Coastal vulnerability assessment of National Park of American Samoa (NPSA) to sea-level rise

A coastal vulnerability index (CVI) was used to map the relative vulnerability of the coast to future sea-level rise within National Park of American Samoa. The CVI ranks the following in terms of their physical contribution to sea-level rise-related coastal change: geomorphology, regional coastal slope, rate of relative sea-level rise, historical shoreline change rates, mean tidal range and mean significant wave height. The rankings for each input variable were combined and an index value calculated for 500-meter grid cells covering the park. The CVI highlights those regions where the physical effects of sea-level rise might be the greatest. This approach combines the coastal system's susceptibility to change with its natural ability to adapt to changing environmental conditions, yielding a quantitative, although relative, measure of the park's natural vulnerability to the effects of sea-level rise. The CVI provides an objective technique for evaluation and long-term planning by scientists and park managers. The National Park of American Samoa consists of carbonate sand and coral rubble beaches, rock cliffs and platforms, and back-reef lagoon shorelines. The areas within National Park of American Samoa that are likely to be most vulnerable to sea-level rise are areas of unconsolidated sediment where coastal slope is shallowest and wave energy is high.