Methodological approaches to reconstructing storms, relative sea-level change, and coastal evolution in the Mid- and Late-Holocene.

Predicting the future impacts of storms requires a robust understanding of storms and coastal evolution in the past. This research presents a novel combination of techniques reconstructing storms, relative sea-level and coastal change to better understand the patterns and relationships of storms and coastal morphology. Storms are reconstructed from coastal dunes by identification of jumps in relative age, determined by portable luminescence, concurrent with changes in grain size characteristics. Reconstructed storms are combined with new documentary storms archives to produce 200-year storm chronologies for the Norfolk and North Welsh coasts. Of these ten, eight were outside the range of regional instrumental datasets extending the record of large storms in these regions by 50-60 years. A new foraminifera transfer function is derived from a 3000-year-old salt-marsh producing one of the world’s longest continuous sea-level records from a salt-marsh. Combined with two new sea-level index points (SLIPs) from a freshwater marsh, and SLIPs from literature the relative sea-level record for North Wales shows a rapid early Holocene rise (~5.3 m ka−1) with stagnation to slow rise (~0.3 m ka-1) in the mid- and late-Holocene. This record leaves no room for a mid-Holocene highstand in the region, improving understanding of UK mid-Holocene emergence and highlighting shortcomings some glacio-isostatic models for sea-level prediction. By combining dune reconstructions, storm archives, historic maps and satellite derived shorelines, the evolution of a North Wales beach dune system over 500 years is reconstructed at varying resolutions. Results show ~650 m of change in the last 500 years punctuated by storm erosion in the 1850s-60s, 1880s-90s late 1930s. By comparing these reconstructed shorelines with the tidal characteristics of storms from tide gauges it is possible to demonstrate statistically significant correlations between local scale shoreline change and the very largest storm events to occur each year (sea levels >3.00m OD).