Evaluating Miami-Dade County’s Four Mitigation Strategies for Reducing Sea Level Rise Risks

Abstract

Coastal communities' defenses against the threat of climate change have encouraged significant investments in sea level rise (SLR) mitigation projects worldwide. These projects defend against long-term flooding, unstable property values, and community displacement. Local governments across the United States have funded various projects to address SLR-related risks. These include the construction of tidal marshes and sea walls, the launch of education campaigns, and the heightening of vulnerable buildings. Miami-Dade County (M-DC), located in Southeast Florida, faces significant challenges due to SLR, especially during hurricane events. In response, the county has implemented four key mitigation strategies: Build on Fill, Build Like the Keys, Expand Greenways and Blueways, and Create Green and Blue Neighborhoods. This research evaluates these strategies' effectiveness, costs, and community impacts in reducing SLR risks. A quantitative approach was employed to assess the impact of each strategy by analyzing pre- and post-project implementation data related to flood frequency, property values, construction and maintenance costs, and environmental effects. The study relied on key data sources from Miami-Dade County's Miniguide Toolbox, FEMA flood maps, property appraiser records, and the U.S. Census. A spatial analysis using GIS tools provided insights into community-level impacts, including displaced housing, transit accessibility, and economic trends, by comparing the effects of the same hurricane event across the four locations representing different mitigation strategies. Additionally, the study utilized En-ROADS Climate Solutions to project future SLR and storm surge impacts for 2040, 2060, and 2080 for the municipalities of Miami Lakes, Doral, and Homestead. Each of these cities provided a snapshot of a recently constructed location not on the coast that is experiencing flooding. This analysis determined the effectiveness of each mitigation strategy under hurricane scenarios by evaluating post-implementation data. The results revealed that Build Like the Keys (Virginia Key) was the most effective for formal risk reduction, successfully transitioning areas from high-risk Zone AE-10 to minimal-risk Zone X. Conversely, while Build on Fill (Star Island) generated the highest property value appreciation, it was directly correlated with the most severe socioeconomic instability, resulting in a net loss of 931 economically disadvantaged households. Green infrastructure strategies, such as Expand Greenways and Blueways and Create Green and Blue Neighborhoods, demonstrated the lowest maintenance costs but showed limited efficacy in altering flood zone designations or preventing market-driven displacement. The findings of this research offered several critical implications for coastal policy and urban planning. First, mitigation selection must be defined by projection-specific goals rather than a 'one-size-fits-all' approach, as strategies that maximize property value often come at the cost of community stability. Second, Build Like the Keys should be prioritized for residential areas seeking both protection and socioeconomic equity, as it maintained the lowest average eviction rates. Finally, low-cost green solutions, while fiscally cautious, failed to provide sufficient structural defense for vulnerable populations, indicating that future policy must integrate social safety nets with environmental engineering to prevent the displacement of disadvantaged families.