New Analysis Shows Prolonged Snow Drought in Western U.S.
When most people think about droughts, most think about a lack of rainfall and dry river beds. But in many parts of the world the amount of annual snowfall can have a much more lasting impact on potential drought conditions.
To help better understand trends and the potential for the impact on water supplies, forest fires and the global ecosystem as a whole, University of California at Irvine are using new techniques to model and analyze factors related to snow droughts across the planet.
Credit: Amir AghaKouchak/UCI
Changes in global weather patterns often affect drought conditions in parts of the world by creating conditions that lead to stronger or weaker than usual rainfall or tropical storms. This is often reported in terms of an El-Nino or La-Nina systems by weather reporters.
These systems, and the rain amounts of rain they bring have an almost immediate effect for potential drought conditions in a region.
Snow drought, however, can be harder to gauge. This is because the effect of variations in snowfall many not be immediately seen until the snowpack which builds up in high elevations starts to run low.
It is not at all uncommon to have snowfall build up in layers and remain virtually un-melted for years with consecutive years of abundant snowfall. Each spring and summer, some of the ice melts and fills rivers and streams, but much of it remains.
Because of this, the impact of a reduced amount of snowfall in a season or two may not be immediately seen. It is when the snowpack starts to run low, in addition to a below average season, that the impact on areas downstream become most apparent.
This is the challenge for scientists when trying to make predictions about impending drought conditions. It is here that the new modeling by researchers come into play.
“Snow is an important global water resource that plays a vital role in natural processes, agriculture, hydropower and the basic socioeconomic conditions of various regions,” said lead author Laurie Huning. “While other forms of drought are well-studied, variations in snow droughts on a global scale have been examined to a far lesser extent until now.”
Armed with new methods, based on a new snow water equivalent index, the researchers looked at data in mountain ranges across the globe going back to more than 40 years.
For the western states of the U.S., the analysis pointed to an increase in snow droughts of twenty-eight percent during the most recent half of that time period.
The study indicates prolonged snow droughts in western state of the U.S. including California, Oregon, Washington. While not as severe, they also saw a similar issue for parts of Eastern Russia and Europe.
Other regions of the world appeared to fair better with a decrease in average snow drought severity. This includes areas surrounding the mountainous regions of Asia and South America.
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