New insights into damage initiation point of depth-damage function revealed from flood risk patterns in the United States
Abstract
Flood is one of the costliest natural hazards in the US. The economic impact of flood to residences is fundamentally estimated using a depth-damage function (DDF) that correlates flood depth to damage as a percentage of building value. The damage initiation point (DIP-flood depth relative to first-floor where damage initiates) of the most commonly used DDFs in the United States - U.S. Army Corps of Engineers (USACE) and Flood Insurance Administrator (FIA) - start below a home's first-floor elevation (FFE). In this study, the effect of DIP of a DDF on the flood risk pattern is examined. Flood hazard is characterized using the Gumbel extreme value distribution's location (μ) and scale (α) parameters, which are estimated from the relationship between flood elevation and the double natural logarithmic transformation of annual non-exceedance probability. The μ parameter represents the 1.57-year return period flood elevation at a location, which is directly related to ground elevation. The α parameter represents the rate of flood intensity escalation at a location, where higher α value represents more intensely increasing flooding at higher return periods. The USACE building and contents DDFs are used to transform flood depths to economic loss values. Flood risk is calculated using the average annual loss (AAL) metric with varying DIPs using Monte Carlo simulation. Results show that when the DDF DIP occurs below the first-floor elevation, the risk function follows an erroneous exponential decay with increasing α parameter. The expected increasing behavior of risk with increasing α parameter is achieved by changing the DDF's DIP to the first-floor elevation of the building (DIP=0). These results make clear the need for significantly more research and specificity of DDF DIPs in flood risk studies.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFM.H41B..03R