Feb 26, 2020 | Blog, Featured researchers
Ken McGwire, Ph.D., is an associate research professor of geography with the Division of Earth and Ecosystem Sciences at the Desert Research Institute in Reno. He specializes in environmental mapping, monitoring and modeling using satellite imagery and geographic information systems (GIS), software for viewing and analyzing geographical data. Ken came to DRI in 1994 from the University of California Santa Barbara, where he earned bachelor’s, master’s, and doctoral degrees in geography. In his free time, he enjoys skiing and backpacking in the Sierra Nevada.
DRI: What do you do here at DRI?
Ken McGwire: I study how things vary in space and across time in the environment, using satellite image analysis, computer mapping, and general database and programming skills. I came to DRI 25 years ago from U.C. Santa Barbara with degrees in physical geography, and what I’ve worked on here at DRI has been all over the place. There are so many cool interdisciplinary connections you can make here; I’ve found a lot of opportunities to apply the sorts of ways I look at the world to other disciplines.
I’ve worked on everything from 3-D imaging projects with paleontologists, to scanning images of ice cores, to working with virologists from the University of Nevada, Reno on epidemiology studies. I was a member of the science team for a NASA satellite mission called “Earth Observing 1,” looking at the ability to map invasive species with a type of technology called hyperspectral imaging. Lately, I’ve been doing a lot of work with some of the older, well-used satellite systems – making use of the long archive of historical observations to look at how the environment has varied and may be changing over time.
DRI: We understand that you’ve recently completed a detailed statewide map of all of Nevada’s wetland areas. Can you tell us about that project?
McGwire: Yes, about two years ago, I was awarded a grant from the US Environmental Protection Agency through the Nevada Natural Heritage Program, in collaboration with the Nature Conservancy, the Spring Stewardship Institute, and the Nevada Division of Wildlife, to develop a better understanding of the distribution of where wetlands are in Nevada, and to develop tools for characterizing how they change over time.
Different land management agencies define wetlands differently – the boundary for what the Forest Service uses to define a wetland may be different from what the Bureau of Land Management uses, for example. So, the first part of that project was to compile a statewide map of Nevada’s wetlands using data from multiple different agencies and sources. This map is now available on the DRI website.
A second part of that project was to develop a wetland analysis tool to help land managers and scientists from across the state better understand how various wetland areas have been changing over time. This tool, called WetBar, is used within the ArcMap GIS software package. It links the state wetland map with information about each wetland, and with an archive of satellite imagery dating back to 1985 that is available in Google Earth Engine.
McGwire’s wetland map and WetBar ArcGIS analysis tool can be used to learn about how wetland areas in Nevada are changing over time. This wetland is located at The Nature Conservancy’s 7J Ranch Preserve near Beatty, Nevada.
DRI: How is this wetland analysis tool used? Can you give us an example?
McGwire: WetBar allows you to identify, group, and sort different wetland sites based on different criteria. I can use it to look at the boundary of a water body like Lake Mead, and how the shoreline of the lake has retreated or flooded over time. For example, using Landsat satellite imagery that goes back to 1985, I can use this tool to select only areas of the lake that have been flooded for 15 to 30 years, and create a map of just that area. This might help researchers get a feel for site conditions prior to visiting a field site, or help them to visualize the impacts of water withdrawals or changes in climate on a water body like Lake Mead.
There are a lot of other ways you can use this tool. You can sort all of the wetland areas in the database by climate sensitivity, based on how much the wetlands have changed in satellite imagery over the last three decades. This could help land managers to prioritize certain sites for protection, or determine how frequently a certain species can withstand flooding. You can use it to monitor reservoir depletion, or how long it takes a reservoir to fill. I recently received funding to provide outreach to people about what this toolbar can do, and try to get feedback on what other functions would make it more useful to decision makers, so more capabilities may be added as the project moves forward.
(Click to enlarge) Screenshot of a wetland map made using the WetBar ArcGIS toolbar. By linking satellite imagery to known data about various wetlands in Nevada, scientists can use this tool to learn about changes in water and vegetation cover over time.
DRI: Does your any of your work take you out into the field? McGwire: Yes, definitely. Most of my fieldwork in the last couple years has been supporting the Great Basin Unified Air Pollution Control District (GBUAPCD)’s efforts to control dust emissions from Owens Lake, which has become mostly a dry lakebed since the 1920s due to water diversion to Los Angeles. The lakebed is in a desert environment, and as the wind blows, clouds of sediment can blow toward Arizona. It was the biggest source of PM10 air pollution in the country for a while.
To mitigate the dust, GBUAPCD has developed a variety of land cover treatments. They’ve turned portions of the lakebed into detention areas, which can be shallow flooded. They do drip irrigation of saltgrass in areas that have natural vegetation, to try to get vegetation to establish and grow on the lakebed. They spread gravel in some areas, and in other areas they’re distributing some of the natural brines from the center of the lake to form a hard salt crust. So I’ve been working with the GBUAPCD to develop monitoring methods to monitor the status of these treatments, which requires creating maps of treatment areas, as well as field visits to monitor conditions on the ground.
What do you enjoy most about your line of work?
McGwire: Working with satellite imagery is very visual, and the scientific investigation aspect of what we do creates a lot of variety in terms of intellectual stimulation. There’s a creative aspect to it, a visual aspect to it, and I enjoy finding ways to make that sort of way of looking at the world useful to other people.
To learn more about Ken McGwire and his work, please visit his DRI directory page.
