Holderness coast - case study

• Holderness coast, Yorkshire:

  • stretch over 61 km, from the Chalk cliff at Flamborough through Holderness to spurn Head.
  • combination of clay geology and high energy environment one of the most rapidly eroding coastlines in Europe
• Physical factors:

  weather - winter storms produce stronger waves and higher sea levels. The rain intensifies sub-aerial processes. The saturated clay cliffs suffer increased runoff leading to slumping.
• Physical factors:

  waves - dominant waves from the north east which is also the direction of the direction of the largest fetch. Destructive waves erode the beaches. Long shore drift then carries this sediment southward. Tides and low energy environment of spurn head allow sediments to collect forming a spit, mud flats and sand dune.
• Physical factors:

  geology - the two main rocks are chalk and boulder clay. The more resistant chalk have survived large scale erosion and this has created classic features. The boulder clay are easily eroded and their retreat has formed the bay of Holderness.
• features and processes:

  • chalk headland and cliffs near flamborough
  • retreating clay cliffs of Holderness bay
  • 6km spit at spurn head
• Flamborough head:

  headland - arch, stack and wave cut platform

  chalk is resistant to erosion and have a distinctive lithology

  horizontal bedding planes - where they assist in the formation of wave cut platforms increasing abrasion.

  wave refraction - further concentrations waves on headlands allowing caves to develop progressively into arches, stacks and stumps
• Holderness cliffs:

  • formed by material left by ice sheets
  • retreating at 1.8 metres each year
  • sub-aerial processes - rainwater enters the clay & weight of water causes material to slide seawater. Removal of vegetation & increased urbanisation can accelerate these effects causing slumping.

  cliff top housing or hotels make matters worse. At cliff root the dine clay is easily removed by waves & estimated that LSD carries half a million tonnes each year in suspension. Little material to form beaches & protect cliffs.
• Spurn head:

  • sediments deposited here where the winds and river estuary have a large but fragile spit (6km)
  • currently growing at 10cm each year, winter storms are threatening to cut through narrow neck and detach from mainland
  • spit is also the site of sand dune and salt marsh ecosystem
• human factors:

  presence of people - turns physical processes into hazards and threatens life and property. Increased population levels due to retirement and the development of leisure and holiday facilities have occurred around Bridlington. The risk of erosion have been much greater at Easington where the gas terminal is under threat.
• human factors:

  interfering with natural processes - such as LSD or implementing defence strategies can have adverse effects. Downward drift impact of groynes at Hornsea, prevents building beaches elsewhere. Rapid erosion rates may be due to sediment starvation.
• human factors:

  global warming - indirect human impact are creating a rise in sea level and increase storminess. Areas such as Spurn head are at greater risk in such conditions, from both coastal flooding and erosion.
• hard engineering:

  • 11.4km of 61 km coastline is currently protected by hard engineering
  • Bridlington protected by a 4.7km sea wall as well as groynes
  • easington gas station protected by revetments
  • spurn head protected by groynes and ripraps
• existing schemes are not sustainable:

  • groynes trap sediment, increasing width of beach. Increases erosion down drift.
  • sediment produced from erosion normally washes into humbery estuary , reduction of sediment is increasing flooding
  • protection is leading to formation of bays causing increased pressure and eventually the cost of maintaining sea defences will be too high
• Managed retreat - relocating caravan parks further inland and allowing the land they are on to erode. However, there are issues surrounding how much compensation businesses will get for relocating and relocation isn't always possible

  Shoreline management plan recommends holding the line at some settlements and doing nothing along the less populated stretches but is unpopular with land owners
• erosion - soft boulder clay is easi;y eroded by wave action.

  mass movement - boulder clay is prone to slumping when its wet. Water makes the clay heavier and acts as a lubricant between particles, making it unstable

  transportation - prevailing winds from the northeast transport material southwards. These winds also create an ocean current which transport material south by long shore drift. Rapid erosion means there is always plenty of sediment to be transported

  deposition - where the ocean current meets the outflow of the humber river, the flow becoes turbulent and sediment is deposited
• headland and wave cut platforms

  • bouder clay overlies chalk
  • chalk is harder and less easily eroded, so it forms a headland (flamborough head)
  • Wave cut platforms has had features such as stacks, cave and archs
• challenges

  • shoreline management plan for holderness recommends holding the line at some settlements and doing nothing along less populated stretches of coastline. Unpopular with owners of land or property
  • managed realignment e.g relocating caravans further inland - issues around compensation
  • 1995, council stopped protecting spurn head
  • easington gas terminal protected by rock revetments - only 1km in front of terminal, meaning villages of easington isn't protected