Landscape Controls on Snow Accumulation in an Alpine Catchment (original) (raw)
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Snow accumulation and distribution in an alpine watershed
1991
Distribution of snow water equivalence (SWE) was measured in the Emerald Lake watershed located in Sequoia National Park, California, by taking hundreds of depth measurements and density profiles at six locations during the 1986, 1987 and 1988 water years. A stratified sampling scheme was evaluated by identifying and mapping zones of similar snow properties on the basis of topographic parameters that account fur variations in both accumulation and ablation.
Annals of Glaciology, 1989
Distribution of snow-water equivalence (SWE) in the Emerald Lake watershed located in Sequoia National Park, California, U.S.A, was examined during the 1987 water year. Elevations at this site range from 2780 to 3416 m a.s.l., and the total watershed area is about 122 ha. A stratified sampling scheme was evaluated by identifying and mapping zones of similar snow properties, based on topographic parameters that account for variations in both accumulation and ablation of snow. Elevation, slope, and radiation values calculated from a digital elevation model were used to identify these zones. Field measurements of SWE were combined with characteristics of the sample locations and clustered to identify similar classes of SWE. The entire basin was then partitioned into zones for each set of survey data. The topographic parameters of the basin used in classification, namely slope and elevation, are constant in time and did not change between survey dates. The radiation data showed temporal...
Improving methods for measurement and estimation of snow storage in alpine watersheds
1990
Accurate assessment of snow storage is critical in alpine water balance and glacial mass balance studies. The distribution and quantity of water stored as snow in alpine watersheds is difficult to measure or estimate, because the rugged topography produces a complex pattern of snow accumulation and ablation. New methods for measurement of the spatial distribution of snow water equivalence in alpine basins are needed that are sufficiently accurate and economically feasible. One possible method is to classify a basin into zones of similar snow water equivalence based on topographic and physical characteristics that control the distribution. The necessary sample size to be within a specified error range is evaluated for spatially independent and autocorrelated data. Snow properties, including snow water equivalence, are spatially correlated even in rough topography. Spatial considerations must be considered when designing sampling schemes and in data analysis of snow properties.
Water Resources Research, 2014
This study investigates causes behind correlations between snow and terrain properties in a 27 km 2 mountain watershed. Whereas terrain correlations reveal where snow resides, the physical processes responsible for correlations can be ambiguous. We conducted biweekly snow surveys at small transect scales to provide insight into late-season correlations at the basin scale. The evolving parameters of transect variograms reveal the interplay between differential accumulation and differential ablation that is responsible for correlations between snow and terrain properties including elevation, aspect, and canopy density. Elevation-induced differential accumulation imposes a persistent source of varariabity at the basin scale, but is not sufficient to explain the elevational distribution of snow water equivalent (SWE) on the ground. Differential ablation, with earlier and more frequent ablation at lower elevations, steepens the SWEelevation gradient through the season. Correlations with aspect are primarily controlled by differences in solar loading. Aspect related redistribution of precipitation by wind, however, is important early in the season. Forested sites hold more snow than nonforested sites at the basin scale due to differences in ablation processes, while open areas within forested sites hold more snow than covered areas due to interception. However, as the season progresses energetic differences between open and covered areas within forested sites cause differences induced by interception to diminish. Results of this study can help determine which accumulation and ablation processes must be represented explicitly and which can be parameterized in models of snow dynamics.
SPATIAL AND TEMPORAL VARIATION OF NET SNOW ACCUMULATION IN
ABSTRACT Distribution of snow-water equivalence (SWE) in the Emerald Lake watershed located in Sequoia N ational Park, California, US A, was examined during the 1987 water y ear. Elevations at this site range from 2780 to 3 416 m asl, and the total watershed area is about 122 ha. A stratified sampling scheme was evaluated by identifying and mapping zones of similar snow properties, based on topographic parameters that account for variations in both accumulation and ablation of snow.
Earth System Science Data Discussions, 2013
The timing, magnitude, and spatial distribution of snow cover and the resulting surface water inputs (SWI) are simulated at a small catchment located in the rain-snow transition zone of southwest Idaho, USA. A physically based snow model is run on this 1.5 ha study catchment, which has an elevation range of 1600-1645 masl. The catchment is divided into relatively steep (mean slope angle of 21 degrees) northeast and southwest facing hill slopes by an ephemeral stream that drains to the southeast. SWI are fundamental controls on soil moisture, streamflow generation, groundwater recharge, and nutrient cycling. Although the timing of melt events is similar across the basin, southwest facing slopes receive smaller magnitude and more frequent SWI from mid winter snow melt, while the northeast facing slope receives greater SWI during the spring. Three spatial patterns are observed in the modeled SWI time series: (1) equal between slopes, (2) majority of SWI on southwest facing slopes, and (3) majority of SWI on northeast facing slopes. Although any of these three spatial patterns can occur during the snow season, four emergent SWI patterns emerge through the melt season: (1) near uniform, (2) controlled by topographic differences in energy fluxes, (3) transitional, and (4) controlled by snow distribution. Rain on snow (ROS) events produce similar SWI between the northeast and southwest facing slopes, with the difference being attributed primarily to snow distribution. Turbulent fluxes dominate the snowpack energetics in four of the five rain on snow events, and advective fluxes from precipitation are greater than 17% during the 2 rain on snow events in December and January. Net radiation fluxes dominate spring melt events. Variations in the method used to distribute precipitation may result in large differences in total precipitation to the basin.
Water Resources Research, 2005
1] We model the spatial distribution of snow depth across a wind-dominated alpine basin using a geostatistical approach with a complex variable mean. Snow depth surveys were conducted at maximum accumulation from 1997 through 2003 in the 2.3 km 2 Green Lakes Valley watershed in Colorado. We model snow depth as a random function that can be decomposed into a deterministic trend and a stochastic residual. Three snow depth trends were considered, differing in how they model the effect of terrain parameters on snow depth. The terrain parameters considered were elevation, slope, potential radiation, an index of wind sheltering, and an index of wind drifting. When nonlinear interactions between the terrain parameters were included and a multiyear data set was analyzed, all five terrain parameters were found to be statistically significant in predicting snow depth, yet only potential radiation and the index of wind sheltering were found to be statistically significant for all individual years. Of the five terrain parameters considered, the index of wind sheltering was found to have the greatest effect on predicted snow depth. The methodology presented in this paper allows for the characterization of the spatial correlation of model residuals for a variable mean model, incorporates the spatial correlation into the optimization of the deterministic trend, and produces smooth estimate maps that may extrapolate above and below measured values. Citation: Erickson, T. A., M. W. Williams, and A. Winstral (2005), Persistence of topographic controls on the spatial distribution of snow in rugged mountain terrain, Colorado, United States, Water Resour. Res., 41, W04014,