Give two statistics that suggest the UK has a ‘coastalised’ population?
- 60% of the population live within 60km of the coastline.
- Coastal areas have a 50% higher population density than inland areas.
What is coastalisation?
The increasing proportion of people in coastal areas.
Describe factors that have led to coastalisation.
- Flat, fertile land is often found on the coastline. For example, the Nile Delta is surrounded by extremely flat land that is regularly deposited with alluvium (containing good nutrients for crops). Flat land is also good for building.
- Equable climate as water has higher specific heat capacity (so takes longer to change temp). This means coastal places have cooler summers and milder winters.
- Coasts are extremely biodiverse, providing food and leisure outlets for the population.
- Building materials available through quarrying (e.g. limestone in Dorset) for quick construction of settlements.
- Inlets create natural habours and esturies that are suitable for docks (e.g. Avonmouth in Bristol).
- Aesthetic enjoyment from coastline.
What methods were used to investigate how Swanage developed over time?
Fieldwork:
- Land use surveys carried out on a chloropleth map (collaborative, use of transects, universal key)
- Questionnaires carried out (stratified, adequete sample size)
- Grafiti audits and environmental bipolar surveys (collaborative, use of transects)
- Footfall counts (5 minutes, specific transects along Swanage)
Research:
- Changing house prices over time to assess how Swanage has developed in terms of increasing/decreasing demand. (RightMove.co.uk/Zoopla)
- ONS figures to assess how Swanage has developed in terms of changing labour market structure (a shift from primary industry to tertiary tourism/services).
- Comparision of historical old OS maps (old-maps.co.uk) with chloropleth map from fieldwork.
- Comparision of current photos (from fieldwork) to older photos (oldukphotos.com)
- Number of reported crimes over time to assess Swanage’s position on the seaside development model (Police.UK)
What results and conclusions can be drawn from the fieldwork in regards to how Swanage has changed over time?
- Based on stratified questionnaire, majority of those in Swanage believe that it had improved over the past 50 years (an average score of 6.6 on a scale of 1-10).
- Land use map shows vast majority (60%+) of modern land use is designaed to residential, with the remainder being primarily services based. Compared to the agricultural/industrial land use shown by old OS map, this shows the shift from primary to tertiary.
- Today, 39% of employment is based in services or distribution according to the Purbeck Labour Market Profile (produced by Dorset County Council). This is further evidence for shift from agriculture and industry).
- ACORN profile shows large proportion of residential property is held by pensioners. Evidence for aging population, as opposed to youthful population in past.
What is meant by ‘coastline’?
The boundary between land and sea.
What is meant by the coastal zone?
Defined as up to 60km onshore.
What is meant by ‘offshore’?
200 nautical miles within the economic exclusion zone.
What is ‘dynamic equilibrium’?
Various factors are shaping the coast. These factors are constantly changing, meaning the coast is also changing.
Explain how beaches are formed.
- Beaches are formed by constructive waves, wherein the swash is stronger than the backwash.
- This usually happens in sheltered environments, where features such as inlets or spits mean that waves have lost energy, and therefore must deposit the sediment in transportation.
How are sand dunes formed?
Sand from offshore bars can be blown onto the shore by strong winds, forming sand dunes.
How is sediment transported along the coast?
Longshore Drift:
- Waves approach the beach at an angle according to the prevailing wind direction.
- The backwash pulls sediment back down the beach at a right angle (due to gravitational pull).
- The sediment is then transported in the prevailing wind direction, until being deposited further along the coast by the wave’s swash.
What is attrition?
Collision of materials carried by waves leads to the creation of smaller rocks.
What is abrasion/corrasion?
Waves throw particles against the rock, often at high velocity, causing physical erosion.
What is corrosion?
The chemical action of the sea water. Acids in the salt water slowly dissolve rocks along the coast, particularly true for limestone.
What is hydraulic action?
Air pockets are explosively copressed by the water. The kinetic force of the water weakens the surrounding rock.
Why do waves break?
As the wave approaches the coast:
- Friction increases due to increasing size of beach/underlying material.
- This slows down bottom of wave, but top of wave (crest) not slowed down as much.
- Eventually, the crest topples over and the wave breaks.
What factors affect wave size?
- Strength/speed of wind (more kinetic energy to be transfered to waves via air resistance).
- Fetch (if wave has had longer to travel in contact with wind, more total energy will have been transfered to wave).
Where and why do we find headlands and bays?
- Discordant coastlines
- Alternating bands of geology of more and less resistant rock mean that there will be alternating headlands and bays.
- Action of sea + sub aerial processes are able to erode less resistant rock, whilst leaving more resistant rock as headlands.
Describe cliff retreat.
- A combination of action of waves (abrasion + hydraulic action) and sub-aerial processes (weathering such as freeze thaw and physical action of rain) create wave cut notch between high and low water marks.
- The overlying rock becomes unstable due to overhang. Continued action of sub-aerial processes and cliff-foot-erosion lead to collapse of overlying rock.
- Cliff retreats as above processes repeat, leaving a wave cut platform behind.
What is a tombolo?
A connection to an island caused by deposition of sediment. This can happen due to longshore drift.
What is a spit?
Exended stretch of material that stretches out to see due to longshore drift.
What is a bar?
A spit grows across the bay due to longshore drift, eventually cutting off the bay from the sea completely.
