Case study: Mappleton, the Holderness Coast

Where is Mappleton located?

• the Holderness coast

• East Yorkshire

• ~3km south of Hornsea

Which sediment cell is the Holderness coast located in?

sediment cell 2

What 3 main factors affect the Holderness coastal system?

• geology

• prevailing winds (wave energy)

• management

What are some of the distinctive coastal landscapes around Holderness?

• steep chalk cliffs

• slumping cliffs

• wave-cut platforms

• beaches

• headland (Flamborough Head)

• sand dunes

• spit (Spurn Head)

What is the erosion rate at Mappleton?

~2m/year

What is the population of Mappleton?

• ~340 people

• ~50 properties
  

What is the main road serving Mappleton?

the B1242, which connects settlements along the Holderness coast

What is the geology of Mappleton?

boulder clay (glacial till)

• deposited during the last ice age (~18,000 years ago)

• soft

• erodes quickly

Why is Mappleton at risk from erosion?

• made of soft boulder clay

• exposed to destructive waves on the Holderness coast, leading to rapid coastal retreat

Why was coastal management implemented at Mappleton?

to protect the B1242 road and the village, as it was cheaper than relocating the road and settlements

What are the main coastal defences used at Mappleton?

• rock groynes

• rock armour (revetment)

• cliff re-profilling

How much did the coastal defences at Mappleton cost?

approx. £2 million in 1991

What materials were used in the coastal defences at Mappleton?

granite imported from Norway was used for rock armour and groynes

What is the purpose/function of groynes?

• trap sediment moved by longshore drift

• build up a wider beach

How do groynes affect longshore drift?

• interrupt longshore drift

• prevent sediment from moving along the coast

What is the purpose/function of rock armour?

• absorb wave energy

• protect the base of the cliffs from erosion

Why is vegetation used on the cliffs at Mappleton?

• stabilise slopes

• help reduce mass movement (e.g., slumping, mudflows)

What is a positive impact of the coastal defences at Mappleton?

• reduced erosion between groynes

• created a wider beach

How have the coastal defences benefited infrastructure at Mappleton?

protected the B1242 road from coastal erosion

How have coastal defences affected tourism at Mappleton?

the wider, sandy beach and facilities (car park and toilets) have attracted more tourists

What is a negative impact of the coastal defences on downdrift areas?

reduced sediment supply has increased erosion further south along the coast

Why does erosion increase downdrift of Mappleton?

groynes trap sediment, so less material is transported further along by longshore drift

Which location is negatively affected downdrift of Mappleton? What are the impacts there?

Cowden

• erosion rates increased significantly after the coastal defences were built (increased from ~1m/year to ~3m/year)

• loss of land and property, including farms and homes

What conflict is caused by Mappleton's coastal defences?

tension between local authorities protecting Mappleton and landowners further along the coast who experience increased erosion

What is the overall evaluation of Mappleton's coastal management?

• effective locally in protecting property and infrastructure

• causes negative downstream impacts

What type of waves affect the Holderness coast?

destructive waves

• erode cliffs

• remove sediment faster than it is deposited

Why is beach formation at Mappleton important?

a wider beach acts as a natural barrier, absorbing wave energy and reducing erosion of the cliffs