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Water in the West: it all starts with snow. But how much is water is in all that snow? USGS scientists have developed innovative new approaches to help measure this critical resource.

Water in the West: it all starts with snow.

A graphic shows a snow-capped mountain. The snowpack on top of the mountain is melting into a water glass to show that snowmelt makes its way to water users.

A majority of the water in the western U.S. comes from the snowpack of the high-elevation mountains. In the winter, the mountains store water as snow. With spring and summer temperatures, the snow melts and flows downstream, through the landscape to water users. Streamflow and water availability for the rest of the year depends on the snowpack and snowmelt conditions. In fact, approximately 75% of the water in Colorado River Basin streams come from the mountain snowpacks of the Upper Colorado River Basin.

Because winter snowpack is so important for the water that landscapes and people depend on, scientists at USGS have been measuring it for decades. Today, as part of the Next Generation Water Observing System (NGWOS) program, USGS scientists are using new technologies to measure snowpack and streamflow in Colorado. This work is called the “Snow to Flow” project.

The Snow to Flow project collects data on mountain snowpack conditions using a range of techniques so that scientists can improve predictions of what river flow will be like the following spring and summer. New snowpack data can improve water-availability estimates for downstream water users.

 

To predict flow data, we need snow data. And to get snow data, we need a talented team of collaborative scientists!
In this photo, a group of 20 scientists pose for the camera. The group is dressed in winter gear and stands in front of Berthoud Pass, Colorado. The pass and the ground are covered in snow. Berthoud Pass has a few patches of dark green trees. A title at the bottom of the photo reads “The Snow to Flow Science Team.”
The Snow to Flow team is comprised of a “village” of remarkable scientists and engineers from the USGS Colorado Water Science Center, USGS National Uncrewed Systems Office (NUSO), and the University of Southern California - Viterbi School of Engineering. The team is pictured here at the Berthoud Pass, Colorado field site on April 18, 2022. The USGS team is led by Suzanne Paschke, NGWOS UCOL River Basin Coordinator, Graham Sexstone, Research Hydrologist, who is responsible for coordinating the collection of ground-based snow pack data, and John Fulton, Surface Water Specialist, who is responsible for coordinating the development of the radar equipped drone (SDRadar) and non-contact methods for measuring streamflow in response to snow melt.

 

Read on to learn about several of the interesting scientists behind the snow data, how they came into this work, and what inspires them each day.
Four pictures are displayed. Each picture shows one of four USGS scientists that work on the Snow to Flow project: Evan Gohring, Andy Creighton, Mark Bauer, and Victoria Scholl. A title at the bottom of the four photos “Meet some of the Snow to Flow scientists.”
USGS Scientists Evan Gohring, Andy Creighton, Mark Bauer, and Victoria Scholl.

 

Together with their teammates, Evan, Andy, Mark, and Victoria collect the data needed to measure snowpack. Each scientist works on one piece of the snow data collection and analysis.

 

This graphic shows a snow-capped mountain with the words “From Snow to Flow” written on the bottom left corner. Next to the mountain, hovering in the air, is a illustration of a drone. On the bottom right corner is an illustration of a ground-based satellite. The names of four Snow to Flow scientists are arranged across the graphic, with an arrow showing where in the illustration each scientist works.
In order to get accurate measurements, the Snow to Flow scientists collect several kinds of data using a few different tools. Evan and the team dig snowpits and collect snow depth, snow density, and weather data. They also place sensors across the snowpack to help the drones collect accurate data. Andy and the team use a tool called ground penetration radar (GPR) to measure snow depth and density. They ski across the snowpack with a sled that holds the GPR system. Mark and the Uncrewed Aircraft System team use two kinds of drone platforms to collect data from the air: one equipped with radar (SDRadar), the other with lidar. Victoria makes maps for the team and ensures that the data is collected accurately and safely.

 

A photo shows USGS scientist Evan Gohring smiling at the camera. Evan is wearing a T-shirt with the USGS logo on it. He is also wearing a ballcap and Evan is standing in front of a stand of aspen trees and a field of snow.
Evan Gohring, USGS Hydrologic Technician.

 

EVAN GOHRING

USGS Hydrologic Technician

 

What is your role, your piece of work, on the Snow to Flow project?

