East River Watershed (CO, USA) 2017 -
Location and Scale
The East River Watershed encompasses a region of ~300 km2. Located near Crested Butte CO in the Upper Gunnison Basin of CO, it is a representative headwater catchment of the Upper Colorado River Basin. The East River is one of two major tributaries that form the Gunnison River, which in turn accounts for just under half of the Colorado River’s discharge at the Colorado/Utah border. The watershed encompasses the drainages of the East River, Washington Gulch (WG), Slate River, and Coal Creek. When combined with the adjoining Taylor River and Ohio Creek watersheds, the three (East-Ohio-Taylor) encompass an area of ca. 2500 km2.
This region collectively constitutes an important component of the Upper Gunnison Basin (UGB), forming the Gunnison River mainstem, which accounts for just under half of the Colorado River’s discharge upon reaching the Colorado/Utah border. This is an important region for the U.S., as the Colorado River and its headwater tributaries supply water for 1 in 10 Americans and irrigate more than 5.5 million acres. The UCRB supports more than 4,200 megawatts of electrical-generating capacity and thermoelectric-cooling water, providing power to hundreds of local areas and millions of people.The East River and its associated drainages constitute a ‘natural laboratory’ in which to study how snow accumulation and snowmelt timing influence concentration-discharge relationships.
Climate change, extreme weather, land-use change, and other perturbations are significantly reshaping interactions among the vegetation, soil, fluvial, and subsurface compartments of watersheds throughout the world. Water-sheds are recognized as Earth’s key functional unit for managing water resources, but their hydrological interactions also mediate biogeochemical processes that support all terrestrial life. These complex interactions, which occur within a heterogeneous landscape, can lead to a cascade of effects on downstream water availability, nutrient and metal loading, and carbon cycling. Despite significant implications for energy production, agriculture, water quality, and other societal benefits important to U.S. Department of Energy (DOE) energy and environmental missions, uncertainty associated with predicting watershed function and dynamics remains high.
To reduce this uncertainty, the Watershed Function SFA project (watershed.lbl.gov), is focused on developing a predictive understanding of how mountainous watersheds retain and release water, carbon, nutrients and metals, started in FY2017. The project is particularly focused on predicting how droughts, early snowmelt and other perturbations impact downstream water availability as well as carbon, nutrient and metal exports at seasonal to decadal timescales. The project is using the East River Watershed as a representative mountainous testbed to develop new conceptualizations and approaches.
The region has a continental, subarctic climate with long, cold winters and short, cool summers, with a mean annual temperature of 0C and average minimum and maximum temperatures of -9.2C and 9.8C, respectively; winter and growing seasons are strongly segregated and greatly influence hydrology and biogeochemistry. The watershed receives ca. 600 mm of precipitation per year, the bulk of which falls as snow, and is representative of many other headwaters systems within the upper Colorado River Basin.
Click http://barstow.lbl.gov/EastRiver/Camera/ for field camera images of the site (updated daily).
Geology within the Upper Gunnison Basin includes a diverse mix of Paleozoic, Mesozoic, and Cenozoic sedimentary rocks that have been intruded by Tertiary igneous laccoliths and ore-rich stocks (Gaskill et al., 1991), as well as extensive pyroclastic flows and Precambrian granite and gneiss (Gaskill et al., 1991).
The headwaters East River catchment has an average elevation of 3,266 m, with 1,420 m of topographic relief and pronounced gradients in hydrology, geomorphology, geology, vegetation, and climate.
Vegetation / Land Use
The Upper Gunnison and East River Watershed are composed of montane, sub-alpine, and alpine life zones that collectively include aspen, meadow, mixed conifer, sagebrush, grasses, sedges, and forbs. Land use in the East River Watershed has included tourism, skiing, cattle ranching, mining activities as well as ranchette and urban development.
The Watershed is also home to the Rocky Mountain Biological Laboratory (RMBL; www.rmbl.org), which has a 90-year history of ecohydrological measurements including detailed precipitation and snow-melt records beginning in 1977 and one of the world’s longest, continuously running soil-warming experiments (Harte and Shaw, 1995; Harte et al., 2015).
Hubbard, S. S., K. H. Williams, D. Agarwal, J. Banfield, H. Beller, N. Bouskill, E. Brodie, R. Carroll, B. Dafflon, D. Dwivedi, N. Falco, B. Faybishenko, R. Maxwell, P. Nico, C. Steefel, H. Steltzer, T. Tokunaga, P. A. Tran, H. Wainwright, and C. Varadharajan. 2018. The East River, Colorado, Watershed: A Mountainous Community Testbed for Improving Predictive Understanding of Multiscale Hydrological–Biogeochemical Dynamics. Vadose Zone J. 17:180061. doi:10.2136/vzj2018.03.0061
Watershed SFA papers: http://watershed.lbl.gov/news-events/publications/
Watershed SFA website: watershed.lbl.gov
Watershed SFA data portal: https://wfsfa-data.lbl.gov/watershed/