Wildfires Are Increasingly Burning California’s Snowy Landscapes and Colliding with Winter Droughts to Shrink California’s Snowpack

Wildfires Are Increasingly Burning California’s Snowy Landscapes and Colliding with Winter Droughts to Shrink California’s Snowpack

Wildfires Are Increasingly Burning California’s Snowy Landscapes and Colliding with Winter Droughts to Shrink California’s Snowpack

February 1, 2023
RENO, Nevada

Wildfires
Winter Drought
Snowpack

Above: Burned trees on a snowy mountain. The trees in the photo were burned by the Caldor Fire.  

Credit: Anne Heggli/DRI.

A new study shows that midwinter dry spells lead to dramatic losses of winter snowpack in burned areas 

The early pandemic years overlapped with some of California’s worst wildfires on record, creating haunting, orange-tinted skies and wide swathes of burned landscape. Some of the impacts of these fires are well known, including drastic declines in air quality, and now a new study shows how these wildfires combined with midwinter drought conditions to accelerate snowmelt.   

In a study published Jan. 20 in Geophysical Research Letters, a DRI-led research team examined what happens to mountain snowpacks when sunny, midwinter dry spells occur in forests impacted by severe wildfire. The researchers found a substantial increase in wildfires burning in California’s snowy landscapes throughout 2020 and 2021, when large blazes like the Dixie, Caldor, and Creek fires concentrated in snow zones. Using a 2013 midwinter dry spell as comparison, they found that similar weather in the winter of 2021-2022 led to 50% less snow cover. The compounding impacts of wildfire on snow melt include an increase in sun exposure due to loss of forest canopy, and a reduction in the snow’s ability to reflect sunlight.  

“It’s already established that wildfires are increasing spring snow melt, but we wanted to know what happens when you add a long winter dry spell on top of that,” said Arielle Koshkin, M.S., a Ph.D. student now at the Colorado School of Mines who co-led the study as part of her master’s research at DRI and the University of Nevada, Reno. “The Caldor fire burned in our backyard, it was so close to where we live and work. So, the following winter, we wanted to investigate what it looked like.” 

Satellite data showed that compared to the 2001-2019 average, 2020 and 2021 saw a nearly ten-fold increase in wildfires burning in California’s seasonal snow zones. “What that implies is that there’s this increasing overlap between the fire and snow and there’s all these cascading and compounding impacts on the system and especially the hydrology,” said Ben Hatchett, Ph.D., a climatologist at DRI who co-led the study with Koshkin. “This huge increase of fire activity in California snowy regions is exactly what we expect to see more of going forward.”  

A strong winter drought followed during the winter of 2021-2022, when Tahoe City experienced a 46-day long midwinter dry spell (the second-longest since reliable records began in 1917; the long-term median is 22 days without precipitation). A comparable midwinter drought following a wet start to the winter occurred in 2013, giving the researchers the ability to compare and contrast the impacts under more typical conditions with those that occurred in a severely burnt landscape.  

“In 2013 and 2022, we had very similar weather patterns, but we didn’t see notable melt in 2013. And in 2022, we also did not see melt in unburned areas,” Hatchett said. “So that gives two lines of evidence suggesting that it’s the fire and not the meteorology that’s driving this.” 

Forests where severe wildfires have burnt the tree canopy have more exposed snowpacks, which enhances the melting caused by sunny days and warm nights (another recent DRI study examined the snowmelt impacts of spring heatwaves). Snowmelt is further exacerbated by the loss of the snowpack’s albedo, or the natural power of white snow to reflect, rather than absorb, the sun’s radiation. Particularly in the winters immediately following a wildfire, snow is dusted with the black carbon of burnt vegetation, which can accelerate snowmelt rates by up to 57%.  

The enhanced snowmelt was so pronounced within the perimeter of the Caldor fire that the researchers found a total of 50 fewer days with snow cover in the winter of 2021-2022 – the lowest number of snow cover days on record.  

Following a wildfire, “there are two timescales of interest: right after the fire, the loss in albedo really dominates,” said Hatchett. “But impacts from the loss of canopy last for decades, maybe longer if the forest does not recover.” 

