coastal environment Flashcards
what physical processes affect coasts and their land forms?
- Marine and Sub-aerial processes.
- Marine processes include erosion, transportation, and deposition by waves.
- Sub-aerial processes include weathering, mass movement, and runoff.
what are “sub-aerial processes”?
- sub-aerial processes are land-based processes that shape the coast.
- They include weathering (the breakdown of rocks), mass movement (e.g., landslides, rockfall and slumping), and surface runoff (water moving overland).
- Unlike marine processes, they occur above sea level but impact coastal landscapes.
what are the three types of weathering, and when do they occur?
- Mechanical weathering- caused by physical forces like freeze-thaw action which breaks rocks into smaller pieces.
- Chemical weathering- occurs when rock minerals are chemically altered or dissolved, often by rainwater(e.g. acid rain)
- Biological weathering- caused by plants, animals, and microbes breaking down rocks, such as roots growing into cracks.
- These processes occur depending on the environment’s climate and biological activity.
what is “mass movement,” and what are its types?
The downhill movement of material due to gravity.
examples:
* Rotational slumping: material moves along a curved surface, common on clay cliffs.
* Landslides: material moves suddenly down a slope, often triggered by heavy rain or coastal erosion.
what are the processes of coastal erosion?
- Corrasion/Abrasion: waves hurl rocks and sediment against cliffs, wearing them down (acts as a sandpaper)
- Attrition: rocks and pebbles are smashed together, becoming smaller and smoother.
- Solution: sea water dissolves soluble minerals in the rocks.
- Hydraulic action: the force of waves compresses air into cracks in the cliff, causing pressure and leading to rock breakage.
what is longshore drift?
- Transportation of sand and pebbles along the coast.
- It occurs when waves hit the shore at an angle, moving material in a zig-zag pattern along the coastline.
- This process shapes beaches and spits.
when does coastal deposition occur?
- When the sea loses its energy and drops the sediment it is carrying.
- This can occur in sheltered areas, such as bays or where the energy decreases due to shallow water or a change in the coastline’s shape.
What are the differences between constructive and destructive waves?
- Constructive waves: low energy, long wavelength and low frequency (6-8 per minute). They build up beaches by depositing material.
- Destructive waves: High energy, short wavelength, and high frequency (10-14 per minute). They erode coastlines by removing sediment.
how do erosion processes form coastal landforms?
Coastal erosion shapes the following landforms:
- Headlands and bays: formed when softer rock erodes faster than harder rock, leaving headlands.
- Cliffs and wave-cut platforms: Waves erode the base of a cliff, causing it to collapse and retreat, leaving a flat platform.
- Caves, arches, stacks, and stumps: Erosion widens cracks in cliffs, forming caves.
- Continued erosion can create arches, which eventually collapse to leave stacks and stumps.
How are depositional landforms such as beaches, spits, and bars formed?
- Deposition occurs when the sea loses energy and drops sediment.
- Beaches: formed by the accumulation of sand and pebbles from the constructive waves.
spits: formed when longshore drift deposits sediment along a coastline, extending out into the sea. - Bars: formed when a spit connects two headlands, cutting off a bay from the sea.
how does geology affect coastal landscapes?
- The type of rock(lithology) and its structure(such as the presence of joints and faults) influence erosion rates.
- Harder rocks like granite erode slowly, forming steep cliffs, while softer rocks like clay erode quickly, forming bays.
What is the impact of vegetation on the coast?
- Vegetation, such as grasses and mangroves anchor soil with roots.
- Reduces Erosion
- Sand dunes, for example, are often stabilised by plants like marram grass, which can withstand harsh coastal conditions.
how do human activities impact the coast?
- Human activities, such as coastal development, tourism, and industry, can accelerate erosion, disrupt ecosystems, and lead to coastal degradation.
- Structures like groynes and sea walls can also interfere with natural processes, sometimes worsening erosion elsewhere.
How does sea-level rise impact the coast?
- Flooding of low-lying areas
- Increased coastal erosion
- loss of habitats.
- Submergent features, such as rias and fjords, occur as land sinks or sea level rise.
What are the features of global coastal ecosystems?
Coral reefs
Mangroves
Sand dunes
Salt marshes
Distribution of coral reefs
- Found between 30 degrees N and 30 degrees S latitude
- In tropical regions: Indian and Pacific oceans, Caribbean
- Temperature- between 23-29°C
Distribution of mangroves
- Found in tropical coastal ares, between the latitude of 30 degreesN and 30 degreesS
- Require warm temperatures above 20°C
What are the features of Coral Reefs?
Features:
-Made up of coral polyps, providing a habitat for diverse marine life.
-Clear, shallow waters with low nutrients and abundant sunlight are vital for coral health.
What are the features of mangroves?
-Consist of salt-tolerant trees and shrubs that grow in inter tidal zones
-A good breeding grounds for many marine species
-Act as a natural barrier against storm surges and erosion.
Distribution of Sand dunes
- Found in coastal areas worldwide where there are lots of SAND
- Particularly in temperate(warm/mild temp.) and desert regions.
What are the features of Sand dunes?
-Formed by wind-blown sand, usually stabilised by grasses like marram grass.
-Act as natural barriers against coastal erosion and provide habitats for specialised plants and animals.
Distribution of salt marshes
- Found in temperate regions, particularly along the coasts of Europe, North America, and parts of Asia.
- Often located in estuaries and behind barrier islands, where they are flooded b tides.
- Occur in temperate climates with varying temperatures.
What are the features of Salt Marshes?
- Coastal wetlands dominated by salt-tolerant grasses and shrubs.
- Provide habitats for migratory birds and nursery grounds for fish and invertebrates.
- Act as a buffer against storm surges and reduce flooding by absorbing excess water.
What are the views on coastal management (conservation vs development)?
Conservation: Preserves natural environement, limits human impact, focuses on sustainability.
Development: Prioritises economic growth, infrastructure projects, tourism can harm ecosystems.
What are the key causes of coastal flooding?
- Storm surges: Raised sea levels from stroms.
- Tsunamis: Large waves from underwater sesmic activity.
- Climate change: Sea-level rise, more frequent/intense storms.
How can coastal flooding be predicted and prevented?
- Forecasting: Weather data and early warning systems.
- Building design: Elevated, flood-ressitant structures.
- Planning: Coastal zoning limits high-risk development.
- Education: Community awareness of flood risks.
What are soft engineering techniques?
- Beach replenishment: Add sand to protect coasts.
- Cliff regrading: Stabilise cliffs
- Ecosystem rehabiliation: Planting to stabilise dunes.
- Managed retreat: Allow natural erosion/flooding, relocate.
What are hard engineering techniques?
- Groynes: Trap sand, reduce erosion
- Revetments: Sloped structures absorb wave enrgy.
- Sea walls: Protect land from waves.
- Gabions: rock-filled cages reduce erosion.
- Rip-rap: Large boulders dissipate wave energy.
What are shoreline management plans(SMPs)?
- Strategic plans for sustainable coastal management, balancing development and conservation.
- Includes methods like ‘hold the line, managed retreat, and do nothin.”
