Methodology

Figure 3. Shoreline grid for National Park of American Samoa. Click on figure for larger image.

In order to develop a database for a park-wide assessment of coastal vulnerability, data for each of the six variables mentioned above were gathered from state and federal agencies (Table 2). The database is based on that used by Thieler and Hammar-Klose (1999) and loosely follows an earlier database developed by Gornitz and White (1992). A comparable assessment of the sensitivity of the Canadian coast to sea-level rise is presented by Shaw and others (1998).

The database was constructed using a 1:3780-scale shoreline for Tutuila, Ofu, Olosega, and Ta'u that was obtained from NOAA/NOS's Biogeography Program (http://biogeo.nos.noaa.gov/projects/mapping/pacific/territories/data/). Data for each of the six variables (geomorphology, shoreline change, coastal slope, relative sea-level rise, significant wave height, and tidal range) were added to the shoreline attribute table using a 500-meter grid (Figure 3). Next each variable in each shoreline segment was assigned a vulnerability value from 1-5 (1 is very low vulnerability, 5 is very high vulnerability) based on the potential magnitude of its contribution to physical changes on the coast as sea level rises (Table 1).