George H. Allen
@geoallen
Hydrologist and satellite enthusiast. Associate Professor at Virginia Tech
🚨Job Alert!🚨 I'm recruiting a postdoc starting Fall '26 or Spr '27 focused on: (1) Satellite remote sensing of inland surface water (2) Hydrologic applications of geospatial foundation models, LSTMs, or other AI/ML approaches. If you're interested, DM me or fill out this form: lnkd.in/gf3fMmx8
We will convene our long-running #AGU session this fall: Remote Sensing of Rivers, Lakes and Wetlands. Consider submitting an abstract! Invited presenters: Dongmei Feng (U of Cincinnati) and Lian Feng (Wuhan U) Conveners: George Allen, Huilin Gao, Jessica Fayne, Ted Langhorst, Anshul Yadav
Q: How much do dams alter river temperatures in the US? A: Quite a lot, according to Landsat data Check out our new paper in Science Advances: Satellite observations reveal widespread alteration of river thermal regimes by US dams doi.org/10.1126/scia...
Our new paper uses #SWOT_satellite data to differentiate between natural & managed lake dynamics across North America. We find that inflows & outflows of managed lakes are significantly more variable than natural lakes, revealing signatures of reservoir operations: doi.org/10.1088/1748...
New paper by Katie McQuillan leverages satellite radar to map lake evaporation at 25× finer resolution than operational surface analysis products, opening up applications from improved gauge placement to evaluating geoengineering strategies doi.org/10.1109/LGRS...
This weekend my research group volunteered at the Claytor Lake Mussel Salvage event near Blacksburg, VA. We surveyed and relocated hundreds of native mussels during the scheduled biennial lake drawdown. #UtProsim @vtgeosciences.bsky.social @vt-science.bsky.social
"Seen" meaning retrieved water surface elevation data over rivers while a flood wave is propagating down a river. Here are three examples of flood waves/flow waves traveling down rivers, including one in the Colorado River, TX - near the Guadalupe River:
This has implications for how we calculate river and stream surface area (RSSA) at the global scale
Scaling these widths across the Mississippi basin, we find an emergent fractal distribution of river widths (black line)
🚨New paper🚨 shows a remarkably clean relationship between river width and stream order across the US 𝑇ℎ𝑒 𝑊𝑖𝑑𝑡ℎ𝑠 𝑜𝑓 𝑅𝑖𝑣𝑒𝑟𝑠 𝑎𝑛𝑑 𝑆𝑡𝑟𝑒𝑎𝑚𝑠 𝐴𝑐𝑟𝑜𝑠𝑠 𝑆𝑝𝑎𝑡𝑖𝑎𝑙 𝑆𝑐𝑎𝑙𝑒𝑠... 🔗 doi.org/10.1029/2025... #hydrology #geomorphology #rivers #RemoteSensing
Using multi-scale remote sensing and fieldwork, we found that river widths of each stream order exhibit a very predictable log-normal distribution:
Hana (grad student in my group) will be doing a research internship at JPL this summer. Here she is on her first day on the job. Good luck, Hana!! 🚀🚀🚀
Hydrologists! Ever heard of a Spatial Hydrograph? Our new paper in @agu.org GRL shows that the SWOT satellite can capture spatial flow waves propagating down rivers—something previously only only observable at river gauges: doi.org/10.1029/2024... #SWOT #hydrology #RemoteSensing #EarthObservation
Congrats to Luisana Rodriguez Sequeira, who successfully defended her Master's Thesis on satellite #remotesensing of #microplastics in rivers! I had the pleasure of co-advising with Dr. Austin Gray @austindoug13.bsky.social. She presented to a standing-room-only crowd—well done, Luisana!
This wind data is useful for estimating lake evaporation rates, lake-air greenhouse gas exchange, and for optimal placement of lake infrastructure. Here's a university press release on the study: news.vt.edu/articles/202...
Our new paper maps wind fields over lakes using radar backscatter from SWOT and Sentinel-1 satellites. This technique achieves a much higher spatial resolution than what is available from atmosphere reanalysis products: agupubs.onlinelibrary.wiley.com/doi/10.1029/...
A graduate student takes a stream width measurement on Stroubles Creek, Virginia Tech.
New paper by Dongmei Feng finds an interesting pattern in global streamflow trends through time: increasing streamflow in upstream river reaches and decreasing flow in downstream reaches: www.science.org/doi/full/10....
Cool paper alert: Yu et al. used SWOT satellite observations of the ocean's surface height to create a global seafloor map at 8-km resolution: about twice the spatial resolution of previous global maps! science.org/doi/full/10....
Great day to show our department's incoming graduate students around the Blacksburg area. Thanks @clasticdetritus.bsky.social for letting me tag along!
Looking for an alternative to MDPI Remote Sensing or Remote Sensing of Environment? Check out the AAAS Science partner journal, Journal of Remote Sensing. Several of us early career folks are guest editing a "Remote Sensing of Hydrology" special issue. Consider submitting your work!
How good are new and future satellites at tracking suspended sediment in rivers? Find out in our new IEEE TGRS paper "Optimizing Satellite Mission Requirements to Measure Total Suspended Solids in Rivers" led by grad student Molly Stroud at Virginia Tech! ieeexplore.ieee.org/abstract/doc...