of sediment a day)

  This area is managed in this way as residents and tourists use the beach for leisure.

  Coastal flooding

  - Overtopping of 9km long shingle beach

  - 10000 properties at risk.
• Summary of Bognor Regis


  An example of hold the line that uses hard engineering including concrete sea walls and groynes.

  Managed as such as there are large amounts of properties within 1km of the shoreline as well as holiday parks.

  Coastal flooding, longshore drift.
• Summary of West Wittering


  An example of adaptive management that uses soft engineering including beach nourishment and embankments.

  Managed due to a limited availability of funding and to maintain access to the beach and spit.

  Not maintaing timber groynes.