Coastal Landscape Case Studies

Question 1

High Energy Coastline, Dorset

Answer 1

The rate of erosion exceeds the rate of deposition

Question 2

Factors that affect the formation of landforms?

Answer 2

Geology, Wave Energy, Sediment Cells

Question 3

Discordant Coastline

Answer 3

Rocks crop at right angles to the coastline, leads to the formation of headlands and bay, due to the alternating bands of resistant and weak rock. Eg Swanage Bay and Peveril Point.

Question 4

Negative Feedback and Positive Feedback

Answer 4

Negative Feedback occurs on the headland, as it is eroded more due to the converging othogonal waves on the headland, eg returning the system to equilibrium.
Positive Feedback is the opposite as it enhances or amplifies change, moving a system away from its equilibrium state and making it more unstable.

Question 5

Erosion of Headland

Answer 5

• Weak areas (cracks/ joints) are attacked by waves- hydraulic action to form a cave
• Cave is widened and deepened by erosion to form an arch eg Durdle Door. Sub-aerial processes attack the top of the arch forming a blow hole.
• The rock eroded more until it collapses, forming an isolated stack eg Old Harry.
• The base of the stack is undercut to form a stump eg Old Harry’s wife.

Question 6

Shore Platform

Answer 6

Waves via erosion undercut the cliffs between the high and low tide marks, forming a wave-cut notch.
After more erosion the cliff collapses, the backwash removes the debris and the wave-cut platform is created from the roots of the eroded cliff.
Increased erosion will lead the formation of a larger wave cut platform. Negative Feedback will occur as the waves break earlier due to the platform leading to a dissipation of wave energy, reducing rates of erosion of cliffs.

Question 7

Formation of a Cove (concordant coastline)

Answer 7

Where rocks run parallel to the coast, continued erosion along a weakness in a rock or a stream, can break through the more resistant rock.
Once waves are able to attack the less resistant rock (the waves diffract) , this layer is quickly eroded backwards and sideways forming a cove. Continued erosion leads to formation of a larger cove, until the sea reaches a more resistant rock to erosion and stops erosion. Eg Lulworth Cove. Queue Song…

Question 8

Types of Erosion

Answer 8

Hydraulic Action, Abbrasion, Attrition and Solution.

Question 9

Low Energy Coastline- Nile Delta

Answer 9

Deposition occurs at a faster rate than erosion.

Question 10

Types of Delta

Answer 10

Arcuate (Nile), Birds Foot (Mississippi), Cuspate (Ebro)

Question 11

Requirements for the formation of Deltas

Answer 11

The river has a high sediment load, as river flows into sea its velocity decreases, so does its competence, so it deposits the sediment.
As sediment mixes with salt water flocculation occurs causing clay particles to coagulate and settle out.
Sediment accumulates at the mouth of the river and the sand and silt builds up forming a fan shaped delta.

Question 12

Aswan Dam effect on Nile Delta

Answer 12

Built in 1970 for flood control and irrigation.
The dam traps sediment from reaching the Nile Delta.
So there is greater erosion of the delta as there is little deposition- negative sediment budget. Sediment decrease from 120 million tonnes a year to almost 0.

Question 13

Sea Level Rise at Nile Delta

Answer 13

Sea levels in the Meditteranean are rising 1.2mm/ year.
Deeper water produces larger waves which leads to greater erosion of delta.
Rates of coastal retreat due to dam and sea level rise: 148mm/year as coastline no longer in dynamic equilibrium.

Question 14

Holderness Case Study

Answer 14

Erosion and Management.

Question 15

Physical and Human Causes of erosion at Holderness

Answer 15

Subject to Powerful waves and sea level rise, Soft boulder clay cliffs, Eroded material transported out to sea, therefore beaches are very thin so don’t protect the cliffs.
Inputs of new resistant points eg Hornsea, Mappleton.
Removal of sediment offshore, 811,044 tonnes dredged illegally.

Question 16

Bridlington, Hornsea and Mappleton

Answer 16

Bridlington - The 4.7km reinforced concrete wall and timber groynes has ensured no erosion.
Hornsea- A stone gabion has been erected, this has reduced rates of erosion, but has increased rates of erosion downdrift.
Mappleton- Two rock groynes and a 500 metre revetment has halted erosion at the village, but has lead to increased erosion downdrift has these areas are being starved of sediment.

Question 17

Effects on the rest of the Holderness coastline of coastal defences.

Answer 17

Due to coastal defences elsewhere Spurn Head was being starved of material, so consequently a series of hard engineering strategies have been implemented delaying the erosion process.
Due to the defences there has been changes in flows of sediment and energy, as areas downdrift of defences have faced high energy waves eroding the coastline greatly and these areas have been starved of sediment intensifying the erosion process. As defences like groynes have prevented the movement of sediment via longshore drift.

Question 18

Dubai Case Study- Economic development

Answer 18

Dubai only has 70km of coatline, so there was a huge reclamation project to expand the coastline and develop luxury residential areas. In 2005 Palm Jumeirah was completed, this consisted of 110 million m^3 of dredged sand. ‘The World’ has also been created using 325 million m^3 of sediment.

Question 19

Unintended impacts in Dubai

Answer 19

The building of the artificial islands has led to unintended impacts, the islands have disrupted to process of Longshore drift which has led to some beaches having plenty of sediment, whereas others are being starved of sediment leading to increased rates of erosion of the cliff line.