G3 WJEC Alevel geography everything you need to know for 1.1 including case studies

1.1 what is a coasteal system and what are the dynamics of coastal environments.

G3 WJEC Alevel geography everything you need to know for 1.1 including case studies

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  • 1.1what is a coastal system and what are the dynamics of coastal environments
    • the coastal system
      • one of:
        • inputs
        • outputs
      • two systems:
        • cliff system
          • inputs
            • sub areal processes
              • weathering
              • atmospheric process
                • wind erosion
          • outputs
            • sediment at base of cliff
              • either deposited
                • through marine processes
              • or transported
                • through marine processes
        • beach system
          • input
            • sediment
              • from longshore drift
            • the cliff
            • offshore
          • throughput
            • longshore drift
          • output
            • longshore drift
            • destructive waves
              • carry sediment offshore
    • coastal sediment cells
      • areas of coast usually defined by headlands within which marine processes are largely confined
        • with limited transfer of sediment from one cell to another
      • very in size depending on the nature of the coast
      • there are 11 sediment cells around England an wales
        • no1: st,Abbs Head
        • no11:solway firth
    • the state of dynamic equilibrium in the coastal system
      • the relationship between inputs and outputs is constantly changing
        • dynamic
          • therefore
            • system works towards an equilibrium position where input equal outputs
    • wave types and characteristics and their variations over time and space
      • two extreme forms of wave:
        • have different characteristics
          • length
          • height
          • velocity
          • frequency
            • stays thesame
        • occur in different places determined by local configuration of the coastline and or prevailing wind conditions
        • constructive
          • lower
            • less
              • up to 100m
                • 8-10sec
                  • 6-8 waves/min
                    • frequency
                      • low/high energy
                        • beach gradient
                          • strong swash or backwash
                    • low
                      • shallow
                        • strongest swash
                          • strong swash or backwash
                          • carries sand and shingle up beach
                            • contribute to the formation of beach ridges and berms
                        • beach gradient
                        • low/high energy
                      • wave period
                        • frequency
                      • wave length
                        • wave period
                      • wave steepness
                        • wave length
                      • wave height
                        • wave steepness
                    • destructive
                      • higher
                        • more
                          • 20-40metres
                            • 5-6sec
                              • 10-14waves/min
                                • high
                                  • deep
                                    • backwash
                                      • due to plunging motion it generates little swash but more powerful backwash
                                        • transports sediment down beach face
                                          • resulting in a net loss of material
                                        • plunging breakers, beer, East Devon
                        • wave height
                        • tend to occur during storms
                    • slow down,shorten, gain height
                    • fetch
                      • maximum distance of open water over which wind can blow
                    • swell waves
                      • shallow gradient waves with long fetch + wavelength
                    • most beaches experience alternating action
                      • constructive waves in summer
                      • destructive waves in winter
                        • resulting in annual cycle of beach growth and decay
                          • constructive waves in summer
                    • wave refraction
                      • concentrates wave energy on headlands
                        • causes erosion on headlands therefore provide shelter to bays therefore negative feedback
                        • hardrock
                      • dissipates energy in bays
                        • causes disposition
                        • bays have soft rock
                          • therefore it should erode quicker
                            • but due to refraction of wave
                              • high energy waves hit headlands
                                • therefore create negative feedback
                      • Holderness Coast
                      • north sea coast between scarborough and whitby
                        • upland coastline
                        • weaker Lias shales form bays
                        • more resistant Jurassic sandstones and limestones form headlands
                        • orthongonal waves refract around headlands
                          • causing orthogonals to converge
                            • bringing more energy per metre of headland than of bays

                Comments

                Mr A Gibson

                Suitable for all students studying coasts. A large and comprehensive resource to print out and stick on the wall!

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