Sea-Level Rise Tool for Hurricane Sandy Recovery

The National Oceanic and Atmospheric Administration (NOAA), the Federal Emergency Management Agency (FEMA), and the U.S. Army Corps of Engineers (USACE) developed a tool that can assist communities affected by Hurricane Sandy in reducing vulnerability of transportation and other infrastructure to future sea-level rise and flood risk. The tool, which involves a set of maps showing floodplains under sea-level rise scenarios and an updated USACE Sea-Level Change calculator showing site-specific flood elevation data, helps communities understand the effects of sea-level rise on future flood risk and incorporate this information into planning and decision-making. 

The sea-level rise maps, which were primarily developed by NOAA using FEMA flood hazard data, show the expansion of floodplain areas associated with future sea-level rise projections in 2050 and 2100. Maps are available for the Sandy-impacted areas of New York and New Jersey counties and New York City. The maps denote the extent of future flood risk related to sea-level rise horizontally, but do not denote vertical flood depth in the risk areas. The areas highlighted on the maps show the most recent boundaries of risk areas for 1% annual flood events, called Special Flood Hazard Areas (SFHAs), and the anticipated SFHA boundaries under different sea-level rise scenarios. For New Jersey and New York counties, the scenarios used range from 0.3 feet to 2.0 feet sea-level rise in 2050 and 0.7 feet to 6.6 feet in 2100. For New York City, which used a different report for its sea-level rise projections, the scenarios range from 8 inches to 30 inches in the 2050s and 15 inches to 75 inches by 2100. The maps can help transportation planners visualize long-term effects of sea-level rise on flood risk and plan infrastructure investments to be outside future floodplain areas, or to be more resistant to flooding.

The flood elevation calculator, which was primarily developed by USACE, complements the mapping tool by providing site-specific estimates for flood elevation (depth) during extreme weather events based on different sea-level rise scenarios. The calculator provides estimated values of flood elevation for each sea-level rise scenario at 5-year intervals until 2100. The calculator adds Base Flood Elevation (BFE) or best available elevation for the chosen location, which users can identify from FEMA data, to the sea-level rise projections under different scenarios. It is intended to provide additional detail beyond what is provided by the sea-level rise maps, so that floodplain managers, engineers, surveyors, and others involved in project planning can determine how much elevation or floodproofing is needed for infrastructure and structures based on the project’s anticipated lifetime.

The maps and the calculator were both developed using two different peer-reviewed sources of data on sea-level rise projections: a NOAA-led interagency report prepared for the National Climate Assessment and, for the New York City boroughs only, the New York City Panel on Climate Change (NPCC) Climate Risk Information 2013 (which was later updated to include projections for 2080 and 2100). Both reports include multiple sea-level rise scenarios, ranging from low scenarios (which consider primarily ocean warming) to high (which consider both ocean warming and melting of mountain glaciers and ice sheets). The tool suggests using lower-rise scenarios for projects with a high risk tolerance, such as those with a short lifespan, and using higher-rise scenarios for projects with low risk tolerance, such as those with a long lifespan or those serving critical functions where losses could be catastrophic.

The tool was designed to encourage communities to increase resilience by providing the information needed to assess flood risk based on future conditions, as FEMA’s mapping products only depict risk based on current conditions. The information is intended for use by state and local government officials and planners, floodplain managers, infrastructure managers, and engineers in coastal counties and cities in New York and New Jersey, many of which are recovering from Hurricane Sandy but lack the information and expertise to analyze risks related to sea-level rise and flooding. By providing map services and site-specific flood elevation data, NOAA, FEMA, and USACE can help inform transportation planning and investments, so that transportation infrastructure is rebuilt to be more resilient to future sea-level rise and extreme weather events.

 

This Adaptation Clearinghouse entry was prepared with support from the Federal Highway Administration. This entry was last updated on January 31, 2016.

If you have any trouble accessing the website link above, please find here an archived page. You may find this has limited use.

https://web.archive.org/web/20161208233146/http://www.globalchange.gov/browse/sea-level-rise-tool-sandy-recovery

Publication Date: June 20, 2013

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