Shore and cliff sensitivity to accelerating sea level rise
Source: gov.uk (2025-01-28)

This summary describes research aimed at understanding the sensitivity of cliffed coasts to sea level rise.

Documents

Quick start guide (https://assets.publishing.service.gov.uk/media/6793a3b62de28ea2d392f395/SC120017_Quick_start_guide.pdf) - includes background on the method and instructions to use the spreadsheet tool and dataset

Spreadsheet tool (https://assets.publishing.service.gov.uk/media/67939f517b75412c254f4b18/SC120017_-_Shore_and_cliff_sensitivity_to_accelerating_sea_level_rise_tool.xlsx) - includes a tool and dataset to estimate the effect of sea level rise on cliff recession for coastal sites in England and Wales

Method report (https://assets.publishing.service.gov.uk/media/6793a39dc74f1dca7492f38d/SC120017_Method_report.pdf) - describes project concepts and includes example applications to show settings where method may be most effective

Technical report (https://assets.publishing.service.gov.uk/media/6793a36d1e5e5352cb24bf41/SC120017_Technical_report.pdf) - describes the modelling and post-processing used to derive the indicators

Scoping technical report (https://assets.publishing.service.gov.uk/media/6797c28f4686aac15860636d/SC120017_Scoping_technical_report.pdf) - presents the results of method development and sensitivity testing

Summary

This project developed a new method to better understand future cliff recession around the coastline of England and Wales. It uses improved modelling tested at different case study sites.

The outputs include cliff sensitivity indicators that can be applied to assess the impact of relative sea level rise on rates of cliff recession.

Background

Understanding how sensitive coastal cliff recession will be to sea level rise is an important aspect of flood and coastal erosion risk management. However, the tools available to support this are very limited.

Until now, the most applied methods assume that cliffs behave like beaches, backed by eroding dunes. These methods do not account for:
- geological strength
- the reshaping of the shore platform underlying the beach
- the time necessary for the profile to respond to a change in water level
Approach

The project scoping stage developed and tested a method for case study sites. This method was then extended around the coastline of England and Wales and produced a tool and method report.

The new method complements existing approaches. It accounts for sites where cliff recession is controlled by erosion and dynamic reshaping of the cliff toe and shore platform. It requires information that is freely available to users, so is well suited to help better understand the effect of sea level rise on the coast.

In recent years, modelling the response of cliffs and shore platforms to sea level change has progressed. The new method uses the results of many such model simulations with a tool called Soft Cliff And Platform Erosion (SCAPE). These simulations modelled erosion and accounted for changes in sea levels for different sections of the coast.

Results

This project introduces a new method and accompanying data set. It incorporates the climate change projections from UK Climate Projections 18 (UKCP18).

The National Coastal Erosion Risk Map (https://www.gov.uk/guidance/updates-to-national-flood-and-coastal-erosion-risk-information) (NCERM), published in January 2025, uses this improved methodology. NCERM provides the most up to date national picture of coastal erosion risk for England, now and in the future.

Following successful trials and tests for compatibility with the NCERM methodology, erosion sensitivity indices were generated for 82 locations around the coast of England and Wales for a range of climate change scenarios over the next 100 years and beyond.

In some cases, historic sea level data were deemed to be unrealistic. The results for these areas, including east coast areas north of the Wash, for Cumbria and some areas in north-west Wales, are not yet being published.

Results show that both historic sea level rise and tidal range influence coastal sensitivity to future sea level rise, with high tidal range and higher waves tending to suppress sensitivity.

The project scoping stage also simulated the amplification of coastal erosion due to the removal or failure of coastal defence structures; this process is known as ‘coastal catch-up’. The models show that this is occurring due to accelerated lowering of the shore platform caused by the presence of hard defences and beach depletion.

Conclusions

New sensitivity indicators allow rapid assessment of the effects of accelerated sea level rise on coastal cliff toe recession. They are easy and cheap to apply and can be used alongside other approaches, such as numerical models, to validate and improve confidence in erosion estimates.

The project provides a national overview of the relative sensitivity of our coasts to future sea level changes.

Industry uptake of the project outputs is being encouraged through:
- indicators of cliff toe sensitivity
- accompanying user guide
- a ‘quick start’ tool
- supporting technical reports
Project information

Project manager: Dr Lee Swift

This project was commissioned by the Environment Agency’s FCRM Directorate, as part of the joint Flood and Coastal Erosion Risk Management Research and Development Programme.

A Welsh translation of the summary is also available. (https://assets.publishing.service.gov.uk/media/67dc04aedb5bf0deba4b4f8f/SC120017_GOV.UK_summary_Welsh_translation.pdf)