The causes and effects of coastal flooding, the threat of rising sea levels, and the conflicting ways people use and value the coast (AO1, AO2).

What this dot point is asking

CCEA wants you to explain the causes and effects of coastal flooding, the growing threat of rising sea levels, and the conflicting ways people use and value the coast. This links the physical processes of the coast to real human consequences and to the management decisions in the later dot points, and it is a common source of higher-tariff "explain" questions.

The causes of coastal flooding

Coastal flooding has mainly physical causes, made worse by climate change.

• Storm surges push seawater inland, overtopping defences and dunes.
• High tides and large waves raise water levels further; the worst floods come when a storm coincides with a high tide.
• Rising sea levels from climate change mean the baseline sea level is higher, so floods reach further inland and happen more often.
• Low-lying land, such as reclaimed land or coasts behind dunes, floods quickly once the sea breaks through.

The effects of coastal flooding

As with rivers, sort the effects into three groups, supported by detail.

• Social. Deaths and injuries, people made homeless, and disruption to water, power and transport.
• Economic. Damage to homes, businesses and ports, loss of farmland to saltwater, and the cost of repairs and defences.
• Environmental. Saltwater poisoning of freshwater habitats, erosion of dunes and salt marsh, and damage to wildlife.

Rising sea levels

Climate change is raising global sea levels in two ways: thermal expansion (warmer seawater takes up more space) and melting ice on land (glaciers and ice sheets adding water to the oceans). Higher sea levels mean storm surges start from a higher base, so low-lying coasts and small islands face more frequent and more serious flooding in the future. This is why CCEA links coastal management to climate change.

How people use and value the coast

The coast is in demand for many, often conflicting, uses.

• Housing and settlement - people want to live by the sea, but homes need protecting.
• Tourism and recreation - beaches and resorts bring income but add pressure and development.
• Ports and industry - sheltered coasts are valuable for trade and jobs.
• Conservation - dunes, cliffs and salt marsh are important habitats that some want left undefended and natural.

Because defending one area can starve another of sediment or increase erosion elsewhere, and because defences are expensive, decisions about the coast create conflict between these groups.

Worked example: explaining a storm-surge flood

Common mistakes

Examples in context

Example 1. Why small low-lying islands are most at risk. Low-lying coasts and small islands sit only a little above sea level, so even a modest rise plus a storm surge can flood large areas, contaminate freshwater and force people to move. This is why sea-level rise is often described as an existential threat for such places, and it is a strong, specific point to use when an answer asks about the effects of rising sea levels.

Example 2. The cost trade-off in coastal defence. Because sea defences are expensive and paid from public money, councils must decide which stretches of coast are worth protecting. Defending a town centre may be judged worthwhile, while protecting a few isolated farms may not, leading to "managed retreat" there. This trade-off between cost and value is exactly the kind of conflict CCEA wants you to explain, and it leads directly into the coastal-management dot points.

Try this

Q1. What is a storm surge? [2 marks]

• Cue. A temporary rise in sea level caused by low pressure and strong onshore winds pushing water towards the coast.

Q2. Give two ways climate change raises sea levels. [2 marks]

• Cue. Thermal expansion of warmer seawater and melting ice on land.

Q3. Give one reason there is conflict over coastal management. [1 mark]

• Cue. Protecting one area can increase erosion elsewhere, or defences cost money some think better spent elsewhere.