The ESLs in the 2018 update have not changed significantly for most UK NTGN gauge sites. 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).
Larger changes in ESLs from CFB 2011 to CFB 2018 are present at some locations in the 2km return level dataset despite smaller changes at UK NTGN gauge locations. This is due to improvements in the interpolation of levels between gauge locations. These have been validated against predicted high tides and local gauge data. Areas of greater change include the Severn Estuary, Solent, Solway Firth, Ornkey Islands, Pentland Firth and Liverpool.