Wolf Creek, Yukon Territory, Canada
The Wolf Creek Research Basin (drainage area about 195 km2) lies in southern mountainous headwaters of the Yukon River Basin in the subarctic region of northwestern Canada (Figure 1). The sub-arctic continental climate is characterized by a large seasonal variation in temperature, low relative humidity and relatively low precipitation. Mean annual temperature is in the order of -3°C with summer and winter monthly ranges of 5o-15o, and -100--20o C. respectively. Summer and winter extremes of 25o and -40o C are not uncommon. Mean annual precipitation is 300 to 400 mm per year with approximately 40 percent falling as snow. With a general northeasterly aspect, elevations range from 800 to 2250 m with the median elevation at 1325 m.
Wolf Creek is situated within the Boreal Cordillera ecozone (Environment Canada, 1995) and consists of three principle ecosystems, boreal forest, sub-alpine taiga (shrub-tundra) and alpine tundra with proportions of 22, 58 and 20% respectively of the total basin area. Permafrost is present in locations on north facing slopes and there is sporadic permafrost throughout the basin, with prevalence increasing with elevation. Study plots are located within each of the ecosystems at elevations of 750, 1250 and 1615 m respectively. The forest site is relatively level with gently undulating terrain consisting of an alternating hummock and hollow landscape. The canopy is dense, consisting primarily of white spruce to heights of approximately 20 m, with some poplar trees to approximately 15 m. The subalpine taiga site is located on an east facing moderate hillslope of approximately 15 degrees. The hillslope itself consists of undulating terrain with numerous hummocks and depressions. The site is vegetated with shrub alder and willow to heights of approximately 2 m. The alpine tundra site occupies a windswept ridge top plateau. Approximately 50% of the site is relatively level, with the balance sloping at approximately 15 degrees to the south. Vegetation is sparse consisting of mosses, some grasses and lichens with occasional patches of scrub willow no more than 0.2 m high.
Various research projects (University of Saskatchewan, Environment Canada) provide and maintain micrometeorological and hydrological instrumentation.
Drainage area to outlet: ~195 km^2
Basin outlet latitude-longitude: 60.32'N, 135.07'W
Stream gauge/water level recorder period of record:Four stream gages capture the relative contribution of flow from each ecozone and the basin outlet. These gages have been in operation from 1993-present. Streams are gauged throughout the year using drillholes in the ice. Special twice-daily rating curves are developed for specific stream gauging sites in spring where snow dams and channel ice change the depth discharge relationship very rapidly.
Precipitation gauges: Nipher shielded snowfall gauges are located at each tower site along with tipping bucket and standard AES raingauges and are monitored year round. Snow particle detectors provide high resolution snowfall rates for each of these sites. At the spruce site precipitation is measured above and beneath the forest canopy.
Water level gages: Groundwater piezometers are located in clusters of three around stations 100, 103, and 105. Measurements are recorded hourly.
Micrometeorological data: Radiation (incoming and reflected shortwave and net), sub-canopy net radiation, air temperature (multiple heights), relative humidity (multiple heights), pressure, wind speed, wind direction, snow particle flux, soil temperatures (multiple depths), volumetric soil moisture content (multiple depths), snowpack temperature, snow depth are observed as 30 min. averages year-round from 1993 to present at all tower sites.
Turbulent flux measurements: Short term measurements have been made using Campbell CSAT3 and KH20 or C7500 eddy correlation systems during intensive observation periods of several months each that include summer, late winter, spring. Data have been collected sporadically starting from 1994 to present.
Soil moisture: Soil moisture data are collected at the tower stations and a few times on grids of 360 points near stations.