Assessing community-level flood risk at the micro-scale by
owner/occupant type and first-floor height
Abstract
Evaluating flood risk is an essential component of understanding and
increasing community resilience. A robust approach for quantifying flood
risk in terms of average annual loss (AAL) in dollars at the community
level is needed to provide valuable information for stakeholder
decision-making. This research develops a computational framework to
evaluate AAL at the community level by owner/occupant type (i.e.,
homeowner, landlord, and tenant) for increasing first-floor heights. The
AAL values are calculated here by numerically integrating
loss-exceedance probability distributions to represent economic annual
flood risk to the building, contents, and use. A case study for a census
block in Jefferson Parish, Louisiana, reveals that homeowners bear a
mean AAL of $4,390 at the 100-year flood elevation (E_100), compared
with $2,960, and $1,590 for landlords and tenants, respectively,
because the homeowner incurs losses to building, contents, and use,
rather than only two of the three, as for the landlord and tenant. The
results of this case study show that increasing first-floor heights
reduces AAL proportionately for each owner/occupant type, and that two
feet of additional elevation above E_100 may provide the most
economically advantageous benefit. The modeled results suggest that
Hazus Multi-Hazard (Hazus-MH) output underestimates the AAL by 11% for
building and 15% for contents. Application of this technique to the
community level while partitioning the owner/occupant types will improve
planning for improved resilience and assessment of impacts attributable
to the costly flood hazard.