Results

Figure 8. Relative Coastal Vulnerability for Padre Island National Seashore. Click on figure for larger image.

The calculated CVI values for Padre Island range from 15.81 to 39.53. The mean CVI value is 27.23; the mode and the median are 25.0. The standard deviation is 5.37. The 25th, 50th, and 75th percentiles are 24.0, 26.0 and 29.0, respectively.

Figure 8 shows a map of the coastal vulnerability index for Padre Island National Seashore. The CVI scores are divided into low, moderate, high, and very high-vulnerability categories based on the quartile ranges and visual inspection of the data. CVI values below 24.0 are assigned to the low vulnerability category. Values from 24.0 to 26.0 are considered moderate vulnerability. High-vulnerability values lie between 26.01 and 29.0. CVI values

Figure 9. Percentage of PAIS shoreline in each CVI category. Click on figure for larger image.

above 29.0 are classified as very high vulnerability. Figure 9 shows a histogram of the percentage of Padre Island shoreline in each vulnerability category. Nearly 130 km (80 miles) of shoreline is evaluated along the national seashore. Of this total, seventeen percent of the mapped shoreline is classified as being at very high vulnerability due to future sea-level rise. Twenty-eight percent is classified as high vulnerability, twenty-nine percent as moderate vulnerability, and twenty-six percent as low vulnerability.