1. Wave Height Increase: As waves move towards shallower water, their height increases. This is because the seabed starts to obstruct the wave's circular motion, causing the wave to slow down. As the waves slow down, their energy is concentrated into a smaller vertical space, leading to an increase in wave height.
2. Wave Steepening and Crest Narrowing: As the wave height increases, the front face of the becomes steeper, while the back face becomes less steep. This is because the bottom of the wave is slowed down more than the top, causing the wave to become steeper. The wave crest also becomes narrower as the wave approaches the shoreline.
3. Wave Length Decrease: As waves move into shallower water, they encounter increasing resistance from the seabed, which causes their speed to decrease. As a result, the wavelength decreases.
4. Wave Breaking: As the wave becomes steeper and the height increases, it becomes unstable and eventually reaches a point where it can no longer maintain its shape. At this point, the wave breaks. Wave breaking occurs when the water particles at the wave crest move past the particles at the wave trough, causing the crest to curl over and collapse.
5. Formation of Whitecaps: When waves break, they create whitecaps. Whitecaps are formed due to entrapped air bubbles in the turbulent and breaking waves. As the wave dissipates, the air bubbles rise to the surface, giving the appearance of white foam or froth.
6. Formation of Longshore Currents and Rip Currents: As waves approach the shore at an angle, they generate longshore currents, which are currents that flow parallel to the shore. Additionally, rip currents can occur where the waves break, creating strong currents that flow back towards the open ocean.
These are the key changes that occur to waves as they approach the shoreline. These changes are essential in shaping coastal landscapes, such as beaches, barrier islands, and headlands.
