2.Changing Coastal Environments
2. Changing Coastal Environments
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2.1.1 Coastal erosion: hydraulic action, corrosion, corrasion, attrition; transportation; deposition; longshore drift.
2.1.2 Types of waves: constructive and destructive and wave refraction. -
2.2.1 The characteristics and formation of landforms: headlands, bays, cliffs, wave-cut platforms, caves, arches, stacks, stumps, beaches, spits, bars, sand dunes.
2.2.2 The formation and characteristics of discordant and concordant coastlines.
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2.3.1 The opportunities of living near the coast.
2.3.2 The hazards of living near the coast.
2.3.3 An evaluation of hard and soft engineering strategies and techniques used to manage coastal erosion and flooding; including sustainable.
2.3.4 The distribution and impacts of tropical storms: cyclones, hurricanes, and typhoons.
2.3.5 An evaluation of the strategies and techniques used to manage the impacts of tropical storms: preparation, planning, protection, prediction.
2.3.6 The global distribution, importance of, threats to, and strategies and techniques used to protect and manage coral reefs and mangroves; including sustainable.
2.3.7 One detailed specific example of a named country or coastal area to include:
• the causes and impacts of coastal erosion
• the strategies and techniques used to protect the coast from tropical storms and manage erosion; including sustainable.2.3.8 One detailed specific example of a named country or coastal area to include:
• why the coral reef is important
• threats to the coral reef
• the strategies and techniques used to protect and manage and the coral reef; including sustainable.
2.1 - Physical processes that shape the coast
Erosion
Erosion is the process where the sea wears away rocks and land along the coast.
Waves crash against the shoreline, gradually breaking down cliffs, beaches, and headlands.
This happens through several processes, including:
Hydraulic action – the force of waves trapping and compressing air in cracks.
Corrasion – waves hurl rocks and sand against the coast, like sandpaper.
Attrition – rocks and pebbles carried by waves smash into each other, becoming smaller and rounder.
Corrosion – some rocks (like limestone) are dissolved by acids in seawater.
Why it matters: Coastal erosion shapes landforms such as cliffs, caves, arches, stacks, and bays, and can also create hazards for people living near the coast.
Types of Erosion
Transportation
Transportation is the process by which the sea moves eroded material (sand, pebbles, mud) from one place to another along the coast. Waves and currents provide the energy needed.
There are four main types of transportation:
A. Solution
Some minerals (e.g. chalk, limestone) are dissolved in seawater.
They are invisible but still transported as part of the water.
B. Suspension
Fine, light material such as sand and silt is carried within the water.
It makes the water look cloudy or muddy.
C. Traction
Large boulders and rocks are rolled along the seabed by strong waves.
Happens in high-energy conditions (e.g. storm waves).
D. Saltation
Smaller pebbles and stones are bounced or hopped along the seabed.
They are lifted by the water, travel a short distance, and then land again.
Deposition
Deposition is the process where the sea drops or lays down material (sand, shingle, silt, pebbles) that it has been transporting.
When Does Deposition Happen?
Deposition occurs when the sea loses energy and can no longer carry its load. This often happens when:
Waves enter a sheltered area such as a bay.
The sea is shallow, slowing wave energy.
There is little or no wind, so waves are weaker.
The swash is stronger than the backwash (constructive waves).
Exam Tip:
If asked “why does deposition take place?” always link to loss of energy in the waves. If asked about landforms, give a named example (e.g. Spurn Head spit, Holderness Coast, UK).
Exam Tip:
In a 4-mark question, always mention the swash, backwash, and angle of waves. Use the phrase “zig-zag movement” to show understanding.
Longshore Drift (LSD)
Longshore drift is the process that moves material (sand, shingle, pebbles) along a coastline in a zig-zag pattern. It happens because of the direction that waves approach the shore.
How it Works
Waves approach the coast at an angle (often driven by prevailing wind).
The swash (water moving up the beach) carries material up the shore at the same angle.
