Cost-effectiveness of Federal CDBG-DR Road Home Program Mitigation Assistance in Jefferson Parish, Louisiana

Abstract

Abstract After Hurricanes Katrina and Rita in 2005, Community Development Block Grant Disaster Recovery (CDBG-DR) assistance was allotted to the State of Louisiana, administered by the Louisiana Office of Community Development (OCD) as the Road Home Program, to provide homeowners with the required matching funds for elevating damaged homes under the Federal Emergency Management Agency (FEMA) Hazard Mitigation Grant Program (HMGP). This research evaluates the cost effectiveness of the Road Home Program elevation mitigation assistance for a sample of homes in Jefferson Parish, Louisiana, using benefit-cost analysis (BCA) based on average annual loss (AAL) prediction. Multiple return period flood depths are determined from FEMA RiskMap non-regulatory flood depth. Flood risk reduction is calculated as the difference between pre- and post-elevation AAL. Benefit-cost ratio (BCR) and net benefit-cost ratio (NBCR) of the elevation mitigation investment are calculated across multiple time horizons, considering several funding scenarios. Optimal first-floor height (FFH) is also determined by foundation type (i.e., crawl space, slab-on-grade) and 100-year flood depth. The analysis reveals that elevating existing homes by either 3 feet or to the base flood elevation (BFE; 100–year flood elevation), whichever is higher, reduces AAL by 96%. This elevation generates mean BCRs of 6.13 and 7.01 over a 30–year mortgage and a 70–year building lifetime, respectively, if the full benefits are attributed to Road Home Program investments. These results enhance understanding of cost effectiveness of federal elevation mitigation investments, benefits of elevating homes above the minimum requirements, and most effective elevated heights for homes.