23. Why are historic rates of erosion slower than the erosion we see now?
The analysis undertaken as part of the Beach Management Plan (BMP) has concluded that here have been periods of more rapid erosion at East Beach in the past. East Devon has benefitted from the coastal monitoring programme (with numerous surveys of Sidmouth and East Beach undertaken each year), however this only covers a relatively limited time period (since 2007) and the BMP is reliant upon maps/aerial photographs to provide a longer-term image; these images are sometimes taken at intervals of ten years or more.
The average erosion rates across these longer periods of time tend to be misleading, as we know from our understanding of the geology and behaviour of these cliffs that falls will tend to occur in a small number of discrete events. Therefore, the BMP has taken all the photographic and map evidence together with anecdotal evidence to determine cliff behaviour over the longer term.