Predicting the response of hard and soft rock coasts to changes in sea level and wave height

Abstract

A mathematical model was used to predict the effect of climate change on soft and hard rock coasts in a 2 m tidal environment. Erosional equations represented the effect of wave impact and bottom generated shear stresses in the intertidal and subtidal zones. Model runs were made for: 2900 years with constant sea level; a further 100 years, representing the last century, with either constant or slow sea level rise (0.2 m per century); and another 100 years, representing the present century, with either slow or fast (1 m per century) sea level rise, and with either no change in storm frequency or with a 10% increase in the frequency of the highest waves. The results suggest that rising sea level will trigger faster rates of cliff recession, whereas increased storm wave frequency may have only a fairly minor effect on erosional efficacy. Model runs were used to derive a series of predictive equations relating cliff recession during the present and last centuries.