waves and their impact on beach morphology Flashcards
what is wave size dependant on
-strength of the wind
-duration the wind blows for
-water depth
-wave fetch
why do waves break in shallow water
-because the crest begins to move foward much faster than the trough which experiences significant friction
-the crest outruns the trough and wave topples foward and breaks
when does the internal orbital motion of the water touch the seabed
when the water depth is half the wave length
what happens when wave approaches the shore
-the wave length decreases and wave height increases
-waves bunch together
what are waves in deep water
-energy moving through water
-water moves up and down not horizontally
-there is some circular or orbital motion of particles but no net forward water particle motion
what does a greater tidal range mean
more biodiversity bc a broader range of habitats allowed for
features of a constructive wave
-low wave height
-long wavelength
-strong swash weak backwash
-pushes sediment landward in a spinning breaker wave bc of elliptical motion
-wave energy absorbed by beach
features of a destructive wave
-high plunging waves bc of circular motion
-short wavelength
-plunging breaker wave removes sediment and creates an offshore ridge bar
what happens to the backwash of a constructive wave
-most of it percolates into the beach bc of the steep berm followed by gentle profile
what factors affect how waves can influence the morphology of the beach
-depth of water
-gradient of shoreline
-energy of waves
-geology of coastline
-human interaction and coastal management
why are larger rocks not carried away by the backwash
-there are bigger gaps in rocks due to bigger rocks so wave percolates instead of dragging rock back
in what beach profile is there a greater range in sediment size and why
-in winter
- high-energy, destructive wave conditions erode, transport, and deposit a wider variety of materials compared to the constructive wave - favors finer, more uniform sediments.
why might beach profiles change over a longer periods of time
-sediment supply reduced from rivers
-interface in sediment supply along coast bc coastal management having knock on effects
-changes to climate creating more winter beach profiles
what do storm beach profiles result from
-high energy deposition of very coarse sediment during most servere storms
what are offshore ridges formed by
-destructive wave erosion
-subsequent deposition of sand and shingle offshore
