FLOOD05157

• County: Statewide
• Community: State of Colorado
• Stream Name: All
• Basin: Statewide
• Title: Manual For Estimating Flood Characterstics of Natural Flow Streams in Colorado
• Date: 1/1/1976
• Prepared For: State of Colorado
• Prepared By: CWCB
• Floodplain - Doc Type: Educational/Technical/Reference Information

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GLOSSARY

bankfull stage.--The stage or depth at which a stream overflows its natural
banks.
ephemeral stream.--A stream or reach of stream that flows briefly only in
direct response to precipitation in the immediate locality ,and whose
channel is at all times above the water table.
equivalent yeGI'S of record.--The number of years of observed record required
to provide an estimate of equal accuracy of that provided by a re9ression
equation.
flood depth.--A term used herein to represent a vertical distance above a line
connecting points of zero flow along a reach of channel.
flood-frequency relation.--A graph showing the number of times per year on the
average that a flood of a given magnitude is exceeded.
flood plain.--The part of a stream valley, adjacent to the stream channel,
that is built of sediments during the present regimen of the stream and
which is covered with water when the stream overflows its banks at flood
stages.
foothill streams.--A term used herein to denote streams which flow from a high
mountain area to a much flatter plain or plateau area. The stream is
subjected to floods resulting from rainfall, snowmelt, or a combination
of both. As defined herein, foothill streams occur in mixed-population
flood areas throughout Colorado except the southwestern part south of
the Gunnison River.
gage height.--The elevation of a water surface above or below a datum corre-
sponding to the zero of the gage.
gaging station.--A particular site on a stream or other body of water where
systematic observations of gage height, discharge, or '",ater qual ity
parameters (or any combination of these) are obtained.
log-PeGI'son Type III distribution,--A statistical distribution used in flood-
frequency analysis, which is described by three parameters; mean, stand-
ard deviation, and coefficient of skewness of the logarithms of the
sample observations.
mixed-population flood GI'ea.--The transition zone between a high mountain area
and a much flatter plain or plateau area where floods are caused by rain-
fall, snowmelt, or a combination of both.
multiple-regression analysis.--A statistical technique by which a relation
between a dependent variable and two or more independent variables can be
derived. The result is usually expressed as a regression equation.
natuPal-flow stream.--A term used in this report to denote a stream on which
diversions and regulation have insignificant effect on annual peak dis-
charges.
orographic effect.--The lifting of moisture-laden air over a high barrier such
as a mountain range with consequent release of precipitation.
outliers.--Those observations in a statistical sample which plot extremely
high or low on the relation defined by all other observations.
peak discharge.--The largest value of streamflow attained by a flood, reported
in cubic feet per second.

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