Variations in Stream-ice Formation and Related Ice-bridge
Construction Issues in the Shaw Creek Watershed Area,
Alaska
Michael R. Lilly1 and Emily K. Youcha2
Shaw Creek Watershed is located in central Alaska on the north side of the
Tanana River. Streams in the watershed have been monitored for the past three years,
along with selected streams south of the Tanana River in the same vicinity. Ground
water recharges streams in both areas, but ground-water is warmer for streams on the
south side of the Tanana River. These ground-water-fed streams rarely freeze up and
when they do, ice cover is normally thin. Comparative streams in the Shaw Creek
Watershed are located in a permafrost-rich environment and form thicker formations of
stream ice. In many of the lower sections of the watershed, pressure ridges form along
the stream channel and overflow ice builds up to elevations greater than stream levels at
freezeup.
These variations are important to understand when considering the design and permitting
of ice bridges for winter stream crossings. The Shaw Creek Watershed streams would
require less man-made ice construction for bridges during mid to late winter. Similar icebridge construction applications on the south side of the Tanana River would require
more effort to construct and maintain ice bridges. Understanding these difference can
better focus information requirements for design and permitting of ice bridges for these
settings.
1
GW Scientific, PO Box 81538 Fairbanks, Alaska 99708
Phone: 907-479-8891; Fax: 907-479-8893; mlilly@gwscientific.com
2
GW Scientific, PO Box 81538 Fairbanks, Alaska 99708
Phone: 907-479-8891; Fax: 907-479-8893; eyoucha@gwscientific.com