Jan 22, 2019 | News releases, Research findings
Reno, Nev. (Jan. 22, 2018): Many Western communities rely on snow from mountain forests as a source of drinking water – but for scientists and water managers, accurately measuring mountain snowpack has long been problematic. Satellite imagery is useful for calculating snow cover across open meadows, but less effective in forested areas, where the tree canopy often obscures the view of conditions below.
Now, a new technique for measuring snow cover using a laser-based technology called lidar offers a solution, essentially allowing researchers to use lasers to “see through the trees” and accurately measure the snow that lies beneath the forest canopy.
In a new study published in Remote Sensing of the Environment, an interdisciplinary team of researchers from Desert Research Institute (DRI), the University of Nevada, Reno (UNR), the California Institute of Technology’s Jet Propulsion Laboratory, and California State University described the first successful use of lidar to measure snow cover under forested canopy in the Sierra Nevada.
“Lidar data is gathered by laser pulses shot from a plane, some of which are able to pass light through the tree canopy right down to the snow surface and create a highly accurate three-dimensional map of the terrain underneath,” explained lead author Tihomir Kostadinov, Ph.D., of California State University San Marcos, who completed the research while working as a postdoctoral researcher at DRI. “Passive optical satellite imaging techniques, which are essentially photographs taken from space, don’t allow you to see through the trees like this. We are only starting to take full advantage of all the information in lidar.”
Rowan Gaffney (UNR) surveying the amount of snow at Sagehen Creek Field Station during the NASA airborne campaigns in March 2016. Credit: A. Harpold.
In this study, researchers worked with NASA’s Airborne Snow Observatory to collect lidar data at the University of California, Berkeley’s Sagehen Creek Field Station in the Sierra Nevada by aircraft on three dates during spring of 2016 when snow was present. Additional lidar data and ground measurements facilities by the long-term operation of Sagehen Creek field station were critical to the success of the study.
Analysis of the datasets revealed that the lidar was in fact capable of detecting snow presence or absence both under canopy and in open areas, so long as areas with low branches were removed from the analysis. On-the-ground measurements used distributed temperature sensing with fiber optic cables laid out on the forest floor to verify these findings.
Tree canopies interact with the snowpack in complex ways, causing different accumulation and disappearance rates under canopies as compared to open areas. With the ability to use lidar data to measure snow levels beneath trees, snow cover estimates used by scientists and resource managers can be made more accurate. The importance of this advance could be far reaching, said team member Rina Schumer, Ph.D., Assistant Vice President of Academic and Faculty Affairs at DRI.
“In the Sierra Nevada, April 1st snow cover is what is used to estimate water supply for the year,” Schumer said. “Being able to more accurately assess snow cover is important for California and Nevada, but also all mountainous areas where snowpack is essential to year-round water supply.”
Snow cover estimates are also used by hydrologists for streamflow forecasts and reservoir management. Snow cover data is important to ecologists and biologists for understanding animal migration, wildlife habitat, and forest health, and it is useful to the tourism and recreation industry for informing activities related to winter snow sports.
Rose Petersky (UNR) surveying the amount of snow under the forest canopy at Sagehen Creek Field Station during the NASA airborne campaigns in April 2016. The photo clearly shows the reduced snow cover under the canopy that is difficult to measure with satellites. Credit: A. Harpold.
Although lidar data is currently collected via airplane and not easily accessible by all who might like to use it, the study team believes that information gleaned from this study could be used to correct data derived from satellite imagery, which is already widely available from NASA’s MODIS sensor and NASA/USGS’s Landsat satellites.
“This is proof of concept for the method that we think could really expand the extent that we measure snow at high resolution in forests,” said team member Adrian Harpold, Ph.D., Assistant Professor with the Department of Natural Resources at UNR. “I’m now working with a student to extend this approach across multiple sites to improve our understanding of the relationship between snow cover in the open versus under the tree canopy. Then, we hope to use that information to correct and improve satellite remote sensing in forested areas.”
This study was part of a larger NASA EPSCoR project titled Building Capacity in Interdisciplinary Snow Sciences for a Changing World, which aimed to develop new research, technology, and education capacity in Nevada for the interdisciplinary study of snowpack. Objectives included an educational goal of training the next generation of scientists.
“This project brought together people who look at snow from different scientific perspectives, and generated a conversation amongst us,” said Alison Murray, Ph.D., Research Professor at DRI and principal investigator of the NASA EPSCoR project. “In addition to bringing together expertise from three institutions in Nevada (DRI, UNR, and UNLV) in hydrology, remote sensing, geosciences, atmospheric chemistry and snow associated life, we developed strategic alliances with NASA’s airborne snow survey. Where the Nevada researchers might have been studying snow on our own, this interdisciplinary project allowed us to look at snow in an integrated fashion and make some important advances.”
The full study, titled Watershed-scale mapping of fractional snow cover under conifer forest canopy using lidar, is available online from Remote Sensing of the Environment: https://www.sciencedirect.com/science/article/abs/pii/S0034425718305467
The Desert Research Institute (DRI) is a recognized world leader in basic and applied interdisciplinary research. Committed to scientific excellence and integrity, DRI faculty, students, and staff have developed scientific knowledge and innovative technologies in research projects around the globe. Since 1959, DRI’s research has advanced scientific knowledge, supported Nevada’s diversifying economy, provided science-based educational opportunities, and informed policy makers, business leaders, and community members. With campuses in Reno and Las Vegas, DRI serves as the non-profit research arm of the Nevada System of Higher Education. Learn more at www.dri.edu, and connect with us on social media on Facebook, Instagram and Twitter.
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