Exploring Coastal Systems & Landforms
Exploring Coastal Systems & Landforms
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Exploring Coastal Systems & Landforms
What do you already know about coastal processes and landforms?
Learning Objective
At the end of the lesson you will be able to describe the key components of coastal systems, explain natural and human processes affecting coasts, and identify major coastal landforms and management strategies.
The Coastal System Framework
Coasts are open systems, exchanging energy and material. Inputs: waves, tides, wind, human activity. Outputs: currents, sediment transfers, evaporation. Processes include erosion, deposition, longshore drift; landforms are stores like beaches, dunes, spits, and marshes.
Dynamic Equilibrium & Feedback Loops
Sediment cells act as self-contained coastal sections. Dynamic equilibrium is the changing balance of inputs and outputs. Negative feedback restores balance (e.g., offshore bars protect the coast); positive feedback exaggerates change (e.g., dune erosion speeds up instability).
Wave Formation & Energy Sources
Waves form when wind, driven by the sun, creates friction on the ocean. Wave energy depends on wind strength, duration, and fetch. Tides, caused by the moon and sun, create tidal ranges such as spring and neap tides.
Marine Erosion: Main Processes
Key processes include: hydraulic action (water pressure), cavitation (bubble implosion), abrasion (pebbles scraping cliffs), attrition (rocks colliding), corrosion (acid dissolution), and wave quarrying (direct rock removal).
Transport & Deposition of Material
Material moves by traction (rolling), saltation (bouncing), suspension (carried in water), and solution (dissolved minerals). Longshore drift moves sediment along the coast. Deposition happens by gravity settling and flocculation when water slows down.
Sub-Aerial Processes: Weathering
Physical: Freeze-thaw, salt crystallisation, wetting/drying. Chemical: Carbonation, oxidation, solution.
Biological
Roots split rock, animals burrow, seaweed and clams produce acids contributing to weathering.
Physical & Chemical
Sub-Aerial Processes: Mass Movement
Rapid Movements
Soil creep and solifluction involve gradual, downslope movement. Soil creep is slowest.
Slow Movements
Mudflows (saturated, fast), landslides/rockfalls (sudden, steep slopes), slumping (material slips down curved surfaces).
Erosional Landforms
Marine erosion forms caves, arches, stacks, and stumps. Wave-cut notches and platforms are created by repeated cliff erosion and collapse. Growing platforms act as negative feedback, slowing further erosion.
Depositional Landforms
Beaches, spits (with recurved ends), tombolos, and barrier beaches (bars) are shaped by sediment build-up from longshore drift and deposition.
Plant Succession in Coastal Areas
Sand dunes progress from pioneer species (like sea rocket), to stabilised yellow and grey dunes by Marram grass, to climax woodland. Salt marshes develop from algal binds, pioneer cord grass, through to climax vegetation (rush and sedge).
Sea Level Change & Landforms
Isostatic & Eustatic Change
Emergent & Submergent Landforms
Emergent: Raised beaches, relic cliffs. Submergent: Rias (flooded valleys), fjords (deep glacial valleys), Dalmatian coasts (parallel valleys).
Isostatic: Land rises/falls locally (rising Scotland). Eustatic: Global sea level rises (melting ice, warming oceans).
Coastal Management Approaches
Soft Engineering
Hard Engineering
Groynes trap sediment, sea walls reflect waves, rip rap absorbs energy, breakwaters reduce energy offshore.
Beach nourishment adds sediment. Dune stabilisation uses plants. Managed retreat turns low-lying land into marshes.
Strategic Management & Policy
Cost-benefit analysis weighs up costs and gains. Integrated management (ICZM) looks at the coast holistically. Shoreline Management Plans offer hold the line, managed realignment, advance, or no intervention.
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