Coastal Landforms and Wave Action

• Coasts represent dynamic interaction zones between land, sea, and atmosphere, resulting in unique landforms and ecosystems
• Natural processes and human activities constantly shape these environments

Coastal Landforms and Formations

• Wave action is a key factor shaping coastlines via erosion, transportation, and deposition
• Erosion happens when wave energy wears away coastal rocks and sediments
• Hydraulic action occurs as water compresses air in cracks, leading to rock fragmentation
• Abrasion (or corrasion) is the process of sediment-laden waves grinding against coastal rocks
• Corrosion (or solution) involves seawater's chemical weathering of rocks
• Transportation moves eroded material along the coast:
  • Traction: Large particles rolling
  • Saltation: Bouncing of smaller particles
  • Suspension: Fine particles carried in water
  • Solution: Dissolving soluble materials
• Deposition occurs when wave energy decreases, causing sediment to settle, forming beaches, spits, bars, and wider coastal plains

Erosional Landforms

• Headlands and bays form where hard and soft rock bands are exposed, with softer rock eroding faster into bays
• Cliffs are steep rock faces shaped by wave erosion and weathering
• Wave-cut platforms are flat areas at the base of cliffs, exposed at low tide, formed as cliffs erode
• Caves are hollowed-out areas in cliffs, formed by wave action
• Arches form when caves erode through a headland
• Stacks are isolated rock pillars left after an arch collapses
• Stumps are the eroded remains of stacks, often visible only at low tide

Depositional Landforms

• Beaches are accumulations of sand/shingle in sheltered coastal areas
• Berms are ridges on beaches formed by deposition during high tide or storms
• Spits are elongated sand/shingle ridges projecting into a bay or estuary, formed via longshore drift
• Bars are similar to spits, extending across a bay and connecting two headlands, potentially enclosing a lagoon
• Barrier islands are long, narrow islands parallel to the mainland, separated by a lagoon and formed by sediment buildup
• Tombolos are sand/shingle bars connecting an island to the mainland
• Sand dunes are sand accumulations shaped by wind, stabilized by vegetation
• They require a large sand supply, a wide beach, and onshore winds
• Salt marshes are coastal wetlands flooded by tides, dominated by salt-tolerant plants

Factors Affecting Coastal Landforms

• Rock type/structure affects erosion rate, with softer rocks (sandstone, shale) eroding faster than harder rocks (granite, basalt)
• Faults/joints in rocks are weaknesses exploited by wave action
• Wave energy determines erosion/deposition rates; high-energy coastlines are erosion-dominated, low-energy coastlines are deposition-dominated
• Tides influence wave action and exposed coastline area
• Coastal currents transport sediment, influencing formation of spits, bars, and barrier islands
• Sea level changes submerge/expose coastal landforms
• Rising sea levels increase erosion, while falling sea levels expose new land

Human Impacts on Coasts

• Coastal development disrupts natural processes, increases erosion, and destroys habitats
• Coastal defenses include hard engineering (seawalls, groynes, breakwaters) and soft engineering (beach nourishment, managed retreat)
• Pollution from industry/agriculture/urban sources contaminates waters/sediments
• Tourism generates income but can increase pollution, erosion, and habitat destruction
• Climate change causes sea level rise, increased storm intensity, and precipitation changes, exacerbating coastal erosion, flooding, and habitat loss
• Hard engineering strategies protect coastlines using structures like seawalls (parallel to coast), groynes (perpendicular to coast), and breakwaters (offshore)
• Soft engineering strategies work with natural processes: beach nourishment, dune stabilization, and managed retreat

Coastal Management

• Integrated coastal zone management (ICZM) balances stakeholder needs, protects the environment, and promotes sustainable development
• Coastal management plans consider long-term impacts of human activities on coastal processes and ecosystems
• Monitoring and evaluation are essential for assessing strategy effectiveness

Specific Coastal Environments

• Estuaries form where rivers meet the sea, mixing fresh and salt water and serving as habitats
• Deltas are formed by sediment deposition at river mouths
• Mangrove forests are coastal wetlands in tropical/subtropical regions, protecting coastlines
• Coral reefs are underwater ecosystems built by coral polyps, which have diverse habitats
• Fjords are long, narrow inlets with cliffs, formed by glacial erosion in high-latitude regions
• Ria coasts form via submergence of river valleys, creating coastlines with inlets and peninsulas, and are common in formerly glaciated areas

Explore the dynamic nature of coasts. Learn how wave action shapes coastlines through erosion, transportation, and deposition. Key processes include hydraulic action, abrasion, and corrosion.