Coastal erosion processes

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Coastal erosion processes

  1. 1. COASTAL STUDIES  FACTORS influencing the RATE OF EROSION TYPES OF WAVES
  2. 2. TYPES OF WAVES
  3. 3. CONSTRUCTIVE WAVES
  4. 4. CHARACTERISTICS  Low energy and are common along gently sloping coasts  The swash STRONGER than the backwash (swash > backwash)  The constructive waves are called spilling breakers  Spilling breakers are produced by waves of long wavelength and low height
  5. 5. DESTRUCTIVE WAVES
  6. 6.  High energy waves that erode the coast.  They are common along steep sloping coasts.  These waves are called plunging breakers where it tend to carry material off the beach and into the sea (BACKWASH > SWASH)  Plunging breakers are produced by waves of short wavelength and high height CHARACTERISTICS
  7. 7. Coastal processes EROSION TRANSPORTATIONDEPOSITION
  8. 8. COASTAL EROSIONAL PROCESSES CORRASION (or ABRASION) ATTRITION SOLUTION (or CORROSION) HYDRAULIC ACTION
  9. 9. C A S H
  10. 10. CORRASION (or ABRASION)  When materials carried by waves are thrown repeatedly against a coast, they gradually erode the coast
  11. 11. ATTRITION  When materials are carried in waves, they collide with one another  Eventually, the materials break down into smaller pieces and become smoother and more rounded over time
  12. 12. SOLUTION (or CORROSION)  Water in the waves reacts chemically with the soluble minerals in the rocks along the coast and dissolves them  Over time, the coast becomes weakened and is eroded.
  13. 13. HYDRAULIC ACTION  The force of moving water currents rushing into a crack in the rock face or cliff face
  14. 14. FACTORS influencing THE RATE OF EROSION TYPE OF WAVE NATURE OF COASTAL ROCKS THE GRADIENT OF THE COAST IMPACT OF HUMAN ACTIVITIES
  15. 15. TYPE OF WAVE Destructive waves cause MORE EROSION that constructive waves – have a more powerful backwash than swash
  16. 16. NATURE OF COASTAL ROCKS Rocks that make up the coast may have different resistance to erosion In terms of mineral composition:  Coasts that are made up of granite, basalt, and dolomite – MORE RESISTANT TO EROSION than,  Coasts that are made up of limestone, shale, and clay In terms of lines of weakness:  Coastal rocks that have more lines of weakness will be MORE EASILY ERODED than,  Those with fewer lines of weakness
  17. 17. THE GRADIENT OF THE COAST Coasts with a STEEPER GRADIENT tend to COLLAPSE FASTER
  18. 18. IMPACT OF HUMAN ACTIVITIES Human through their activities can speed up or slow down the process of coastal erosion  Construction works – speed up  Dredging – speed up  Constructing groynes to trap sand and rock debris and others - slow down
  19. 19. COASTAL STUDIES Types of COASTAL PROCESSES? 1. Erosion 2. Transportation 3. Deposition Coastal erosional processes:- 1. Corrasion 2. Attrition 3. Solution 4. Hydraulic action CASH Factors influencing the rate of erosion:- 1. Type of wave 2. Nature of coastal rocks 3. The gradient of the coast 4. Impact of human activities Types of WAVES? 1. Constructive waves 2. Destructive waves

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