Journal of Coastal Zone Management

Determination of Wave Kinds and their Generation

Marcel van^* Department of Coastal Structures and Waves, Deltares University, Delft, Netherlands
^*Correspondence: Marcel van, Department of Coastal Structures and Waves, Deltares University, Delft, Netherlands, Email:

Received: 30-Sep-2022, Manuscript No. JCZM-22-18194; Editor assigned: 03-Oct-2022, Pre QC No. JCZM-22-18194 (PQ); Reviewed: 17-Oct-2022, QC No. JCZM-22-18194; Revised: 30-Jan-2023, Manuscript No. JCZM-22-18194 (R); Published: 08-Feb-2023, DOI: 10.35248/2473-3350.23.26.560

Description

Short waves, defined as waves with periods of less than about 20 sec, while long waves, also known as long period oscillations, are oscillations with periods of between 20 and 40 minutes. Water level variations are oscillations of the water level with periods or recurrence intervals longer than around an hour, such as astronomical tide and storm surge. Wind waves and swell are examples of short waves, while surf beats, harbour resonance, seiches and tsunamis are examples of long waves. Natural waves can be thought of as a wave field made up of numerous single wave components, each of which has a distinct wave height, period and propagation direction. Uneven wave fields are those with a wide range of wave heights and durations.

Types of short waves

Short waves are wind generated waves that move in the direction of the shore. Either the wind is actively pushing them or they may have already left their generating area. The main energy source feeding the beach is incident waves. They experience processes called refraction and shoaling when they move from deep water to the coast. In shallower water, incident waves become more irregular as they travel from deep ocean. Since the overall energy flux should remain constant while their celerity and wavelength decrease, a rise in wave height must occur while a drop in wavelength.

Wave orbital velocities increase beneath crests relative to troughs as waves move closer to the beach and the wave shape becomes increasingly distorted with peaked wave crests and longer, rounder wave troughs. Particularly seaward of the wave breakpoint, where there will be a propensity for the incident waves to drive sediment toward the shore, this property is of vital relevance to sediment movement.

The single most crucial factor in coastal morphology is the short waves. According to the type of water region and the predominant wind climate, wave conditions vary greatly from site to site. In the short waves, there are:

• Sea or wind waves, often known as storm waves. These are waves that the nearby wind field has created and affected. It is challenging to detect clearly defined wave fronts because wind waves are typically uneven and directed, high and relatively steep (high and short). The waves are also known as short crested waves. Because wind waves induce silt to migrate offshore (as opposed to onshore), creating a generally flat shore face and a steep foreshore, they are often detrimental to the coastal profile.

• Swell is a term used to describe waves that have been generated by distant wind fields and have travelled across vast distances over deep sea. As a result, their path of propagation may differ from the direction of the nearby wind. Swell waves are typically unidirectional, regular, quite tall and relatively long. The coastline profile often builds up to a steep shore face due to swell waves.

Wave formation

As a result of the wind's influence on the water's surface, wind waves are created. The following factors affect the wave field's duration, propagation direction, wave height and wave period at a certain location:

• The field of winds (speed, direction and duration).

• The water area or the meteorological fetch of the wind field (geographical fetch).

• The water depth over the region where waves are generated.

As was already said, swell is made up of wind waves that were created elsewhere but changed as they moved away from their source. The short period components are attenuated significantly more than the long period components by dissipation mechanisms like wave breaking. The resulting long crested swell will consist of relatively long waves as a result of this process, which functions as a filter (wavelength).

Transforming waves

The various transformational forms that are covered here are mostly associated with wave occurrences that occur in the natural world. The seabed influences the waves as they approach the beach through mechanisms like refraction, shoaling, bottom friction and wave breaking. When the waves are too steep, though, wave breaking also happens in deep water. The waves will be altered by diffraction if they come into contact with large objects or sudden changes in the coastline. Waves will overtop a reef or other underwater structure if they come into contact with the wave transformation.