< HKDSE Geography < M2b

Waves start out as ripples in the sea, which are created as winds blow over water. Water moves in an orbital motion to form waves. As waves approach shore, they will be deformed as the seabed rises.They break when their orbit comes in contact with the sea bed. After breaking, the water continues to rush up the shore as swash, and thereafter rush down the shore as backwash. Load may be deposited by swash; beach materials may be eroded by backwash.

Constructive Waves vs. Destructive Waves

PropertyConstructive WavesDestructive Waves
Property of Waves
Wave heightLowerTaller
WavelengthLongerShorter
Wave frequencyLowerHigher
VelocityLowerHigher
Wave gradientGentlerSteeper
Energy
SwashStrongerWeaker
BackwashWeakerStronger
Dominant ProcessDepositionErosion
Wave energyWeakerStronger
Shape of the coast
Depth of the seabedShallowerDeeper
Position of breakerFarther away from the coastNearer to the coast
Shore gradientGentlerSteeper
Breaker typeSpilling breakerPlunging breaker
 
HKDSE Geography : Core Module 2 - Managing Rivers and Coastal Environments: A Continuing Challenge II (Coasts)
Coasts
Coastal Landforms
Erosional Landforms · Depositional Landforms · Other Landforms
Humans and Coasts
Human Activities · Human Impacts on Coasts · Hard Management · Soft Management
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