The backwash (water moving back down) is pulled by gravity and moves straight down the slope of the beach, at 90° to the coastline.
Repeated swash and backwash cause material to move step by step along the coast.
Why is it Important?
Longshore drift is the main process transporting sediment along coasts.
It plays a key role in forming depositional features such as:
Spits
Bars
Tombolos
It can also lead to erosion in some areas when sediment is removed.
Waves
What are Waves?
Waves are created by the wind blowing across the surface of the sea.
The strength, duration, and distance of the wind (called the fetch) control the size and power of waves. In the diagram A would produce the largest and strongest waves. This is because it has the largest fetch.
Parts of a Wave
Crest – the top of the wave.
Trough – the lowest point between two waves.
Swash – the forward rush of water up the beach after a wave breaks.
Backwash – the water running back down the beach under gravity.
Why Do Waves Break?
As waves move from deep water into shallow water, the base of the wave slows down due to friction with the seabed. The top of the wave continues moving faster than the bottom. This causes the crest to become steeper until it collapses forward, breaking onto the shore.
Types of waves
Constructive Waves
Low, gentle, and less frequent.
Strong swash, weak backwash → material is deposited.
Create wide, gently sloping beaches made of sand or shingle.
Destructive Waves
High, steep, and frequent.
Strong backwash, weak swash → material is eroded and dragged away.
Create narrow, steep beaches with coarse material.
Wave Refraction
What is Wave Refraction?
Wave refraction is the process by which waves bend and change direction as they approach the coastline. It happens because different parts of the wave reach shallow water at different times, causing the wave to slow down unevenly.
How it Works
In deep water, waves move at the same speed in straight crests.
As waves approach an irregular coastline, one end of the wave reaches shallow water first (e.g. around a headland).
Friction with the seabed slows this part of the wave, while the rest in deeper water continues faster.
The wave bends towards the headland, concentrating energy there.
In bays, waves spread out, and energy is reduced, leading to deposition.
Exam Tip:
Use phrases like “energy concentrated on headlands” and “energy dispersed in bays”.
Often tested in diagram + explanation style questions (3–4 marks).
2.2 - The Main landforms associated with these processes
Discordant Coastlines
Coastlines where the bands of hard and soft rock run at right angles to the shoreline.
Rock types: Hard rocks (e.g. chalk, limestone) alternate with soft rocks (e.g. clay, sands).
Features formed:
Softer rock erodes faster (by hydraulic action and corrasion) forming bays.
Harder rock is more resistant and sticks out into the sea, forming headlands.
Waves refract around headlands → energy concentrated on them (erosion), energy dissipated in bays (deposition).
Classic features: headlands, bays, cliffs, wave-cut platforms.
Concordant Coastlines
Coastlines where the bands of rock run parallel to the shoreline.
Rock types: Usually a continuous band of hard rock (e.g. limestone, chalk) and soft rock (e.g. clay, sands) running parallel behind protected from the shore.
Features formed:
The hard rock acts as a barrier, protecting the softer rock behind.
The coastline remains fairly straight and uniform.
However, if erosion breaks through the hard rock (e.g. along a fault or weakness), the sea can erode the softer rock behind → forming coves (e.g. Lulworth Cove, Dorset).
Headlands and Bays
What are they?
Headlands are areas of hard rock that stick out into the sea.
Bays are curved inlets where the softer rock has been eroded away.
How do they form?
A coastline has alternating bands of hard and soft rock.
Waves erode the softer rock faster (processes: hydraulic action, corrasion, corrosion).
This creates bays.
The harder rock is more resistant, so it erodes slowly and sticks out as headlands.
Wave refraction causes more energy to hit the headlands (further erosion) and less energy in the bays (deposition → sandy beaches often form).
Exam Tip:
In a 4–5 mark answer, always link rock type + erosion rate + landform. If asked to include a 2 stage diagram.
