The SACS Tier 2 Economics Risk Assessment is an estimate of storm surge inundation risk to public and private property within the South Atlantic Division (SAD) area of responsibility (AOR). This includes all coastal and riverine areas within the zone of tidal influence in North Carolina (NC), South Carolina (SC), Georgia (GA), Florida (FL), Alabama (AL), Puerto Rico (PR), and the US Virgin Islands (VI). The risk is expressed as the expected annual damages (EAD) to structures and their contents described in dollars.

Risks are described as a range between the EAD under existing sea level conditions (low) and the EAD assuming up to 3 ft of future sea level change (high) for the continental U.S. and 2.33 ft of sea level rise for Puerto Rico and the U.S. Virgin Islands. The EADs are presented in a geospatial format at the census block level. These results are initially aggregated to the census block level. Additional SACS Geospatial Data aggregates these values to the Place, County, and State/Territory.

The primary use of this risk assessment is to help inform coastal storm risk management (CSRM) decisions regarding the relative distribution of economic risk over space. Other uses include trying to understand the rough order of magnitude range of economic risks associated with a CSRM problem or the achievable risk management from a CSRM measure or solution.

The primary dimension of economic risk considered in this effort is storm surge (inundation) risk to infrastructure, public and private property. Damages are presented as consequences of annual exceedance probability (AEP) events and risks are presented as the expected annual damages for the series of storms. Damage values are reflective of structure and content depreciated losses expressed in 2018 price levels. The SACS Tier-II Economic Risk Assessment consists of surge damages to structure and content depreciated values by census block. The risk for CONUS areas was estimated using the FEMA flood loss mitigation model Hazus. Due to Hazus limitations, the FEMA FAST model was used to estimate storm surge risk for the OCONUS areas. Hazus (Hazus) is a multi-hazard loss estimation methodology developed by the Federal Emergency Management Agency (FEMA) for use by federal, state, region, local governments, and private enterprises in planning for risk mitigation, emergency preparedness, response, and recovery. Hazus uses Geographic Information Systems (GIS) technology to estimate physical, economic, and social impact of disasters.

To assess potential impacts of coastal flooding as part of the South Atlantic Coastal Study (SACS) the Hazus Flood Model was applied. The analysis included only coastal flooding and omitted any riverine and precipitation contributions to flood water elevations.

The Hazus methodology can be applied at any of three levels of analysis:

(1) Level 1 – Relies on the extensive national databases embedded in the model. Applies default hazards, inventories, and damage functions.

(2) Level 2 – Combines user specified local hazard, inventory, and damage functions with default databases.

(3) Level 3 – Involves extensive user specified local hazard and inventory data as well as detailed engineering data.

As the level of analysis increases, the level of effort and data sophistication also increases which the level of uncertainty decreases. Given the extent of the AOR a Level 1 analysis was applied.

For additional information and detailed methodology on the HAZUS and FAST model inputs, please reference the Tier 2 Economic Risk Assessment Technical report located at the following link: https://www.sad.usace.army.mil/SACS/

The SACS Tier 2 Economics Risk Assessment is an estimate of storm surge inundation risk to public and private property within the South Atlantic Division (SAD) area of responsibility (AOR). This includes all coastal and riverine areas within the zone of tidal influence in North Carolina (NC), South Carolina (SC), Georgia (GA), Florida (FL), Alabama (AL), Puerto Rico (PR), and the US Virgin Islands (VI). The risk is expressed as the expected annual damages (EAD) to structures and their contents described in dollars.

Risks are described as a range between the EAD under existing sea level conditions (low) and the EAD assuming up to 3 ft of future sea level change (high) for the continental U.S. and 2.33 ft of sea level rise for Puerto Rico and the U.S. Virgin Islands. The EADs are presented in a geospatial format at the census block level. These results are initially aggregated to the census block level. Additional SACS Geospatial Data aggregates these values to the Place, County, and State/Territory.

The primary use of this risk assessment is to help inform coastal storm risk management (CSRM) decisions regarding the relative distribution of economic risk over space. Other uses include trying to understand the rough order of magnitude range of economic risks associated with a CSRM problem or the achievable risk management from a CSRM measure or solution.

The primary dimension of economic risk considered in this effort is storm surge (inundation) risk to infrastructure, public and private property. Damages are presented as consequences of annual exceedance probability (AEP) events and risks are presented as the expected annual damages for the series of storms. Damage values are reflective of structure and content depreciated losses expressed in 2018 price levels. The SACS Tier-II Economic Risk Assessment consists of surge damages to structure and content depreciated values by census block. The risk for CONUS areas was estimated using the FEMA flood loss mitigation model Hazus. Due to Hazus limitations, the FEMA FAST model was used to estimate storm surge risk for the OCONUS areas. Hazus (Hazus) is a multi-hazard loss estimation methodology developed by the Federal Emergency Management Agency (FEMA) for use by federal, state, region, local governments, and private enterprises in planning for risk mitigation, emergency preparedness, response, and recovery. Hazus uses Geographic Information Systems (GIS) technology to estimate physical, economic, and social impact of disasters.

To assess potential impacts of coastal flooding as part of the South Atlantic Coastal Study (SACS) the Hazus Flood Model was applied. The analysis included only coastal flooding and omitted any riverine and precipitation contributions to flood water elevations.

The Hazus methodology can be applied at any of three levels of analysis:

(1) Level 1 – Relies on the extensive national databases embedded in the model. Applies default hazards, inventories, and damage functions.

(2) Level 2 – Combines user specified local hazard, inventory, and damage functions with default databases.

(3) Level 3 – Involves extensive user specified local hazard and inventory data as well as detailed engineering data.

As the level of analysis increases, the level of effort and data sophistication also increases which the level of uncertainty decreases. Given the extent of the AOR a Level 1 analysis was applied.

For additional information and detailed methodology on the HAZUS and FAST model inputs, please reference the Tier 2 Economic Risk Assessment Technical report located at the following link: https://www.sad.usace.army.mil/SACS/