I am part of an amazing team establishing meteorological, snow, and stream gaging sites in the western United States. We use new and emerging technologies to better understand, measure, and model snowpacks and their contribution to streamflow.

Our team makes periodic trips to maintain instrumentation and make additional field measurements, like direct snowpack measurements. These sites allow our team to monitor a variety of water metrics: snow-water equivalent, snowmelt timing, soil saturation, streamflow and many other factors that influence snowpack contribution to water yield in the Rocky Mountains.

 

Snow-water equivalent

The USGS measures the snowpack using a metric called the snow-water equivalent. When the snowpack melts, the snow-water equivalent tells us how much water will flow down through the landscape to water users like you.

This graphic shows how snow-water equivalent is calculated. A grey jar with a red lid dominate the graphic. Inside the jar is snow. On the top, the snow is loosely layered. On the bottom of the jar, the snow is more compact. Text alongside the right of the jar reads “snow depth.”

 

To calculate this metric, scientists measure how deep the snow is across an entire area and the density of that snow – is it loose or compacted? Wet or dry?

Did you ever have to guess how many candies are in a jar without opening the top? Just like you had to come up with a way to estimate how many candies are in the jar without dumping them out and counting them, USGS scientists had to have a way to measure how much water is stored in snowpack.

 

What was your path like to get here?

I studied at Colorado State University before working for the Colorado Forest Restoration Institute, US Forest Service, National Park Service, and NASA. It is a pleasure to work with the great minds in the USGS Colorado Water Science Center.

 

What are you most proud of?

I am proud to have contributed to projects throughout my career that have helped water users, researchers, and land managers better understand the natural resources we rely on.

 

Favorite quote?

“We make our world significant by the courage of our questions and the depth of our answers.” – Carl Sagan

A panoramic photo shows deep snow spread across the top of a mountain. Dark green evergreen trees dot the landscape. In the center of the photo, a large hole has been dug into the snow. Next to the snowpit is a shovel, a pole marking the spot, and Evan’s ski and science gear.
Evan and the team dug a snowpit to collect snowpack data at Berthoud Pass, Colorado.
In the snowpit, Evan collects snow depth, snow density, and weather data at Berthoud Pass, Colorado.
A photo shows USGS scientist Dr. Andy Creighton smiling at the camera. Andy is on a pair of dark skis posing in a filed of snow. Behind her, rocky mountains are dusted in snow and evergreen trees. Andy is wearing bright snow gear that includes yellow ski boots, red ski pants, a turquoise hoodie, and a yellow backpack. Andy is also wearing sunglasses.
Dr. Andy Creighton, USGS Hydrologist.

 

 

DR. ANDY CREIGHTON

USGS Hydrologist

 

What is your role, your piece of work, on the Snow to Flow project? 

My focus is on using ground-based geophysics to measure the variation in snow density across the entire snowpack.

To do this, my team uses a tool called ground-penetrating radar (GPR) to collect radar wave velocity data. This radar machine is pulled across the snowpack in a sled to measure snow depth and density. We are also working to calculate the snow-water equivalent metric from GPR measurements. Using GPR to measure snow-water equivalent will lead to more accurate estimates than current methods, which has large implications for our ability to better forecast water availability.

 

 

Ground-penetrating radar (GPR)

Ground penetrating radar uses radio waves to detect changes in the electrical properties of surface layers. Rocky ground and snow have different electrical properties. Additionally, wet snow and dry snow have different electrical properties. So, GPR measures the difference in electrical properties of the ground it is pulled over and it records these properties on a map. When the GPR is pulled across the snowpack, the map shows the snow depth and snow density across the landscape. From these two metrics, USGS scientists can calculate what the snow-water equivalent is of the entire snowpack.

This graphic shows a quote from Andy’s narrative. It reads: “This is my first permanent government position, now I get to ski and do alpine hydrogeophysics - talk about a dream job!“ Yellow quotation marks bookend her quote.

What was your path like to get here?

