Table 1 shows the six variables described in the Introduction and includes both quantitative and qualitative information. The five quantitative variables are assigned a change-potential ranking based on their actual values, whereas the non-numerical geomorphology variable is ranked qualitatively according to the relative resistance of a given coastal landform to erosion. Shoreline change-potential is estimated using the relative resistance of the landform to erosion and the wave energy in the area. Rock-cliff areas are assigned low shoreline change-potential regardless of wave energy, because rock cliffs are not likely to experience significant erosion or accretion annually. Unconsolidated sediments within fjords are classified as moderate shoreline change-potential. Beaches along the exposed coast and areas where the termini of glaciers reach to or near the shoreline are classified as high shoreline change-potential. Regional coastal slopes range from very high change-potential, <4.59 percent, to very low change-potential at values >14.7 percent. The rate of relative sea-level change is ranked such that no change in sea level (0 mma-1) up to the modern rate of eustatic rise (1.8 mma-1) as very low change-potential. Since the global (eustatic) or "background" rate is common to all shorelines, the sea-level ranking reflects primarily local to regional isostatic or tectonic adjustment. Wave energy regime contributions to change-potential range from low within fjords to high along the outer coast. Tidal range is ranked such that microtidal (<1 m) coasts are very high change-potential and macrotidal (>6 m) coasts are very low change-potential.
Table
1. Ranges for Vulnerability Ranking of Variables on the U.S. Pacific Coast.
