FLOOD01592

• Designation Number: 248
• County: Hinsdale
• Community: Lake City
• Stream Name: Lake Fork of the Gunnison River and Henson Creek
• Title: Floodplain Information Report - Lake Fork of the Gunnison River and Henson Creek, Lake City, Colorado
• Date: 10/1/1985
• Designation Date: 1/1/1986
• Floodplain - Doc Type: Floodplain Report/Masterplan

CrlAPTERI'1
rlYDROLOGIC ANALYSIS

Figure 2-

June 1921 Flood
Henson Creek as

_ Gunnison A~enue bridge
it was washing out

o~er

Flood Characteristics
Most of the annual flood flows on Henson Creek and the Lake Fork of the
Gunnison within the study area result from rapid springtime w~lting of the
snow pack in the high mountain basins, which comprise the majority of the
drainage area for both streams. According to available stream flow records,
peak flows occur primarily from May through early July. Snow ~~lt may
occasionally be augmented by rain. Stream flows from snowmelt runoff are
characterized by sustained periods of high flow and marked daily fluctuation.

Periods of thunderstorm activity normally occur during the summer months
after the high runoff has receeded. Cloudbursts are normally localized and
only occasionally produce high flows in the stream. A re~iew of available
runoff records indicate only one summertime peak flow (outside the normal
runoff period).

....
'0"

Methods of Analysis
A hydrologic analysis was carried out to establish peak discharge frequency
relationships for floods of 10-, 50-, 100-, and 500-yearrecurrence intervals
for the Lake Fork of the Gunnison and Henson Creek in the study area.

Streamflow records are available for 9 years on Henson Creek
and for 14 years on the Lake Fork of the Gunnison (1918 - 1937),
station on the Lake Fork is located ~ mile upstream of the Renson
The gauging station en Henson Creek is located 1~ miles abo~e its

(1918- 1937)
The gauging
Creek confluence.
rrouth.

13

Peak flows caiculated from the on. stream records were compared to fifteen
other gauglng and study sites In nearby similar basins. Thesefifteensites
were cnosen for tne comparison beCdu~e of Ule high corr.:,ation betwe.m
basin characteristics such as slope, precipitation, elevation. size and
vegetation. Table 1 lists basin characteristics of these streams. Peakflows
from six of these stations are from the U.S.G.S. Open File Report 84-137
(reference 2 ) and were determinedlJsing Log-Pearson Type III analysis as
outlinedbytheWaterResOlJrcesCouncit. Peak flows for these six stations
are listed in Table 2. Peak flows from the remaining n:ne s:tes are from
recent flood insurance or flood plain reports and may include heavier welg~ting
on precipitation analysis than the U.S.G.S. flows. Table 3 shows the peak
Jbchdrge$ from thes" streams.

Ftgure

3 _ June 1921 Flood . Oen~er & Rio Grande Railroad
yards with new channel from flood waters

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