Coasts as energy buffers Flashcards
what proportion of the world live within 10k of low elevation coastal zones
1/3
how long are spring-neap cycles
2 weeks
when are the equinoxes
late march and late september
what is the result of a small increase in the height of a wave
a big increase in energy
explain how energy gets dispersed as waves interact with the seabed and come into the shore
friction, heat and turbulent energy
the orbits of the waves become deformed, break to release heat and turbulent energy
results in percolation, reflection and longshore transfer
compare the erosive capabilities of the tides and waves
different materials need different velocities to be eroded.
but tides are generally not effective at eroding any sediment
waves are much more effective
what is shoaling
process of waves coming into shallower water, starting to feel the seabed and changing in height
in intermediate water, the height increases, period remains constant the speed decreases and length decreases
what is refraction
buffering effect whereby the part of a (laterally) wave in shallower water travels slower than that in deep water, so the wave crest rotates to move along the bottom contours.
wave energy is redistributed
name three types of breakers
spilling, plunging, surging/collapsing
what is the surf zone
the zone of breaking waves
describe a dissipative coast
lot of the energy is dissipated out, energetic waves, offshore sediment transport and a flatter beach
describe a reflective coast
much of the energy is reflected back, onshore transport of sediment, steeper beach slope, offshore bars moved onshore
by what annual rate is global sea level rising over the past decades
over 3mm
what is a morphodynamic approahc
sees how processes are linked by negative and positive feedbacks, current paradigm of coastal research
what are estuaries
tide-dominated coastal landform that mixes fluvial and marine processes
features are shortlived as they are filled in quikcly by sediments
