What is a shore profile? How is it created? Explain the concept of an equilibrium profile in regard to a shore profile

Question

What will be an ideal response?

Answer 1

ANSWER: Grain size strongly controls the slope of a beach, called its shore profile. Just as in a stream, fine sand can be moved on a gentle slope—coarse sand or pebbles only on a much steeper slope. Whether the sediment moves shoreward or not depends on the balance (equilibrium) between shoreward bottom drag by the waves, size of bottom grains, and downslope pull by gravity. This balance is called the equilibrium profile. Thus, the slope of the bottom is controlled by the energy required to move the grains, which is related to water depth, wave height, and grain size. Shallower water, smaller waves, and coarser grains promote steeper slopes offshore, just as in rivers. In the breaker zone offshore, waves can easily move the sand, and the beach surface is gently sloping. As breakers sweep up onto the shore, the water is shallower, their available energy decreases, and the shore profile steepens. Sand there can move back and forth only on such a steeper slope.