Mapping statewide flood vulnerability in Florida

FDEP joined forces with Fathom and two local engineering firms, Taylor Engineering and Jones Edmunds, to complete the mandatory flood vulnerability assessment by the time the project was ready to launch.

First, they needed data, some of which was already available. FDEP had created a database of critical assets with more than 3 million data points including roads, rail networks, government buildings, critical infrastructure, and natural and cultural resources.

The National Oceanic and Atmospheric Administration (NOAA) had data on sea-level rise projections, while published flood hazard data was available from the Federal Emergency Management Agency (FEMA), the United States Geographical Survey (USGS) and Flood Hub. However, there were large gaps in data coverage across the state and the flood datasets were not compatible and lacked the necessary future conditions.   

What the team needed was a consistent, seamless, statewide view of flood hazard for pluvial, fluvial and coastal flooding, for both current and future conditions. 

Fathom, in partnership with the local engineering firms, was able to develop a bespoke statewide perspective of flood risk under current and future scenarios to provide a complete picture of flood risk in Florida.

Fathom has extensive experience of LiDAR-based 2D flood-modeling in the US. Its climate-driven US Flood Map covers inland and coastal flooding over the whole of the continental US, with Fathom’s cutting-edge FABDEM data filling any gaps in LiDAR coverage. Crucially, Fathom provides a series of future views up to 2100 under any known emission scenario.

Having worked with the Texas Water Development Board on a similar project in 2019, Fathom came on board to develop three separate models for pluvial, fluvial and coastal flooding in Florida, for the time horizons of 2040 and 2070. 

To achieve a truly local understanding of flood risk, Fathom worked with Jones Edmunds to adapt its models to represent the specific nature of flood events in Florida. Modifications to Fathom’s modeling framework included:

• Updating its design storm events to 1-day and 7-day durations
• Using local soil maps to account for run-off being generated both by rainfall infiltration and by saturation due to the high water table
• Incorporating NOAA’s impervious mapping data 
• Using change factors provided by the USGS
• Working with the state’s Chief Resilience Officer to align future climate scenarios to RCP 4.5, in line with proposed new legislation

Once these models were developed, the next step was to validate them. Jones Edmunds compared Fathom’s data to both FEMA and locally derived city and county flood maps. Then Taylor Engineering and Jones Edmunds took Fathom’s flood hazard data and mapped it over the critical assets data to determine the depth of flooding and its impact for each asset.

For the first time, FDEP now had a comprehensive picture of the flood risk to assets, infrastructure and communities across Florida. The team were able to conduct a sensitivity and vulnerability analysis for each of the 67 counties in line with the stringent requirements – and all within the short timeframe.

The data can also be represented via a dashboard, which FDEP can use internally to assess the flood risk of any asset type, in any county, and in any flood scenario.

Ultimately, the vulnerability analysis will inform future planning, enabling the state government to enhance flood resilience for Florida.