What happens to wave energy as depth decreases toward shore?

• A. It increases as depth decreases toward shore, causing waves to steepen and break
• B. It decreases near the shore
• C. It remains constant with depth
• D. It is unaffected by depth

Answer: (A)

As depth gets shallower, waves slow down and their interaction with the seabed causes the crests to grow taller in a process called shoaling. The amount of energy carried by the wave stays (roughly) the same as it travels toward shore, but because the wave slows, the energy becomes more concentrated in a smaller cross-section. That increased energy density makes the waves steeper, with larger height relative to the wavelength, until they become unstable and break near the shore. So, wave energy concentrates as depth decreases, leading to steeper waves and breaking.