What process occurs when waves refract around headlands?

When waves refract around headlands, the process that takes place is known as refraction. Refraction occurs when waves encounter varying depths of water as they approach the shore, causing them to bend. This bending happens because waves travel more slowly in shallower water compared to deeper water. As waves approach a headland, the portion of the wave in shallower water slows down, while the part in deeper water continues moving at a faster pace. This differential speed causes the waves to bend towards the headland, concentrating their energy on the sides, which can lead to increased erosion in those areas.

Understanding refraction is crucial as it helps explain coastal features and the distribution of wave energy, which in turn influences sediment transport and the formation of various coastal landforms. The other processes listed, such as swash, diffraction, and percolation, are distinct and refer to different coastal dynamics or movements. For instance, swash refers to the movement of water up the beach after a wave breaks, while diffraction describes the bending of waves around obstacles, which is a slightly different phenomenon than refraction. Percolation pertains to the movement of water through soil or porous materials, which is not directly related to wave actions.