Wave-cut platforms
A wave-cut platform is a flat, rocky area found at the base of a retreating cliff. It is left behind after the cliff face has been eroded and collapsed many times. Wave-cut platforms are usually exposed at low tide and may have features like rock pools, seaweed, and sharp uneven rock. They are evidence of cliff retreat and show how the coastline has changed over time.
How do they form?
Waves attack the base of a cliff using hydraulic action, corrasion, and corrosion.
This erodes a wave-cut notch at the high tide level.
As the notch gets bigger, the cliff above becomes unstable.
Eventually, the cliff collapses under its own weight.
The cliff retreats inland, and the fallen rock is carried away by waves.
A flat, rocky area is left at the base, exposed at low tide – this is the wave-cut platform.
The process repeats, making the platform wider and the cliff retreat further.
Exam Tips:
Always use the sequence notch → collapse → retreat → platform in your answer.
In a short definition question, write something like:
“A wave-cut platform is a flat, rocky surface at the base of a cliff, formed by wave erosion and cliff collapse.”
Cave, Arch, Stack and Stump
What are they?
Crack or fault - an area of weakness that can be more easily eroded.
Cave – a hollow in a cliff formed when waves erode a weakness (crack or fault).
Arch – when a cave is eroded through a headland, forming a natural opening.
Site of collapse - This shows the area where an arch used to stand.
Stack – an isolated vertical column of rock left when an arch collapses.
Stump – the eroded remains of a stack, usually visible at low tide.
How do they form? (6 steps)
Waves attack a cliff with hydraulic action, corrasion, and corrosion. A crack or joint in the rock is gradually widened.
Continued erosion (Hydraulic action and corrasion) enlarges the crack into a cave.
Further erosion deepens the cave until it breaks through the headland, creating an arch.
The arch roof becomes unstable and eventually collapses.
The collapsing of the arch leaves behind a solitary column of rock called a stack.
The stack is further eroded at its base until it collapses, leaving a stump.
Exam Tips:
Always use the sequence crack → cave → arch → stack → stump.
Mention erosion processes (hydraulic action, corrasion, corrosion) for full marks.
Beaches
A beach is a landform made of sand, shingle, or pebbles found between the high tide and low tide marks. Beaches are depositional features, created when waves drop material they were transporting.
How do they form?
Constructive waves (strong swash, weak backwash) deposit sand and shingle.
Material often comes from cliff erosion, rivers, or longshore drift.
Deposition is greatest in sheltered bays where wave energy is low.
Types of beaches
Summer beaches → wide and sandy (constructive waves).
Winter beaches → narrow and steeper, with more shingle (destructive waves).
Spits
Exam Tip:
Always include the sequence of wind + longshore drift + headland + hook + estuary + salt marsh for full marks.
A labelled diagram showing longshore drift arrows, the spit, hooked end, and salt marsh is often expected in 4–7 mark questions.
A spit is a narrow ridge of sand or shingle that sticks out into the sea, joined to the land at one end.
Formed by longshore drift depositing material where the coastline changes direction (e.g. a river mouth).
Example: Spurn Head, UK.
What is a spit?
A spit is a long, narrow ridge of sand or shingle that sticks out into the sea, connected to the land at one end.
Formation of Spits
Prevailing wind and swash direction – waves approach the coast at an angle, driven by the prevailing wind.
Longshore drift – material is moved along the coast in a zig-zag pattern by swash and backwash.
Headland / change in coastline – when the coastline ends or changes direction (e.g. a river mouth), sediment is carried out to sea beyond the headland.
Hooked end – the tip of the spit may curve inland due to wave refraction or secondary winds.
Estuary limits growth – if a river estuary is present, its flow prevents the spit from fully crossing the water.
Salt marshes – sheltered water behind the spit becomes a low-energy zone where mud and silt build up, creating salt marshes.
A bar is when a spit grows across a bay, joining two headlands.
This can trap water behind it, forming a lagoon.
Example: Slapton Ley, Devon, UK.
A tombolo is when a spit connects the mainland to an island.
