Discussion

Figure 14. Relative Coastal Vulnerability for Channel Islands National Park.

The data within the coastal vulnerability index (CVI) show variability at different spatial scales (Figure 14). However, the ranked values for the physical process variables vary less over the extent of the shoreline. The value of the relative sea-level rise variable is low at Santa Barbara Island and moderate vulnerability for the northern islands. The significant wave height vulnerability is moderate to very low. The tidal range is high vulnerability (1.0 - 2.0 m) for all of the Channel Islands.

The geologic variables show the most spatial variability and thus have the most influence on CVI variability (Figure 14). Geomorphology in the park includes high vulnerability sand and gravel beach shoreline; moderate vulnerability alluvial fans and beaches backed by cliffs, and low and very low vulnerability rock and cliff features (Figures 3 - 8). Vulnerability assessment based on shoreline change is constant at moderate vulnerability for all of the Channel Islands (Figure 9). Regional coastal slope is in the very low to very high vulnerability range for Channel Islands.

The most influential variables in the CVI are geomorphology, coastal slope, and significant wave height; therefore these may be considered the dominant factors controlling how the Channel Islands coastline will evolve as sea level rises.

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