SAFL building

Every week during the academic year, SAFL hosts prominent figures in environmental science and fluid mechanics. They come from all over the US and the world to share their insight and inspire us to tackle important questions in the field. These seminars are free and open to the public. Join us to learn about the latest research advancements and network with contacts in the field.

SAFL seminars are held on Tuesdays, from 3:00 to 4:15 p.m., either online, in the SAFL Auditorium or as hybrid events. 

Spring 2023 Seminar Series

February 14th Jacqueline Reber, Iowa State University

February 21st – Blair Johnson, UT Austin

February 28th – Hamid Moradkhani, University of Alabama

March 14th – Grae Worster, University of Cambridge

March 21st – Guiju Song, General Electric

March 28th – Michael Lamb, California Institute of Technology

April 4th Vicente Diaz, University of Minnesota

April 11th – Kenneth Belitz, United States Geological Survey

April 18th Ruben Juanes, Massachusetts Institute of Technology 

April 25th – Keith Moored, Lehigh University

May 2nd Peter Sullivan, National Center for Atmospheric Research

We will record seminars and post them here when given permission by the speaker. To see if a recording is available, scroll down this page to "Past Seminars."

Seminar Notifications
To sign-up for our SAFL Seminar email list, click here.

Upcoming Seminars

“Stay Ashore” … Offshore Wind O&M Automation - Guiju Song, GE Research

Guiju Song, Platform Leader, Offshore Wind, at GE Research located in Niskayuna, NY

AbstractOffshore wind energy is critical to realize the world’s greenhouse gas reduction goal. In the US, the Biden administration has set up the goal of deploying 30GW of offshore wind capacity by 2030. Reducing the levelized cost of energy (LCOE) is key to the large-scale deployment. Offshore operation & maintenance (O&M) cost could potentially contribute to 35% of the LCOE. Therefore, GE launched the “Stay Ashore” O&M strategy aiming to apply digital innovations and automation to significantly lower the offshore O&M cost.  The “Stay Ashore” vision contains four element steps – connect, analyze, manage, and optimize. This seminar focuses on deep diving GE’s research projects funded by the National Offshore Wind Research and Development Consortium (NOWRDC) as the examples for the two steps of “analyze” and “manage”.

The first project is titled as “Enabling condition based- maintenance for offshore wind”. Applying digital innovations such as AI and digital twin to enable condition-based maintenance (CBM) has been proved to be effective in many industries. However, the offshore wind farms in operation today in the US water only have 42 MW of capacity commissioned in the recent few years. There is not a lot of operational history and data to track. Therefore, one of the key challenges in implementing AI and digital twin for offshore wind is lacking historical operational data required for AI/ML model development and validation. Our team was funded by NOWRDC to investigate and develop technical solutions to realize full CBM in offshore wind. To address the data sparsity challenges, we first explored the feasibility of utilizing physics-based models (digital twins) to augment the limited available operational data. Second, an AI/ML modeling method was carefully selected and developed to accurately estimate blade health state over time. Third, the limited data collected from the real-world turbines was utilized to calibrate the AI model.

The second project is titled as “Autonomous Vessel-Based Multi-Sensing System for Inspection and Monitoring”.  The current available inspection and monitoring strategies for offshore wind are either cost prohibitive or limited by varying offshore operational conditions such as weather and sea states. Our project aims to develop a multi-sensing system to conduct robust inspection at varying sea conditions. Such system can enable adaptation of proven technologies from onshore to offshore wind, advance offshore O&M strategy, reduce LCOE, and accelerate the U.S.’s ability to economically deploy offshore wind technology.

At last, I will summarize the key ingredients in our success of completing the first project and elaborate how this innovation can be leveraged and expanded to other applications. I will then reiterate our perspectives on the “Stay Ashore” vision for the offshore wind O&M. 

Guiju Song

AboutDr. Guiju Song is currently the Platform Leader, Offshore Wind, at GE Research located in Niskayuna, NY. In this role, Dr. Song leads the strategic growth and multi-generation technology planning process for Offshore Wind at GE Research. She manages a multi-million R&D project portfolio and supports transitioning the technologies developed by GE Research to new products of GE’s Offshore business. Dr. Song is also a Principal Investigator (PI) and a T2M (technology to market) manager for GE’s government funded Offshore Wind projects.  Prior to her current role, Dr. Song led a team to develop artificial intelligence (AI) and digital technologies to solve challenging industrial problems in the renewable energy and aerospace industries. During her 18+ years of professional experience, Dr. Song has been instrumental in leading multi-disciplinary teams, bridging AI/ML with physics to enable better industrial asset reliability and performance management. As a result of her innovative work in this cross-disciplinary area, Dr. Song has filed 31 US patents. Before joining GE, Dr. Song conducted postdoctoral research in Oregon Health & Science University on Bio-medical engineering. and received her Ph.D. in Optical Engineering from the Chinese Academia of Sciences in 2001.

