In the simplest terms coastal erosion is the removal of material from land by the sea. This removal of material causes the coastline to recede, which in turn can cause risks to the built environment, such as infrastructure or houses. The causes of coastal erosion are linked to the physical characteristics of the land and the sea. 

Land 

For land the key characteristic is geology, with other processes such as elevation and proximity to the open ocean also having an impact on erosion: 

• Geology impacts erosion primarily based on how hard or soft the rock is. Harder rocks such as granite erode more slowly, while softer rocks like mudstone erode more rapidly. Unconsolidated sediments erode most quickly of all. These unconsolidated sediments are often termed as ‘Superficial Deposits’ which broadly means a loose collection of rock and soil, often deposited by past glacial activity. 
• Elevation impacts erosion quite simply – with all other factors being equal, the higher the elevation of the land on the coast the slower the rate of erosion. 
• Proximity to open ocean simply means exposure to the sea. Sheltered river deltas will erode at a slower pace (again with all other factors being equal) than exposed sections of coast. 

Ocean 

For ocean the key factors are sea level, wave energy and coastal sediment cells: 

• Sea level is as simple as it sounds – the mean height of the sea. Tidal regimes mean that sea level varies around the coast of the UK, so some areas will have a higher mean sea level than others. The higher the sea level the more it will erode, quite simply because it touches more of the land. 
• Wave energy refers to general character of the sea adjacent to the land. Areas with high energy tend to have rougher seas, and this often correlates with having a greater ‘fetch’ or distance over which the wind can build up powerful waves. As such coastlines in the west of the UK facing the Atlantic will have higher wave energy than more sheltered coasts on the east. 
• Coastal sediment cell is the name given to several coastal processes which result in deposition of material eroded from one area to another area. This results in accretion, which can result in a temporary advance of coastline, with this often easily eroded in turn. Areas which experience accretion are less likely to suffer coastal erosion. 

With a good understanding of these processes, and how they interact at the land sea interface, it is possible to make projections on the susceptibility of the coastline to erosion, both under present conditions and in the future, as these processes, and as such the rate of erosion, change with the climate. 

In short Shoreline Management Plans (SMPs) are initiatives put in place to manage risks from future coastal change. Generally, this management focuses around defending land and assists from coastal flooding and erosion. The extent to which the land is defended (or in some cases not) is dependent on factors ranging from potential economic damages, the cost of implementing defences, and the environmental consequences of doing so. 

At a management level SMPs are strategic initiatives put in place by the Environment Agency and councils. Each plan roughly corresponds to a sediment cell and tends to be a joint initiative between several councils (where administrative boundaries are crossed). These plans are split into policy units which describe the strategy put in place for that section of coastline.

These strategies fall into 4 categories: 

• Hold the existing defence line – this refers to maintaining or changing current defenses (such as sea walls) so that further coastal erosion does not occur.
   
• Advance the existing defence line – this refers to constructing new defences in order to reclaim land from the sea.
   
• Managed realignment – this refers to allowing the coastline to shift due to natural processes, but with management to control the degree of movement.
   
• No active intervention – this refers to no further intervention in coastline management, effectively allowing natural processes to determine the coastline. 

How does Coastal Erosion effect property? 

Coastal erosion effects a property by quite simply eroding away the ground and foundations upon which it lies. In an area with a Shoreline Management Plan of No Active Intervention this can, in effect, make the property a stranded asset. This refers to an asset which may experience a sharp decline in value in the future, and further may be difficult to sell in the present.

Coastal erosion can also have an impact on planning. As part of Shoreline Management Plans councils are required to take coastal changes into account before awarding planning permission, with this including considerations for future change under a changing climate. 

How is the risk to property projected to change? 

Using NGRM:Climate we are able to project that properties within the erosion zone will rise from ~4,000 properties currently to ~11,000 in 2050 and ~18,000 by 2080 under a medium (RCP4.5) emissions scenario. Under a high emissions scenario (RCP8.5) the number at risk increases to ~12,500 in 2050 and ~23,000 in 2080. 

How can risk be reduced? 

Unfortunately, there are few ways of proofing against coastal erosion that are affordable to an individual budget. On a governmental level the Environment Agency and local councils can reduce the risk of damages by using a combination of hard and soft defences. 

Hard defences refer to recognisable architecture such as sea walls which physically protect the coast from the sea. 

Soft defences are terminology often used for natural defences which protect the coast behind them. These can take the form of wave dissipating landforms such as sandbanks, or buffer wetlands and saltmarshes.