Ordnance Survey data collection and the mapping of tidal features

Tidal lines have often been recorded on maps and have the potential to aid the understanding of coastal processes, to help inform predictions of coastal change and associated sea level rise. One of the principal forms of cartographic tidal data available are the Ordnance Survey maps which have periodically reviewed and displayed tidal line data. Initially, the Ordnance Survey collected the data using land survey techniques and later developed remote sensing based approaches. This review examines the approach of the Ordnance Survey to the mapping of tidal lines on the maps of England and Wales from 1868 until the 1960s.