rapid fire coastal systems/landscapes Flashcards
distinguish between an open and closed system
closed system=transfer of energy in/out system boundary but not matter
(carbon cycle, sediment cells)
open system=both transferable
(coasts, ecosystems)
difference between negative and positive feedback
N=effects on action nullified by subsequent knock-on effects (counter-acted; gryones=more deposition=less transportation to neighbouring beach)
P=effects amplified/multiplied (loop/cycle; tourism in florida Orlando, D&P increasing+expansion)
4 major subsystems
Atmo(air)sphere
Lith(land)sphere
Bio(living things)sphere
Hydro(water)sphere
4 types of coast
OFFSHORE beyond influence of waves
NEARSHORE waves are breaking “breakerzone”
FORESHORE low and high water zone (under-tidel/surf zone)
BACKSHORE usually above the influence of waves
constructive VS destructive waves
C=strong swash and weaker backwash. Builds material up the landward side of the beach
D=weak swash and stronger backwash, this carties material away from the beach and can lead to gentle beach profiles/shapes
what is meant by breakerzone
zone within waves approaching commerce breaking, typically in water depths of 5-10 metres
4+ sources of energy in coastal system with features
WIND main input of energy forming waves/sandunes
-also factor of EROSION/TRANSPORTION materials can dispersed (by energy from wind by process of ABRASION
FETCH longer=higher wave energy=bigger waves
WAVES undulations of water surface caused by winds blowing across the ocean + energy transferred by friction
3 factors affecting wave height
fetch; wind speed; wind duration.
change in waves in shallow water
deep water=constant wavelength; waves move into breakerzone and touch seabed=wavelength shortens (frictional resistence); waves become unstable and once depth < 1.3 times waveheight, they break as surf
PROCESS EXPENDS MASS ENERGY USED TO MOVE SAND/SHINGLE
wave refraction
As waves approach a coast they are refracted so that their energy is concentrated around the headland but reduced around bays. Indicated by bending of wave crests leading to them becoming parallel to the shore=swash-alingned. Positive correlation between wave energy and water depth.
3 types of current
LONGSHORE CURRENT (clittoral drift) waves hit the coast at an angle. This creates a flow of water running parallel to the shore RIP CURRENTS stongs moving away from the beach. They are formal when water is piled up along the coast by incoming waves. UPWELLING the movement of cold water from the deep ocean towards the surface.
tides/waves/currents
TIDES controlled by moon (periodic); high/low tide=sea level
WAVES controlled by wind
CURRENTS seasonal/permanent
tidal surges (storms)
- caused by meteorological conditions
- sea level can rise by 1cm for every 1millibat drop in pressure
- strong winds drive the water towards the shore=pling-up water against the coast
low energy VS high energy coast
LOW=low wave energy=deposition>erosion e.g=Baltic sea
HIGH=strong winds; erosion>deposition
e.g. Cornish coast
PVLI (most expensive place to build, scale high to low)
Peak
Land
Value
Intersection