Charles C.S. Song Fellowship Award Ceremony with Distinguished Lecture by Prof. Michael Lamb

Join us on Tuesday, March 28th at 3pm for a celebration of the 2023 Charles C.S. Song Fellowship recipient Shih-Hsun Huang, with a distinguished lecture by Prof. Michael Lamb.

Michael Lamb, Professor in the Division of Geological and Planetary Sciences at the California Institute of Technology

Distinguished lecture: Mud flocculation and the global sediment cycle

AbstractRiver sediment loads are dominated by mud, which builds lowland landscapes and buries large amounts of organic carbon. While mechanistic theories exist for transport of suspended sand, mud in rivers is often thought to constitute washload—sediment with settling rates so slow that it does not interact with the land surface. The washload hypothesis, however, is seemingly at odds with the muddy terrain that abounds globally. Here I summarize recent work by our group to show that mud in many rivers is flocculated with settling velocities much larger than expected for individual particles, which allows it to interact with and deposit on the land. Our results help to explain why muddy landscapes exist today, why they were less abundant earlier in Earth history, and why anthropogenic disruption of the global sediment cycle is causing major unintended land loss.

Mike Lamb

AboutMichael Lamb is a professor in the Division of Geological and Planetary Sciences at Caltech. Lamb’s research combines theory, field observations and flume experiments to understand landscape form and dynamics through the mechanics of erosion, sediment transport and deposition. Current projects include riverbank erosion in permafrost, coastal land building at river deltas, and ancient rivers on Mars. He received his PhD from U.C. Berkeley in Earth and Planetary Science, M.S. in Oceanography from the University of Washington, and B.S. in Geology and Geophysics from the University of Minnesota. He got his start at SAFL as a “junior scientist” from 2000-2001, conducting experiments on turbidity currents in the Garcia Flume, with the help of Gary Parker, Jeff Marr, Chris Paola, Tom Hickson, Chris Ellis and others. His grandfather worked somewhat successfully with Lorenz G. Straub.

2023 Charles C.S. Song Fellowship recipient Shih-Hsun Huang, advised by Prof. Judy Yang

Presentation titleExperimental investigations of hyporheic flow in channels with vegetation and large woody debris

AbstractIn-channel aquatic vegetation and large woody debris exert drag on the surface flow and create the heterogeneity of a hydraulic head along the stream bed, which drives a bi-direction flow through the sediment-water interface, or hyporheic flow. Hyporheic flow increases the retention time of solutes, organic matter, and fine particles, which controls the biogeochemical cycles of the benthic habitats and determines the retention and degradation of contaminants in the stream. While aquatic vegetation and large woody debris have been recognized to induce hyporheic flow in recent field and numerical studies, visualization and systematic quantification of hyporheic flow induced by aquatic vegetation and large woody debris remain lacking due to the opaqueness of sediment, vegetation, and woods. I will describe how we developed a refractive index match-based method to quantify the impact of vegetation and large woody debris on hyporheic flow in a laboratory flume.

Shih-Hsun Huang

AboutShih-Hsun Huang is a PhD candidate in civil engineering at the St. Anthony Falls Laboratory, studying under Professor Judy Yang. His research is focused on the mass transport across the sediment‐water interface in an aquatic environment. He currently studies the impact of in-channel vegetation and large wood debris on the hyporheic flow. Shih-Hsun received his master's degree in civil engineering from National Taiwan University in 2018. He also completed his bachelor's degree in both civil engineering and life science from National Taiwan University in 2016.


Past Seminars

Heinz G. Stefan Fellowship Award Ceremony with Distinguished Lecture by Prof. Grae Worster

Join us on Tuesday, March 14th at 3pm for a celebration of the 2023 Heinz G. Stefan Fellowship recipient Xiating Chen, with a distinguished lecture by Prof. Grae Worster.

