FLOOD00265

• County: Weld
• Community: Evans
• Title: FIS - Evans
• Date: 10/1/1978
• Prepared For: Evans
• Prepared By: FEMA
• Floodplain - Doc Type: Current FEMA Regulatory Floodplain Information

5.0 L~SURANCE APPLICATION

In order to establish actuarial insurance rates, the Federal Insurance
Administration has developed a process to transform the data from the
engineering study into flood insurance criteria. This process includes
the determination of reaches, Flood Hazard Factors, and flood insurance
zone designations for each flooding source studied in detail affecting
the City of Evans.

5.1 Reach Determinations

Reaches are defined as lengths of watercourses having relatively the
same flood hazard, based on the average weighted difference in
water-surface elevations between the 10- and IOO-year floods. This
difference does not have a variation greater than that indicated in
the following table for more than 20 percent of the reach:

Average Difference Between
10- and 100-year Floods

variation

2 to 7 feet

1.0 foot

One reach meeting the above criterion was required for the South
Platte River, the flooding source of the City of Evans. The location
of the reach is shown on the Flood Profiles (Exhibit 1) .

5.2 Flood Hazard Factors

The Flood Hazard Factor (FHF) is the Federal Insurance Administration
device used to correlate flood information with insurance rate
tables. Correlations between property damage from floods and their
FHF are used to set actuarial insurance premium rate tables based on
FHFs from 005 to 200.

The FHF for a reach is the average weighted difference between the
10- and 100-year flood water-surface elevations expressed to the
nearest one-half foot, and shown as a three-digit code. For example,
if the difference between water-surface elevations of the 10- and
100-year floods is 0.7 foot, the FHF is 005; if the difference is
1.4 feet, the FHF is 015; if the difference is 5.0 feet, the FHF is
050. When the difference between the 10- and 100-year water-surface
elevations is greater than 10.0 feet, accuracy for the FHF is to the
nearest foot.

5.3 Flood Insurance Zones

After the determination of reaches and their respective Flood
Hazard Factors, the entire incorporated area of the City of Evans was
divided into zones, each having a specific flood potential or hazard.
Each zone was assigned one of the following flood insurance zone
designations:

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