EQ2 Flashcards
what does sediment move along in
sediment cells
how many major sediment cells are in england and wales
11
TRUE or FALSE can major sediment cells be divided further
TRUE
Each major cell can be divided into a number of sub cells
what are each sediment cell operating within
Each cell operates between physical barriers that prevent sediment from moving any further along the coast
what is interlinked within sub cells
erosional processes
transport processes
deposition
can some coastal features operate as sinks, source and transfer zones
NO
ONLY some coastal features operate as SINKS AND SOURCES
- depends on whether the dominant processes are erosion or deposition at a given time
what is a source
give examples
a place where sediment is generated
such as cliffs, sand dunes or offshore bars and even river systems
what is a transfer zone
places where sediment is moving along the shore
via longshore drift and offshore current
what is a sink
locations where the dominant process is deposition
-depositional landforms are created such as spits and offshore bars
define sediment budget
The amount of sediment available within a sediment cell
what state does a system act in under natural conditions
DYNAMIC EQUILIBRIUM
TRUE or FALSE can dynamic equilibrium be disrupted
TRUE
dynamic equilibrium can be disrupted by storms leading to increased erosion
what do negative feedback mechanisms do to the dynamic equilibrium
Negative feedback mechanisms help maintain the balance by pushing the system back towards equilibrium.
what do positive feedback mechanisms do to dynamic equilibrium
Positive feedback mechanism is where one change has led to another change which leads to disequilibrium in the coastal system.
does positive feedback lead to equilibrium or disequilibrium
DISEQUILIBRIUM
does negative feedback lead to equilibrium or disequilibrium
EQUILIBRIUM
what are 2 factors that impact the state of dynamic equilibrium
Coastal management
Global warming
how does coastal management impact the state of dynamic equilibrium
can decrease erosion leading to less sediment input
how does global warming impact the state of dynamic equilibrium
Increased storms due to global warming could lead to long term erosion of sand dunes with no chance to recover between storm events.
Rising sea level could increase erosion of spits and estuaries, removing sediment faster than it can be replaced.
what do waves directly influence which in return shapes the….?
erosion, transportation and deposition,
so they shape the coastline.
how are waves caused
by friction between wind and water
what is wave size dependant on
-The strength of the wind
-The duration the wind blows for
-Wave fetch - the uninterrupted distance across water over which the wind blows
-Water depth - see waves as they approach a shoreline
how are waves affected when approaching the shoreline
the water shallows and the shape of the waves changes significantly.
what happens when the internal orbital motion of water touches the sea bed
friction occurs and this slows down the wave
what happens to the wave length and wave height as it approaches the shore
wavelength = decreases
wave height = increases
makes waves look like they bunch together
why do waves break in shallow water
because the crest of the wave begins to move forward much faster than the wave trough due to friction with the sea bed.
what causes a wave to break
the wave crest outruns the trough and the wave topples forward = breaks.
two types of waves
constructive
destructive
what is the wave height, energy and frequency of CONSTRUCTIVE waves
LOW
LOW
LOW
what is the wave height, energy and frequency of DESTRUCTIVE waves
HIGH
HIGH
HIGH
do destructive waves have a greater swash or backwash
BACKWASH > swash
beach loss
do constructive waves have a greater swash or backwash
SWASH > backwash
beach gain
what is beach morphology
the shape of the beach, including its width and slope and features. It also includes the type of sediment found at different beaches location
what creates different beach profiles
the seasonal changes in wave type
what wave type create winter beach profiles
destructive waves – sediment dragged offshore
what wave type create summer beach profiles
constructive waves - sediment dragged onshore
what factors create winter beach profiles
-Berms are eroded by plunging waves
-Strong backwash transports sediment offshore(depositing is at offshore bars)
-Sometimes the backwash exerts a current known as a rip/undertow - dragging sediment back as the next wave arrives over the top
what factors create a summer beach profile
-Constructive waves are less frequent wave energy dissipates and deposits over a wide area (weakening backswash)
-The swash of constructive wave deposits larger material at the top of the beach creates a berm
-As a berm builds up the backswash becomes weaker. It only has enough energy to move smaller material so the beach materials are smaller the closer you are to the shoreline
what are examples of changes in beach profiles
-sediment supply is reduced from rivers due to dams
-coastal management has effect on processes further along the coast
-global warming makes the UK stormier on average, more destructive waves, making winter beach profiles more common
what are the 4 ways sediment is transported
solution
saltation
suspension
traction
what is longshore drift
the movement of materials along a coast by wave action which approach at an angle to the shore but recede directly away from it
what can affect longshore drift
tides and currents
what are tides
changes in the level of seas and oceans – caused by the gravitational pull of the moon
what is tidal range
The relative difference in height between the high and low tides
what does a high tidal range mean
powerful tidal currents, as tides rise and fall
what are examples of depositional landforms
Spits
Beaches
Offshore bars
Barrier beaches
Tombolos
Cuspate forelands
what is a spit
A spit is a long narrow feature, made of sand or shingle, which extends from the land into the sea
how does longshore drift influence the spits formation
Sand or shingle is moved along the coast by longshore drift, but if the coastline suddenly changes direction (e.g because of a river estuary) sediment will begin to build up across the estuary mouth and the spit will start to form
what causes a recurved spit
end of the spit will begin to curve round as wave refraction carries material round into the more sheltered water behind the spit
where are beaches commonly found
Beaches are commonly found in bays.
what sort of environment does wave refraction create in beaches
Wave refraction creates a low-energy environment, which then leads to deposition
what are the two different aligned beaches
drift aligned beach
swash-aligned beach
what are offshore bars
are submerged ridges of sand - created by waves offshore from the coast
how do destructive waves create offshore bars
Destructive waves erode sand from the beach with their strong backwash and deposit it offshore as bars
what is a barrier beach
Where a beach or spit extends across a bay to join two headlands, it forms a barrier beach
is it true barrier beaches can form lagoons?
YES
Barrier beaches and bars can also trap water behind them to form lagoons.
what is a separated barrier beach called
barrier island
what is a tombolo
a beach that has formed between a small island and the mainland
how does deposition occur to form the tombolo
Deposition occurs where waves lose their energy and the tombolo begins to build up
what is a cuspate foreland
triangular-shaped headland that extends out from the main coastline.