The coastal vulnerability index (CVI) values for this region (Figure 4) correlate best with the geomorphology (Figure 5) variable. The open-ocean shoreline, for example, is composed primarily of high-risk sandy barrier islands, while risk due to geomorphology is lower for the lagoons and along the bluffs of northern Long Island. The coastal slope (Figure 6) is relatively steep (low risk) throughout much of this area, but becomes lower (relatively higher risk) in southern New Jersey.
The smaller-scale variations in the CVI values are influenced primarily by changes in shoreline erosion rate (Figure 7). Two ways in which the erosion rate impacts upon the CVI are evident. First, the lack of data for lagoon shorelines along southern Long Island and southern New Jersey causes erosion rates there to default to the values for the open-ocean shoreline (e.g., Jones Island). This is partially an artifact of the original CEIS data set, but also the coarse grid size (0.25 degrees) used by Gornitz and White (1992) from which these data were obtained for this study. Second, where other variables are essentially equal (e.g., southern New Jersey), the erosion rate data dominate the CVI. The combined effect of these two problems is particularly visible just north of Cape May, where a short reach of shoreline, extending from the barrier island coast to the lagoon, has an anomalously low CVI ranking. This is in contrast to the reach of shoreline just south of the Mullica River that has a similar physiographic setting. As described above, updated and higher-accuracy shoreline change data are needed to rectify such problems.