Temporal and spatial variations of chalk cliff retreat in East Sussex, 1873 to 2001

Abstract

Spatial and temporal variations of chalk cliff retreat rates over a 130 yr period are examined for 22 km of the East Sussex chalk coastline between Brighton and Belle TouteTout lighthouse, England. Data are derived from maps surveyed between 1873 and 1925/28 and air photographs dating from 1973 and 2001. The long-term average cliff retreat rate over the period 1873 to 1973 is 0.36 m y − 1 and from 1873 to 2001 is 0.35 m y − 1 . Over the whole 23 km study area, rates calculated over shorter time slices indicate a decline in cliff retreat: 0.37 m y − 1 between 1873 and 1925/28; 0.35 m y − 1 between 1925/28 and 1973; 0.27 m y − 1 between 1973 and 2001. Temporal variations are unlikely to be due to variations in precipitation and frost days though the relationship remains uncertain due to the resolution of available cliff retreat and climatic data. Changes in wave climate are small and cannot be responsible for the decline in cliff retreat. The study suggests that the most important factors causing the measured decline in cliff retreat rates are firstly, the loss of cliff toe beaches over time and secondly, widening of the rocky shore platforms that front the cliffs. Some of the spatial variability in retreat rates can be explained by local variations in lithology.