Whilst a detailed methodology is available within the methodology report, a brief summary is outlined here:
The high-water shorelines were extracted from the extent of erodible shores within the Ordnance Survey’s 6-inch county series (dating from the 1890s), the Ordnance Survey’s 1970s maps and then compared with the present-day shoreline based on current mapping updated where possible with detailed survey data.
One million data points were used to compare the changes during the historic period (1890s to 1970s) and recent period (1970s to modern). Where the amount of recent erosion was greater than potential mapping errors (10m or 0.5m/yr) then the recent annual erosion rate was projected landwards to consider areas at future risk. The anticipated erosion areas were constrained by a Coastal Erosion Susceptibility Model (CESM) .
This research is still currently underway therefore the metholdogies are not yet finalised. However, below is an outline of the workstreams in progress:1) Erosion enhanced flooding: Create a map and spatial database summarising natural coastal defence features.