FLOOD06982

• County: Weld
• Stream Name: Cache La Poudre River
• Basin: South Platte
• Title: Flood Plain Information Report Cache La Poudre River
• Date: 4/1/1996
• Prepared For: Orr Land Company
• Prepared By: Messner Engineering Associates
• Floodplain - Doc Type: Floodplain Report/Masterplan

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GLOSSARY

Backwater effect -

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

Channel -

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

Cloudburst -

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

Conveyance capacity -
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 floodway which can pass through a specified area at depths and velocities
governed by the hydraulic dimensions of the floodway.

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

Flood -

An overflow on lands not normally covered by water and that are used or
usable by man. Floods have two essential characteristics - 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 ofland areas, temporary backwater effects in sewers and local
dl'llinage 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.

Flood crest -

The maximum stage or elevation reached by the waters of a flood at a
given location.

Flood frequency -

The average recurrence interval of specific discharges or water stages
which cause flooding.

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