Flooding management – compared to erosion management Article in handout
Revetments had previously been laid along the cliff but post 1998 these were removed following a storm breach and has now been left unmanaged
Article in handout
Managed retreat – often termed sustainable – allowing nature to find its equilibrium e.g. let salt marshes develop to create natural buffer zone …. Only intervene if it becomes necessary.
NO coming back
Transcript of "Coastal Erosion And Management On The North Norfolk"
Coastal erosion and management on the north Norfolk coastline A2 coursework
Cley next the sea <ul><li>Managed to prevent coastal flooding and protect the wetland habitat. </li></ul><ul><li>Salthouse village is protected only as a consequence of the wetland habitat being there. </li></ul><ul><li>Salthouse flooded in 1953 – 1 death </li></ul><ul><li>Flooded in 1993 and 1996 when A149 was cut off for 6 weeks </li></ul>
Looking east from Cley Shingle ridge is bulldozed to maintain the barrier to protect Salthouse village
Looking west from Cley towards Blakney Point (coastal spit) Westerly movement of material by LSD Management conflict-managed retreat V secondary buffer ridge??
Looking up the beach from the shoreline Shingle ridges/berms Top of beach
Landuse behind Cley Managed shingle ridge Flat saltmarsh land Salthouse village
Weybourne <ul><li>Do Nothing approach. </li></ul><ul><li>Rapid retreat as no management plan. </li></ul><ul><li>Agriculture is main landuse </li></ul>
Looking west towards Cley Unmanaged shingle ridge
Looking east towards Sheringham Chalk/unconsolidated sand and glacial till cliffs Revetments had previously been laid Along the cliff but post 1998 these were removed following a storm breach and has now been left unmanaged
Cliff face showing evidence of slumping Under the shingle beach there is a chalk WCP Evident during storm periods Slumping
Sub-aerial weathering Conglomerates Unconsolidated sand Chalk with flint nodules
Chalk-evidence of bedding planes Wave cut notch by corrasion Cave Weybourne crag
Cley next the Sea Flat saltmarsh Gently dipping slopes away from the sea
Sub-aerial weathering Evidence of gulleying due to sub-aerial weathering through the Unconsolidated glacial till and sand deposits
5 coastguard cottages approximately 10m from cliff (potential interview)
Sheringham <ul><li>Hold the existing line approach. </li></ul><ul><li>Multiple defences used </li></ul><ul><li>Victorians built first sea wall </li></ul><ul><li>Major tourist town – high value landuse </li></ul><ul><li>Great ice cream and fish and chips! </li></ul>
Undefended Sheringham-looking west towards Weybourne Sheringham golf course Chalk dipping beneath sealevel Leaving glacial deposits exposed Evidence of slumping LSD now eastwards
Start of defences (west of Sheringham centre)-Groynes Hinged doors allow shingle movement from west to east WEST EAST
Sheringham West Beach Original Sea Wall not included in sea wall replacement scheme – the wider beach offered greater protection Rock Armour buried by shingle helps to prevent scouring of sea wall Sheringham town centre
Fishermen’s Slope – in 1986 beach level fell by 2.5 m due to scouring Sea wall from 1900 resurfaced with concrete in 1988 and entirely replaced in 1993 -4 Rock Armour and Rock groynes Narrow beach here = more erosion
Sheringham East Drainage pipe in cliff to Help prevent saturation of soil Drainage hole allows water to Flow onto promenade
Sheringham East – the end of the sea defences Cliff slumping along undefended stretch 1988 – Beach nourishment used 12000 tonnes of flints were deposited into The bays East of the ‘tank’
High value landuse in Sheringham town centre – Sea Defences hold the existing line £1.5 million spent in 1998 on replacing and repairing wooden groynes And installing rock groynes
West Runton <ul><li>Managed Retreat. </li></ul><ul><li>Agricultural landuse </li></ul><ul><li>Fossil evidence from Tropical climatic period </li></ul>
West Runton has few tourist amenities; Low value; Managed retreat Short sea wall protects café and toilet block Dark band at base of cliff marks line of a tropical river which meandered East to West 600 000 yrs bp – Known as Cromer Forest Bed Many fossil remains found including the West Runton Elephant Cliffs are glacial till and prone to Slumping – results in a gentle profile
WCP forms rocky outcrop Erratics from Northumberland (Dolerite) and Norway (Rhomb Pomphry) found here
Low value landuse – agriculture and caravan park Weight of farm machinery has encouraged cliff collapse along the coast
Overstrand <ul><li>Hold the existing line </li></ul><ul><li>Multiple hard engineering strategies </li></ul><ul><li>Main issue is slumping of boulder clay cliffs </li></ul><ul><li>Red lining – no new development allowed between a designated line and the cliff. Redefined every 5 years. </li></ul>
Gabions allow water to pass through and hold back slumped material Sea Wall also provides a promenade (tourist amenity)
Wooden Groynes prevent LSD Sand beach means a gentle profile
Boulder Clay cliffs are prone to slumping Gabions hold back slumped material - A successful measure Drainage holes are found in concrete wall Bore holes sunk into ground in high risk areas to remove water
The old coastal path was closed off and the road diverted.
