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Global Rivers Group
@Virginia Tech

We use satellites, models, and fieldwork to study Earth's freshwater

Home: Overview

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. 

Home: Services


Updated April 5, 2024

Apr 5, 2024— Hana, Yohtaro, Luisana and George present their research at the Virginia Tech Office for GIS and Remote Sensing Research 2024 Symposium. No bagels to be had. 


Mar 22, 2024—Carter Boyd and Emily Ellis win best research presentation at the 2024 Graduate Student Research Symposium. John Morgan wins best sculpture for his fish masterpiece. Congratulations, Carter, Emily and John!  

Mar 21, 2024—GRG grads Molly Stroud, Carter Boyd, Emily Ellis, Hana Thurman, and Luisana Rodriguez Sequeira give talks on their research projects at the 2024 VT Geosciences Graduate Student Research Symposium. Lab alum, John Morgan, also enters his large fish sculpture. Great representation by the GRG at GSRS, well done grads! 

Mar 11, 2024Emily Ellis publishes her first review paper! The paper is published in WIREs WATER and is entitled, Bridging the divide between inland water quantity and quality with satellite remote sensing: An interdisciplinary review. This paper summarizes the current understanding, research trends, and potential steps forward for bridging chemical and physical hydrology. Congratulations, Emily! 

Feb 21, 2024—George receives a NASA Early Career Investigator Award (ECIP-ES) to investigate and quantify river and stream surface light availability at the global scale. 

Feb 16, 2024—George is selected for the 2024 Early Career Award for Applied Research by the Universities Council on Water Resources (UCOWR) for outstanding contributions in applied research related to water. 

Feb 9, 2024—George travels to Southern Methodist University in Dallas, TX to visit the Department of Earth Science and give a seminar talk entitled, "Beyond the gauge: A global view of rivers and lakes".  

Feb 7, 2024—Ryan Riggs defends his dissertation entitled "Improving Access To River Discharge Data Through Satellite Remote Sensing". Ryan's committee was impressed with his presentation and the overall quality of his dissertation. Ryan is graduating with a tenure track job offer from an R1 university, multiple postdoc offers including one from the USGS Mendenhall program. 

Feb 6, 2023—George travels to College Station, TX to attend Ryan Riggs' dissertation defense and meet with old friends and collaborators. Ryan is George's first PhD student. 

Dec 11, 2023—George, Katie, Emily, Molly, Carter and Yohtaro travel to San Francisco to attend, convene, and present their research at the 2023 AGU Fall Meeting:

Nov 29, 2023—Molly Stroud publishes her first journal article! The paper is published in IEEE Transactions on Geoscience and Remote Sensing and is entitled, Optimizing satellite mission requirements to measure total suspended solids in rivers. This paper shows how well satellites can track suspended sediment in rivers by resolving the observational trade space through a data degradation experiment. Congratulations, Molly! 

Oct 12, 2023—Three Virginia Tech undergraduate students join the Global Rivers Group as Undergraduate Research Assistants. Welcome, Tori Cooper, Jordan Lavey and Shaurya Prakash!

Sep 17, 2023—Katie and Ryan travel to Toulouse, France to attend the first SWOT Science Team Meeting since the launch of the SWOT satellite in December 2022: 

Sep 13, 2023—Baby boy Alden Allen joins the Global Rivers Group family. 

Aug 29, 2023—The GRG hosts Dr. Fangfang Yao as a visiting scholar for 2 days in Blacksburg. Fangfang is a postdoctoral researcher at University of Virginia and studies global remote sensing of hydrology, particularly lakes  

Aug 26, 2023—The GRG participates in the "Fall into the New" river cleanup event near Blacksburg. We spent the morning traversing the New River in 4 canoes, collecting items including cans, golf balls, and a tire! 

Aug 14, 2023—Luisana Rodriguez Sequeira joins the Global Rivers Group as an incoming Masters student in Geosciences. Luisana graduated cum laude from the University of California at Santa Cruz in 2022 as a double major in Earth Sciences and Mathematics. She will be working on a project investigating relationships between water quality and plastic pollution in freshwater bodies. Welcome aboard, Luisana! 

Aug 10, 2023—Dr. Katie McQuillan joins the Global Rivers Group as a Virginia Tech Presidential Postdoctoral Fellow. Katie received her PhD from NC State University in the Geospatial Analytics Center working with Dr. Katie Martin. She will be working on using the SWOT satellite's measurements to estimate evaporation rates in reservoirs. Welcome to the GRG, Katie! 


Aug 8, 2023—Paper published in Earth System Science Data entitled "Lake-TopoCat: a global lake drainage topology and catchment database", led by Md Safat Sikder and Jida Wang at Kansas State University. This paper harmonizes global lake and river hydrography data together to create novel and freely available lake topography dataset:

Aug 2, 2023—George, Ryan, Emily, Molly, Carter, Yohtaro and Katie all submit their abstracts to the 2023 AGU Fall Meeting in San Francisco, CA. See you there! 


July 31, 2023—Hana Thurman joins the lab as an incoming M.S. student in Geosciences. Hana graduated summa cum laude from the University of Virginia with a B.S. in Environmental Sciences and Engineering in 2019. She will be using new radar data from the recently launched NASA/CNES SWOT satellite to study inland waters. Welcome to Blacksburg, Hana! 

July 20, 2023—George, Molly, Emily and Yohtaro lead 46 11th and 12th graders to Kentland Farm, VA to conduct field activities along Toms Creek and the New River as part of the VT College of Science Physical Science Summer Camp Program. Campers also contributed to GRG research by generating training and validation data for machine learning algorithms, designed to classify streams from from high-resolution remote sensing imagery. 

July 13, 2023—Paper published in River Research and Applications entitled, "When does a stream become a river?", in which we propose that "streams" are flowing water bodies in channels narrower than 15 m and "rivers" are in channels 15 m or wider.

July 3, 2023—Carter and George travel to Nederland, Colorado to do fieldwork in beautiful Indian Peaks Wilderness. Carter will spend 4-6 weeks surveying headwater streams with GRG team members as part of our NSF funded project on constraining scaling principles of the river-atmosphere interface. 

June 20, 2023—George presents findings from Riggs et al (2023) and Riggs et al (2023) at the SWOT Discharge Algorithms Working Group meeting. 

June 14, 2023—George travels to Bristol, UK to attend the RIOS workshop, which had the goal of establishing a global river observation network with an emphasis on carbon dynamics.  

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