FLOOD09948

• County: Hinsdale
• Community: Lake City
• Stream Name: Gunnison River, Henson Creek
• Basin: Gunnison
• Title: Floodplain Information Report
• Date: 10/1/1985
• Prepared For: Lake City, Hinsdale County
• Prepared By: Westwater Engineering
• Contract/PO #: &&
• Floodplain - Doc Type: Floodplain Report/Masterplan

ASpect

aac~water Effect

Channel

Cloudburst

Correlation

Confluence

Conveyance
CapacIty

~signated
floodplaln

GLOSSAR~

Drainage Basin

Is the general basin orientation from a higher to a
lower point 1n relation to east, ~est, north and south
directions.

I
i
I

The rise in surface elevation of flowing water upstream
from and as a result of an obstruction of flow.

Flood

A natural or artificial watercourse of perceptible
extent with definite bed and banks to confine and
conduct continuously or periodically flowing water.

A sudden and extremely hea~y downpour of rain that is
small in areal extent; of short duration; and may be
accompanied by lightning, thunder, and strong gusts of
wind.

The process of establishing a relation between a variable
and one or more related variables.

A point where two or more streams meet.

a. Channel conveyance capacity is the rate of discharge,
in cubic feet per second, which can flow in a water
course with the water surface not greater than the
height of the channel banks.
b. Floodway conveyance capacity is the rate of discharge
in the overflow portion of the floocway which can
pass through a specified area at depths and velocities
governed by the hydraulic dimensions of the floocway.

Flood, IOO-Year

The area designated as a floodplain by official action ot
the board of county commissioners or city council with
the prior concurrence of the Colorado ~ater Conservation
Board.

FlOOd Frequency

Flood Peak

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A pa~t of the surtace or t~e earth that is occupied
by a drainage system, whicn consists of a surface
Stream or a body of impounded surface water together
~ith all tributary surface streams and bodies of
impounded surface water.

An overflow on lands not normally covered by water and
that are used or usable by man. Floods have two essential
characteristics; the inundation of land is temporary;
and the land is adjacent to and inundated by overflow
from a river or stream or an ocean, lake or other body
of standing water.

Normally, a flood is considered as any temporary rise in
streamflow or stage, but not the ponding of surface water,
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 channels, creation of unsanitary conditions or
other unfavorable situations by deposition of materials
in stream channels during flood recessions, use of ground
water coincident with increased streamflow and other
problems.

A type of flood, inciuding the water surfac~ elevation
and territorial occupation thereof, which can be expected
to occur at any time in a given area based upon recorded
historical precipitation and other valid data, but with
an average statistical one percent chance of being
equalled or exceeded during dny one year. The term is
used interchanqeably with a one percent flood or
Intermediate Regional Flood.

(See Probability) The average recurrence interval of
specific discharges or water stages which cause flooding.

The maximum instantaneous discharge of a flood at a
given rocation. It usually occurs at or near t~e time
of the floon crest.

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