Grae Worster, Professor of Fluid Dynamics in the Department of Applied Mathematics and Theoretical Physics at the University of Cambridge

Distinguished lecture: The dynamics of super-absorbent hydrogels


Abstract: Super-absorbent polymers placed in water can form hydrogels with polymer fractions of less than 1% by volume, with the water molecules being adsorbed by the hydrophilic polymer to form an elastic material.  They are used in disposable diapers, for soil remediation, for controlled drug delivery and as actuators in microfluidic devices.  The water is not fixed in place but can flow through the porous polymer scaffold to drive swelling and shrinkage.  We have developed a new continuum-mechanical approach to modelling super-absorbent hydrogels, which allows for strongly nonlinear swelling while remaining linear in deviatoric strains, in effect treating hydrogels as instantaneously incompressible, linear elastic materials but with material properties that can vary strongly with polymer concentration.  I will describe this model and illustrate its features by solving simple examples of swelling spheres, transpiration through cylinders, and by analysing a morphological instability that can arise during swelling.

Grae Worster

About: Grae Worster completed his PhD at the University of Cambridge, UK in 1983.  His early career included being an Instructor in Applied Mathematics at MIT and an Assistant Professor in Applied Mathematics and Chemical Engineering at Northwestern University.  He is currently Professor of Fluid Dynamics in the Department of Applied Mathematics and Theoretical Physics, University of Cambridge UK, and until recently was Editor of the Journal of Fluid Mechanics.  His research has included mathematical and experimental studies of buoyancy-driven flows and phase change, particularly in situations where these two phenomena interact, applying fundamental understanding to environmental problems including the mechanisms affecting brine drainage from sea ice, the flow and stability of marine ice sheets, and dynamics of frost heave.  His focus has been on formulating mathematical descriptions of multi-component systems, including alloys, colloidal suspensions and, latterly, hydrogels.  Since its foundation in 2003, Grae has been a regular lecturer at the African Institute of Mathematical Sciences (AIMS), and he wrote the first book in their library series on "Understanding Fluid Flow."

2023 Heinz G. Stefan Fellowship recipient Xiating Chen, advised by Prof. Xue Feng 

Presentation titleInteraction between green infrastructure and urban hydrology at multiple scales

Abstract: Green infrastructure and other urban greenery are widely implemented to reduce stormwater runoff and mitigate urban heat island effects, but their hydrological functions and related dominant processes differ across scales (e.g., the local, green infrastructure scale, the catchment scale, the regional watershed scale). In this presentation, I will focus on the tree-level soil-plant-atmosphere continuum with preliminary experimental results from ash trees in the City of St. Paul. Using sap flux measurements (evapotranspiration), soil moisture and canopy temperature in urban trees, we reveal some important ecophysiological features that control the urban heat-vegetation-and-water dynamics. I hope to incorporate these physical observations into the watershed-scale understanding of green infrastructure performance, further providing empirical guidelines for integrating municipal forestry and water resources management.

Xiating Chen

About: Xiating Chen is a PhD candidate in water resources engineering at the St. Anthony Falls Laboratory studying under Professor Xue Feng. Her research is focused on eco-hydrological functions of urban trees and other green infrastructure at both local and watershed-scale, through combined field observations and modeling approaches. Xiating received her Bachelor of Science in Engineering degree from Duke University.

The Role of Data Assimilation, Deep Learning and Crowd Sourcing in Hydrometeorological Prediction and Hazard Risk Awareness - Hamid Moradkhani, University of Alabama

Hamid Moradkhani, Alton N. Scott Endowed Chair of hydrology in the Department of Civil, Construction and Environmental Engineering and the founding and current Director of the Center for Complex Hydrosystems Research at the University of Alabama

Abstract: Extreme events impose significant global-scale socio-economic vulnerability and risk that are likely to increase in the future under climate change and human development. In particular, floods and droughts are the most prevalent catastrophic natural hazards in the United States. Such events cause billions of dollars in damage annually and significant losses of life and resources. The massive impacts provoked by these extremes are clear motivation for improved understanding of the key drivers to characterize them, account for associated uncertainties and quantify the vulnerabilities and risks. This presentation will explore the concept of hydrometeorological predictability and strategies that leverage the integration of in-situ and satellite data, data assimilation, deep learning, and Earth system modeling to better characterize and predict such events. Additionally, I will discuss the use of crowd-sourcing and social media for hazard risk awareness and disaster management.


