Email
Password
Remember meForgot password?
    Log in with Twitter

article imageSnowpack levels in western U.S. show 'dramatic' decline

By Karen Graham     Mar 4, 2018 in Environment
A new study of long-term snow monitoring sites in the western United States found declines in snowpack at more than 90 percent of those sites - and one-third of the declines were deemed significant.
Scientists from Oregon State University and the University of California, Los Angeles found that dramatic decreases in snowpack levels in the American West over the past six decades will end up causing water shortages that cannot be fixed by building additional reservoirs.
Looking at data going back to 1955, the researchers found the average snowpack in western states has declined 15 to 30 percent, and the amount of water lost from that snowpack reduction is comparable in volume to Lake Mead, the West's largest man-made reservoir.
The loss of water storage will have an impact on municipal water supplies as well as industry and agriculture, according to the study published in NPJ Climate and Atmospheric Science, a Nature publication on March 2, 2018.
On February 1  the Department of Water Resources (DWR) manual snow survey east of Sacramento found l...
On February 1, the Department of Water Resources (DWR) manual snow survey east of Sacramento found little snowpack there, two months into what is typically California’s wettest three months.
DWR
"It is a bigger decline than we had expected," said Philip Mote, director of the Oregon Climate Change Research Institute at Oregon State University and lead author on the study.
"In many lower-elevation sites, what used to fall as snow is now rain. Upper elevations have not been affected nearly as much, but most states don't have that much area at 7,000-plus feet." Mote added the new study is a follow-up to a study completed in 2005. However, this latest analysis shows the decline has accelerated, said Mote.
"The solution isn't in infrastructure. New reservoirs could not be built fast enough to offset the loss of snow storage - and we don't have a lot of capacity left for that kind of storage. It comes down to managing what we have in the best possible ways."
Interestingly, the decline in snowpack isn't because of a lack of precipitation - It is because of a warming climate. And this is significant, say the scientists. Spring is coming earlier and earlier, for one, and this means much of that precipitation will not be stored as long in the mountains, which can result in lower river and reservoir levels during late summer and early fall.
Snowpack in the Colorado Rockies as seen from the NSF/NCAR C-130 research aircraft.
Snowpack in the Colorado Rockies as seen from the NSF/NCAR C-130 research aircraft.
UCAR. Photo by Carlye Calvin
The Study used data and computer modeling
Data from 1,766 sites in the western U.S., mostly from the U.S. Department of Agriculture's Natural Resources Conservation Service and the California Department of Water Resources went into the study, focusing on measurements taken on April 1, historically the high point of the snowpack in most areas.
However, the authors also looked at data from Jan. 1, Feb. 1, March 1, and May 1 - which led to the range of the decline of 15 to 30 percent.
The researchers also used computer modeling of the hydrology cycle - This takes daily weather observations and computes the snow accumulation, melting, and runoff to estimate the total snowpack in the western U.S.
Astounding footage from a drone shows just how low the water level is in Lake Mead on Jan. 30  2016.
Astounding footage from a drone shows just how low the water level is in Lake Mead on Jan. 30, 2016.
Eagle Eye Drones
"We found declining trends in all months, states and climates," Mote said, "but the impacts are the largest in the spring, in Pacific states, and in locations with mild winter climates." This is because Washington, Oregon, and California receive more precipitation because of the Pacific Ocean's influence, and more snow falls at near freezing temperatures.
However, the Cascade Mountains, which transect the region, are not as steep as the Rocky Mountains, they have more area that is affected by changes in temperature. "When you raise the snow zone level 300 feet, it covers a much broader swath than it would in the inland states," Mote said.
Mote said snowpack levels in most of the western U.S. for 2017-18 thus far are lower than average - a function of continued warming temperatures and the presence of a La Niña event, which typically results in warmer and drier conditions in most southwestern states.
More about snowpack, western states, hydrology, Climate change, Science
More news from