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100-Year Flood-It's All About Chance

General Information Product 106

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Abstract

In the 1960's, the United States government decided to use the 1-percent annual exceedance probability (AEP) flood as the basis for the National Flood Insurance Program. The 1-percent AEP flood was thought to be a fair balance between protecting the public and overly stringent regulation. Because the 1-percent AEP flood has a 1 in 100 chance of being equaled or exceeded in any 1 year, and it has an average recurrence interval of 100 years, it often is referred to as the '100-year flood'. The term '100-year flood' is part of the national lexicon, but is often a source of confusion by those not familiar with flood science and statistics. This poster is an attempt to explain the concept, probabilistic nature, and inherent uncertainties of the '100-year flood' to the layman.

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
100-Year Flood-It's All About Chance
Series title:
General Information Product
Series number:
106
Edition:
-
Year Published:
2010
Language:
ENGLISH
Publisher:
U.S. Geological Survey
Contributing office(s):
Office of Surface Water
Description:
Poster (1 MB); Full resolution poster (12 MB PDF file)
Online Only (Y/N):
N
Additional Online Files(Y/N):
Y