Coastal Erosion

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Coastal erosion

Coastal erosion is one of the coastal processes that allow the removal of sediment along the coastline, such as different rocks, particles, and limestones. Waves then transport the eroded sediment to other coastal areas. This process serves as a challenge to coastal communities since the eroded materials are hard to replace.

In the past, coastal erosion helped maintain balance in coastal areas. However, with the increased onset of storms, typhoons, and tsunamis, increased erosion became detrimental to these coastal areas. In general, the more we experience coastal erosion, the more our coastal areas change and impact biodiversity here.

Coastal erosion constantly shapes the terrain of the earth and the availability of land for humans and other organisms as the ocean continues to remove land and deposit sediment in our oceans. With this in mind, let’s look at what coastal erosion is, and the different factors that contribute to it.

What is Coastal Erosion?

In science, erosion refers to the surface processes that remove rocks, soil, and other sediment from a location, subsequently transporting these to another location. With this in mind, coastal erosion, thus, is the coastal process that involves wearing away and breaking up rock and sediment along the coast. This process refers to the displacement of land or the long-term removal of sediment along the coastline. These events can either be a rapid-onset hazard, meaning it occurs very quickly or a slow-onset hazard, meaning it occurs over many years.

Two key factors play a role in coastal erosion, namely natural factors and human-induced activities. Understanding how these factors work helps society come up with control methods that help mitigate the damaging effects of coastal erosion, since this can become a hazard to communities when people are not able to adapt to its damaging effects

Different factors can cause coastal erosion, but normally, this coastal process happens because of the action of waves, currents, tides, wind-driven water, and other meteorological processes. Coastal erosion can also occur due to subsidence and mass wasting processes on weak slopes. Extreme weather events can also increase the intensity of coastal erosion, in the form of strong winds, tsunamis, and storm surges. For example, heavy rainfall can increase the saturation of soils, thus reducing their strength, and increasing the chances of slope failures such as landslides.

Often, human-induced activities can influence coastal erosion. For example, construction events that occur on coastlines can change coastal sediment transport pathways and can even increase the frequency of coastal erosion. The rapid onset of climate change can also increase the frequency and rates of coastal erosion, which can have many damaging effects on ecosystems and biodiversity on this coastline.

The transport of materials plays a key role in the erosion process. Take note that during erosion, no replacement of sediment takes place, since the process only refers to the removal and transport of this sediment to another location. The constant occurrence of coastal erosion events and the removal of sediment result in the development of different geomorphic landforms. Some of these landforms include, but are not limited to tunnels, bridges, caves, arches, and pillars.

Read more about Identifying Coastal Landforms

Types of Coastal Erosion 

Waves are the primary drivers of coastal erosion. As materials are broken down by waves, sediment falls into the ocean and is transported to different areas. In particular, destructive waves, or waves that have stronger backwashes than swashes, are the most common types of wave that cause erosion. These waves occur during stormy conditions and are characterised by big, strong waves that have high energy. In contrast, constructive waves occur during calmer weather, have low energy, and tend to cause deposition, rather than erosion. Because of their characteristics, destructive waves can erode the coastlines in a number of ways.

Hydraulic Action

Hydraulic action is the first type of coastal erosion that occurs when destructive waves that strike a cliff face compress air found in the crevices of these cliffs. The pressure exerted by the compressed air erodes the surrounding rocks, causing sediment and materials to break off.

Abrasion

Abrasion occurs when bits of rock and sand hit the surrounding landscapes, performing a scratching action that causes friction and scraping, which results in the chipping and breaking off of pieces from cliff faces.

Attrition

Attrition, on the other hand, is another type of coastal erosion that happens when waves grind rocks and pebbles into each other on the shore, causing sediment and these materials to weather and become smoother, smaller, and rounder.

Solutions

Solutions occur when acids contained in the seawater help dissolve specific sediment that reacts with these acids. The dissolved sediment is eroded and transported to new locations by the action of waves.

Corrosion

Corrosion is a similar process where the sea’s acid components corrode rocks on a cliff face. Examples of sediment that is prone to corrosion are limestones and their derivatives, since these have a relatively high pH, making them susceptible to the corrosive properties of the sea’s acid components.

Frequently Asked Questions 

What is Coastal Erosion?

Coastal erosion refers to the removal of sediment and rocks from the coastline primarily due to the action of waves, currents, tides, and other meteorological factors. Some of the main factors that induce coastal erosion are natural factors and human-induced activities.

How do waves affect Coastal Erosion?

Waves break down different sediment and rocks along the coastline that eventually drop into the ocean and are transported to different locations. Waves, in particular, have the capacity to remove sediment and transport it to distant locations. The continued occurrence of waves on beaches, most especially during aggressive weather changes the landscape of beaches.

What are the drivers of Coastal Erosion?

Waves, tides, and wind remain the main drivers of coastal erosion because of the energy they possess. The more we experience powerful storms and changes in weather patterns, the higher the frequency of coastal erosion along our shorelines. Additionally, human-induced activities can also affect the frequency and pathways of coastal erosion.

Is Coastal Erosion a long-term event?

Coastal erosion can either have a rapid onset which can last for days to weeks, or a slow onset which could occur for years or even decades. Short-term coastal erosion usually happens during meteorological events such as storm surges or typhoons. Long-term coastal erosion is usually characterised by waves that crash upon the coastline, thus shaping the landscape.

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 

Cite/Link to This Article

  • "Coastal Erosion". Geography Revision. Accessed on March 28, 2024. https://geography-revision.co.uk/gcse/coastal-landscapes/coastal-erosion/.

  • "Coastal Erosion". Geography Revision, https://geography-revision.co.uk/gcse/coastal-landscapes/coastal-erosion/. Accessed 28 March, 2024.

  • Coastal Erosion. Geography Revision. Retrieved from https://geography-revision.co.uk/gcse/coastal-landscapes/coastal-erosion/.