Spatial controls on the distribution and dynamics of a marginal snowpack in the Australian Alps

Abstract

Seasonal snowpacks in marginal snow environments are typically warm and nearly isothermal, exhibiting high inter‐ and intra‐annual variability. Measurements of snow depth and snow water equivalent were made across a small subalpine catchment in the Australian Alps over two snow seasons in order to investigate the extent and implications of snowpack spatial variability in this marginal setting. The distribution and dynamics of the snowpack were found to be influenced by upwind terrain, vegetation, solar radiation, and slope. The role of upwind vegetation was quantified using a novel parameter based on gridded vegetation height. The elevation range of the catchment was relatively modest (185 m), and elevation impacted distribution but not dynamics. Two characteristic features of marginal snowpack behaviour are presented. Firstly, the evolution of the snowpack is described in terms of a relatively unstable accumulation state and a highly stable ablation state, as revealed by temporal variations in the mean and standard deviation of snow water equivalent. Secondly, the validity of partitioning the snow season into distinct accumulation and ablation phases is shown to be compromised in such a setting. Snow at the most marginal locations may undergo complete melt several times during a season and, even where snow cover is more persistent, ablation processes begin to have an effect on the distribution of the snowpack early in the season. Our results are consistent with previous research showing that individual point measurements are unable to fully represent the variability in the snowpack across a catchment, and we show that recognising and addressing this variability are particularly important for studies in marginal snow environments.

Vertical influence of temperature and precipitation on snow cover variability in the Yarlung Zangbo River basin, China

“…Climate change is expected to result in a continued decline in snow cover area (SCA), an earlier snowmelt may lead to more frequent Spring flooding at the local scale (Hamlet and Lettenmaier, 2007), and Summer irrigation water shortages may occur in regions that are dominated by a large snow cover (Vano et al ., 2010; Viviroli et al ., 2011). In order to determine the response of snow cover to climate change, improve the precision of hydrological forecasting, and effectively manage water resources in snow‐dominated catchments, it is necessary to investigate the distribution and variation of water storage in the seasonal snowpack (Brown and Robinson, 2011; Bilish et al ., 2019).…”

Streamflow variability and the role of snowmelt in a marginal snow environment

“…The proportion of precipitation falling as snow at the area-weighted mean elevation of the catchment (1,783 m a.s.l. ), hereafter referred to as p snow , was estimated from the measured dry bulb air temperature using the method described by Bilish et al (2019).…”

“…and has been surveyed weekly throughout each snow season since 1954. Many previous studies of the Australian snowpack have used the Spencers Creek record as a primary input, although Bilish et al (2019) showed that using this site alone did not adequately represent the high degree of variability in the local area. It is therefore recognized that these SWE measurements may not be directly related to the total volume of water stored in the snowpack at Pipers Creek.…”

“…These snowpacks occur in many areas of the world (e.g., López-Moreno 2005;Nolin and Daly 2006;Bormann, Evans, and McCabe 2014;Fayad et al 2017) and can be considered a hybrid of the maritime and ephemeral snow cover categories in the classification system of Sturm et al (1995). This combination of deeper, more persistent snow and shallower, ephemeral snow in close proximity leads to marginal snowpacks having distinct dynamical characteristics, with a reduced ability to scale point measurements to the catchment (Bilish et al 2019). It is likely that the quantitative impacts of a reduction in snow cover on snowpack water storage and conversion to runoff are also influenced by the marginal nature of the snowpack in these settings and may differ from those reported for other snow-affected areas.…”

Quantifying the impact of synoptic weather types and patterns on energy fluxes of a marginal snowpack

“…The Australian Alps is a marginal snowpack environment (Bilish et al, 2018(Bilish et al, , 2019, where precipitation is crucial to agriculture, the generation of hydroelectric energy, and recreation. Water generated in the Australian Alps contributes to agriculture in the Murray-Darling Basin that accounts for 62 % of Australia's water use for irrigation (Australian Bureau of Statistics, 2020).…”