About: Dr. Hamid Moradkhani is the Alton N. Scott Endowed Chair of hydrology in the Department of Civil, Construction and Environmental Engineering and the founding and current Director of the Center for Complex Hydrosystems Research at the University of Alabama. Previously, he was a professor of Civil and Environmental Engineering and director of Remote Sensing and Water Resources lab at Portland State University. His research emphasis is on Bayesian data assimilation, predictive science, machine learning, data analytics, remote sensing and high-performance computing in the context of Earth system science. In addition, his research advances our understanding of hydrologic science through modeling climate-water-human interactions and food-energy-water nexus. He is the Editor of AGU Water Resources Research and before that was the Editor of AGU Earth’s Future and on the editorial board of several other journals. He is a Fellow of the American Society of Civil Engineers, Fellow of the Environmental and Water Resources Institute, and the Diplomat of water resources engineering and recipient of several awards, including the AMS Horton Lecturer Award, ASCE Arid Lands Hydraulic Engineering award, Outstanding Research and Innovation Award from the American Association of Water Resources Engineers, Faculty Research Excellence Award, and Branford P. Millar Award, for exceptional scholarship in research, instruction, university and public service.

The role of turbulence in environmental transport - Blair Johnson, UT-Austin

Blair Johnson, Assistant Professor in Civil, Architectural & Environmental Engineering at the University of Texas at Austin


AbstractHigh levels of turbulence can increase instantaneous localized shear and in turn transport across interfaces. For example, the uprush in the nearshore can be characterized as bore-advected offshore wave-generated turbulence; resulting sediment suspension in the swash is observed to be greater than would be predicted by traditional mean shear models. To isolate the role of turbulence in transport processes, we conduct laboratory experiments in facilities with mean shear free homogeneous isotropic turbulence generated via randomly actuated synthetic jet arrays. We use particle image velocimetry and laser induced fluorescence to characterize turbulence and mass transport. We explore the boundary layer that develops when homogeneous isotropic turbulence interacts with a sediment bed, a sharp density stratification, and ice.  For sediment experiments, we explore requisite turbulence levels for suspension and development of morphological features, including within-bed sediment dynamics.  At a density interface, we explore conditions of flow and density that encourage mixing and generation of internal waves. For ice experiments, we evaluate how turbulence can increase melt rates at low temperatures through rapid stirring of meltwater. These various boundaries each highlight the ability of turbulence to drive evolution of critical environmental systems.

Blair Johnson

AboutBlair Johnson is an Assistant Professor in Civil, Architectural & Environmental Engineering at the University of Texas at Austin.  Her research focuses on environmental fluid mechanics and experimental methods.  Dr. Johnson completed her B.S. (2008) at Johns Hopkins University in Civil Engineering, with a concentration in Structures and a minor in Piano at the Peabody Conservatory of Music.  She attended Cornell University where she received her M.S. (2012) and Ph.D. (2016) in Environmental Fluid Mechanics & Hydrology in Civil & Environmental Engineering.  In 2012 she was a visiting researcher at the Instituto de Hidraulica Ambiental (IH Cantabria) in Santander, Spain.  Following graduate school, she held a Postdoctoral research position in Mechanical & Aerospace Engineering at Arizona State University from 2016-2017.

Earthquakes or slow-slip? How we use laboratory experiments to link material properties to slip dynamics - Jacqueline Reber, Iowa State University

Jacqueline Reber, Associate Professor in the Department of Geological and Atmospheric Science at Iowa State University.

Jacqueline Reber lab

AbstractConstraining the rheology of the lithosphere is of fundamental importance for understanding plate tectonics as well as earthquake generation. This task, however, is exceedingly difficult as a variety of deformation mechanisms contribute to the integrated strength of the lithosphere. Rocks at high-pressure and high-temperature conditions flow viscously by a number of deformation mechanisms whereas at low-pressure and low- temperature conditions rocks crack, fracture, lose cohesion and slide frictionally. At intermediate crustal depth, deformation is hence achieved by a complex spatial and temporal interplay between “viscous” and “brittle” processes. The interaction between these end-member cases where viscous flow cannot accommodate all the imposed displacement and abundant pervasive fracturing occurs leads to “semi-brittle” deformation. Semi-brittle deformation links the time scales associated with fracturing and earthquakes with the time scales associated with a flowing viscous crust leading to a mixture of stick-slip and creep. The co-occurrence of brittle and viscous deformation in rocks can be observed in the field over many length scales and in various lithologies.

