FLOOD08180

• County: Pueblo
• Community: Pueblo
• Basin: Arkansas
• Title: City and County of Pueblo Flood Hazard Mitigation Plan
• Date: 8/1/1994
• Prepared For: Pueblo
• Prepared By: Office of Emergency Management
• Floodplain - Doc Type: Flood Mitigation/Flood Warning/Watershed Restoration

Puebw Fwod Hazard Miti"ation Plan

During a Vt'lJ' large flood (about a 500
year flood) these streams can produce
velocities of approximately 25 ft/see.
Just 3ft/see combined with depths of 3
ft or more are generally considered
hazardous to life as well as to
property.
Water flowing in excess of ./ ft/sec is
capable of transporting sediment and
causing severe erosion of stream banks
and embankment fill aroulld bridge
abutments. When velocities drop below
2 ft/sec, debris and silt deposits occur,
which extt'nds flood damage and
creates adverse health conditions. The
saturation effects of flooding of long
duration can effectively weaken bridge
abutments, levees, earthen d'ams, and
other embankment works so that they
faiL

Flood Types: A river basin is fed by a
network of stream channels thaI: convey the
normal flow of water from smaller
watersheds contained within the basin
Flooding results when the flow of water
becomes greater than the carrying capacity
of the individual stream channel. Rate of
rise, peak discharge (magnitude), and
duration of flooding are all phys.ical features
and weather conditions which contribute to
the characteris,tics of the water in the river
system. The following describe sources of
riverine flood,:

Snowmelt floods- Snowmelt flooding
typically occurs May through June.
Generally this occurs when there are warm
spring temperatures creating a fast snowmelt
and/or a combination of spring runoff and
rainfall over the affected watershed. Serious
flooding can result when a heavy spring rain
accompanies a snowmelt in May and June.

Flash floods- These floods result from
intense summer thunderstorms_ This flood
event is characterized by an intense
cloudburst, a sudden rise in stream level,
short duration, and little or no warning_
Typically the flash flood season in Pueblo
stretches between May to September.

General rain floods- These floods are caused
by general rainfall events that occur over a
wide geographic area for several days,
totally saturating the shallow soils_ These
floods are characterized by a slow, steady
rise in the stream level and a peak discharge
oflong duration_ Because of the slow rate of
stream rising there is usually time available
for warning. The Midwest floods of 1993,
and more recently, the Georgia floods of
1994 are good examples of this kind of
flooding

Dam failure- Floods caused from dam
failures are rare, but when they occur they
can be devastating. Pueblo Dam, a massive
buttress-head and earthfill dam, is designed
to handle at least a 1 OO-year flood If Pueblo
Dam broke (considering the worst -case
scenario of water level at full capacity and a
complete breach), the water would inundate
nearly all of the downtown area of Pueblo
More specifically, this inundation zone
would primarily include the area from the
State Hospital in Pueblo south to the
Arkansas River, and would have =or
impacts out east near Avondale. Inundation

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