National Assessment of Coastal Vulnerability to Sea-Level Rise: Preliminary Results for the U.S. Gulf of Mexico Coast
Coastal Vulnerability Index
The coastal vulnerability index (C.V.I.) presented here is similar to that used by Gornitz et al. (1994), as well as to the sensitivity index employed by Shaw et al. (1998). The index allows the six physical variables to be related in a quantifiable manner that expresses the relative vulnerability of the coast to physical changes due to sea-level rise. This method yields numerical data that cannot be equated directly with particular physical effects. It does, however, highlight those regions where the various effects of sea-level rise might be the greatest.
Click on chart for larger image
 |
|
Table 1. Ranking of coastal vulnerability index variables for the U.S. Gulf of Mexico. |
Once each section of coastline is assigned a risk value based on each specific data variable, the coastal vulnerability index is calculated as the square root of the geometric mean, or the square root of the product of the ranked variables divided by the total number of variables as
where,
- a = geomorphology
- b = coastal slope
- c = relative sea-level rise rate
- d = shoreline erosion/accretion rate
- e = mean tide range
- f = mean wave height
The C.V.I. values reported here apply specifically to the U.S. Gulf of Mexico coast, but are also comparable to the values for the U.S. Atlantic coast since the data ranges for the Gulf of Mexico are categorized using overall values for both coasts. Absolute C.V.I. values given for the Pacific coast, however, (e.g., Thieler and Hammar-Klose, 2000) are not directly comparable to the data presented here. We feel this approach best describes and highlights the vulnerability for each of the different continental margin types that make up the U.S. coast.
|
