Florida Keys Study Ranks Roads in Need of Flood Mitigation

Monroe County, home of the Florida Keys, is a limestone archipelago that extends 115 miles from a point south of Miami westward to Key West in the Gulf of Mexico.

The Keys have experienced record “king tides,” flooding low coastal areas threatened by climate change and sea level rise. Ocean water flows into drainage systems and inundates streets and yards. And, once flooded, those neighborhoods may remain flooded for weeks to months.

To address this challenge, Monroe County engaged our team to conduct a roadway vulnerability assessment for the 311 miles of county-maintained roadways. The report identified the highest priority roads in need of flood mitigation, using geographic information system technology to create dynamic maps. We also developed engineering design concepts and cost estimates for the county’s capital improvement plan.

The vulnerability assessment began with defining the future sea level rise conditions. HDR and Monroe County studied four different sea level rise scenarios and settled on two for further analysis. Our coastal hydrology team provided the projected sea level rise increase in feet for each scenario for seven future years (2025, 2030, 2035, 2040, 2045, 2060 and 2100), referenced to a local tidal datum.

Prioritization scores for each scenario and year combination provided the data needed to identify the top road segments in need of sea level rise mitigation design. Throughout the project, we developed a series of Esri ArcGIS Online web apps for use in strategic meetings and public use. To help Monroe County connect with a community hit hard by fair-weather king tide flooding, the team developed an eye-opening animation of future flooding expected in the neighborhood. Monroe County Road Criticality Viewer