FLOOD07843

• County: Statewide
• Basin: Statewide
• Title: Nationwide Summary of US Geological Survey Regional Regression Equations for Estimating Magnitude and Frequency of Floods or Ungaged Ssites 1993
• Date: 1/1/1993
• Prepared By: USGS
• Floodplain - Doc Type: Educational/Technical/Reference Information

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merely a qualitative evaluation. In general, one would
expect the extrapolated 500-year flood-peak discharge
to be less than the envelope-<:urve values, assuming
that several watersheds in a given region have experi-
enced at least one flood exceeding the 500-year value
during the period of data collection. For the
Fenbo\1oway River near Foley, Florida, estimates of
the SOO-year flood range from 11,500 to 12,800 cubic

20,000

feet per second. The envelope-curve value from
Crippen and Due (1977) and Crippen (1982) is 101,000
cubic feet per second given that the watershed is in
region 3 as defined by Crippen and Due (1977) and
Crippen (1982). Figure 3, from Crippen and Due
(1977), is provided in this report so the analyst can
determine the appropriate flood region for a site of
interest.

A. Regional values of the 2- to
SOD-year flood discharges

. Extrapolated value of the
500-year flood discharge

10,000

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2000

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500

S 10 25 50
RECURRENCE INTERVAL, IN YEARS

100

FIgure 2. Reglonalllood-frequency curve for the Fenholoway River near Foley, Florida.

ESTIIIATION OF EXTREME FLOODS 15