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The question is: Explain the formation of waves and how they determine the profile of a beach
However waves can be either constructive or destructive. When a wave breaks, water is brought onto the beach which is called swash then afterwards the water is dragged back into the sea which is called backwash. If the swash is stronger than the backwash it is a constructive wave, if though the backwash is stronger than the swash it is a destructive wave.
These waves are formed in stormy conditions from powerful waves where the wind has been blowing strongly for a long amount of time and manifest when there is high energy and long fetch (the distance the wave has travelled). Their destructive action erodes the beach.
They are formed in calm conditions and as such they are less powerful than destructive waves. When they break on the shore they deposit sediment which builds up the beach.