A PHYSICAL AND SOCIOECONOMIC INDEX
OF COASTAL VULNERABILITY (EXTENDED ABSTRACT)

This paper was authored by Richard C. Daniels, Tammy W. Beaty (Oak Ridge National Laboratory) and Vivien M. Gornitz (Goddard Institute for Space Studies, New York).
Effective coastal zone management at the state, regional, or national level requires the ability to identify areas with high population densities and housing values that would be adversely affected by increases in storm frequencies, sea levels, or coastal erosion rates. Several options have been proposed as possible responses to these threats, chief among these are (1) hardening and maintaining the current shoreline; (2) accommodation by raising buildings to the projected higher flood level; or (3) abandoning the current coastline and retreating inland.

To assist in this planning process an index of socioeconomic development was combined with a coastal vulnerability index (CVI) to produce a new economic vulnerability index (EVI) for the U.S. coastal zone. The EVI considers both physical (e.g. mean wave height, elevation) and socio-economic variables (e.g., population density, housing values) in determining the relative economic impact of inundation or coastal erosion (Table 1). This is the first such index to consider the U.S. East, Gulf, and West Coast as an integrated unit.



Table 1. Percentage of each coasts shoreline in each of five risk classes based on physical variables alone (CVI), and physical and economic variables (EVI). Risk class ranges are based on the 20th, 40th, 60th, and 80th percentiles.


              Very                                 Very
      Coast   Low     Low     Moderate     High    High


EVI
       East   15.2    24.5      18.0       20.7    21.7 
       Gulf   21.5    19.0      25.9       25.9     7.8 
       West   26.8    15.3      14.8       11.5    31.7 

CVI
       East   20.1    25.1      17.6       29.4     7.7 
       Gulf    1.5     5.9       7.8       22.4    62.4 
       West   32.2    27.9      21.9       15.8     2.2

The EVI answers two questions, what coastal areas are at risk and what would be the relative (to all coastal counties) economic and social impact of their loss. Thus, the EVI may be used to target limited research, planning, and construction funds to areas where the economic cost of abandoning the shore may approach or exceed the cost of holding the coast in place.

The decision to abandon any coastal area to the sea is complicated by many conflicting interests. For example, local property owners have a vested interest in protecting their land, as do city and county governments who may lose tourism dollars if their beaches and historical coastal sites are inundated or washed away. State governments and federal agencies, on the other hand, could be expected to attempt to take the least-cost path. Unfortunately, individuals and local governments often do not have the resources needed to take proactive measures (relatively low cost) to prevent the loss of their high value assets. As a result, state governments and federal agencies are lobbied to assist in rebuilding the beach, building the seawall, or moving the building (high cost) before their catastrophic loss.

The EVI provides some of the information needed to make these recommendations in advance. Other information needed for the decision-making process includes an estimate of the costs associated with implementing the most appropriate mitigation measure (e.g., beach nourishment). With such information policy-makers will have the information necessary to make defensible least-cost decisions years or decades prior to the actual loss.


This research was sponsored by the U.S. Department of Energy's Office of Health and Environmental Research and was conducted at the Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee.


Contact:

Carbon Dioxide Information Analysis Center
Environmental Sciences Division
Oak Ridge National Laboratory
Oak Ridge, Tennessee 37831-6335
Phone: (423) 574-0390 or 241-4846

Reading:

Gornitz, V.M., Daniels, R.C., White, T.W., and K.R. Birdwell. 1994. The development of a coastal risk assessment database: Vulnerability to sea-level rise in the U.S. Southeast, pp. 327-338. In Coastal Hazards: Perception, Susceptibility and Mitigation, Finkle, C.W. Jr. (ed). Special Issue No. 12, The Coastal Education and Research Foundation, Fort Lauderdale, Florida.