AO1 (5 marks)/AO2 (15 marks)

Marking instructions
Markers must apply the descriptors in line with the general marking guidance and the qualities outlined in the levels-based mark scheme below.
Responses that demonstrate only AO1 without any AO2 should be awarded marks as follows:
Level 1 AO1 performance: 1 mark
Level 2 AO1 performance: 2 marks
Level 3 AO1 performance: 3 marks.
Level 4 AO1 performance: 4–5 marks.

Indicative content guidance
The indicative content below is not prescriptive and candidates are not required to include all of it. Other relevant material not suggested below must also be credited.
Please remember that the descriptors provide guidance as to the appropriate level.
Bullet points covering the indicative content do not translate directly into marks.

Relevant points may include:
AO1

Global sea level rises increases risk (Bangladesh or the Maldives).
Local factors increase flood risk on some low-lying and estuarine coasts (height, degree of subsidence, vegetation removal).
Storm surge events (depressions, tropical cyclones) can cause severe coastal flooding.
Climate change may increase coastal flood risk (frequency and magnitude of storms, sea level rise).
Rising population in coastal regions increases risk significantly.
Costs of protecting some coasts may become unsupportable especially in regions/locations with long term negative isostasy.
Sea levels have risen by over 20cm in the last 100 years and is much greater than the rate of sea level rise during the past 3,000 years. Coastal flood risk is therefore rapidly increasing globally.

AO2

Sea level rise is thought to be increasing in the future by as much as 2m in the next 100 years and many estimates put the risk higher than that.
A key cause of rising flood risks is eustatic changes where global warming is causing sea temperatures to rise and so the sea expands and so causes sea levels to rise and so increasing flood risk in areas such as the Pacific Islands.
There is also isostatic downwarping. This is caused by the rebound of glaciated land relative to the sea. In areas of the south of England flood risk is increasing as a result of the south of England sinking into the sea so increasing flood risk whilst Scotland rebounds upwards.
Downwarping can occur due to the accretion (build up) of sediment brought down by rivers that create the deltas such as in Bangladesh thereby increasing flood risk.
Tectonic activity can change the relative sea level with areas in tectonically active areas undergoing displacement and so an increased flood risk.
Rising sea levels are not the only physical factor causing flood risk to increase. Climate change will put more energy in to the atmosphere and so the conditions for a tropical storm to start (26.5oC) will occur more often and so there will be more hurricanes increasing coastal flood risk.
Higher sea surface temperatures will cause the tropical storms to have lower pressure and so have faster wind speeds and so increase the flood risk of areas affected by such storms.
More energy in the atmosphere will mean that depressional storms that hit the UK will have lower pressure and so stronger wind speeds as well further increasing flood risk.
Sea level rise is not the only cause of increased flood risk. Human factors can also cause increased flood risk. Increased populations in settlements at vulnerable coastlines is also causing an increased flood risk.
Human intervention can increase flood risk in some places by reducing it in others.
In other areas, such as the Maldives, the flood risk has developed due to the removal of mangrove swamps. These are vital natural barriers against flooding as they trap sediment and so raise the level of the beach front. Without the protection of mangrove swamps there is little to stop rising sea levels caused by eustatic change and so removal of vegetation increases flood risk.
A lack of resources also can increase flood risk. Countries such as Bangladesh are relatively poor and cannot afford defences such as sea walls and flood barriers that other richer countries can afford.

Accept any other appropriate response.

Coastal Erosion & Sea Level Change (Edexcel A Level Geography)

Topic Questions