FLOOD05097

• County: Hinsdale
• Community: Lake City
• Stream Name: Henson Creek
• Basin: Gunnison
• Title: Lake City Community File
• Date: 1/1/2001
• Prepared For: CWCB
• Prepared By: CWCB
• Floodplain - Doc Type: Community File

CHAPTER IV
HYDROLOGIC ANALYSIS

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
melting 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 melt may occassionally 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
local ized and cnly occassicnally produce high flows in the stream. A
review of available runoff records indicate only one summertime peak
flow (outside the normal runoff period).

Methods of Analysis
A hydrologic analysis was carried out to establish peak discharge
frequency relationships for floods of 10-, 50- 100-, and 500-year
recurrence 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 (1918 -
1937) and for 14 years on Lake Fork of the Gunnison (1918- 1937). The
gauging station on the Lake Fork is located % mile upstream of Lake
City. The gauging station on Henson Creek is located 1~ miles above
its mouth.
Three separate steps were used to calculate flood flows; all three
approaches were based on initially calculating peak flows from stream
fl ow record s.
1. Peak flows from records on the 2 study streams.
2. Regional curve for the adjacent area streams.
3. Regression equation for the entire Colorado mountain area.