Coastal Systems and Landscapes Assessment 1 Revision
- Created by: caswinchester
- Created on: 12-10-16 17:08
View mindmap
- Coastal Systems & Landscapes
- Coastal Zones
- Backshore: The area between the HWM and the landward limit of marine activity.
- Foreshore: Area between HWM and LWM. It is the most important zone for marine activity in times not affected by storm activity.
- Inshore: Beyond point where waves cease to impact the seabed. Activity is limited to deposition of sediment
- Nearshore: area extending seaward from HWM to area where waves begin to break
- Swash Zone: Area where turbulent layer of water washes up the beach following the breaking of a wave
- Surf Zone: Area between wave breaking point, waves move up the beach as swash in swash zone
- Breaker Zone: Area where waves approaching the coastline begin to break. Usually where the water depth is 5-10m
- Coasts as natural systems
- Inputs: Waves, Wind, Tides, Sea Currents, Sediment, Geology of the coastline, Sea level change
- Components: Erosional landforms & landscapes (Erosional processes), Depositional landforms & landscapes (Wind + water transportation)
- Outputs: Dissipation of wave energy, Accumulation of sediment above tidal limit, Sediment removed beyond local sediment cells.
- Components: Erosional landforms & landscapes (Erosional processes), Depositional landforms & landscapes (Wind + water transportation)
- Sources of Energy
- Wind
- Vital input, primary energy source
- Important agent of transportation & erosion
- Variation in strength & direction affects wave energy
- High speeds, uninterrupted,higher wave energy
- Prevailing winds control direction of waves
- Fetch = distance the wind blows over open water without interruption
- Length of fetch = magnitude & energy of waves reaching coastline
- Frictional drag plays vital role in wave formation
- Agent of erosion
- Wind
- Inputs: Waves, Wind, Tides, Sea Currents, Sediment, Geology of the coastline, Sea level change
- Currents
- Waves
- Oscillatory Wave: A wave in open sea with full circular motion of particles
- Translatory Wave: a breaking wave in which the circular motion of particles is broken by friction
- Crest - highest point of the wave
- Trough - lowest point of the wave
- Wave height - distance from trough to crest
- Wavelength - distance between crests
- Frequency - Time taken for one wave to travel the distance of one wavelength (or between two crests) passing a fixed point
- Littoral Drift
- Most waves do not approach "head-on", instead at an angle
- Generates a flow of water running parallel to the shoreline
- Not only moves water along surf zone, also transports sediment parallel to shoreline
- Generates a flow of water running parallel to the shoreline
- Most waves do not approach "head-on", instead at an angle
- Sediment & Sediment Cells
- Sediment: Any material (usually broken down by erosion or weathering) transported by wind, water, ice and/or gravity
- Sources of Sediment
- Rivers: The majority of coastal sediment originates from rivers, especially in high rainfall areas where rivers are most active
- Cliff Erosion: An important local sediment source, especially in areas with soft/unconsolidated rock
- Long Shore Drift: Sediment is transported from the input to the output (one end of the coastline to the other, basically)
- Wind: In glacial or desert areas, wind blown sand can be deposited in coastal areas
- Long Shore Drift: Sediment is transported from the input to the output (one end of the coastline to the other, basically)
- Cliff Erosion: An important local sediment source, especially in areas with soft/unconsolidated rock
- Glaciers: Ice shelf calving causes ice to fall into the sea
- Offshore Sources: e.g. tides & currents, storm surges, tsunamis and hurricanes
- Rivers: The majority of coastal sediment originates from rivers, especially in high rainfall areas where rivers are most active
- If more sediment is removed than added, the coastline will RECEED
- More material is ADDED: net accretion, surplus of sediment, shoreline builds towards sea
- Processes of erosion control level of deficit
- More material is REMOVED: net loss, deficit of sediment, shoreline retreats landward
- Processes of erosion control level of deficit
- More material is REMOVED: net loss, deficit of sediment, shoreline retreats landward
- More material is ADDED: net accretion, surplus of sediment, shoreline builds towards sea
- Sediment Budget: Like a bank account, defined as the balance between sediment added and removed
- Can be used to identify sources of sediment
- Calculating budget requires identification of all sources & sinks and estimation of sediment + and - per year
- Calculation is extremely difficult, requires complex calculations, estimations & models
- Calculating budget requires identification of all sources & sinks and estimation of sediment + and - per year
- Can be used to identify sources of sediment
- Sediment Cells
- 11 cells around the coast of England
- Divided by natural features such as headlands
- Movement of sediment more or less contained within a cell
- Each cell can be divided into smaller sub-cells
- 11 cells around the coast of England
- Sub-Aerial Processes
- Weathering
- Slowly breaks down rock
- Occurs in-situ
- Biological
- Chemical
- Most likely to occur in hot, wetter climates
- Optimum condutions: 45°+ f, 50+ in. of rain (mean annual)
- Most likely to occur in hot, wetter climates
- Physical
- Slowly breaks down rock
- Mass Movement
- 7 types
- Landslides
- Block of rock moving rapidly downhill
- Side plane is often a bedding plane roughly parallel to ground
- Frequently triggered by earthquakes and heavy rain
- Slip surface is lubricated, friction reduced
- 1993 - 60m of cliff slid onto beach near Scarborough (HOLBECK)
- Block of rock moving rapidly downhill
- Rockfalls
- Mudflows
- Involves earth & mud flowing downhill, usually over weak bedrock
- Often after heavy rainfall
- Water trapped in rock
- Increases pressure, particles forced apart, causes slope failure
- Rotational Slip
- Soil Creep
- Solifluction
- Run-Off
- Landslides
- 7 types
- Weathering
- Geomorphological Processes
- Lithology
- Important in determining erosion rates
- Tough & resistant rock erodes more slowly than soft rock
- UK's fastest erosion rates: Holderness Coast, Lincolnshire
- Unconsolidated glacial till deposits were eroded by 120m in past century
- Important in determining erosion rates
- Geoological Structure
- Cracks, joints, bedding plains & faults create weakness
- Variationsin rock type can lead to headland + bay formation
- Formation is the result of subsequent differential erosion
- Waves
- Often break at the coastline with considerable energy
- Rate + type affects erosion
- Most erosion happens during winter storms with destructive waves
- Lithology
- Coastal Zones
- Currents
- Affect land temperature, cold currents = cold & dry winds, often result in deserts
- Causes
- Prevailing Winds
- Sea Floor Features
- Heat & Temperature
- Provides energy, causes molecules to expand
- Most heat found at the equator
- South of the equator currents circle ANTI CLOCKWISE
- North of the equator currents circle CLOCKWISE
- Cold water more dense, sinks down
- The permanent or seasonal movement of surface water in seas or oceans
- Currents
- Rip Currents: The area between two circulating currents
- Strong currents moving away from shoreline
- develop when seawater is piled up along the coastline by incoming waves
- May initially run parallel to the coastline before flowing into breaker zone, maybe at headland or where shoreline is changing direction
- Can be extremely hazardous to swimmers & small boats
- May initially run parallel to the coastline before flowing into breaker zone, maybe at headland or where shoreline is changing direction
- develop when seawater is piled up along the coastline by incoming waves
- Strong currents moving away from shoreline
Similar Geography resources:
Teacher recommended
Teacher recommended
Comments
No comments have yet been made