A field examples of semi-brittle deformation will serve as starting points to investigate how forces are distributed between the brittle and viscous phases, how deformation localizes, and how the two phases impact the deformation dynamics. By combining field observations with physical and numerical experiments, deformation evolution can be observed and documented, length scales from micro to the macro scale can be investigated, and resulting deformation dynamics do not need to be preassigned, but can emerge from the material interactions. By employing various experimental materials, we can quantify the impact of the strength contrast between the brittle and viscous phases, the distribution between the phases, as well as the role of fracture formation and geometries on slip dynamics. The results show that semi-brittle rheology significantly impacts deformation dynamics, deformation localization, and the force distribution within the different material phases. All these aspects have a direct impact on the stability of fault zones and how deformation will manifest itself.

About: Jacqueline Reber is a structural geologist interested in the interaction and coexistence of brittle and ductile structures in rocks. To investigate the impact of complex rheologies on the formation of such structures, Jacqueline uses a combination of physical modeling, numerical modeling, and field work. In the structural experiment lab at Iowa State University, Jacqueline uses a wide variety of analog materials ranging from silicone and sand to polymers to simulate the behavior of rock in different deformation regimes. Jacqueline combines the lab results with field observations and numerical models to investigate the physical processes leading to stunning and complex deformation patterns in nature.

Bacterial biofilm as a model for studying mechanical instabilities - Jing Yan, Yale University

Jing Yan, Assistant Professor of Molecular, Cellular and Developmental Biology and a member of the Quantitative Biology Institute (Qbio) at Yale University.

embedded biofilm

AbstractBiofilms, surface‐attached communities of bacterial cells, are a concern in health and in industrial operations because of persistent infections, clogging of flows, and surface fouling. On the other hand, biofilms also display many interesting mechanical instabilities and behave as unique active materials. In this talk, I will discuss our recent progress in using Vibrio cholerae as a model to reveal the physical principles behind biofilm formation, in particular in confined environment, both at the single cell level and at the continuum level. In this process, we discovered a deep connection between biofilm growth and phenomena in soft materials including cavitation, delamination, and stress birefringence. 

Jing Yan

About: Jing Yan is currently an Assistant Professor of Molecular, Cellular and Developmental Biology and a member of the Quantitative Biology Institute (Qbio) at Yale. Originally from Shanghai, China, he obtained his B.S. degree from the College of Chemistry and Molecular Engineering at Peking University in China, with extensive undergraduate research experience in organic synthesis. In 2009, he switched to the field of soft matter physics and pursued Ph.D. degree in the Department of Materials Science and Engineering at the University of Illinois at Urbana-Champaign. Working with Steve Granick, he developed novel reconfigurable, active colloidal materials during his Ph.D.

In 2014, he stumbled into microbiology at Princeton as a joint postdoctoral researcher in the department of Molecular Biology and Mechanical and Aerospace Engineering. Working with Bonnie Bassler, Howard Stone, and Ned Wingreen, he studied bacterial biofilms with an interdisciplinary approach. With new imaging techniques, he discovered the spontaneous cellular ordering inside V. cholerae biofilms that leads to the formation of tenacious biofilm clusters. His study on the biofilm material properties leads to innovative methods to remove harmful biofilms. He received the Career Award at the Scientific Interface from Burroughs Wellcome Fund in 2016.

Jing received the Career Award at the Scientific Interface from Burroughs Wellcome Fund in 2016 and NIH Director’s New Innovator Award in 2021.  

Lorenz G. Straub Award Ceremony with Distinguished Lecture by Prof. Marccus Hendricks

Join us on Tuesday, November 29th at 3pm for a celebration of the 2021 Lorenz G. Straub Award recipient Dr. Andrew Feldman, with a distinguished lecture by Prof. Marccus Hendricks.

Marccus Hendricks, Associate Professor of Urban Studies and Planning and the Director of the Stormwater Infrastructure Resilience and Justice (SIRJ) Lab at the University of Maryland

Distinguished lectureSocio-Physical Infrastructure and Environmental Risks: People, Pipelines, and Pathways

AbstractThe impact of hazard exposures such as stormwater runoff is rarely evenly felt across a community. Neighborhoods of color, particularly of low-wealth, will often face worse stormwater problems especially in the era of climate change; with more frequent and intense stormwater runoff. Dr. Marccus Hendricks will discuss the equity and environmental justice issues related to stormwater infrastructure planning that result in vulnerable systems, leading to everyday challenges in stormwater, urban flooding, and other environmental risks. Specifically, he will examine conceptual frameworks and contextualize what it means for physical systems to operate in a social world. He will describe several ongoing studies where his lab investigates a number of risks at the nexus of stormwater, infrastructure, resilience, and environmental justice. Furthermore, he will discuss pathways forward that integrate justice and participation into the inspection and improvement of community spaces, particularly in marginalized areas.


