The amount of water stored in peak snowpack in the McKenzie River watershed of the Oregon Cascade Range will fall by about 56% by the year 2050, as a result of climate change, new research from Oregon State University has found. The research also suggests that similar impacts will be seen in other similar low-elevation maritime snow packs around the world.
The new findings — based on an estimated 3.6 degree Fahrenheit temperature increase by the year 2050 — make it very clear just how much water security/availability will be affected in the coming years as the result of rising temperatures and shifting weather patterns. The research — in particular — highlights “the special risks facing many low-elevation, mountainous regions where snow often falls near the freezing point. In such areas, changing from snow to rain only requires a very modest rise in temperature.”
The researchers note that with decreased water supplies there will be a lot of pressure placed on human activity/infrastructure. Large impacts will be felt by humans — especially with regard to agriculture, products/services provided by natural ecosystems, hydropower, industry (heavy water-use), recreation, etc.
The new research is some of the first to focus on a whole watershed, rather than individual rivers, lakes, etc. “In Oregon we have a water-rich environment, but even here we will have to manage our water resources differently in the future,” stated lead researcher Eric Sproles, a doctoral student at OSU at the time of the research.
“In the Willamette River, for instance, between 60-80% of summer stream flow comes from seasonal snow above 4,000 feet,” he stated. “As more precipitation falls as rain, there will more chance of winter flooding as well as summer drought in the same season. More than 70% of Oregon’s population lives in the Willamette Valley, with the economy and ecosystems depending heavily on this river.”
Total annual precipitation in may end up either higher or lower in the region in the near-future. The researchers “did calculations for precipitation changes that could range 10% in either direction, although change of that magnitude is not anticipated by most climate models. The study made clear — so far as snowpack goes — that temperature is the driving force, far more than precipitation. Even the highest levels of anticipated precipitation had almost no impact on snow-water storage.”
“This is not an issue that will just affect Oregon,” stated Anne Nolin, a professor in the College of Earth, Ocean, and Atmospheric Sciences, and co-author of the study. “You may see similar impacts almost anywhere around the world that has low-elevation snow in mountains, such as in Japan, New Zealand, Northern California, the Andes Mountains, a lot of Eastern Europe and the lower-elevation Alps.”
“The focus of this study was the McKenzie River, a beautiful, clear mountain river that rises in the high Cascade Range near the Three Sisters volcanoes, and supplies about 25% of the late summer discharge of the Willamette River. Researchers said this is one of the most detailed studies of its type done on a large watershed.”
Some of the most interesting findings from Oregon State University’s study:
– The average date of peak snowpack in the spring on this watershed will be about 12 days earlier by the middle of this century.
– The elevation zone from 1,000 to 1,500 meters will lose the greatest volume of stored water, and some locations at that elevation could lose more than 80 days of snow cover in an average year.
Changes in dam operations in the McKenzie River watershed will be needed, but will not be able to make up for the vast capability of water storage in snow.
– Summer water flows will be going down even as Oregon’s population surges by about 400,000 people from 2010 to 2020.
– Globally, maritime snow comprises about 10% of Earth’s seasonal snow cover.
Snowmelt is a source of water for more than one billion people.
– Precipitation is highly sensitive to temperature and can fall as rain, snow, or a rain-snow mix.
The new research was just published in the journal Hydrology and Earth System Sciences.