The enhanced snowmelt midwinter creates challenges for forecasting water availability from the natural snowpack reservoir. During the winter months, water managers need to leave room in reservoirs to prevent flooding; this means that earlier snowmelt may not be captured for later use in the dry season. Studies like this provide water managers with the tools to make more accurate predictions of the timing and magnitude of snowmelt.  

The fires have made major landscape disturbance that we’re not taking into account in our forecasting abilities,” Koshkin said.I think this study is showing that wildfire impacts are huge, and we need to implement this into our ability to understand how water runs off the landscape. It’s part of our world and it’s increasing and it’s going to affect more snowy places. So, it’s important to make sure that we understand the outcomes in our models and management plans.” 

Koshkin plans to expand on this research for her Ph.D. studies by examining regional variation of fire impacts on snow. She notes that how wildfire impacts snowmelt in the Sierra Nevada may look different in Colorado or Idaho, due to different weather and snowpack conditions.  

The researchers emphasize that the wildfire impacts seen in this study are the result of high-severity wildfires, and not lower-severity burns like prescribed fires. “This study really highlights the importance of bringing fire back onto our landscape in the sense that we need fire – good fire is the answer to our wildfire problem,” Hatchett says. “Bringing a more natural regime of fire, through prescribed and cultural fire, back onto our landscape will help reduce the likelihood of future severe fire.” 

“We can recognize that this could be our new normal,” Koshkin said, “but we also have the ability to adapt and manage and mitigate as much as possible.” 

 

Scientists measure albedo on a snowy mountain

Study authors Arielle Koshkin and Ben Hatchett measure albedo in the Sierra Nevada foothills. 

Credit: Anne Heggli/DRI.

More information:

The full study, Midwinter dry spells amplify post-fire snowpack decline, is available from Geophysical Research Letters:  https://doi.org/10.1029/2022GL101235 

Study authors include: Benjamin Hatchett (DRI), Arielle Koshkin (DRI/UNR), Kristen Guirguis (Scripps Institution of Oceanography), Karl Rittger (CU Boulder), Anne Nolin (UNR), Anne Heggli (DRI), Alan Rhoades (Lawrence Berkeley National Lab), Amy East (USGS), Erica Siirila-Woodburn (Lawrence Berkeley National Lab), W. Tyler Brandt (Scripps Institution of Oceanography), Alexander Gershunov (Scripps Institution of Oceanography), and Kayden Haleakala (Scripps Institution of Oceanography/UCLA).  

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About DRI

The Desert Research Institute (DRI) is a recognized world leader in basic and applied environmental research. Committed to scientific excellence and integrity, DRI faculty, students who work alongside them, and staff have developed scientific knowledge and innovative technologies in research projects around the globe. Since 1959, DRI’s research has advanced scientific knowledge on topics ranging from humans’ impact on the environment to the environment’s impact on humans. DRI’s impactful science and inspiring solutions support Nevada’s diverse economy, provide science-based educational opportunities, and inform policymakers, business leaders, and community members. With campuses in Las Vegas and Reno, DRI serves as the non-profit research arm of the Nevada System of Higher Education. For more information, please visit www.dri.edu.

Study Develops Framework for Forecasting Contribution of Snowpack to Flood Risk During Winter Storms

Study Develops Framework for Forecasting Contribution of Snowpack to Flood Risk During Winter Storms

flooding along the South Fork of the Yuba River in California

May 3, 2022
RENO, NEV.

Forecasting
Flood Risk
Winter Storms

Above: During January 2017, a rain-on-snow event caused flooding along the South Fork of the Yuba River in California. Climate change is expected to make such events larger and more frequent.

Credit: JD Richey. 

Study Develops Framework for Forecasting Contribution of Snowpack to Flood Risk During Winter Storms

New research advances effort to create a decision-support tool for reservoir operators and flood managers

Anne Heggli in the snow

Lead author Anne Heggli of DRI digs through deep snow to reach a monitoring site during a 2019 field project at the UC Berkeley Central Sierra Snow Laboratory in the Tahoe National Forest.

Credit: M. Heggli. 

Reno, Nev. (May 3, 2022) –In the Sierra Nevada, midwinter “rain-on-snow” events occur when rain falls onto existing snowpack and have resulted in some of the region’s biggest and most damaging floods. Rain-on-snow events are projected to increase in size and frequency in the coming years, but little guidance exists for water resource managers on how to mitigate flood risk during times of rapidly changing snowpack. Their minute-by-minute decisions during winter storms can have long-lasting impacts to people, property, and water supplies.

