Now You See It, Now You Don't: Characterizing Ephemeral Snowpacks in the Great Basin

It is expected that some seasonal snowpacks (persisting all winter) will transition to ephemeral snowpacks (persisting <60 days) due to increased ablation and shifts from snow to rain as a consequence of regional warming. This transition to ephemeral snowpacks will be particularly important in the Great Basin because it receives minimal precipitation and has few high elevation mountain ranges. Consequently, increased snow ephemerality potentially threatens water resources derived from mountain snowmelt. However, the current range and extent of ephemeral snowpacks in the Great Basin remains relatively unknown and under measured. We analyzed snow cover information obtained from MODIS imagery using an object-based approach to investigate three questions: 1) How does the range and extent of ephemeral snowpacks in the Great Basin increase in warm and dry years?, 2) What topographic areas are at risk for increasing ephemerality due to changes in the climate regime? and 3) What vegetation types are common in ephemeral snow zones? We found that the extent of snow-covered area declined between a colder, wetter year (2011) and a warmer, drier year (2015) by an area roughly the size of the state of Georgia. Moreover, the proportion of ephemeral snowpack increased by 19% from the wet year to the dry year. While the ecohydrologic consequences of these results remain relatively unknown, this research could potentially aid resource managers in selecting conservation locations and strategies (i.e. fire fuel reductions, grazing allotments, and species conservation) to adapt to variable and changing snowpack dynamics.