Abstract
The United States Federal Emergency Management Agency (FEMA) provides
model-output localized flood grids that are useful in characterizing
flood hazards for properties located in the Special Flood Hazard Area
(SFHA ─ areas expected to experience a 1% or greater annual chance of
flooding). However, due to the unavailability of higher-return-period
flood grids, the flood risk of properties located outside the SFHA
cannot be quantified. Here, we present a method to estimate flood
hazards for U.S. properties that are located both inside and outside the
SFHA using existing annual exceedance probability (AEP) surfaces. Flood
hazards are characterized by the Gumbel extreme value distribution to
project extreme flood event elevations for which an entire area is
assumed to be submerged. Spatial interpolation techniques impute flood
elevation values and are used to estimate flood hazards for areas
outside the SFHA. The proposed method has the potential to improve the
assessment of flood risk for properties located both inside and outside
the SFHA and therefore to improve the decision-making process regarding
flood insurance purchases, mitigation strategies, and long-term planning
for enhanced resilience to one of the world’s most ubiquitous natural
hazards.