Wooden Revetments Flint nodules caught in gaps – reduce effectiveness of the sea defence
HDE and a Revetment 5ft 5 ¾ My bag! Steel girders – foundations for defence?
Clifton Way <ul><li>1990 – 45m cliff recession </li></ul><ul><li>Nov 1992- 15/20m recession </li></ul><ul><li>Jan 1994 – 20 /25m in just over 2 weeks. </li></ul><ul><li>30 year old Bungalows deemed worthy of protection. </li></ul><ul><li>£1.4 million spent on regrading scheme and putting in defences </li></ul>
Slope was regraded after a loss of 100,000 tonnes of material in 1994 Lack of vegetation Drainage channels
Rock armour at base to prevent further slumping and undercutting 1995 – area excavated and layers of sand and synthetic matting, Chalk and boulder clay were used to rebuild the slope. Drainage channels, bore holes and inspection holes were installed
Council access road had been re - routed twice before 1994 New access road to beach for maintenance
Revetments placed infront of rock armour Access road Bungalows are here!
Managing the coast <ul><li>Shoreline management plan – based on sediment cells </li></ul><ul><li>Reviewed every 5 years </li></ul><ul><li>‘…it is a live working document and must be capable of change’ </li></ul>
Four options <ul><li>Do Nothing – no defences except for safety measures </li></ul><ul><li>Hold the exisiting line – intervene to hold the existing defence where it is. </li></ul><ul><li>Advance the existing line – move existing sea defence forwards </li></ul><ul><li>Managed retreat – allow nature to take its course and intervene where necessary </li></ul>
Possible project titles <ul><li>How effective are the coastal management strategies at X? </li></ul><ul><li>A comparison of beach and cliff profiles at X and Y? </li></ul><ul><li>A comparison of coastal protection strategies at X and Y? </li></ul><ul><li>What factors influence the beach and cliff profiles at X? </li></ul><ul><li>How do the beach and cliff characteristics of defended and undefended Sheringham differ? </li></ul><ul><li>How are the coastal defences at X perceived? </li></ul><ul><li>Do residents and tourists perceive coastal management strategies differently? A case study of Sheringham. </li></ul><ul><li>What physical and human processes influence the coastline at X? </li></ul><ul><li>Is there any evidence of longshore drift on Sheringham beach? </li></ul><ul><li>Which has the most effective coastal management strategy – Sheringham or Overstand? </li></ul><ul><li>Protecting coastlines against erosion is more important than protecting them from coastal flooding? A study of Cley –next- sea and Sheringham. </li></ul><ul><li>To what extent do physical processes affect the type of coastal management strategy chosen? A comparison of Sheringham and Weybourne </li></ul><ul><li>An evaluation of human influence on beach and cliff profiles at Sheringham, Weybourne and Overstrand </li></ul>
What now???? <ul><li>Thursday </li></ul><ul><li>1 day group fieldwork – visit and collect data at each site (5 in total) </li></ul><ul><li>Thursday eve- Collate data. Decide on title and devise any further data collection techniques (EIA, CBA etc) </li></ul><ul><li>Friday </li></ul><ul><li>Individual data collection </li></ul><ul><li>Friday eve – write up methodology and process data </li></ul><ul><li>Saturday – extra data collection / photos etc </li></ul>
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