My path to this project was a bit circuitous. I started out as an undergraduate research assistant at Clemson University as a Geology major with no geophysics experience working with ground-penetrating radar (GPR) applications for imaging the movement of water through the surface of the Earth. I honestly wasn’t that interested in the project when I started out- I just needed a campus job, and yet here we are 10 years later still working with water and GPR. While in graduate school at the University of Wyoming, I studied various geophysical methods and developed a passion for arctic and alpine hydrology.

After graduating, I worked a couple of temp and term government positions. I worked for the National Park Service as a Park Ranger/EMT at Rocky Mountain National Park where I taught all about tundra geology, ecology, and meteorology. I also worked for the U.S. Forest Service as a hydrologist studying the impacts of forest management strategies on water quality and quantity in an experimental watershed. And now we’re here! This is my first permanent government position and I started right as the pandemic began, so it was a little rough in the beginning but now I get to ski and do alpine hydrogeophysics - talk about a dream job!  

This graphic shows a quote from Andy’s narrative. It reads: “I was the first woman to be a part of a self-sustained snowmachine expedition across the North Slope of Alaska. It was amazing to be able to break down some of those barriers that are still in place for women in science.” Yellow quotation marks bookend her quote.

 

What are you most proud of? 

My field work in graduate school involved being a part of a self-sustained snowmachine expedition across the North Slope of Alaska. We would be out on the tundra for weeks, hundreds of miles from any infrastructure, sleeping in tents when it would blizzard and the temps would be below zero. I was the first woman to be a part of this field campaign, so while it was incredibly brutal to survive in such extreme conditions, and attempt to do science too, it was amazing to be able to break down some of those barriers that are still in place for women in science. My absolute favorite part of these field campaigns was getting to name lakes and drained lake basins. Whenever I see those names still used in recent publications, I smile to myself- and fan girl a little. 

 

 Favorite quote? 

“Sometimes it’s a little better to travel than to arrive.” – Robert Pirsig, Zen and the Art of Motorcycle Maintenance 

A photo shows USGS scientist Andy Creighton smiling at the camera. Andy is on a pair of dark skis posing in a filed of snow. Behind her, rocky mountains are dusted in snow and evergreen trees. Andy is wearing bright snow gear that includes yellow ski boots, red ski pants, a turquoise hoodie, and a yellow backpack. Andy is also wearing sunglasses.
Andy pulls the ground-penetrating radar (GPR) behind her on a sled.
A photo shows USGS scientist Mark Bauer smiling at the camera. Mark is kneeling and holding the USGS drone with both hands. Mark wears a ballcap and an orange vest over his green USGS T-shirt. Behind Mark is a field of brown grass and a leaf-less tree sits in the background.
Mark Bauer, USGS Geographer.

 

 

MARK BAUER

USGS Geographer

 

What is your role, your piece of work, on the Snow to Flow project?

I’m part of the USGS National Uncrewed Systems Office team that measures the snow depth across watershed basins. To do this, we utilize light detection and ranging (lidar) technology, which consists of a scanner payload that is flown on a UAS (drone). The scanner bounces light pulses outward to an object and then those light pulses travel back to the scanner. The length of time it takes for the light pulse to travel back to the drone tells us the elevation of the surface. We use these measurements to create a 3D model of the topographic area. 

We also scan areas with and without snow. We use the difference in elevation between snowy and bare ground to get an estimate the of the snow depth. Our measurements are accurate of within a few centimeters. 

A photo shows USGS scientist Mark Bauer looking up at the airborne USGS drone. Mark is holding a neon green radio is in right hand. Behind Mark is a white SUV. Mark is wearing an orange USGS beanie and a red hoodie sweatshirt. The drone is flying above tree-covered mountains. Mark stands in a snowy parking lot.
Mark communicates with the ground team (including Evan and Andy) to let them know that the USGS UAS is starting its flight over the snowpack.

 

What was your path like to get here?

My path started at Northern Illinois University studying geography, with an emphasis on natural environmental systems. I focused on geographic information systems (GIS) mapping and remote sensing image analysis. Early on, I worked with Motorola, creating maps for planned cellular networks before turning gears to remote sensing of natural hazards at the U.S. Geological Survey. About 12 years ago, I had the opportunity to remotely pilot the first UAS flights within the Department of the Interior.  We repurposed older military drones that were donated for science data collection. The program continued to grow, and as a remote pilot and geospatial analyst, I grew along with it. I’m grateful that I can be a part of a team that flies UAS for mapping and scientific measurements. 

