Coastal Processes, Landforms, Opportunities, Hazards & Management (IGCSE 0460 – Topic 2.3)
1. Syllabus Checklist – Quick Review
| Syllabus requirement |
Coverage in the notes |
Suggested improvement |
| 2.1 Physical processes that shape the coast (hydraulic action, corrosion, corrasion, attrition, long‑shore drift, deposition, wave refraction) |
All seven processes listed with description and typical landform. |
Add short example for each process (e.g., “hydraulic action – sea‑cave formation at Durdle Door”). |
| 2.2 Coastal landforms (erosional, depositional, discordant & concordant coasts) |
Erosional and depositional landforms listed; discordant & concordant coasts described. |
Include a concise table linking each landform to its dominant process and a real‑world example. |
| 2.3 Opportunities and hazards of living near the coast |
Opportunities and hazards presented in bullet lists. |
Group hazards under the relevant process (e.g., erosion‑related, flooding‑related) for clearer cause‑effect links. |
| 2.4 Coastal management – hard, soft and managed retreat |
Hard, soft and integrated approaches described; comparison table provided. |
Add a short “when to use which method” decision flow‑chart description. |
2. Physical Processes that Shape Coasts
| Process |
How it works (key idea) |
Typical landform / example |
| Hydraulic action |
Wave pressure forces air into cracks; the compressed air expands explosively, widening the crack. |
Sea caves (e.g., Durdle Door, UK) |
| Corrosion (solution) |
Seawater, slightly acidic because of dissolved CO₂, dissolves soluble rocks such as limestone. |
Enlarged fissures, sea caves in limestone coasts |
| Corrasion (abrasion) |
Sand, pebbles and rock fragments are hurled against the cliff base by the swash, grinding it away. |
Wave‑cut platforms, cliff retreat |
| Attrition |
Rocks and pebbles collide while being moved by waves, becoming smaller and smoother. |
Rounded beach pebbles; supply of fine sediment |
| Long‑shore drift |
Waves approach the shore at an angle; swash moves sediment up‑coast, backwash moves it down‑coast, producing a net movement along the shore. |
Spits, bars, beach accretion on the up‑drift side of groynes |
| Deposition |
When wave energy falls (e.g., in sheltered water), the carried sediment settles out. |
Beaches, spits, offshore bars, tombolos, dunes |
| Wave refraction |
Wave fronts bend as they enter shallow water; the part in shallower water slows, aligning the wave more parallel to the coast. |
Energy concentrated on headlands, reduced on bays |
Wave energy formula (useful for exam calculations):
$$E = \frac{1}{8}\,\rho\,g\,H^{2}$$
- ρ = density of seawater (≈ 1025 kg m⁻³)
- g = 9.81 m s⁻²
- H = wave height (m)
Constructive vs. Destructive Waves
| Type |
Key characteristics |
Typical coastal effect |
| Constructive |
Low height, long wavelength, gentle swell; strong swash, weak backwash. |
Net deposition → wide, gently sloping beaches; formation of offshore bars. |
| Destructive |
High height, short wavelength, steep breaking; strong backwash. |
Net erosion → steep beaches, cliffs, wave‑cut platforms; removal of beach material. |
3. Coastal Landforms
3.1 Erosional Landforms (dominant erosion)
- Headland – protruding point of resistant rock (e.g., Old Harry, Cornwall).
- Bay – recessed area of less resistant rock between headlands (e.g., St Ives Bay).
- Cliff – steep rock face formed by wave erosion.
- Wave‑cut platform – flat, often rocky area at the base of a retreating cliff.
- Sea cave – hollowed out by hydraulic action and solution.
- Sea arch – formed when a cave breaks through a headland.
- Sea stack – isolated column left after an arch collapses.
- Sea stump – low, flat remnant of a heavily eroded stack.
3.2 Depositional Landforms (dominant deposition)
- Beach – accumulation of sand or shingle where the swash deposits material.
- Spit – narrow finger of sediment extending from a coast at a change in direction (e.g., Spurn Head, England).
- Offshore bar – ridge of sand/shingle parallel to the shore, often attached to a spit.
- Lagoon – shallow water body protected from the sea by a bar or spit.
- Tombolo – sand/shingle bar that joins an island to the mainland (e.g., Chesil Beach, Dorset).
- Barrier beach/shoreline – long, parallel strip of sand protecting a lagoon or estuary.
- Dune – wind‑blown accumulation of sand on a beach, usually stabilised by vegetation.
