key words Flashcards
saltation
smaller sediment bounces along the sea bed, being pushed by currents. The sediment is too heavy to be picked up by the flow of the water
sediment cell
sections of the coast border by prominent headlands. Within these sections, the movement of sediment is almost contained and the flows of sediment should act in dynamic equilibrium
Sediment budget
use of data of inputs, outputs, stores and transfers to assess the gains and losses of sediment within a sediment cell
SMP
identifies all the activities, both natural and human which occur within the coastline area of each sediment cell and then recommends a combination of four actions for each stretch of that coastline
what four actions taken by SMP
hold the line, advance the line, managed retreat, no intervention
subaerial processes
the combination of mass movement and weathering that affects the coastal land above sea
submergent coast
a coast that is sinking relative to the sea level of the time
till
deposits of angular rock fragments in a fine medium
wave quarrying
when air is trapped and compressed against a cliff which causes rock fragments to break off the cliff over time
coast
locations where the land meets the sea
inputs
energy or matter that enters the system
outputs
energy or matter that leaves the system
flows/transfers
movement of energy or matter within the system
stores/components
when energy or matter remains within the system for a period of time
negative feedback
when a consequence is nullifed
positive feedback
when a consequence is amplified
example of negative feedback at the coast - CAMBER SANDS
tourists leads to trampling of sand dunes and damage of marram grass which lead to aeolian erosion resulting in blow outs - if left alone marram grass can release seed that will recolonies the damaged section and lower wind speeds - return the dune to normal state
how many tourists per week does camber sands experience in peak summer?
25,000
example of positive feedback at the coast - CAMBER SANDS
dominated by marram grass - in the foredune it grows vertically which lowers the wind speeds and then reudced the wind to transport sand through saltation - leads to the depositon of sand which raises the height the substrate that the marram grass is growing in. It will continue to grow taller and lower wind speeds.
how much coastline in camber sands?
1500m
what kind of marram grass is dominated in camber sands?
Ammophila arenaria
dynamic equilibrium
where negative feedback loops create stability in the system
cause of wind energy
unequal levels of heating across the earth’s surface leads to areas of high and low air pressure. Air will move in to balance out the unequal pressure. = Forms convection currents that lead to surface winds
cause of wave energy
friction of wind blowing across water and transferring energy
wave height
vertical distance between the highest and lowest point of a wave
wave crest
highest point of a wave
wave trough
lowest point of the wave
wavelength
distance between two wave crests
wave fetch
distance of open water that the wind blow across
two additional factors that cause large waves
strenght of the wind and the duration the wind has been blowing for
constructive waves characteristics
low energy
deposit materials on coast
swash is stronger than backwash
destructive waves characteristics
help erode and remove sediments such as sand and rock particles
backwash is stronger than swash
causes of tidal energy
sun and moon’s influence over the ocean - height difference between low and high tides gives rise to tidal currents in coastal areas, drives the turbines - tidal energy - tidal power
Causes of ocean currents
ocean currents are caused by differences in water density.
what is the process that creates deep currents called?
thermohaline circulation
high energy coasts
these tend to be stretches of the Atlantic-facing coasts, where the waves are powerful (large fetch) for most of the year
low energy coasts
stretches of the coastline where waves are not powerful often the rate of deposition exceeds the rate of erosion
sources of sediment
sources are places where sediment is generated, such as cliffs of eroding sand dunes. Some sources are offshore bars and river systems and these are an important source of sediment for the coast
sediment budget
sedimentary budgets are a coastal management tool used to analyse and scribe the differences sediment inputs (sources) and outputs (sinks) on the coasts
sediment cell/littoral cell
a sediment cell is a largely self-contained stretch of coastline. regarded as closed systems as sediment not usually transferred from one to the other. Reality= some sediment does get transferred between neighbouring cells
Geomorphological processes
any process that alters the earths surface (e.g erosional, transportation and depositional processes.)
Sub-aerial weathering
the break down of rock upon the earth surface (rock broken down without movement)
salt weathering
the granular disintegration or fragmentation of rock material produced by saline soiloutions or by salt-crystal growth
freeze-thaw weathering
the free-thaw weathering process is also known as frost shattering. Water (e.g from rain or melted ice) becomes trapped in a crack or joint n the rock - if the air temperature drops below freezing, the water will freeze and expand by 9-10% putting pressure on the rock
chemical weathering
the erosion or disintegration of rocks, building materials, etc., caused by chemical reactions rather than mechanical processes
chelation
a form of chemical weathering - organic acids released during decomposition release iron and aluminium from the A horizon combine with them to form chelates
mass movement
a geomorphic process - the movement of soil and rock debris down slopes under the influence of gravity
slumping
downward intermittent movement of rock debris, usually the consequence of removal of buttressing earth at the foot of a slope of unconsolidated material
rockfalls
free or bounding fall of rock debris down steep slopes under the influence of gravity
regolith
a region of loose unconsolidated rock and dust that sits atop a layer or bedrock
erosion
the breakdown of rocks by wind, water or other natural agents
abrasion
a process of erosion that occurs when material wears away at the surface over time
Hydraulic action
sheer power of the water as it smashes against the cliffs. Water is pressurised in cracks within the cliff face
cavitation
compression of air in sea-facing joints as waves crash against cliffs can cause sea water to be severely compressed
corrosion
chemical erosion - rocks or stones can be eroded as water gets into cracks and hole and dissolves the rock through chemical changes
attrition
rocks and pebbles repeatedly knock into each other, causes the rocks to erode or break
transportation
the movement of material in the sear and alone the coast by waves
solution
rock formations such as limestones being dissolved in a river setting - carbon dioxide in the presence of water forms carbonic acid that dissolves limestone
suspension
method of transporting very fine sediment in water
traction
method of transportation - for large stones or boulders in a river - the stones are Rolled along the river bottom by the water as too large to be transported in the water
swash
when a wave reaches the shore - the water rushes up the beach.
backwash
the water that runs back down the beach
longshore drift
process of transportation that shifts eroded material along the coastline - waves approach the coast at an angle
deposition
laying down of sediment carried by wind, flowing water, the sea or ice - can be transported as pebbles, sand and mud or salts dissolved in water
river competence
rivers and streams carry sediment that ranges in size from clay (smallest) to boulders (largest) - the competence of a rover or stream referee to the largest particles that a river can transport
loss of capacity
population size decreases above carrying capacity bc of factors depending on species - including:
insufficient space, food supply, sunlight - carrying capacity of an environment varies for different species
