FLOOD03593

• County: Garfield
• Community: Glenwood Springs
• Basin: Statewide
• Title: Debris-flow Hazard Analysis and Mitigation An Example from Glenwood Springs
• Date: 1/1/1977
• Prepared For: State of Colorado
• Prepared By: USGS
• Floodplain - Doc Type: Educational/Technical/Reference Information

case the probability of debris flows is the smne .or greate'::. thal~ the probability

of the rainstorm event. Debris flow probability may be greater because

a rainstorm of lesser intensity (and greater probability) may also be capable

of triggering future events of approx~nately the same magnitude.

A first objective, therefore, in determining the debris flow probability,

or fixing a lower limit to the probabilit:" is to estimate the return period

of the rainstorm.

B. The July 24, 1977, Rainstorm

The rainfall measured at the National Oceanic and Atmospheric Admini st r at ion

(NOAA) weather station in GIE!Uwood Springs during thE! several days preceding

and including the debris flows is given in Table 4.

Date

Ju1y18
July 19
July 20
July 21
July 22
July 23
July 24

'fable 4

Rain in
Inches (mm)
o .02 -co-:sT)
0.00 (0.00)
0.00 (0.00)
0.24 (6.10)
0.15 0.80)
0.00 (0.00)
1.08 (27.4)

Sufficient rainfall occurred during the three days preceding the flows

to wet although probably not saturate, the soil.

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