WWRC 89-05
Long-Term Trends in Glacier and Snowmelt Runoff Wind River Range, Wyoming
Introduction
The Wind River Range is an unbroken 100-mile long barrier in
west central Wyoming that is host to 63 glaciers covering 17
square miles in area. Seven of the ten largest glaciers in the
American Rocky Mountains are found in the Wind River Range, with
areas from 393 to 1130 acres (Bonney, 1987) while the total area
of glaciers in the Wind River Range is larger than that of all
other glaciers, 134 covering 12 square miles, in the American
Rockies (Field, 1975; Davis, 1988).
Glaciers contribute an undocumented amount to streamflow in
Wyoming. Glaciers can be considered as natural reservoirs which
store water in the winter and release it in the summer. Glacier
runoff is likely to be most important during the late summer and
early fall when low flows are critical for consumptive water
users and instream flow needs. In addition, glaciers may release
especially large quantities of water in years of low precipitation
when water from other sources such as winter snowpack may be
in short supply.
According to most authors (e.g., Meier, 1951; Dyson, 1952;
and Mears, 1972), glaciers in the Wind River Range have generally
been in a negative regime since 1850. While the most pronounced
retreat occurred in the late 1930s, the glaciers continued to
retreat, some at an alarming rate. Dyson (1952) reported that
glaciers in the Wind River Range were retreating at a rate of 7
to 41 percent per year. Systematic studies of glacier mass
balance have not been conducted on Wind River glaciers since the
one- or two-year studies in the 1950s. Trends in glacier regime
over the last four decades need to be documented and modeled
relative to external and internal controls to better understand
the implications of long-term trends for water supply in the
Green and Missouri River drainages and obligations under interstate
compacts.
Objectives
The objectives of this study were to:
- analyze temporal trends in snowdepth and/or water
equivalent for all climatic stations in the Wind River
Range,
- analyze temporal trends in runoff from existing
streamflow gaging stations affected by glacier runoff
and snowmelt from the Wind River Range,
- use aerial photos and ground photos to document the
trends in glacier regime as far back as photos are
available, and
- perform field reconnaissance for direct measurements of
runoff from the Wind River Range glaciers.
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