3.3 Coast Types – Influence of Rock Arrangement
| Coast type |
Rock arrangement |
Typical landforms |
| Discordant coast |
Hard and soft rock bands run perpendicular to the shoreline. |
Prominent headlands and deep bays; often a series of sea arches and stacks. |
| Concordant coast |
Rock layers run parallel to the shoreline. |
Long, uniform beaches; occasional breaches where a softer band is exposed, forming a lagoon. |
3.4 Summary Table – Landform, Dominant Process & Example
| Landform |
Dominant process |
Typical location / example |
| Headland |
Erosion of resistant rock |
Discordant coast – Lulworth Cove, Dorset |
| Bay |
Erosion of weaker rock |
Between headlands – St Ives Bay, Cornwall |
| Sea stack |
Continued erosion of an arch |
Old Man of Storr, Scotland |
| Spit |
Long‑shore drift & deposition |
Spurn Head, East Yorkshire |
| Offshore bar |
Deposition in shallow water |
Bar at the mouth of the River Exeter |
| Dune |
Wind transport & deposition of sand |
Sand dunes of the Norfolk Coast |
4. Opportunities & Hazards of Living Near the Coast
4.1 Opportunities (benefits)
- Tourism & recreation – beaches, cliffs, water sports.
- Fishing & aquaculture – rich marine resources.
- Maritime transport – ports, harbours, shipping lanes.
- Renewable energy – offshore wind farms, tidal turbines.
- Natural habitats – dunes, salt‑marshes, estuaries support biodiversity and provide ecosystem services.
4.2 Hazards (grouped by cause)
- Erosion‑related
- Coastal erosion – loss of land, damage to buildings and infrastructure.
- Landslides & cliff collapse – undercutting or heavy rain destabilises cliffs.
- Flood‑related
- Storm surge & coastal flooding – temporary sea‑level rise during severe storms.
- High tides & king tides – regular but extreme inundation events.
- Material‑related
- Salt spray & corrosion – accelerates deterioration of metal, concrete and timber.
5. Coastal Management Strategies
Management seeks a sustainable balance between protecting people/property and allowing natural coastal processes. Strategies fall into three categories.
5.1 Hard Engineering (structural solutions)
- Sea wall – vertical or sloping concrete/stone barrier that reflects wave energy.
- Groynes – perpendicular structures that trap long‑shore drift sediment, building up the beach in front of them.
- Revetments – sloping armour of rock, concrete or timber placed on the foreshore to absorb wave energy.
- Rock armour (rip‑rap) – large stones laid on a slope or at the base of a cliff to dissipate energy.
5.2 Soft Engineering (working with natural processes)
- Beach nourishment – adding sand or shingle to widen a beach and provide a buffer.
- Dune regeneration – planting marram grass or other stabilising vegetation and installing sand fences.
- Managed realignment (retreat) – deliberately allowing a low‑lying area to flood, creating salt‑marsh or mud‑flat habitats.
5.3 Integrated / Sustainable Approaches
- Combining hard and soft measures (e.g., sea wall backed by a nourished beach).
- Land‑use planning – restricting development within the coastal erosion hazard zone.
- Early‑warning systems for storm surge and high tides.
- Community involvement, regular monitoring and adaptive management.
5.4 Decision‑making Flow (when to use which method)
- Is the main problem erosion of a cliff?
- Yes → consider sea wall or rock armour.
- No → go to 2.
- Is the problem loss of beach width that also affects tourism?
- Yes → beach nourishment ± groynes; dune regeneration if wind‑drift is significant.
- No → go to 3.
- Is the area low‑lying and the cost of protection > long‑term benefit?
- Yes → consider managed realignment.
- No → evaluate a hybrid hard‑soft solution.
5.5 Comparison of Management Options
| Strategy |
Advantages |
Disadvantages |
| Sea wall |
Immediate, long‑term protection; low maintenance after construction. |
High initial cost; can increase downdrift erosion; visual impact. |
| Groynes |
Builds up beach locally; relatively inexpensive. |
May cause erosion further down‑drift; requires regular inspection. |
| Revetments / rock armour |
Effective on steep cliffs; dissipates wave energy. |
Expensive to install; can be unsightly; may affect natural habitats. |
| Beach nourishment |
Preserves natural appearance; enhances recreation; can be combined with groynes. |
Recurring cost; sand can be lost quickly; may disturb marine life during placement. |
| Dune regeneration |
Low cost; improves biodiversity; natural defence against moderate storms. |
Less effective against extreme events; requires ongoing vegetation management. |
| Managed retreat |
Allows natural processes; creates valuable habitats; long‑term cost saving. |
Loss of land, property and infrastructure; often socially unpopular. |
6. Suggested Diagrams for Revision or Exam Practice
- Cross‑section of a headland showing cliff, wave‑cut platform, sea cave, arch, stack and stump.
- Wave refraction diagram around a headland, indicating zones of high and low energy.
- Long‑shore drift illustration with a spit, offshore bar, lagoon and direction of sediment transport.
- Side‑by‑side comparison of a hard‑engineered coast (sea wall + groyne) and a soft‑engineered coast (beach nourishment + dune regeneration) on a coastal profile.
- Sketch of discordant vs. concordant coastlines, labeling typical landforms for each.
- Flow‑chart (as shown in 5.4) summarising the decision‑making process for selecting a management strategy.