coastal systems: systems in physical geog Flashcards
what’s a system?
assemblage of interrelated parts that work together by a driving force.
why is the coast considered as an open system?
because it receives inputs from outside the system and transfers outputs away from the coast and into the other systems.
what’s the definition of an open system?
a system where both energy and mass are transferred across boundaries. there is also a flow of matter.
what’s the definition of a closed system?
flow of energy in or out of the system but no matter flow. the system has a fixed mass.
what’s the definition of an isolated system?
where there’s not interaction between the system and surrounding. they’re mostly theoretical.
what’s a sediment cell
sediment cell is section of the coast that os divided into sections, these are sediment cells. they’re boarded by prominent headlands. this means that the movement of sediment is almost contained, and therefore the flows of sediment act in dynamic equilibrium.
how many sediment cells in England and Wales?
11
what is dynamic equilibrium?
dynamic equilibrium refers too the maintenance of a balance in a natural system, despite it being in a constant state of change. the system has the ability to counteract any changes, due to the inputs and outputs constantly changing to maintain the balance.
dynamic equilibrium in sediment cells.
input and output of sediment are in constant state of change but remain in balance.
what is within each sediment cell?
sub cell
how will dynamic equilibrium be upset?
long term- human interventions
short term- natural variations.
what are inputs?
where matter/energy is added into a system.
what are the three main areas of inputs?
marine; waves, tides, salt spray
atmosphere; sun,air pressure, wind speed and direction.
humans; pollution, recreation, settlement, defences.
what are outputs?
where matter or energy leaves the system.
what are some examples of outputs?
ocean currents
rip tides
sediment transfer
evaporation
what are sinks/stores?
matter or energy builds up in the system.
what are some examples of sink/stores?
beaches
sand dunes
spits, bars, tombolos
headlands and bays
nearshore sediment
cliff
wave cut platforms
caves, arch, stack, stumps
salt marshes
tidal flats
offshore band/bars
what are transfers/processes?
where matter/energy moves in the system.
examples of transfers/processes?
wind blown sand
mass movement processes
longshore drift
weathering
erosion: hydraulic action, attrition, abraision, solution
transportation: traction, bedload, suspension, solution.
deposition: gravity settling, flowing water.
what’s negative feedback?
this is where the effects of a change in the system are lessened.
what’s positive feedback?
this is where the effects of a change in the system are exaggerated and increased, therefore making the system more unstable and removing it from dynamic equilibrium.
coastal systems at different scales.
scales of coastal systems can vary, for example, from a sediment cell to a beach.
what are the subsystems of the earth?
lithosphere-solid outer layer of earth
cryosphere-frozen water
biosphere-the regions of the surface of earth that’s occupied by living organisms.
hydrosphere- all the waters on the earths surface.
atmospherical-atmosphere of the earth.
what’s back shore
area bet the high water mark and the landward limit of marine activity. changes only happen here during severe storm events.
what’s foreshore
area bet the hwm and the lwm. most important area for marine processes.w
what’s inshore
area bet the lwm and point where waves cease to have any influence pn the land beneath them
what’s offshore
area beyond the point where waves cease to impact upon the seabed and in which activity is limited to deposition of sediments
what’s surf zone
region of breaking waves
what’s breaker zone
waves approaching coastline start breaking bet. 5-10m
nearshore
zone extending from lwm beyond Surfline. it defines an area influenced by nearshore or longshore currents.
what’s swash zone
part of the beach alternitively covered and exposed by swash and backwash
