WMOD00297 ‎(2)‎

• Project Name: Project Skywater
• Title: Project Skywater - Fiscal Years 1975-78 Report
• Prepared By: US Department of Interior Bureau of Reclaimation
• Date: 3/1/1979
• Weather Modification - Doc Type: Report

Not all these impacts are necessarily deleterious; an increase in the
area of snowbank edge habitats in alpine areas may, for example,
increase the niches available for rare plant species.

Finally, even in the small areas where the study concluded the
greatest impacts would occur, the changes involved are unlikely to
approach the magnitude of other manmade impacts on mountain eco-
systems. Even so, project scientists noted that any change works in
phase with other ~mpacts and natural occurrences. Consequently,
scientists must be alert to greater than expected total changes.

CONTRACTOR: University of Colorado, Institute of Arctic and Alpine
Research, Boulder, Colorado
CONTRACT NO. 14-06-0-7155
PRINCIPAL INVESTIGATOR: J. D. Ives
PERIOD: July 1, 1974, to June 30, 1976
FUNDING: FY75 - $35,057
FY76 - $11 ,675

The objective of this contract was to develop a methodology to
accurately forecast avalanche occurrences through the study of the
complex relationship which exists among terrain, climate, snow
stratigraphy, and avalanche formation. When the study was initiated
in 1971, only a limited amount of climatological data was available
for the study area, the Red Mountai n, Molas, and Coal Bank Pass
regions of the San Juan Mountains. Avalanche processes in this
high-incidence region are well understood as the result of this
study.

Evidence suggests that avalanche release within subfreezing snow
layers is primarily dependent on precipitation to trigger unstable
layers deep within the snow cover. While frequency and magnitude
are influenced by precipitation rates and amounts, they are deter-
mined primarily by the snow structure within the release zone at the
time precipitation loading occurs. Magnitude is affected by the
mechanical strength of snow layers in midtrack, for this determines
the penetration depth of sliding snow and the volume of the avalanche.
The study was able to produce the first approach to an operational,
real-time statistical forecast model for major avalanche chutes
during the dry and wet seasons with an accuracy of 88 and 82 percent,
respectively. It is the first model to be applied to groups of
starting zones and individual paths to predict magnitude of avalanche
occurrence.

Particular emphasis was placed on the study of fracture lines during
the final two study seasons. Attention was directed toward the
temperature gradient. Periodic snowpit investigation at these sites

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