COASTAL STORM INDUCED EROSION PREDICTIONS FOR FEMA FIS COASTAL HAZARD RISK MAPPING
Flood Insurance Studies (FISs) produced by the Federal Emergency Management Agency (FEMA) per the National Flood Insurance Program (NFIP) regulations and guidelines adopt storm-induced erosion criteria often called the “540 ruleâ€. The methods used in the erosion analysis have been in place since the 1980s. The method requires dunes to be classified as fully eroded, or “removedâ€, when their cross-sectional reservoir is smaller than 540 square feet. Since the rule’s first application, additional data and recent evidence have become available leading FEMA to identify this approach as an area of the program in need of updating and improvement. Experts involved in conducting coastal hazard analyses for FEMA studies recommend exploring opportunities to improve FEMA guidelines for erosion criterion and revise NFIP regulations and guidance, as needed, to ensure that storm-related erosion hazards are appropriately evaluated and mapped along US coastlines.