Global Rivers Group
@Virginia Tech
We use satellites, models and fieldwork to study Earth's freshwater
We're an academic research group in the Department of Geosciences at Virginia Tech. We are recruiting students and postdocs who are interested in using emerging technology to solve problems involving freshwater resources.
What we do
We study inland waters using satellite data, fieldwork, and computer models. We seek to understand how climate change and land use are altering the global water cycle, in particular river and lake hydrology. With rapid advancements in sensor technology, computing power, and model sophistication, it is an exciting time to be studying freshwater at the global scale.
Why we do it
Water is widely considered to be the world’s most vital natural resource, yet freshwater systems are being rapidly degraded by human activities. Our work is motivated by a desire to promote the conservation, management, and understanding of Earth's surface water resources.
News
Updated Dec 2, 2025
Dec 1, 2025—Paper published in GSA Today titled "SWOT Satellite: A New Tool for Fluvial Geomorphology" and featured on the December issue cover. This paper was led by Molly Stroud at Virginia Tech and showcases how SWOT's inSAR data can be used for a wide array of applications in the field of fluvial geomorphology. Well done Molly and congratulations!
https://doi.org/10.1130/GSATG630A.1
Nov 15, 2025—Emily, Yohtaro and Steve present their research at the 2025 Virginia Tech Science Festival. https://ceni.icat.vt.edu/programs/science-festival.html
Nov 12, 2025—George is named a Highly Cited Researcher by Clarivate. 🏆 Highly Cited Researchers demonstrate significant and broad influence in their field of research. News article:
https://news.vt.edu/articles/2025/11/research-highly-cited-clarivate-2025.html
Nov 8, 2025—The Global Rivers Group volunteer at the Claytor Lake Mussel Salvage and cleanup event near Blacksburg, VA. Emily, Yohtaro, Hana, David, Steve and George surveyed and saved hundreds of native mussels during the scheduled lake drawdown.
Nov 7, 2025—Emily and Hana present an interactive lesson on river hydrology to kindergarten students at Eastern Elementary School in Giles County, VA. Their visit was covered by a local newspaper, the Virginian Leader: https://2175.newstogo.us/editionviewer/default.aspx?Edition=80ec6b01-7854-449f-bd9c-b026c17bc426
Oct 31, 2025—Paper entitled "A transferable deep learning framework to propagate extreme water levels from sparse tide-gauges across spatial domains" published in the journal Expert Systems With Applications. Led by Sam Daramola in the Department of Civil and Environmental Engineering at Virginia Tech, this study presents a geographically transferable machine learning approach to predict coastal flooding. Hana and George are coauthors: https://doi.org/10.1016/j.eswa.2025.130222
Oct 10, 2025—Hana and George travel to Arcachon, France to attend and present at the 2025 SWOT Science Team Meeting: https://swot2025.org/
Sep 25, 2025—Emily travels to Salem, Virginia to present her research at the annual Flip the Fair science fair and expo, attended by local fifth grade students.
Sep 12, 2025—George appears on the VT GeosChat Podcast with Rose McGroaty. Excerpt 1; Excerpt 2; Full Episode
Aug 29, 2025—Molly Stroud successfully defends her PhD dissertation entitled, "Exploring Innovative Methods to Study Inland Waters Using Remote Sensing". 🎉 Molly's dissertation focused on developing new approaches for satellite remote sensing (multispectral, hyperspectral, SAR, lidar) of suspended sediment and bedload transport within rivers and lakes. Molly will start a research postdoc in September 2025 with Cayelan Carey and Quinn Thomas in VT Biological Sciences.
Aug 18, 2025—Steve Yoon joins the Global Rivers Group as a PhD Student. Steve completed his Bachelors at UNC Chapel Hill and his Master's at SMU in Dallas, Texas. Welcome Steve!
Jul 30, 2025—George travels to Oxford, England to meet with international collaborators Louise Slater and Michel Wortmann.
Jul 22-23, 2025—David, Brenna and George run a field trip and workshop for 48 rising high school seniors as part of the VT College of Science Explore Physical Sciences Summer Camp Program. Students collected field measurements along Toms Creek and analyzed their observations, among other activities!
Jul 22, 2025—New review paper published in Reviews of Geophysics titled, "Progress towards satellite requirements to capture water propagation in Earth's rivers", which was led by Dr. Arnaud Cerbelaud at JPL. This paper summarizes recent efforts to identify the type of remote sensing observations that could enhance understanding and representation of river dynamics, and makes suggestions to further the field. George is a co-author. https://doi.org/10.1029/2024RG000871
Jun 8, 2025—Paper published in Geophysical Research Letters titled, "Mapping Reservoir Water Surface Area in the Contiguous United States Using the High-Temporal Harmonized Landsat and Sentinel (HLS) Data at a Sub-Weekly Time Scale". This paper generated accurate, high-frequency observations of lake surface areas over the contiguous U.S. using the Harmonized Landsat Sentinel-2 data product. The study was led by Anshul Yadav and supervised by Dr. Huilin Gao at Texas A&M University. George Allen and Katie McQuillan are co-authors. https://doi.org/10.1029/2024GL114046
Jun 4, 2025—Paper published in Earth System Science Data titled, "Mapping the world’s inland surface waters: an update to the Global Lakes and Wetlands Database (GLWD v2)". Led by Bernhard Lehner at McGill University, this paper presents the first fine-scale harmonized global map of inland surface waters. George is a co-author. https://doi.org/10.5194/essd-17-2277-2025
Jun 3, 2025—George is promoted to Associate Professor with tenure at Virginia Tech! https://news.vt.edu/articles/2025/06/bov-promotion-tenure-2025.html
Jun 1, 2025—The Washington Post covers Hana's paper on SWOT's ability to observe flow waves traveling down Earth's rivers: wapo.st/43UuquB
May 29, 2025—Carter's paper published in Geophysical Research Letters, "The Widths of Rivers and Streams Across Spatial Scales: A Framework for Improving River-Atmosphere Biogeochemical Exchange Estimates". This paper shows that river widths can be represented at different stream orders using a predictable log-normal distribution, which when summed across a river network, forms a characteristic Pareto distribution. Very nicely done, Carter!
https://doi.org/10.1029/2025GL115713
May 27, 2025—Hana starts her summer internship at the Jet Propulsion Laboratory (JPL) in Pasadena, CA. She will work with Dr. Cedric David and Dr. Arnaud Cerbelaud on studying rivers with the SWOT satellite. Have fun, Hana! 🚀
May 21, 2025—NASA publishes a news article covering Hana's recent study on observing flow waves with SWOT: https://www.nasa.gov/missions/swot/nasa-french-satellite-spots-large-scale-river-waves-for-first-time/