shoreline erosion

Question 1

what are the major processes involved in coastal erosion and how can these be mitigated

Question 2

beach erosion

Answer 2

• most susceptible to erosion during stores
• storm surges are elevated water levels due to onshire winds, low air pressure
• waves have exceptional erosive force
• beachprofiles change (during strorms): dunes move landward; material between dunes and water removed. material moves away from water and onto land
• erosion narrows tourist beaches. barrier islands re most at risk
• may be completely overwashed in storms. ex. texas coast, carolinas
• ex. huricane harvey destroyed the shireline

Question 3

cliff erosion

Answer 3

• any surface over 60deg is a cliff
• rock and sediment cliffs are vunerable to erosion by waves
• pounding by breakers (wave action)
• milling by debris moved by waves
• headlands are mosr susceptible to wave erosion
• wave refraction- wave energy is concentrated on headlans, spread out in bays, producing strightened coastlines
• wave erosion concentrated at waterline: toe erosion
• debris removed by currents: produces steep cliffs, wave cut platform, and sea stacks. there can be rocks resistant to erosion adn they stick up
• soft sediment in coastline are prone to mass movement processes: slides, smlup flows

Question 4

scarborough bluffs

Answer 4

• high erosion rate (am/year)
• due to ‘soft’ sediments and urbanization
• urbanization on glacial sediment
• apartment building and townhouses at ricks
• by mid 1980 recognized need to protect bluffs
• we need to understand the processes
  -erosion processes:
• toe erosion; waves remove debris at base of cliff; sediment transport to west
• slumping; shallow rotational slump; occur after periods of intence snow melt
• slides and debris fows: common in spring, after storms. sediment moves downslope
• piping: groundwater emerging on cliff face. washes out sand and produces ‘pipes’. causes collapse of overlaying sediment; cliff top retreat
• surface run off: produces gullies and ravines

Question 5

coastal protection measures

Answer 5

• encourage growth of vegetation
• stabilize tow of slop: build groins to trap sediment moving in longshore drift system
• build marinas to trap sediment; ex. bluffers park
• protect toe of slope with armoured toe berms. toe berms protects cliff from wave erosion; prevents removal of sediment
• restructuring creeks: contain surface water flow in pipes; reduce slopes
• large scale engineering: reduce overall slope by terracing, cutting slope back, drainage system