coasts Flashcards
dynamic equilibrium
the maintenance of balance in a natural system despite being in a constant state of change
inputs
material or energy moving into the system from outside
outputs
material or energy moving from the system to the outside
stores/ components
individual elements or parts of a system
transfers/flows
processes that link the inputs, outputs and stores in a coastal system
feedback loops
mechanisms that enhace changes within a system, taing it away from dynamic equilibrium (positive feedback) or mechanisms which balance changes taking the system back towards equilibrium
sediment cells
a stretch of coastline usually bordered by two prominent headlands where the movement of sediment is more or less contained
littoral zone
area of land between the cliffs or dunes on the coast and the offshore sea that is beyond the influence of the waves
factors that affect wave energy
-strength of wind
-duration of the wind
-size of the fetch
wave formation
-winds move across surface on the water causing frictional drag ( resistance to the wind by the water) which creates small ripples and waves. this leads to a circular orbital motion of water particles in the ocean
-as the seabed becomes shallower towards the coastline the orbit of the water particles become elliptical leading to more horizontal movement of the waves
-the height of the wave increases but the wavelength and wave velocity decrease
-this causes water to back up from behind the wave and rise to a point where it starts to topple over and break
constructive waves
-deposit material which creates depositional landforms and increases the size of beaches
-distant weather systems generate these waves in a open ocean
-long wavelength
- 6 -9 per min
-low waves which surge up the beach
-strong swash weak backwash
-occurs on gently sloped beaches
-usually associated with gentle beach profile although overtime will build it up
destructive waves
-remove depositional landforms through erosion which work to decrease the size of the beach
-localised storm events with stronger winds operating closer to the coast are responsible for these waves
-short wavelength
- 11-16 per min
- high waves which plunge onto the beach
-weak swash strong backwash
-occurs on steeply sloped beaches
-usually associated with a steeper beach profile although overtime they will flatten the beach
tidal range
height between the tides
spring tide
-highest high tide
-lowest low tide
-sun and moon are in alignment
-both of their gravitational forces combine to effectively pull oceans towards them
neap tides
-smallest possible tidal range
-lowest high tide
-highest low tide
-sun ad moon are perpendicular
-their gravitational forces act against each other
rip currents
-powerful underwater currents occurring in areas close to the shoreline on some beaches when plunging waves cause the build up of water at the top of the beach
-backwash is forced under the surface due to resistance from breaking waves
wave refraction
the distortion of wave fronts as they approach an indented shoreline
