Wave refraction: coastal processes

• what is wave refraction and what happens to energy in headlands and bays

  Distortion of wave fronts as they approach indented shoreline so energy concentrated at headlands and dissipated in bays. Erosion and deposition created
• what happens when wave front nears coast

  Base of wave slows due to friction caused by shallower water in front of headland
• what shape does the bathymetry follow on sea floor

  follows shape of coastline so directly in front of headland the sea floor is shallower
• what happens when base of wave slows

  as base of wave slows wave height increases and wave length shortens
• why does the wave front start to bend

  the section of wave front still in deeper water hasn't yet slowed as the base of wave hasn't been significantly affected by friction. so wave front starts to bend- wave refraction
• what happens as wave moves closer to headland

  the 'bending' becomes more pronounced as the section of wave front in front of headland continues to slow down whereas section of wave front in front of bay is still able to travel at original speed
• how can we show the direction of wave front travelling

  use orthogonals which is a line or arrow drawn perpendicular (right angle) to wave crest
• what do the orthogonals show

  wave energy become more concentrated around headland as wave crests refracted towards headland. so greater erosion occur at headland. also show energy dissipated in bay so depositional features occur because not enough energy for transportation of sediment
• what concept does it show

  negative feedback- variations in rock strength lead to initial formation of headlands and bays. this causes wave refraction which in turn encourages erosion of headlands and deposition in bays which works against initial erosion.
• what would happen if conditions stayed stable

  state of equilibrium would be reached, where shape of coastline would remain static due to balance between the potential erodibility of rocks and effect of wave refraction