Case studies for coasts
Changing Landscapes - coasts
· Sediment cell – South Downs sediment cell
o Sub-cell 4d along the Sussex coast
o Between Selsey Bill and Beachy Head
o Defended with rock reefs, wooden and rock groynes
o Pebble beeches
o Dominant drift direction west to east
o Up to 5000m³ gravel and sand lost round Beachy Head
o Dredging of Shoreham Harbour, Brighton Marina, Newhaven Harbour
· Build-up and removal of a beach (system feedback) – Crantock Beach, Cornwall
o Northwest facing beach in Northern Cornwall
o River Gannel flows on the northern edge of the beach
o Ever-changing environment
o Employs a shoreline management plan
o Has experienced excessive erosion in recent years (since 2013), especially after the 2013-2014 storms
o Erosion of up to 3m in depth
o Mobile zone is degrading, whilst the beach zone is more stable
· Coast working as a system – Aquitaine Coast
o Located in the southwest of France
o Complete shore system composed of beach, dunes and pine tree forest
o Sandy beaches and dunes
o Employing hold the line/limited intervention
o Sea wall, groynes, beach nourishment, dune restoration
o Stores of the cap ferret spit, arachon estuary, dune du pilat and araguin offshore bar
o Outputs of the ocean and longshore drift
· Microtidal range – Eastern Australia
o Found in parts of New South Wales and Queensland
o Wave action plays a larger role in Charing the coast than tidal energy
o Example is Yalimbah Creek
· Macrotidal range – most of the UK coast
o Key regions include Bristol Channel and Severn Estuary (up to 15m)
o Strong tidal currents and dynamic sediment movement
o Other examples include Humber and Mersey estuaries
o Drive rapid sediment transport, leading to extensive tidal flats, formation of tidal deltas, and notable erosion/deposition patterns
· 1.1.3 High and low energy environment – Gower Peninsula
o Mixed energy coastal environment with high and low energy areas
o High energy areas- Rhossili bay- experiences strong winds and waves, making it popular for surfing
o Low energy area- Oxwich bay- large, sheltered bay with extensive dunes and salt marshes
· 1.1.5 Headland and Bay – Swanage Bay and Studland Point, Dorset
o When bands of softer rock on a discordant coastline is eroded faster than the bands of harder rocks, creating areas of lad that stick out form the mainland
o Has alternating bands of limestone/chalk and clays/sands
o Ballard point- made of chalk
o Durlston head- made of limestone
o Located in Dorset
· Stacks and stumps – Old Harry and Old Harry’s wife, Dorset
o The erosion of a cave into an arch, that then collapses to form a stack
o The stack then gets eroded into a stump
o Old harry is a stack and his wife is a stump, near Ballard point
o Made of chalk, which is resistant enough for a cave-arch-stack sequence
· Cove – Lulworth Cove
o On the Dorset coast, next to the village of Lulworth
o Bedrock surrounding the cove is sedimentary, and so was easily erodes
o Entrance is a breach in the very resistant Portland stone
· Blowhole – Nakalele Point, Hawaii
o Northernmost point on the island of Maui
o Water released by the blowhole can reach up to 100 feet in the air
o Rock in the area is jet black lava rock
· Soft rock cliff – Highcliff, Barton-on-Sea (boulder clay rock)
· Hard rock cliff – Cornish Coastline (basalt rock)
· 1.1.6. Bar – Chesil Beach
o Spits that extend across two sides of a headland, forming a lagoon behind it
o Located in Dorset
o Behind the spit there is The Fleet, which is a lagoon
· Cuspate foreland – Dungeness foreland, Kent
o Triangular shaped projections that form from longshore drift moving in two different directions
o Located in Kent
o Formed over the last 5000 years
o Comprised largely of gravel
o Attracts 1 million tourists annually
· Spit – Orford Ness
o Linear deposits of sand and shingle that is attached to land on one end
o Formed by longshore drift
o Creates sheltered areas behind that often allows the formation of a salt marsh
o Largest vegetated shingle spit in Europe
o Stretches for about 10 miles
o Located on the Suffolk coast
· Tombolo – Chesil Beach
o Longshore drift forming a spit that connects an island to the mainland
o Connects the isle of Portland to Abbotsbury
o Largest tombolo in the United Kingdom
· 1.1.7. Sand dunes – Ainsdale Dunes, Sefton
o On the northwest coast of England
o Contains a range of habitats
o Largest dune area in England
· Mudflat/ salt marsh – Morecambe Bay
o Northwest coast of England
o 310km^2 of intertidal sand flats
o Salt marshes develop along the bays margins
o Makes Morecambe bay a crucial habitat for wildlife
· Coral reef – Great Barrier Reef
o Located north-east of Australia
o Mad up of 2900 individual reefs and 900 islands
o Threatened by human activity which causes bleaching of coral (global warming)
· 1.1.8. High energy event – December 2013 storm (UK East coast)
o Gale-force winds of up to 100mph
o Sea levels peaked at 5.8km and 4.7m in Hull and Dover respectively
· Rias – Kingsbridge Estuary, Devon
o A river valley at the coast that has been inundated by the sea as relative sea level rises, resulting in a “drowned valley”
o Formed on a submergent coastline
o Has very little freshwater input, high salinity levels and a large tidal range
o Supports diverse intertidal habitats (mudflats and salt marshes
o Has steep banks and a relatively deep channel compared to its width
· Fjord – Sognefjorden, Norway
o A glaciated valley at the coast that has been inundated by the sea. Has steeper rising walls, a straighter long profile and is deeper than a ria due to glaciers over-deepening the valley
o Formed on a submergent coastline
o Located in western Norway
o 205km long, and up to 4,5km wide
· Raised beach – Isle of Arran, Kings Cave
o Raised beaches are shore platforms and beaches that are found stranded above the present-day high tide level
o Formed on an emergent coastline
o Located in Scotland
o Kings cave is a notable area which provides evidence of the past sea levels
o Flat shore platform elevated above the current coastline
· 1.1.9 [Case study] Management of coastal processes – Holderness
o Located in East Yorkshires coastline
o Composed predominantly of soft erodible boulder clay
o Notoriously one of Europe’s fastest eroding cliffs (over 2m/year)
o Use of sea walls, groynes and revetments
o Use of managed retreat in certain areas
o Integrated coastal zone management
o Decision making involves tradeoffs between protecting property and allowing natural coastal change
· 1.1.10 [Case study] Management of human activity – Ainsdale sand dunes
o Designated as a national nature reserve and site of special scientific interest (SSSI)
o Threats from trampling by visitors, off road vehicles and cycling, urban development (encroaching)
o Managed by fencing and boardwalks, sand dune stabilisation and education and signage