Map of Coastal Change-Potential

Data Ranking System

Table 1 shows the six variables described in the Introduction, which include 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 susceptibility of a given landform to physical change. Shoreline change-potential is estimated when vector shorelines are not available for determining rate of shoreline change. Rock cliff areas are assigned low shoreline change-potential, 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 open coast and areas where glaciers reached at 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 mm/yr) up to the modern rate of eustatic rise (1.8 mm/yr) as very low change-potential. Since the global or "background" rate is common to all shorelines, the sea-level ranking reflects primarily local to regional isostatic or tectonic adjustment. Mean wave height contributions to change-potential range from very low (<1.1 m) to very high (>2.6 m). 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.