Example: Chesil Beach linking Portland to mainland Dorset, UK.
Sand Dunes
What are they?
Sand dunes are mounds or ridges of sand found at the back of beaches, shaped by the wind. They are depositional landforms, created when sand is blown inland.
How do they form?
Onshore winds blow dry sand from the beach inland.
Sand is trapped by an obstacle (e.g. driftwood, rocks, plants).
Small embryo dunes begin to form.
Plants such as marram grass grow on dunes, trapping more sand with their roots and stabilising the dune.
Over time, dunes get bigger and move further inland, forming a succession:
Embryo dunes – small, unstable, little vegetation.
Foredunes / Yellow dunes – higher, partly vegetated, sand still visible.
Grey dunes – larger, fully vegetated, soil develops (grey colour).
Mature dunes – stable, often with shrubs and trees.
Exam Tip:
In an exam, always link dunes to wind + sand movement + vegetation stabilisation.
2.3 - Coasts present opportunities and hazards for people
Opportunities of Living Near the Coast
Hazards of Living Near the Coast
Coastal Erosion
Why is coastal erosion a major hazard?
Coastal erosion is the wearing away of land and beaches by waves, currents, and tides. It is a major hazard because it destroys homes, farmland, businesses, and important infrastructure such as roads and ports. In some areas, whole communities are forced to relocate.
Example:
On the Holderness Coast (UK), soft cliffs made of boulder clay are eroding rapidly — up to 2 metres per year. Villages, farmland, and even roads have been lost to the sea, making it one of the fastest eroding coastlines in Europe.
Human management:
Although erosion is a natural process, humans can use different coastal management strategies to protect people and property from damage. These are divided into hard engineering and soft engineering approaches.
Shoreline Management Plans
A Shoreline Management Plan (SMP) is a strategy used to decide how to manage different stretches of coastline. Instead of each town making decisions alone, SMPs look at the coast as a whole and plan for the long term (50–100 years).
Purpose:
To reduce risks from coastal erosion and flooding.
To balance environmental, social, and economic needs.
To make coastal management more sustainable.
Decision-Makers in SMPs
1.National Government Agencies
2.Local Authorities (Councils)
3.Stakeholders
Hold the Line
Shoreline Management Plans Compared to War Tactics
Hold the Line → Like defending a fortress wall: troops hold their ground and strengthen their defences to stop the enemy (the sea) from advancing.
Advance the Line
Advance the Line → Like pushing troops forward: the army moves into enemy territory, gaining land but at huge cost.
Managed Retreat
Managed Retreat → Like a tactical withdrawal: the army gives up less important land to regroup and strengthen elsewhere, reducing long-term losses.
Do nothing
Do nothing → Like abandoning a battlefield: commanders decide it’s not worth the fight, so the army retreats completely and lets the enemy take over.
Hard Engineering and Soft Engineering
What is Hard Engineering?
Hard engineering involves building man-made structures to control the sea and reduce its power. These are usually expensive but provide strong protection.
Examples: sea walls, groynes, rip-rap, offshore breakwaters.
What is Soft Engineering?
Soft engineering works with natural processes to reduce the impact of the sea. It is often cheaper, more environmentally friendly, and more sustainable in the long term.
Examples: beach nourishment, dune regeneration, managed retreat, planting mangroves.
The Distribution and Impacts of Tropical Storms: Cyclones, Hurricanes, and Typhoons
Distribution of Tropical Storms
Tropical storms form over warm oceans close to the equator, where sea surface temperatures are above 27°C. They develop between the Tropics of Cancer and Capricorn but never exactly at the equator, as the Coriolis force is too weak there.
In the Atlantic and eastern Pacific Oceans, they are called Hurricanes.
In the western Pacific Ocean, they are called Typhoons.
In the Indian Ocean and around Australia, they are called Cyclones.
The arrows on the map show their typical paths (westward and then curving polewards), while the shaded red areas highlight where these storms most often occur.
