Development of a coastal vulnerability index: a geomorphological perspective

Sustainable coastal resource management requires the safeguarding and transmission to future generations of a level and quality of natural resources that will provide an ongoing yield of economic and environmental services. All maritime nations are approaching this goal with different issues in mind. The UK, which has a long history of development and flood protection in coastal areas, has chosen to adopt shoreline management, rather than coastal management, so placing coastal defence above all else as its primary and statutory objective. This paper aims to provide a geomorphological perspective of long-term coastal evolution and seeks to compare the UK approach with wider interpretations of coastal management. Based on a literature review, it is argued that coastal management (CM) and shoreline management, as a subset of CM, should share the same ultimate objectives, which are defined by many authorities as sustainable use. The objectives, both strategic and pragmatic, which follow from such an aim may appear to conflict with a reading of many of the texts for international and national CM or designated area management which emphasizes stability rather than sustainability. The result is that coastal defence is seen not merely as a means to an end but as an end in itself. It is argued within this paper that sustainable use of the coast, however, demands both spatial and temporal flexibility of its component systems, and management for change must therefore be the primary objective. Response of the natural system to independent forcing factors must be encouraged under this objective, whether such forces are natural or anthropogenic. In achieving such an objective the concept of shoreline vulnerability may prove useful. A simple and preliminary Vulnerability Index is proposed, relating disturbance event frequency to relaxation time (the time taken for the coastal feature to recover its form). This index provides a first order approximation of the temporal variability that may be expected in landform components of the shoreline system, so allowing management to provide more realistic objectives for long-term sustainability in response to both natural and artificial forces.