Coastal Erosion

Coastal erosion

One of the key components of the coastal processes refers to coastal erosion. Coastal erosion drastically allows for the removal of material at our beach areas. The material includes different rocks, particles or limestones, for example. These molecules or sediment picked-up by the ocean experience transportation to other coastal areas. The key challenge we face during coastal erosion relates to the significant increase in material removal and the lack of replacing them.

In the past, coastal erosion formed part of a balanced approach to maintaining the coastal zone areas. The subsequent increases in storms, typhoons, and tsunamis resulted in extraordinary occurrences of this event. The more we experience levels of coastal erosion, the more our coastal zones change and impact on human life. 

Coastal erosion constantly transforms the shape of the earth and the availability of land for humankind to live. The ocean continues to remove land and deposit the sediment in the ocean. We need to understand the meaning of coastal erosion, what it entails and the drivers of it. Let us see what it means.

What is Coastal Erosion?

Coastal erosion normally happens because of different waves or currents we see in our shoreline areas. Also, coastal erosion happens because of slope weakening processes. These events of erosion normally increase during events of tsunamis, storms and other significant weather patterns. An increase in weather patterns related to storms, for example, allows for the cutting of slopes or cliffs at the coastal zone areas. If heavy rain happens, it increases the soil capacities and subsequent impact on their strengths. During these times, one notices constant occurrences of landslides.

The transport of material plays a key role in the coastal erosion process. During erosion, no replacement takes place of the material removed but only transported to another space. Coastal erosion typically happens in coastal dune and shoreline areas. Many times human-induced activities for example construction impact on the natural processes. Subsequently, it increases erosion because of the impacts on natural cycles.

Different coastal erosion types happen. Some erosion events develop quickly within a few days, and others take a longer time. Research displayed that historical erosion can take decades. Many times we noticed the destruction of geographical areas over many years. Sometimes these events take place over millions of years. 

Two key factors play a role during coastal erosion, namely natural or as previously mentioned human-induced activities. Some environmental activities relate to waves or wind that causes the loss of sediments and destroy the ocean zone. Rocks and cliffs also erode at our beaches.

A significant component of our global coastal zone areas experiences erosion. Seawater replaces coastal land inclusive of the human habitats evident along the beaches. Coastal erosion also destroys the ecology, biodiversity, and sustainability of earth life. Because of the extensive increase in weather patterns and climate change, coastal erosion became a threat to humankind. 

These events result in the loss of significant amounts of sediments or sand taken by the ocean. 

Types of Coastal Erosion

The ocean and energies it carries result in the continuous events of erosion we notice at our shorelines. Waves remain the main drivers to increase coastal erosion levels and to cut into our rocky areas. The breaking down of materials by waves or windbreak happens and the sediment falls onto the ocean bottom. It gets transported and carried to another place in the sea. Deposition happens when a material becomes deposited or left behind in alternative spaces by the sea.

To explain this further, we need to understand the meaning of destructive and constructive waves. These different natural events support the development of coastal erosion

Destructive waves normally happen during significantly stormy conditions. Waves carry majestic energy levels and increase in height. Besides these waves “washes up” on the coastal areas and retreats taking material with them. Destructive waves contain powerful backwashes and induce erosion levels at the beaches. 

Constructive waves normally contain low energy levels and create a build-up of material at the coastal areas. The constructive waves increasingly wash-up at the shoreline instead of retreating. These wash-up waves play a key role to develop the beach landscapes. 

Different waves erosions occur referring to a solution, hydraulic activities, attrition, compression, and abrasion.

  • A solution that happens when seawater acids dissolve sediments surface and rocks.
  • Hydraulic activities trapped into different cracks experience compression when waves break. It weakens the cliff and erodes during the process. 
  • Attrition happens when waves create small pebbles or pieces of rocks because of grinding activities by the waves. The particles become smaller each day and transported by the waves. 
  • Compression normally happens at rocky landscapes evident of cracks. Air enters the cracks and results in compression. The constant occurrences of waves crashing against the rock allow for increased compression and decompression. The cracks become bigger and create pieces of rocks to fall into the ocean. 
  • Abrasion when pieces of sand or rock hit the surrounding landscapes, they subsequently chip into the cliff surfaces, for example. 

Shapes created because of Coastal Erosion

The constant occurrences of coastal erosion resulted in the development of different geomorphic shapes across the world. Some shapes or landscapes noticed globally include caves, arches, stumps, and stacks.  

Frequently Asked Questions

What are Coastal Processes?

Coastal processes allow for the build-up and breakdown of coastal areas. Meaning the processes ensure for constant change to happen by the use of energy. These energy resources one finds in the wind, waves or tides. Climate and weather patterns play a key role during these processes. Stormy weather increases the influences of coastal courses, for example. In this case the impact of waves play a key role to increase the levels of coastal erosion as part of the coastal processes. 

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 are the drivers of coastal erosion? 

Waves, tides, and wind remain the coastal erosion drivers. The more we experience powerful storms and weather patterns changes, the more energy these drivers carry. 

Why are waves so powerful? 

Powerful waves happen in the event of increased energy levels during the events of typhoons, for example. Powerful waves comprise the ability to impact the shorelines significantly and more difficult for gravity to manage them. Waves are powerful when they carry significant energy levels.

Why do we see waves as the main coastal erosion driver? 

Waves form a key part to create levels of coastal erosion because of the strength they carry at the oceans. Also, the energy waves carry progress and constantly move along significant distances. The energy in a wave can move for thousands of kilometers. Waves constantly crash at the rocky areas alongside the cliffs and shorelines. They therefore constantly impact the strength of the soil and sediments to survive.  

Is coastal erosion a short- or long-term event? 

Coastal erosion comprises short-term periods evident of a few days when we experience storm surges or typhoons or longer times. These longer periods can present decades. For example, coastal erosion impacted significantly the geological-historical shapes of the earth’s layout. Also, it results in creating islands and disappearance of rock areas.  

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://www.ga.gov.au/scientific-topics/community-safety/coastalerosion
  3. https://www.sciencedirect.com/topics/earth-and-planetary-sciences/coastal-erosion 
  4. https://www.gsi.ie/en-ie/geoscience-topics/natural-hazards/Pages/Coastal-Erosion.aspx 
  5. https://www.gsi.ie/en-ie/geoscience-topics/natural-hazards/Pages/Coastal-Erosion.aspx