FLOOD02161

• County: Statewide
• Community: Statewide
• Stream Name: All
• Basin: Statewide
• Title: Benefit-Cost Analysis of Hazard Mitigation Projects - Riverine Flood Infrastructure
• Date: 3/15/1995
• Prepared For: FEMA
• Prepared By: FEMA
• Floodplain - Doc Type: Educational/Technical/Reference Information

BETA VERSION 3/15/95

Flood Frequency
Table

Flood Frequency
(Years)

Expected Annual
Number of
Floods

B-C Program: Infrastructure

FLOOD PROJECT FREQUENCY

Expected
Frequency Annual
(Years) Number of
Floods

GREEN Blocks (Data Input). For the recent flooding, the GREEN
Blocks should include the approximate expected frequency of flooding at
the location of the project under evaluation. One of the numbers should
correspond to the approximate frequency of the flood which caused the
disaster. While all six ofthese numbers can be changed by the user, the
flood frequency data MUST be entered in increasing order, from the
smallest to the largest flood frequency (i.e., years). Thus, at the specific
site where the mitigation project is proposed, if the recent flooding was
estimated to occur every 25 years, no change in the GREEN Blocks
need be made since 25 years is already listed. However, if the recent
flooding was estimated to occur every 35 years, enter 35 in place of
either the 25- or the 1 OO-year flood frequency.

The Expected Annual Number of Floods does not mean that this
number of floods occurs every year, but rather "expected" indicates the
long term statistical average number of floods per year.

The estimates of the Expected Annual Number of Floods are shown in
scientific notation because these numbers may vary over an extremely
wide range, including very small numbers. For an explanation of
scientific notation, see the Technical Appendix to this chapter.

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