FLOOD00934

• Designation Number: 69
• County: Gunnison
• Community: Gunnison
• Stream Name: Gunnison River,Tomichi Creek
• Title: Floodplain Information Report - Gunnison River/Tomichi Creek, Gunnison, CO
• Date: 12/1/1976
• Designation Date: 7/1/1977
• Floodplain - Doc Type: Floodplain Report/Masterplan

Tabl.. 6 Usu tlL.. "';i~", s"rf"~,, "hvati"ns CUi. ll1" ltl-, 50-,
100- and 500-yea,. flO{ld events at crO$S ~ectton points.

Floodc<lArea

In CoLorado, th" 100-yea, frequency flood has been sel~cted to
delineate and regulate floodplains. Therefore, the flood area maps show
only the boundary of the IOo-year floodplain. The mapping ha~ a 2 feet
contOl.lr interval alld 1 inch "qlH;l to 400 feet scale. If needed, the 10-,
50- and 50o-year floods can readily be delineated on the~e maps using
the information presented in Table 6.

Asp..ct

Backwater Effect

Channel

ThelOO-year floodplain as delineated on the Flooded Area maps
meets the requirements of House Bill 1041. Upon officinl approval of
thi~ report by the Colorado Water Conservation Board, the area outlined
by the 100-year flood boundary will be designated a floodplain area and
the lo~al offi~ials may regulate it ~~~ordingly.

Cloudburst

Flood Elevations

Water surface elevations for the 10-, 50-, 100_, and 50o-ye~r
floods can b.. found in four different loeatlon5 in this rep"rt.. The5e
locations include: (1) The flood fr..quency-..levation :md discharge data
presented in Table I) for selected points along the river reache~; (2)
the limits of the 100-year flood in plan pre~ented in Plates 3 through
14; (3) tha flood profiles a-re shown In Plates 1.'.> through 22; andp1at"s
23 through 31 shows the water surface elevation for different frequen-
cies at tY1>ical croas sectiona throughout the study reach.

Correlation

Confluence

C~nv~ya~ee_Cap~~
city

The flood profiles may he u~ed in ",('119 whe,., ~onttov"r9Y
arises aver the lOO-year flood boundary on the Flooded Area PlateR.
Since the Flood Profil.,s give the el~vatlonB and distance or stationing
from a known point, the high water ~lcvntions can he conveyed to the
ground.

Desiganted Flood-
plaill

n

GLOSSARY

Is th" gelleral basin orientation f,e", a hillhe, to a
lo",er point in relation to east, west. north and ~outh
directions.

The rise in surface elevation of flowing water up-
stream fron and aa a result of an obstruction of flow.

A natural or artificial ~atercourse of perceptible
extent with definite bed and banks to confine and Con-
duct continuously or periodically flowin~ wster.

A sudden and extremely he~vy downpour of rain that i8
small in areal extent; of sbort duration; and may be
accompanied by lightning, thunder, and strong gusts of
wind.

The process of est~bll.sbing n relation between s
variable and onc or more related variables.

A po:lnt where two or more stre!\rJIs ...."to

a. CIll'",,,el conveyan~~ capacity is the rate of ,1i,-

chtlr~e, tn cu~tc fect ~cr cecond, w~ic~ e~n flch

in a water course with the Water surface not

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greater than thc hei~ht of the channel banks.
Fioodway conveyance ctlpacity is the rate of dis-
charl':<' in the. ov"rlfow portion of the flood"ay
which call pas~ throll!\h " $p"c1fied area at depths
,md velocities f\overned by the hydralic dimensions
of the floodway.

Th~ arcn dcsignat"d as a floodplain by official action
of tile board of county c01nll\is~ioner$ or city cou""U
with the prior C.OnCllrr"n,.,' of the Color<ld" W3ter Con-

se-rv:itl.on Board.

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