APPLYING THE COASTAL VULNERABILITY INDEX (CVI) IN COASTAL NATIONAL PARK UNITS

The Coastal Vulnerability Index (CVI) has proved to be a valuable tool for evaluating the potential for coastal change in a given area. It has been applied on both a national scale and more recently was refined to resolutions appropriate for aiding the National Park Service in managing its valuable coastal resources. The CVI ranks the following variables in terms of their physical contribution to sea-level related coastal change: geomorphology, regional coastal slope, rate of relative sea-level change, the rate of historical shoreline change, mean tidal range and mean significant wave height. The rankings for each variable are combined and an index value is calculated, such that the CVI highlights those regions where the physical effects of sea-level change might be the greatest. When the CVI project was established for twenty-five coastal National Park Units, a primary goal was to choose parks that represented the geologic diversity of the coastal national parks and test the applicability range of the CVI. In order to apply the CVI in all of the selected parks, we assumed that the variables most important to coastal change and shoreline evolution are the same and independent of the geologic or sea-level setting. The CVI methodology highlighted coastal change potential in all twenty-five of the selected National Park Units. However, two of the selected parks are experiencing relative sea-level fall. Because the impacts associated with sea-level fall are different and not well-understood when compared to impacts associated with sea-level rise, a new name was given to the calculated index, the Coastal Change Potential Index (CPI), to differentiate assessments in areas with falling relative sea level from areas where relative sea level is rising. For the purposes of the USGS/NPS cooperative project, the CVI is applied to coastlines that from a resource preservation perspective may experience undesirable coastal change, such as loss of land, infrastructure, or natural and cultural resources as a result of sea-level rise. Alternatively, in areas where sea level is falling and associated impacts may include dewatering of wetlands and estuaries, decreases in harborage area, channel shoaling, erosion near rivers and streams, grounding of tidewater glaciers, and habitat loss, we address the potential for coastal change using the CPI.