This graphic shows a quote from Mark’s narrative. It reads: “The program continued to grow, and as a remote pilot and geospatial analyst, I grew along with it.“ Yellow quotation marks bookend her quote.

What are you most proud of?

I’m proud of being awarded a Departmental and Star Award for outstanding contribution to aviation safety, outstanding leadership, and technical contributions in support of the 2018 Mount Kilauea volcano research. This multi-bureau effort required our team to assist in surveillance of the volcanic eruption for situational awareness while conducting scientific measurements under extremely hazardous conditions. The use of UAS allowed scientists to expand on data collection capabilities while significantly reducing risk to staff in the field. It was my first experience with ground-shaking earthquakes and 180 foot tall lava fountains which had me in awe of the earth’s natural process. I’m grateful that I was able to be part of this groundbreaking (no pun intended) research team! 

 

Favorite quote?

“The Earth is Art, The Photographer is only a Witness.”
– Yann Arthus Bertrand 

Mark checks the spatial data downloaded from the drone to make sure that the first UAS flight accurately collected snowpack data.
A photo shows USGS scientist Victoria Scholl smiling off to the right of the photographer. Victoria stands in front of a gravel parking lot with mountains in the background. Victoria is using an iPad and controller to pilot a drone. Victoria wears a brimmed-hat, sunglasses, and a grey T-shirt. Blue skies with lots of clouds frame the top of the photo.
Victoria Scholl, USGS Physical Scientist.

 

 

VICTORIA SCHOLL

USGS Physical Scientist

 

What is your role, your piece of work, on the Snow to Flow project?

I also work as a scientist on the USGS NUSO team. Our group's mission is to help federal researchers use uncrewed aircraft systems (UAS, also known as drones) for diverse research applications. 

For the snow to flow project, my role was assisting with project planning, communication between teams, and project documentation. This project involved coordination between a series of teams including multiple UAS crews and field crews. I created georeferenced maps with important features that could be accessed offline from each person's mobile device in the field. For instance, the field-based crews needed to avoid avalanche terrain, navigate to snow pits and deploy ground control targets at predetermined locations across Berthoud Pass.

This graphic shows a quote from Victoria’s narrative. It reads: “My background is in imaging science: the capture, processing, display, and analysis of imagery.“ Yellow quotation marks bookend her quote.

Due to the mountainous terrain, the UAS crews wanted a map showing the downlink signal strength between the aircraft and the controller held by the UAS operators. 

To facilitate communication between teams, I closely monitored our radios and reported when UAS flights began and ended. In support of science communication efforts, I photographed the field work and wrote content for website and social media use to share this snow to flow project with the public. 

 

What was your path like to get here?

My background is in imaging science: the capture, processing, display, and analysis of imagery. I became interested in scientific applications of cameras and decided to pursue a graduate degree in geography, a multidisciplinary field with ample opportunities for applied environmental remote sensing. Alongside my graduate studies, I worked as a part-time temporary intern with the USGS NUSO team with a focus on spectral data processing and calibration. After my temporary position ended, I applied to be a full-time scientist with the USGS NUSO team. I enjoy the versatility of our work. From mapping snowpack in the mountains to identifying invasive grasses at coastal marshes, no two UAS projects are the same.

Victoria is crouched down in the snow, working on the USGS drone. The drone is black with yellow accents. Victoria is wearing dark snowgear and a ballcap. Snow covers the foreground. In the distant background, snowy mountains and a few evergreen trees dot the landscape.
Victoria works on the USGS UAS equipment. 

 

What are you most proud of?

I'm proud of being awarded a Fulbright research fellowship to improve forest inventory efforts using airborne lidar in the beautiful country of Switzerland. For a year, I lived in Zurich and was fortunate to connect with and learn from amazing people from all over the world. I met lifelong friends who helped me become more open-minded and appreciative of differing perspectives and cultures. 

 

Favorite quote?

"It is invaluable to have a friend who shares your interests and helps you stay motivated." - Maryam Mirzakhani 

 

Learn more about the science behind the Snow to Flow project in this interactive Storymap!