FLOOD05505

• County: Gunnison
• Community: Gunnison County
• Stream Name: Gunnison River, Tomachi Creek
• Basin: Gunnison
• Title: Floodplain Information Report
• Date: 12/1/1976
• Prepared For: Gunnison County
• Prepared By: ECI
• Contract/PO #: &&
• Floodplain - Doc Type: Floodplain Report/Masterplan

lJ"aina~e Basin

Flood

nood~OO-'(e"-.f

Flood Frequency

FloodPcak

A part 0; the surface oi the earth that is occupied
by a drainage system, ~hich consists of a surface
strea", or a body of impounded surface water together
withalltributarysurfacestrearnsandbodiesofim-
pouode.d surface_ water.

Floodplain

An over!lo", on hnds not nonnally covered by water aud
that are uaed or usable by ma". Floods have t",oessen-
tial characteristics; the inundation of land 1s temporary;
and the land is adjacent to and inundated by overflow
from a river or stream or an ocean. lake or otber body
of standIng water.

Flood Prof He

Normally, a flood is considered as any temporary rise
in streamflow at stage, but not the ponding of sutface
watet, that results in significant adverse effects in
the vicinity. Adverse effects may include damages
from overflow of land areas, temporary backwater effects
in sewers and local drainage channela, creation of
unsanitary conditions or other unfavorable situations
by deposition of rnaterials in stream challnels during
flood recessions, use of ground ~ater coincident ~ith
increased streamflow and other problems.

FloodSta!';e

Left Bank

Log-Pearson Tyl'E.
III Distribution

A type or flood, including the "'ater surface ~l,,"atl'-'n
and territorial occupation ~hereof. which can be ex-
pected to occur at any time in a given nrea baaed upon
recorded historical precipitation and other valid data,
but ~ith an average atatistical one percent chnnce of
beingequallerlorexce<,-dedduringanyon.,yc_sr. The
term is used interchang<,sbly ~ith a one percent flood or
intermediate Regional flood.

Low Hazard Zunes

lleander

Peak Diacharjl;e

(See PrObability) The average recurrence intervsl
of specific discharges or water stages which causc
flooding.

PreCipitation

The maximum instantaneo\Js diacharge of a flood at a
given locatio". Ituau:lllyoccur""tornearthetiroe
of th.. flo<ld crest.

"
,0

An area iu "uJ aJjdc.mt to ., sUe""'. ~hlch are" is
subject to flooding aa the reault of the oCCurrence
of a IOo-year flood and ",hich area thus is so adverse
to past, current, or foreseeable construction or land
use aa to constitute a aignificant hazard to public
h~alth and safety or to property.

A graph showing the relationship of ~ater surface
elevation to location, the latter generally expresaed
as distance above ",outh for n stream of water flowing
in an open channel. 1t is generally drawn to ahow
Rurface elevation for the crest of a specific flood,
but may be prepdred for conditiona at a given time or

stage.
The stage or elevation at ~hich overflo", of the natural
banks of a stream or body of water begins in the r"ach
or area in ~hich thc elevation is measured.

The hank on the left side of a river, stream or ",ater
course as the observer looks down~tream.

A statistical distribution u~ed in flood frequen~y
analysis, which is des~ribed by three pnra",eters;
mean, standard deviation, and cocffici~nt of ske~~esa
of the logarithms of the sample observations.

That area of the floodplain in which the watera of
a 100-year flow will nOt attain a maximum depth greater
~han one and ono-half feet.

The winding of a stream ohannel.

The larg~gt value of a~reamflow attainod by a flood.

u~ually reJ-'"n.." rtO ut01t~ of "ubi" f~~l p"r ~~"'-',,...

Is the dischrage of ",ster, in liquid or solid state, out
of the atmosphere. generally upon a land or water sur-
fac... Precipitation indudes rainfaU, anCIW, hnl1, and
Rl~~t. and is therefore a mor~ g~neral term than rainfall.

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