Decadal to centennial shoreline change illustrated by case studies fromIreland and South Africa

The significance and relevance of shoreline change measurements depends to a large extent on the temporal and spatial scale at which they are made. For management purposes, decadal to century scale temporal changes are usually deemed most important. On most shorelines of the world, however, the record of historical change is fragmentary and of variable quality - yet it is the only record that exists. Interpretation of historical coastal behaviour requires a combined deductive and inductive approach in which all available evidence of change and potential driving forces is compiled and interpreted in the context of knowledge of coastal processes that is often derived from short-term observations or experiments. By reference to several examples in South Africa and Ireland, the approach to assessment of historical scale shoreline change is described and the importance of understanding of long term coastal behaviour for the proper interpretation of shoreline changes is discussed.