Sea Level Rise Vulnerability Assessment | Pensacola, FL

The City of Pensacola is preparing for sea level rise. Recognizing the threats that higher tides mean for coastal cities, Pensacola applied for and received a grant from the Florida Department of Environmental Protection (DEP) to conduct a vulnerability assessment and develop a resilience plan based on the results. This Story Map is one of the products of Resilience Planning Grant R2116, and describes in summary the data, methodology, and analysis undertaken by the City and the Project team. (Click on the image for a closer view)

Pensacola knows that the need for climate adaptation and mitigation planning stems from significant evidence of climate change and its effects on coastal cities and regions. Researchers and scientists point to the changing climate as a direct result of human activities with devastating consequences for communities around the world. The City and its regional partners, including Escambia and Santa Rosa Counties, as well as other local governments, are pursuing an aggressive and overarching climate-planning strategy to address underlying climate change threats. The planning process included the establishment of the Climate Mitigation and Adaptation Task Force (Task Force) in 2017 . The report produced by the Task Force provides a general outline of the direction for the City of Pensacola and the region to undertake specific actions to counter threats and impacts of climate change and extreme weather.

Sea level rise is one of the major contributors to increased risk of damage due to coastal flooding. Since 1880, global sea levels have increased by about 22-24 cm. Between 2006 and 2015, the rate of increase was more than double that of the previous decades, ~3.6 mm/year compared to ~1.4 mm/year. In Pensacola, at the time of this report sea level was trending upwards at a rate of ~2.46 mm/yr.

Coastal flooding occurs when ocean water levels rise to the point of negatively impacting the surrounding coastal infrastructure. Communities on the coasts are particularly vulnerable to flooding events since nearly  40% of the US population  lives in coastal areas. These areas also tend to be more crowded than inland communities, as they are hotspots for  commerce and tourism .

Causes of coastal flooding include  storm surges , where storms cause water to rise and infiltrate areas of higher elevation than normal, and  king tides  and  perigean spring tides , which are abnormally high tides caused when the moon is closer to the Earth, usually during a full moon or new moon. When combined with the effects of sea level rise, coastal floods have negative effects on people living close to the coast. (Click on the image for a closer view)

For the purposes of this project we chose to model potential tidal inundation due to sea level rise induced flooding only (not factoring in rainfall, storm surge or other hydrologic considerations). Utilizing a  bathtub modeling approach , the project team assessed the City of Pensacola for its vulnerability to sea level rise inundation using  ESRI's ArcGIS platform . The Project Team employed the 2017 sea level rise projection (Projection) produced by the National Oceanic and Atmospheric Administration (NOAA), which includes several “curves” representing different future scenarios including “medium,” “high,” and “extreme,” however we focused on the intermediate high curve. The image below depicts the 2017 NOAA sea level rise projections, which have been adjusted to reflect local tide gauge records from Pensacola. 

With increases in sea level in the coming decades, the effects of storm surges and high tides could increase the vulnerability of coastal areas to flooding events than in previous decades. Therefore, it is important to predict which areas will have the greatest impact in the upcoming years and enact mitigation plans accordingly. This Vulnerability Assessment presents an updated analysis of the City of Pensacola's vulnerabilities, with a particular focus on ecological and social vulnerabilities in order to guide future planning efforts.

To determine potential exposure to sea level rise we employed the best available light detection and ranging (LiDAR) derived digital elevation model (DEM), the sea level rise projections described above, and various classes of infrastructure and community composition to identify areas of significant overlap. This type of assessment should be used for planning purposes only. Additional site-specific assessment is recommended to hone in on property level improvements that could not be considered at this scale.

1. Hydric Environment
2. Critical Infrastructure
3. Parcel Level Land Use
4. Emergency Management
5. Potable Water
6. Sanitation and Sewer
7. Storm Water
8. Transportation
9. FEMA Floodplain
10. Social Vulnerability

Below is a map of the U.S. Centers for Disease Control and Prevention (“CDC”) tool created to assist emergency response planners and public health officials in identifying and mapping communities that will most likely need support before, during, and after a hazardous event. The 2018 Social Vulnerability Index (“SVI”) uses U.S. Census data to determine the social vulnerability of each census tract. Percentages are based off of total social vulnerability of each census tract. Census tracts are outlined and colored based on the score displayed in the legend below. (Click on the image for a closer view)

A summary of the vulnerability assessment is included below followed by an interactive map series that focuses in on specific planning horizons (2040, 2070, and 2100).

Below, is a scrolling narrative which describes the priority planning areas, potential impacts, and provides examples of flooding and adaptation measures implemented around Pensacola City. Included on the map is the projected impact footprint by year. Legend is shown below.

Based on the results of the Vulnerability Analysis, the Project Team has developed recommendations for the City, both to guide mitigation measures based on this assessment and to improve the quality of future assessments. Some of these recommendations will be presented here, but for a comprehensive list of recommendations see the Final Project Report.

• Perform a detailed survey of its coastline in order to address all locations identified as Tidally Flooded Areas
• Conduct a vulnerability assessment of its seawalls to develop a comprehensive report describing their existing conditions and identifying potential failures
• Conduct a survey of coastal stormwater inlet elevations and associated roadway crown elevations 
• Repair, restore, and strengthen seawalls and other shoreline protection
• Install back-flow prevention on low-lying stormwater pipes
• Identify potential land sites for acquisition for future stormwater pumping stations