sediment cells Flashcards
what are sediment cells
sediment cells are sections of the coastline which consist of zones of erosion, zones of transport and zones of deposition. sediment cells are mostly self-contained as they function separately from one another, there are geographically bounded by significant disruptions to the coastline
what is dynamic equilibrium
it is the maintenance of a balance in a natural system, despite it being in a constant state of change.
what can interrupt dynamic equilibrium
by human interventions or by natural variations
what is dynamic equilibrium in relation to sediment cells
where the inputs and outputs are balanced
what are coastal inputs
marine: waves, tides, salt spray
atmosphere: sun, air pressure, wind speed and direction
humans: pollution, recreation, settlement, defenses
what are coastal outputs
-ocean currents
-rip tides
-sediment transfer
-evaportation
what are coastal stores
-beaches
-sand dunes
-spits
-bars and tombolos
-headlands and bays
-nearshore sediment
-cliffs
-wave-cut notches
-wave-cut platforms
-caves
-arches
-stacks
-stumps
-salt marshes
-tidal flats
-offshore bands and bars
what are the transfers in the coastal system
they are the processes that link the outputs, inputs and stores in the coastal system:
-wind-blown sand
-mass-movement processes
-longshore drift
-weathering
-erosion
-transportation
-deposition
what are the sources of energy in the coastal system
-wind
-gravitational
-flowing water
what is a negative feedback loop
this lessens any chance which has occurred within the system
what is a positive feedback loop
this exaggerates the change making the system more unstable and taking it away from dynamic equilibrium
what are the sediment sources along the coast
-rivers
-cliff erosion
-wind
-glaciers
offshore
-longshore drift
how are rivers a sediment store
-most of the sediment in the coastal zone is a result of an input from rivers
-sediment may be deposited in estuaries which are areas where the river flows into the sea
-the sediment is then transported throughout the coastal system by waves, tides and currents
how is cliff erosion a source of sediment
it is a very important in areas with unconsolidated cliffs which would erode easily.
how is wind a source of sediment
-wind is a coastal energy source which would cause sand to be blown up or along the beach
-sediment is transported by wind in circumstances like sand dunes
how are glaciers a source of sediment
-in coastal systems like in antarctica, greenland, alaska and patagonia the glaciers flow directly into the ocean depositing sediment which was stored in the ice
what are offshore sediment stores
sediment is transferred to the coastal zone when waves, tides and currents erode offshore sediment sinks such as offshore bars, storm surges and tsunamis may also transfer sediment into the coastal zone
how is longshore drift a source of sediment
because sediment is moved along the beach due to prevailing winds which would alter the direction of the waves, this allows sediment to be transported from one section of coastline to another section of coastline
what are sediment budgets
sediment budgets would use data of inputs, stores and transfers to assess the gains and losses of sediment within a sediment cell
what is the littoral zone
it is the area of land between the cliffs or dunes on the coast and the offshore areas that is beyond the influence of the waves.
why is the littoral zone always changing
-short term factors = tides and storm surgers
-long term factors= changes in sea level and human intervention
