- Coastal Flood Boundaries - additional help and further information
- Where can I access the Coastal Flood Boundaries data and guidance documents?
- How is sea level rise accounted for in the Coastal Flood Boundaries?
- I am concerned about the large differences in values in some locations and the effects on my project
- Levels have fallen in my area of interest since the previous Coastal Flood Boundaries update. How can this be when sea levels are known to be rising?
- What has changed in Coastal Flood Boundaries 2018?
- I’ve been given mean high water springs (MHWS) and highest astronomical tide (HAT) predicted Tide Levels by another source. They don’t match up to those in the Coastal Flood Boundaries. Which should I use?
- How are levels within ‘Inland Extensions’ or ‘Estuaries’ derived?
- How should I use Coastal Flood Boundaries levels in estuaries and tidal rivers?
- What are the key outputs of Coastal Flood Boundaries 2018?
- What has been done to update the Coastal Flood Boundaries in 2018?
- Why are regular updates, and therefore likely change in the estimates, necessary?
- How often is the Coastal Flood Boundaries dataset updated?
- How can I generate my Base Tide Curves?
- Are waves included in the Coastal Flood Boundaries?
- What information is included in the extreme sea levels shapefiles?
- What is the accuracy of the Coastal Flood Boundaries extreme sea levels?
- What is the vertical datum of the Coastal Flood Boundaries Level?
- What is the base year for Coastal Flood Boundaries levels?
- What is meant by Annual Exceedance Probability (AEP) and which extreme sea level probabilities are included?
- How does the Coastal Flood Boundaries inform us about flood risk around the UK coast?
- Who should use the Coastal Flood Boundaries (CFB) data?
- What are the Coastal Flood Boundaries?
I am concerned about the large differences in values in some locations and the effects on my project
Created: 03 October 2019 Updated: 03 October 2019
Improved methods and longer observed gauge data series have been used to produce the new extreme sea level information. This has led to differences compared to previous estimates.
Differences of less than 0.1m are not considered significant as these are within the accuracy of ESL estimation. Gauge locations with changes in level larger than 0.1m for the 200-year return period include Mumbles, Newport, Barmouth (Wales), Felixstowe and Cromer (England). Areas of greater change between gauge sites include the Severn Estuary, Solent, Solway Firth, Ornkey Islands, Pentland Firth and Liverpool.
The new levels have been validated against other statistical methods and extensively checked against local knowledge and information. The new levels provide the best available source of information extreme sea level information and so should be used in all flood risk management and decision making.
Lower and upper confidence levels are provided with all extreme sea levels and may be used to inform flood risk where there remains uncertainty.