A new study by a team from DRI, University of California, Berkeley, the National Weather Service, and University of Nevada, Reno, provides the first framework for a snowpack decision support tool that could help water managers prepare for potential flooding during rain-on-snow events, using hourly data from existing snow monitoring stations.

“During rain-on-snow events, the people managing our water resources always have decisions to make, and it’s really challenging when you’re dealing with people’s lives and property and livelihood,” said DRI Graduate Assistant and lead author Anne Heggli, M.S. “With this work, we’re leveraging existing monitoring networks to maximize the investment that has already been made, and give the data new meaning as we work to solve existing problems that will potentially become larger as we confront climate change.”

snow depth sensor installation

Lead author Anne Heggli of DRI installing a snow depth sensor at the UC Berkeley Central Sierra Snow Laboratory in the Tahoe National Forest for the 2021-2022 winter.

Credit: P. Kucera. 

To develop a testable framework for a decision support tool, Heggli and her colleagues used hourly soil moisture data from UC Berkeley’s Central Sierra Snow Laboratory from 2006-2019 to identify periods of terrestrial water input. Next, they developed quality control procedures to improve model accuracy. From their results, they learned lessons about midwinter runoff that can be used to develop the framework for a more broadly applicable snowpack runoff decision support tool.

“We know the condition (cold content) of the snowpack leading into a rain-on-snow event can either help mitigate or exacerbate flooding concerns,” said study coauthor Tim Bardsley of the National Weather Service in Reno. “The challenge is that the simplified physics and lumped nature of our current operational river forecast models struggle to provide helpful guidance here. This research and framework aims to help fill that information gap.”

“This study and the runoff decision framework that has been built from its data are great examples of the research-to-operations focus that has been so important at the Central Sierra Snow Lab for the past 75 years,” said study coauthor Andrew Schwartz, Ph.D., manager of the snow lab. “This work can help inform decisions by water managers as the climate and our water resources change, and that’s the goal – to have better tools available for our water.”

The idea for this project was sparked during the winter of 2017, when Heggli and her brother were testing snow water content sensors in California. Several large rain-on-snow events occurred, including a series of January and February storms that culminated in the Oroville Dam Spillway Crisis.

“I noticed in our sensors that there were these interesting signatures – and I heard a prominent water manager say that they had no idea how the snowpack was going to respond to these rain-on-snow events,” Heggli explained. “After hearing the need of the water manager and seeing the pattern in the data, I wondered if we could use some of that hourly snowpack data to shave off some level of uncertainty about how the snowpack would react to rain.”

Heggli is currently enrolled in a Ph.D. program at UNR, and has been working under the direction of DRI faculty advisor Benjamin Hatchett, Ph.D., to advance her long-term goal of creating a decision support tool for reservoir operators and flood managers.

The results of this study can next be used to develop basin-specific decision support systems that will provide real-time guidance for water resource managers. The study results will also be used in a new project with the Nevada Department of Transportation.

“Anne’s work, inspired by observation, demonstrates how much we still can learn from creatively analyzing existing data to produce actionable information supporting resource management during high-impact weather events as well as the value of continued investment to maintain and expand our environmental networks,” said Hatchett, DRI Assistant Research Professor of Atmospheric Science.

More information:

The full text of the study, Toward snowpack runoff decision support, is available from iScience: https://www.cell.com/iscience/fulltext/S2589-0042(22)00510-7. 

This project was funded by University Corporation for Atmospheric Research’s COMET Outreach program, Desert Research Institute’s Internal Project Assignment program, and the Nevada Space Grant Consortium Graduate Research Opportunity Fellowship. Study authors included Anne Heggli (DRI), Benjamin Hatchett (DRI), Andrew Schwartz (University of California, Berkeley), Tim Bardsley (National Weather Service, Reno), and Emily Hand (University of Nevada, Reno).

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About DRI

The Desert Research Institute (DRI) is a recognized world leader in basic and applied environmental research. Committed to scientific excellence and integrity, DRI faculty, students who work alongside them, and staff have developed scientific knowledge and innovative technologies in research projects around the globe. Since 1959, DRI’s research has advanced scientific knowledge on topics ranging from humans’ impact on the environment to the environment’s impact on humans. DRI’s impactful science and inspiring solutions support Nevada’s diverse economy, provide science-based educational opportunities, and inform policymakers, business leaders, and community members. With campuses in Las Vegas and Reno, DRI serves as the non-profit research arm of the Nevada System of Higher Education. For more information, please visit www.dri.edu.

