Demonstrating Floodplain Uncertainty Using Flood Probability Maps1

:  The U.S. Federal Emergency Management Agency (FEMA) flood maps depict the 100‐year recurrence interval floodplain boundary as a single line. However, because of natural variability and model uncertainty, no floodplain extents can be accurately defined by a single line. This article presents a new...

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Bibliographic Details
Published in:Journal of the American Water Resources Association 2007-04, Vol.43 (2), p.359-371
Main Authors: Smemoe, Christopher M., Nelson, E. James, Zundel, Alan K., Miller, A. Woodruff
Format: Article
Language:English
Subjects:
Boundaries
Flood damage
Flood insurance
flooding
floodplain delineation
geospatial analysis
Insurance rates
Probability
risk assessment
simulation
statistics
surface water hydrology
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Summary::  The U.S. Federal Emergency Management Agency (FEMA) flood maps depict the 100‐year recurrence interval floodplain boundary as a single line. However, because of natural variability and model uncertainty, no floodplain extents can be accurately defined by a single line. This article presents a new approach to floodplain mapping that takes advantage of accepted methodologies in hydrologic and hydraulic analysis while including the effects of uncertainty. In this approach, the extents of computed floodplain boundaries are defined as a continuous map of flood probabilities, rather than as a single line. Engineers and planners can use these flood probability maps for viewing the uncertainty of a floodplain boundary at any recurrence interval. Such a flood probability map is a useful tool for visualizing the uncertainty of a floodplain boundary and represents greater honesty in engineering technologies that are used for flood mapping. While institutional barriers may prevent adoption of such definitions for use in graduated flood insurance rates (as most other insurance industries use to account for relative risks), the methods open the door technically to such a reality.
ISSN:1093-474X
1752-1688
DOI:10.1111/j.1752-1688.2007.00028.x