Flood Severity, Socio-Economic Impacts, and Elevation Strategy Effectiveness in a Subset of Louisiana Post-Hurricanes Katrina and Rita

FEMA's Hazard Mitigation Grant Program (HMGP) assisted survivors of Hurricanes Katrina and Rita, necessitating a 25% homeowner contribution for post-disaster home elevation. The federal Community Development Block Grant Disaster Recovery (CDBG-DR) program allocated $13.4 billion to Louisiana, offering $30K grants per home, aligning with HMGP needs. This study focused on elevated residential homes in a subset of Louisiana's housing data, aiming to understand the intersection of flood risk when disaggregated by frequency, vulnerable populations, and mitigation costs.

The analysis investigating the correlation between flood frequency/severity and variables such as race and ethnicity, and socioeconomic status, exploring their interconnections. Subsequently, we explored how flood risk changed both pre- and post-implementation of elevation strategies across various return periods, aiming to determine the proportional attribution of the total AAL to these different periods. Additionally, it examined the comparative flood risk before and after elevation strategies across diverse socioeconomic statuses. Finally, it analyzed the absolute benefits of elevation strategies, particularly the avoided AAL, compared with investment values and socioeconomic statuses.

The result of this study indicates that Poverty levels remain consistent across different return periods, a notable increase in Non-white population percentages with longer return periods, and a peak in Renters' percentage at floods with a return period of ≥200 years. It’s demonstrated that a substantial percentage of the total AAL is attributed to less frequent but more severe events—those occurring with return periods between 100 and 500 years, as well as those with return periods greater than 500-year. The results show inconsistencies in the Avoided AAL values across different investment levels suggest that the relationship between investment in elevation costs and Avoided AAL is not directly proportional.

The study results provide multifaceted insights, aiding in the identification of vulnerable communities and offering guidance for resource allocation decisions, and demonstrating the impact of elevation strategies. The economic analysis enhances understanding of federal mitigation investments' cost-effectiveness across diverse socio-economic statuses.