Constructive and Destructive Waves

Destructive Waves

Waves allow for the build-up or breakdown of our beaches. The intensity of the waves especially relies on the amount of energy it carries. Increased energy resources allow for significantly higher waves and more coastal erosion to occur. Two main concepts we need to take into consideration relate to constructive and destructive waves. These waves form part of the coastal processes and the formulation of our beach areas. 

The power of waves becomes more intense with an increase in wind and tidal conditions. The heaviness of the wind impact significantly on the manner the waves operate within the coastal processes. The friction between the ocean floor and the wind creates the swells we see when visiting the beach. The waves need the energy to ensure continuous rotation of water and the creation of circular movements. Energy allows waves to progress and move forward until they reach the shoreline.

These different characteristics allow for the waves to collect or deposit sediments, sands and rock particles. Both constructive and destructive waves play a role to keep the natural balance. Unfortunately, with an increase in storms, typhoons, and tsunamis, the earth’s balance changed. Humans and biodiversity experience a threat of losing their habitats because of these occurrences. 

It, therefore, remains important to understand the complexities of constructive and destructive waves. Let us see what these different terms mean in the natural environment.

What are the meanings of a Swash and Backwash?

Before we move into the meanings of constructive and destructive waves, we first need to understand the swash and backwash activities. 

Swash means when the wave breaks, and the water travels towards the beach. Swash pushes the sediment up to the shoreline area. The wave progressive activity allows for the development of new beach areas.

Backwash means the wave water returns and move back down the beach. It takes various sediments and beach material with and dumps them in the sea. The backwash aims to return material to the ocean. The stronger the waves, the more likely we experience destructive natural phenomena.

What are Constructive Waves?

Constructive waves build the coastal zone areas, especially the beach areas. The build-up process comprises various key characteristics. These attributes relate to the occurrence of a backwash, swash, and deposition. If the swash presents a stronger approach than the backwash, the material carried gets dropped at the beach. This normally happens in the event of significantly low wave events and gentle slopes. As explained before, energy plays a key role to manage the movement of waves in the oceans. During calmer, less stormy conditions, the natural characteristics look significantly different. 

Constructive waves seem to lack the breaker component and just move onto the beaches. Because of limited interferences, the wave completes the action and deposits the material at the beachfront. It, therefore, completed its action. The waves deposit the sediment pushed up and the backwash just disappears in the sand. Because of the length in time, the deposited material increases. The backwash receives limited time to retrieve the material deposited at the beaches. Subsequently, more material becomes deposited than returned.

About nine constructive waves per minute can happen. To achieve a constructive wave, one needs a long wavelength, weak backwash, strong swash and suppressed wave gradients. 

The frequency in constructive waves seems less and prevents the continuous occurrence of sand removal. The slowness evident in the wave actions also prevents the deepened removal of sand material. The wave actions seem to stay at the top layers instead of cutting into the deeper gradients. It, therefore, prevents intensive erosion to take place. 

What are Destructive Waves?

In the event of destructive waves, the event removes particles, sediment or sand from the beach. The backwash looks stronger than the swash. It, therefore, creates significant erosion at the ocean coastlines. Especially during stormy conditions, the waves become significantly high and happens on high-dune or hill areas.

The characterisation, in this case, relates to experiences of high gradient waves with short wavelengths, strong backwash, and weak swash.

Destructive waves typically happen during the development of strong storm events. The waves increase in energy over long distances. Subsequently, the waves also increase their weight because of extensive wind levels. The moment the powerful waves reach the shoreline and beach areas, they break with power. Subsequently, they remove material from the shoreline because of a stronger backwash.

The outcome, therefore, is a destructive phenomenon and more material becomes captured by the strong waves. It also increases erosion in the coastal zone areas. Less sediment, sand and geological material becomes available to build-up the beach. An average of fifteen destructive waves may occur every minute. 

Beach areas across the area experience significant impacts because of weather conditions related to global warming and climate change. The biodiversity at our beach areas continues to experience threats by increased destructive waves. These waves cut into the beach areas and habitable land becomes less available.

The wave frequency plays a key role in the coastal processes and impacts by destructive waves. High-frequency waves, for example, become associated with destructive activities. The occurrence also became evident in continuous high-energy seaward movements. The waves, therefore, remove the material to a much lower level than during constructive waves.

Frequently Asked Questions

What are wave and coastal erosion? 

Waves break down different pieces of sediments and rocks that drop down to the ocean floor or transported to the beach area. The continue occurrence of waves at the beach areas, especially during stormy weather changes the beach outline. It cuts into the beach areas.

What drives constructive and destructive waves? 

Energy drives the occurrences of both constructive and destructive wave types. The more energy you find, the higher your waves and the more destructive they become. The less energy the wave contains, the more it focuses on the build-up processes.

What is the role of frequency in waves? 

Destructive waves generally contain a higher frequency rate, and more waves happen within a limited time. The waves also become more powerful within a set time. Constructive waves comprise lesser waves within one minute, for example. The reduced waves allow for a more gentle approach when the waves hit the shoreline. 

What are the impacts of destructive waves? 

Destructive waves cause significant coastal erosion in the coastal zone areas. For example, the cliff landscapes continue to lose sediment taken by the oceans. The actual habitat for humans, animals, and plants become less.

What are the impacts experienced because of constructive waves? 

Constructive waves normally impact the environment more pleasant. These waves were typical during the good weather beach days, push up the sediment and sand material. Because swash takes longer than the backwash, it comprises sufficient time to drop the material than take it. These constructive waves allow for the formation of diverse dunes and also changing the shapes and sizes of the beach areas.  

Is climate change influencing the waves? 

Globally we experience extensive increases in warmer weather, storms and other natural disasters. Subsequently, it influences the manner our oceans operate. The planet remains extensively sensitive when it relates to our marine areas. In the case of an earthquake for example, tsunamis sometimes occur. These powerful waves become destructive and easily destroy a shoreline. For these specific reasons, scientists continue to develop an understanding of the earth’s changing climate conditions.

References 

  1. Fourie Jean-Pierre et al., 2015, The influence of wave action on coastal erosion along Monwabisi Beach, Cape Town, South African Journal of Geomathics, Vol. 4 (2), pp. 1 – 14
  2. https://senior.stpauls.br/geography/form-3/1-coasts/3-what-are-the-differences-between-constructive-and-destructive-waves
  3. http://www.geography-site.co.uk/pages/physical/coastal/waves.html 
  4. Sweeting M. M., Wave – Trough Experiments on Beach Profiles, 1943, The Geographic Journal, Vol. 101 (4), pp. 163 – 168.
  5. Yoshida J, etal., 2014, Framework for Proper Beach Nourishment as an adaption to Beach to beach erosion due to sea level rise, Special Issue No. 70. Proceedings of the International Coastal Symposium 2014, pp. 467 – 472