DRI welcomes new graduate students to Reno and Las Vegas campuses

DRI welcomes new graduate students to Reno and Las Vegas campuses

Each year, the Desert Research Institute (DRI) welcomes new graduate students from the University of Nevada, Reno (UNR) and University of Nevada, Las Vegas (UNLV), who work under the direction of DRI faculty on our northern and southern campuses to conduct research across a variety of scientific fields as they pursue their master’s and doctoral degrees. Read below to get to know our new grad students!  


Natasha Sushenko

Natasha Sushenko

Natasha Sushenko
Las Vegas Campus

Natasha Sushenko is originally from Las Vegas, Nevada, and is currently pursuing a M.S. in microbiology at UNLV. At DRI, she is working in the Environmental Microbiology Lab with faculty advisor Duane Moser, Ph.D.

“I’m currently working on a NASA EPSCoR Space Biology project that involves studying strains of Klebsiella pneumoniae, an opportunistic pathogen, that have been isolated from the International Space Station (ISS),” Sushenko said.  “We are growing these strains under simulated microgravity while exposed to the disinfectants used on the ISS, and will later perform metatranscriptomic analysis to evaluate the strains for antimicrobial resistance and virulence gene expression.”

 


Victoria Wuest

Victoria Wuest

Victoria Wuest
Las Vegas Campus 

Victoria Wuest is originally from Las Vegas, Nevada, and is pursuing a M.S. in biological sciences with a concentration in ecology and evolutionary biology at UNLV. At DRI, she is working in the Environmental Microbiology Lab under the direction of Duane Moser, Ph.D. 

“I am working on a project to extract human mtDNA from ancient quids found in Mule Springs Rockshelter in Nevada,” Wuest said. “I am also studying the application and implementation of eDNA of endangered and invasive fish in the warm water springs of Nevada.” 

 

 


Manuel de Cespedes Molina

Manuel de Cespedes Molina

Manuelde Cespedes Molina 
Las Vegas Campus

Manuel de Cespedes Molina is originally from Camaguey, Cuba. He is currently pursuing a Ph.D. in Anthropology at UNLV. At DRI, he is working in the Division of Earth and Ecosystem Sciences under the supervision of Maureen King, M.A. 

“My work at DRI is involved with the Cultural Resource Management Program that supports the National Nuclear Security Administration Nevada Field Office’s historic preservation obligations at the Nevada National Security Site,” de Cespedes Molina said.  

 

 


Marc Berghouse

Marc Berghouse

Marc Berghouse
Reno campus 

Marc Berghouse is originally from Redwood City, Calif., and is currently pursuing a Ph.D. in Hydrology at UNR. At DRI, he is working in the Division of Hydrologic Sciences under the direction of Dr. Rishi Parashar.  

“I will be working on modeling the physics of microbial motility – the ability of a microbe to move through its environment – at the micro and field scales, Berghouse said.  

 

 

 


Anne Heggli

Anne Heggli

Anne Heggli
Reno campus 

Anne Heggli is originally from Cool, Calif., and is pursuing a Ph.D. in Atmospheric Science at UNR. At DRI, she is working under the direction of advisor Ben Hatchett, Ph.D. in the Division of Atmospheric Sciences. 

“I am working on the development of a Snow Runoff Readiness Advisory to provide information regarding the likelihood and magnitude of impactful snowmelt-derived runoff and flooding during extreme weather events,” Heggli said.  

 

 

 


Porraket Dechdacho

Porraket Dechdacho

Porraket (Porra) Dechdacho
Reno campus 

Porra Dechdado is originally from Nakhon Si Thammarat, Thailand. She is currently pursuing a M.S. in hydrogeology at UNR. At DRI, she is working with Dr. Rishi Parashar in the Division of Hydrologic Sciences. 

“I am working on a project to develop and evaluate iron-based strategies for arsenic removal from contaminated groundwater using metal organic framework and iron rich compost,” Dechdado explained. 

 

 

 


Zakaria Jibrin, DEES (Coming soon)