HOLDERNESS Flashcards
what are the three main location points at the holderness coast
1) flamborough head
2) bridlington bay –> spurn head
3) spurn head
composition of flamborough head
chalk headland, many typical landforms associated with coastal erosion
composition of bridlington bay to spurn head
extensive erosion and sediment transfer.
rapid cliff retreat
composition of spurn head
spit formed at the estuary of the river Humber
inputs into the holderness
erosion from the weak unconsolidated till cliffs (unsorted material deposited directly by glacial ice)
outputs of the holderness
finer sediments washed offshore
another OUTPUT is Spurn Head, whilst a significant amount of sediment continues to move south towards East Anglia
what role does LSD play in transfer of sediment
coarser sediment is moved southwards
factors affecting the coastal system
geology
storms
protection
geology
chalk makes up the majority of the coastline (relatively resistant)
present day coastline is the result of sediment carried and dumped by ice sheets during the last glacial period.
sea levels rose at the end of the last glacial, forming the North Sea and eroding the thick glacial till > cliffs
what rock makes up the majority of the coastline
chalk
storms
north easterly winds drive powerful waves.
extreme low pressure in the North Sea – storm surges several metres high. low frequency but high magnitude events – significant flooding and erosion.
cause LSD from North to South.
what direction does the wind blow to drive powerful waves
NE
protection
hard engineering – rock armour, sea walls, groynes.
deprived areas further south of sediment > exacerbating coastal erosion downwind
what is the composition of flamborough head
chalk – resistant sedimentary rock
distinctive layers – roughly horizontal (faults)
vertical cracks run through the cliffs (joints)
joints and faults are readily exploited to form classic cliff features – e.g. caves
what are the waves like at flamborough head
waves refracted when approaching the coastline
waves therefore lose energy in the bay, depositing material > beach formation
more exposed headlands receive full force of the waves – steep cliffs
what processes occur at flamborough head
frequent rockfalls due to sea undercutting cliffs
high tide line seen in figure 5
causing wave cut platforms and stacks
erosion from bridlington bay to spurn head
rates of erosion in excess of 1m per year (up to 10m per year in some areas)
generates vast amounts of sediment that feeds the sediment cell
fine sediment carried offshore
coarse sediment carried away southwards by lsd > builds up beaches, reduces erosion > negative feedback
what does the sediment transfer from bridlington bay to spurn head do
spurn head is nourished by this sediment transfer
protects towns bordering the river humber from storm waves and flooding
further south, the wash is an important sediment sink
what is spurn head
temporary sediment store or sink
recurved end resulting from direct wave action
v narrow > frequently breached by storms (hence only a temporary store)
first formed 8000 years ago – end of the last glacial period
what management techniques have been found at spurn head
groynes and revetments built to stabilise the spit
military forts established on spurn point, royal engineers took over task of maintenance
but in 1960 the yorkshire naturalists trust took over, but they couldn’t afford to maintain the defences
what happened in 2013
in 2013, a huge tidal surge hit spurn point.
sea defences could not cope
buildings and road access destroyed
what does the SMP for the holderness coast suggest for the next 50 years
1) holding the line at some settlements (e.g at bridlington, withernsea, Hornsea, Mappleton and Easington gas terminal)
2) suggests doing nothing along less populated stretches, but this is unpopular with owners of land or property along the stretches where nothing is being done
3) Managed Realignment has been suggested
what is managed realignment
the purposeful, coordinated movement of people and buildings away from risks
explain what they would do for managed realignment at the holderness coast
relocate caravan parks (sandy caravan parks) further inland and allowing the land they are on to erode.
this = more sustainable scheme as it would allow the coast to erode as normal without endangering businesses or messing up the dynamic equilibrium. however, there are issues surrounding how much compensation businesses will get for relocating. also relocation isn’t always possible e,g there maybe no land for sale
what happened in 1995
holderness Borough council decided to stop trying to protect spurn head from erosion and over washing - do nothing became the new strategy.
this saves money and allows the spit to function naturally, over washing may damage marsh environments behind the spit.
a coastguard station on the spit may also be at risk.