Watershed

The societal and ecological impact of snowpack

Boulder Watershed

Survey crew below Mount Kiowa. 2004 Snow Survey. Photo: Todd Ackerman.

The TundraCam looks out on the upper section of the Boulder watershed. South Arapahoe Peak, visible from the camera, forms the boundary of the City of Boulder’s watershed. Arapahoe Glacier, from which Boulder gets part of its water supply, lies just below the peak to the east. Lake Albion, one of a staircase of lakes within Green Lakes Valley, is also visible from the TundraCam. The Green Lakes Valley is the headwaters of North Boulder Creek.

Note: the public is not allowed to visit the upper section of the City of Boulder Watershed in order to protect water quality and to provide a rare relatively pristine environment for environmental research. Most other Front Range mountain areas are clearly impacted by recreational activity.

Children's Book

Cover of Children's book about the ecosystems in the Boulder Creek watershed.

My Water Comes from the Mountains explores the ecosystems along Boulder Creek as snowmelt flows through the mountains, becomes the water supply for the City of Boulder, and moves into prairie habitats as the irrigation supply for farmers, plants, and animals. The author, Tiffany Fourment, began this project while participating in the Schoolyard program at Niwot Ridge. NSF funding supported production of the book and enabled its distribution to local elementary schools. Designed for third to fifth grade students, My Water Comes From The Mountains is consistent with the science standards for those grades. Its strengths include its focus on the local environment and its integration of material on natural and human-influenced systems.

Alpine Snowpack in the West

Oblique aerial photo of upper Niwot Ridge and Green Lakes Valley. Photo: Nel Caine.

Boulder is not alone in getting water from the mountains. Most of the water supply of Colorado, along with the rest of the American West, begins as alpine snowpack. The headwaters of the three major rivers of the southwestern United States (the Arkansas, Colorado, and Rio Grande) are located in the Colorado Rockies.

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Precipitation

Shoshoni and Pawnee peaks at sunrise from the D1 climate station on Niwot Ridge on summer solstice, June 21, 1991. A strong upslope storm bathed everything but the highest peaks in clouds. Photo: Bill Bowman.

Of the approximately 930 mm (36 inches) of precipitation per year that the Saddle site receives, about 80 percent falls as snow. The snowpack is highly susceptible to the effects of global climate change if it leads to altered precipitation and/or wind patterns in the mountains. Because of the importance of snowpack to life in the American West, scientists continue to monitor long-term climate from Niwot Ridge and investigate the timing of snow, patterns of deposition, depth and chemical composition, evaporation, and melting and runoff.

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Subnivean Lab

Lysimeter array similar to that used for the Subnivian Lab. Photo: Tim Bardsley.

The Subnivean Laboratory, visible from the TundraCam, is used to study the timing and spatial variability of snowmelt. “Subnivean” means under the snow, and the lab is used to investigate what happens between the snow and the ground. An array of lysimeters at the ground surface catch meltwater from the bottom of the snowpack. The meltwater is piped underground where instruments measure and record the amount of water flowing from each basin. A weather station records data that is compared with the measured snowmelt. The lab also houses instruments and equipment for investigating snow surface energy exchanges and biogeochemical processes within and below the snow.

Snow Fence

Snow fence in action. Photo: Mark Losleben.

A 60-meter long (200-foot) and 2.6-m high (8.5-feet) snowfence, also visible from the camera, is used to modify the timing, amount, and duration of snow. The porous fence traps wind-blown snow in an area where thick accumulations rarely occur naturally. By manipulating the snow cover, scientists can assess the effects of climate change on alpine ecology and biogeochemical cycles, especially those linked to nitrogen (N) and carbon (C) dynamics.

Other Research

Snow pit layer profile and density measurements. Photo: Tim Bardsley.

Nearby in the Green Lakes Valley, researchers are monitoring lake-ice cover on Lake Albion, Silver Lake, and Green Lakes 1-5. They are also monitoring the daily flow of water from the upper Green Lakes basin and measuring the water quality of the streams. Niwot Ridge is home to a Snotel site were depth and density of the snowpack is measured monthly December through April.

 

Niwot Ridge in Spring

Clouds over Green Lakes Valley during the Spring, 2005 Snow Survey, Niwot Ridge LTER. Photo: Kurt Chowanski.