January 2000 - Tech Tip Supplement
When digging a snowpit for stability evaluation it is important to
consider the location carefully. The points most people consider are
whether the snowpit area is representative of a slope they are debating
entering and whether the location is safe. Sometimes these two considerations
are at odds with each other. Especially when a Rutschblock test is desired
since it needs to be on a representative slope angle.
Another thing to consider is whether the snowpit area has been disturbed
by skiers, snowboarders, etc. Even though tracks may not be visible
it is possible that there are buried tracks through the area which had
an effect on underlying layers. I can remember one particular slope
in Utah where many people dug snowpits all winter long. It was frequently
tracked up and dug up, then buried in new snowfall events. Many profiles
there may not have been truly representative.
Finally, it is a good idea to use your sectional probe to check snow
depth around the proposed profile area. If you dig in an area of shallow
or very uneven snowcover the profile may be quite different than elsewhere.
One reason for this is that temperature gradients through the snow are
steeper in thin areas. Probing first may also reduce the chances of
digging into a pocket of shrubbery where branches will protrude from
the snowpit wall.
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