Report links wind-blown dust with early runoff
By Summit Voice
SUMMIT COUNTY — Along with above-average temperatures and dry and sunny weather, spring dust storms in March and April likely were a significant factor in this year’s record early snow-melt season, according to the Silverton-based Colorado Center for Snow and Avalanche Studies.
Snow that’s darkened by wind-deposited dust absorbs much more heat and hastens the warming of the snowpack to an isothermal state (32 degrees from top to bottom).
In its year-end report, the center explains that the dust layers continue to absorb and add solar energy to the snowpack long after the original dust layer is deposited.
As a result, streamflows in most drainages peaked well ahead of average and yielded well below average runoff. Streamflows quickly started dropping to levels usually not seen until the end of summer.
Averaged statewide, the snow-water equivalent in the snowpack was less than half the peak of 2011, and and melt rates in 2011 were more than double those in 2012.
Desert dust blowing from the Southwest into the Rockies has been implicated in air quality violations and avalanches, and some studies suggest the problem could get worse in the coming decades, as global warming dries out the desert Southwest, killing vegetation that stabilizes soils.
In one recent study, a research team from the U.S. Geological Survey and UCLA looked at climate, vegetation and soil measurements collected over a 20-year period in Arches and Canyonlands National Parks in southeastern Utah.
The long-term data suggests that perennial vegetation in grasslands and some shrublands declined with temperature increases. The study then used these soil and vegetation measurements in a model to project future wind erosion.
“Accelerated rates of dust emission from wind erosion have large implications for natural systems and human well-being, so developing a better understanding of how climate change may affect wind erosion in arid landscapes is an important and emerging area of research,” said Seth Munson, a USGS ecologist and the study’s lead author.
Results of the study, Responses of wind erosion to climate-induced vegetation changes on the Colorado Plateau, appeared in the Proceedings of the National Academy of Sciences. The research team included Seth Munson and Jayne Belnap, U.S. Geological Survey, Moab, Utah, and Gregory S. Okin, Department of Geography, University of California, Los Angeles.
The Silverton research helps show how that dust affects the snowpack in the Colorado Rockies and the subsequent production of critical water supplies. Tracking those impacts on an ongoing basis will provide critical information for water managers.
The center’s funding was a bit uncertain for a time this spring, but key stakeholders stepped up to ensure at least another year of data. The full list of organizations helping fund the dust-on-snow studies is online here.