FLOOD04156

• County: Statewide
• Basin: Statewide
• Title: Flood Hazard Mitigation Plan for Colorado 409
• Date: 2/1/1998
• Prepared For: State of Colorado
• Prepared By: CWCB
• Floodplain - Doc Type: Flood Mitigation/Flood Warning/Watershed Restoration

199B - Colorado Flood Hazard Mitigation Plan (4091

were estimated by the Colorado water Conservation
Board and the U.S. Geoiogical Suvey (USGS). The
CWCB obtained detailed surveyed cross-sections on
the North Fork of the South Platte River, Sand Draw,
and Buffalo Creek. The estimated flow rates on July 12
range from 4 to 25 times the published FEMA 100-
year flow values. Obviousiy, the Buffalo Creek flash
flood produced enormous flow magnitudes and was
extremely dangerous.

2.4 Risk Information

To reduce the community's vulnerability to hazards,
some knowledge of the risklthreat must exist. Thus,
hazards assessment has two important components

1. Hazard Identification - What are the hazards
that pose a threat to the community or a
particular segment of the population? What
is their expected magnitude? How fre-
quently could they be expected to occur?
Where are they likely to occur?

2. Vulnerability Analysis - What is the risk
from the threat? What are the likely Im-
pacts? What are the economic, sociai, and
political ramifications of these impacts?

In most communities, substantial work has al-
ready been completed on a hazard assessment,
and maps portraying these risks are readily avail-
able. This is an integral step in the emergency
pianning process. Hazard assessment is the foun-
dation upon which the local Emergency Opera-
tions Plan (EOP) is bui~. It is also the foundation
for hazard mitigation planning, as well.

A hazard assessment provides the information
that identifies the need to mitigate, as well as the
ability to accurately focus mitigation efforts on a
particular problem area. However, simply identify-
ing vulnerability from an identified risk does not
guarantee that any action wlil be undertaken to
mitigate that situation. Thus, a critical component
necessary to mitigate the impacts of hazards is a
determination of acceptable risk. When vulnera-
bility to a hazard risk is determined to be at an
acceptable level, mitigation activities are not pur-
sued. However, when communities determine that
the vulnerability to a given risk is too great to
chance (a determination of unacceptable risk),
mitigation is pursued. (See Figure 2 - 10).

This concept of acceptable risk is central to the
community's determination as to whether mitiga-
tion is undertaken or not. This determination is
typically answered based on community values
being combined with technical information. Hazard
assessments allow communities to focus on haz-
ard mitigation planning needs. However, imple-

I'ile:FHMP-ctIapte'-2.pub

mentation of mitigation measures will only occur fol-
lowing the public's acceptance of both the problem
and the solution. This requires a determination that
there is unacceptable risk.

To sum up, the hazard mitigation planning process
begins with the five preliminary steps relating to haz-
ard assessment. First, the hazards affecting the juris-
diction must be identified. Second, the community's
vulnerability to those hazards must be determined.
Third, a determination of whether that vulnerability
constitutes an unacceptable risk must be made.
Fourth, if an unacceptable risk exists, it must be
communicated to those who are in the position to
effect its change. Fifth, the people receiving this risk
information must agree that the risk is unacceptable,
that there are viable solutions to the problem, and that

Figure 2-10

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Chapter 2 - 12

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