Key Knowledge Flashcards
1
Q
What is coastal system made up of
A
- inputs
- flows/ transfers
- stores & components
- outputs
- feedbacks
2
Q
Inputs
A
- things that enter the system from outside sources/systems
EXAMPLES - wind
- fluvial (river based) sediment
- precipitation
- ocean currents
3
Q
Flows/transfers
A
- process of movement within a system
EXAMPLES - erosion
- LSD
- mass movement
4
Q
Stores/components
A
- parts of the system not necessarily in motion
EXAMPLES - beaches
- bars
- spits
- sand dunes
5
Q
Outputs
A
- material/energy moving out of a system
EXAMPLES - wave cut platforms
- bays
- headlands
- evaporation
- rip tides
6
Q
Factors influencing he coastline
A
- terrestrial (tectonics, supply of sediment, fluvial processes, industrial + residential development)
- Marine processes (wave shape/size, biotic features, sea level change, wave direction, glaciations)
- human intervention (sea defences, pollution, purism + recreation, industrial + residential development, sea level rise, conservation
- atmospheric 9global warming, fetch, winds, precipitation, temperature, sub-aerial processes, solar energy)
7
Q
Sources of energy (what its caused by*)
A
- wind (high and low air pressure)
- waves (wind, friction)
- currents
- tides (the moon, sun, gravity)
8
Q
Wind energy
A
- formed by air moving between areas of different pressure (from high to low) along a pressure gradient
- low pressure: air is rising (heated)
- high pressure: air is sinking (cooled)
- the steeper the gradient the faster the wind moves. So areas with large pressure gradients experience strongest winds
9
Q
Formation of waves
A
- created by energy passing through water, causing it to move in a circular motion. However, water does not actually travel on waves. Waves transmit energy, not water. Waves are most commonly caused by wind: wind-driven waves are created by frictional drag between wind and surface water. As wind blows across the whole ocean surface the continual disturbance forms a wave crest. As the wave approaches the shore, disturbance to the circular motion beneath the surface leads to more horizontal wave movement and wave breaks
10
Q
Why are some areas subject to powerful waves and some aren’t
A
Prevailing wind direction -> SW in England
11
Q
Constructive waves
A
- strong swash & weak backwash
- add material along the coastline
- low wave with long wavelength
- formed by distant weather systems
- never reach back of beach
12
Q
Destructive wave
A
- strong backwash & weak swash
- tall in relation to length
- common during winter storms
- remove material from coastline
- generally steep beach profile
- causes cliff face erosion
13
Q
Spring (high) and Neap (low) tides
A
- the spring tides are exceptionally high and the neap tides are very low as the gravitational pul (in spring tide) is pulling in the same direction
- in coastal management we need to know how high the spring tide is in order to build effective defences (e.g. a high enough sea wall)
14
Q
3 marine geomorphical processes
A
- erosion
- transportation
- deposition
15
Q
Processes of erosion
A
- hydraulic action (impact on rock of the sheer force of water)
- wave quarrying (breaking wave traps air as it hit cliff face)
- abrasion/corrosion (eroded material thrown against rock by waves)
- attrition (rocks slowly worn down into smaller and rounder particles
- solution (corrosion) (where seawater interacts with freshwater supplies, carbon based rock e.g. limestone may e dissolved)
16
Q
Factors affecting rate of erosion
A
- strength of waves
- weathering
- certain landforms reduce impact (beaches: increased distance a wave travels)
-headlands refract waves around them, reducing their erosive power - human activity
17
Q
Types of transportation
A
- traction (large particles pushed along seabed by force of water)
- suspension (small particles are carried along in water)
- saltation (pebble-sized particles are bounced along the seabed by force of water)
- solution (soluble materials dissolve in the water and are carried along)
18
Q
High energy coasts
A
- small particles (clay/sand) easily transported whilst larger and heavier material is deposited, forming shingle beaches
19
Q
Low energy coast
A
- even the smallest material is deposited forming mudflats and salt marshes
20
Q
Sub-aerial processes
A
- weathering
- mass movement
- runoff
21
Q
Coastal weathering types (3)
A
- biological
- chemical
- mechanical (physical)
22
Q
Biological weathering
A
- the breakdown of rocks by organic activity
- thin plant roots growing into small cracks in cliff face. These cracks widen as roots grow, which breaks up the rock
- water running through decaying vegetation becomes acidic, which leads to increased chemical weathering
23
Q
Chemical weathering
A
- involves a chemical reaction where salts may be dissolved or a clay like deposit may result which is then easily eroded
- ways in which it can happen:
> carbonation - rainwater absorbs carbon dioxide from the air to form a weak carbonic acid
> oxidation - iron -> musky red powder
> solution - dissolving
24
Q
Mechanical (physical) weathering
A
- involves the break up of rocks without any chemical reactions taking place
- freeze thaw weathering (water enters cracks -> freezes -> expands)
- salt crystallisation
- wetting and drying
25
Q
Positive feedback
A
- if the rate of debris removal exceeds the rate of weathering and mass movement then a positive feedback can operate, as the rate of weathering and mass movement could increase
26
Q
Negative feedback
A
- if debris removal is slow and ineffective, this will lead to a build up of an apron of debris (scree) that reduced the exposure of the cliff space. Weathering and mass movements rates will decrease
27
Q
Types of mass movement
A
- soil creep/solifluction
- mudflow
- run off
- landslide/debris/slide/slump/slip
- rock fall
28
Q
soil creep/solifluction
A
- the slowest but most continuous form of mass movement involving the movement of soil particles downhill. Particles rise and fall due to wetting and freezing and in a similar way to LSD, this causes soil to move down the slope
29
Q
Mudflow
A
An increase in the water content of soil can reduce friction, leading to earth and mud to flow over underlying bedrock, or slippery materials such as clay. Water can get trapped within the rock increasing pore water pressures, which forces rock particles apart and therefore weakens the slope
30
Q
Run off
A
- overland flow may erode the cliff ace and coastal area or pick up sediment , that then enters the littoral zone, when it is transported in he are via suspension.
31
Q
Landslide/debris/slide/slump/slip
A
- contrary to a landslide, the slope is urged, so often occur in weak and unconsolidated clay and sand areas. Build up in pore water pressure leads to the land collapse under its own weight
32
Q
Rock fall
A
- occurs on sloped cliffs (over 40 degrees) when exposed to mechanical weathering, though mostly occurs on vertical Cliff faces and can be triggered by earthquakes. It leads to scree (rock fragments) building up at the base of the slope. Scree is a temporal store which acts as an input to a coastal zone
33
Q
Sediment cells
A
- stretch of coastline within which sediment movement is more or less contained
- generally boarded by 2 headlands or deep water and contain inputs, transfers and stores of sediments
- 11 in total however divided further into sub sediments
34
Q
Transfers (flows)
A
- LSD (littoral) as well as onshore processes such as wind and currents
