Please enable JavaScript.
Coggle requires JavaScript to display documents.
Holderness Coast - Hard Engineering - Coggle Diagram
Holderness Coast - Hard Engineering
Geology
The more resistant chalk has survived large-scale erosion and created the classic features of Flamborough Head
The boulder clay is more easily eroded and caused the retreat and formation of the sweeping bay of Holderness
Inputs
Winter storms produce stronger waves and higher sea levels. Additionally, the rain they bring intensifies land-based processes
Dominant waves are from the north east which is also the direction of the largest fetch. Destructive waves erode beaches and attack the foot of the cliffs, removing the clay in suspension.
LSD carries material south
Tides and lower energy environments of the Humber Estuary allow sediment to collect forming a spit, mudflats and sand dunes near to Spurn Point
Flamborough Head Processes
The head is made of chalk with bedding plane. Verticle joints allow waves to penetrate the cliffs which leads to the formation of geos and caves. Wave quarrying results from the force of the waves or form the air being trapped in faults.
Wave refraction concentrates waves on headlands. They can lead caves to turn into arches, stacks and stumps.
Sub-aerial processes like weathering and rockfalls also have a part to play to make these features.
Processes on the Holderness Coast
Boulder clay cliffs were formed by ice sheets and are retreating by 1.8m/year
Rainwater enters the clay causing it to become heavy and slide seawards. This can occur in natural slip planes or a slumping motion. Removal of vegetation or urbanisiation may increase this.
Waves remove the sedimanet and LSD move it southwrds. Therefore little material is left to form beaches and protect the coast.
Rip currents may create ords (deep hollows) which increase erosion.
Processes at Spurn Point
Sediment is deposited here where the waves, winds and river estuary have created a fragile recurved spit
Historical evidence suggest changes happen in cycles
There are also sand dunes and saltmarsh ecosystems
Future
The presence of people along the coast turns physical processes into hazards and threatens life and property. Increasing populations due to retirement, leisure and holiday facilities have occurred around Bridlington and Hornsea. The risks from erosion have been publicised at Easington where the gas terminal is under threat.
Interfering with natural processes such as LSD or using unsustainable defense strategies can have adverse effects. The down drift impacts of groynes mean that sediment is being prevented from building beaches elsewhere.
Global warming and short-term changes in climate, an indirect human impact, are creating a rise in sea level and increasing storminess. Areas like Spurn Head and the shoreline of the Humber Estuary are at risk from coastal flooding and erosion.
Locations
Bridlington - Hold the line
Operational fishing town
Protected by Flamborough Head (wave refraction) and the Smithic sand bank which lies offshore (10km long and 2.7m high at low tide)
4.7km long promenade and groynes
Skipsea
Small concrete revetment
Hornsea - Hold the line
Coastline fixed since defences (concrete wall and groynes) built in1900
Problems with sea water inundation due to breaching of sea wall. A second seawall now constructed behind the orignial
South Hornsea unprotected and erosion accelerated. Council have committed to building a stone groyne when cliff edge is 30m from their doors
Mappleton - Hold the line
In 1991, £2 million spent on 2 rock groynes and a rock revetment to protect the B1242 (coastal road)
The beach to the north of the groynes is now substantially thicker
Granite rip rap along he base of the cliff to prevent hydraulic action
Cliff is landscaped so gentle angle making it less likely to slump
Seeded cliff face so less likely to be eroded by heavy rain
Tourism has increased and cliff is inactive (sea doesn't reach it)
Withernsea - Hold the line
In 1875, a sea wall built and rebuilt more recently. " rock revetments and groynes offer further protection as well as a 'toe' of larger rocks and rock armour to the south of Withernsea which is now seeing increased erosion.
In 1992-93 storms caused removal of most of beach frontage. 4m of sand stripped away causing cracks in sea wall, which needed emergency repairs.
Easington - Hold the line
20% of gas comes onshore at the Easington gas terminal
Sea Wall coats £4.5 million and will protect gas supply for 50 years
The lagoons, south of Easington village, comprises salt marsh, shingle and sand dune
Kilnsea - Managed retreat
Incentives given through grants to encourage re-location and 'set-back' schemes. Cost effective in the longer term.
Difficult to argue politically if residents involved
Letting sea flood land in a managed way. May help to reduce tides in estuary environments. Only expected to last 20-30 years