Wave shoaling

Wave shoaling is a physical phenomenon that occurs when ocean waves travel from a deep to a shallow area, such as approaching a beach. The process causes the waves to slow down, increase in height (amplitude), and change direction to align more closely with the bottom contours. This is a critical process in coastal engineering, oceanography, and marine geology.

Physics of Wave Shoaling

The physics of wave shoaling is governed by the principles of conservation of energy and wave propagation. As waves travel from deep to shallow water, the wave length decreases while the wave height increases. This is due to the conservation of wave energy, which is proportional to the wave height squared and inversely proportional to the wavelength.

The change in wave speed is described by the shallow water equations, which state that the wave speed is proportional to the square root of the water depth. As the water depth decreases, the wave speed decreases, causing the wave to "bunch up" and increase in height.

Effects of Wave Shoaling

Wave shoaling has significant effects on coastal erosion and sediment transport. As the wave height increases, the wave energy increases, which can lead to increased erosion of the coastline. This is particularly evident during storm surge events, when the increased wave energy can cause significant damage to coastal structures and landscapes.

In addition, wave shoaling can cause changes in the direction of sediment transport along the coastline. This can lead to the formation of sandbars and spits, and can influence the shape and position of beaches.

Measurement and Prediction

The measurement and prediction of wave shoaling is a key aspect of coastal engineering. This is typically done using wave models that incorporate the physics of wave shoaling, as well as other factors such as wave refraction, diffraction, and reflection. These models can be used to predict the wave conditions in a particular area, and can inform the design of coastal structures and coastal management strategies.