About the speakerDr. Marccus Hendricks is a recently tenured Associate Professor of Urban Studies and Planning and the Director of the Stormwater Infrastructure Resilience and Justice (SIRJ) Lab at the University of Maryland. His other appointments at the university include the Department of Civil and Environmental Engineering and the Maryland Institute for Applied Environmental Health. He holds a Ph.D. in Urban and Regional Science and a Master of Public Health, both from Texas A&M University. To date, he has primarily worked to understand how social processes and development patterns create hazardous human-built environments, vulnerable infrastructure, and the related risks in urban stormwater management and flooding. Other work has focused on technological disasters, namely fertilizer explosions, and cascading events such as wet- weather events that overwhelm sanitary sewers and cause overflows, household backups, and contamination. His work emphasizes participation and action that uses methods including photography, visual inspection, and environmental sampling.

Hendricks’ research has been published in several journals including the Journal of the American Planning Association, Journal of Planning Education and Research, American Journal of Public Health, Environmental Justice, Journal of Infrastructure Systems, Risk Analysis, Landscape Journal, and Sustainable Cities and Society. In the popular media realm, his work has been covered by or quoted in the Associated Press, CNN, NPR, USA Today, Scientific American, Huffington Post, Baltimore Sun, and, to name a few.

Hendricks received two early-career awards from the National Academies of Science Gulf Research Program and The JPB Environmental Health Fellows Program at Harvard T. H. Chan School of Public Health. More recently, he was named as a 2021 “Fixer” by the media company Grist for their annual Grist 50 Fixer list and has been appointed to Springer Nature’s US Research Advisory Council, the U.S. EPA’s Science

Advisory Board, and by the Biden Administration as an author on the human social systems chapter of the U.S. Fifth National Climate Assessment.

2021 Lorenz G. Straub Recipient Dr. Andrew FeldmanNASA Postdoctoral Program Fellow at the NASA Goddard Space Flight Center

Doctoral thesisSoil-Plant-Atmosphere Coupling during Interstorm Periods

AbstractThe future trajectory of net terrestrial carbon uptake and agricultural yields are dependent on how vegetation responds to climate forcings. However, characterizing vegetation responses to water stress and other environmental drivers is challenging because these forcing factors are inter-related, especially on seasonal timescales. Here, recently available global mapping measurements from microwave satellite sensors are used to characterize water exchange in the soil-plant-atmosphere continuum. These satellites enable evaluation of time evolution of landscape-scale plant water content during interstorm periods, providing insights into underlying mechanisms and allowing disentangling of their drivers. My thesis asks: what are the fundamental landscape-scale plant responses to rainfall events and interstorm drying? With a focus on soil-plant hydraulics in this presentation, I’ll more specifically ask: at what timescale do plants take up water after a rain event and why?

Following soil moisture pulses in wetter global locations, rapid soil-plant water coupling occurs as expected under pre-dawn soil-plant equilibrium. By contrast, in global drylands, plant water content commonly increases over multiple days after pulses. Longer dryland plant water content increases (> 3 days) are attributed to rapid growth, providing evidence for a long-standing ecological hypothesis. In contrast, shorter (1-3 day) plant water increases under dry conditions are due to slow plant rehydration, ascribed here to high soil-plant resistances using a plant hydraulic model. These results together suggest that intermittent pulses of water availability have the strongest influence on dryland vegetation. However, responses extend across climate gradients implicating widespread sensitivity to rainfall timing.


About the recipientAndrew Feldman is a NASA Postdoctoral Program Fellow at the NASA Goddard Space Flight Center located in Greenbelt, MD. He works primarily with Ben Poulter on carbon cycle science in the Biospheric Sciences Laboratory. He is a hydrologist who studies the coupling of the terrestrial water, carbon, and energy cycles mainly using satellite remote sensing platforms across optical, thermal, and microwave frequencies. Andrew is also a new member of the NASA ECOSTRESS Science Team. Prior to joining NASA, Andrew was a graduate research assistant at Massachusetts Institute of Technology, Cambridge, MA, where he received S.M. and Ph.D. degrees in hydrology in the department of civil and environmental engineering in 2018 and 2021, respectively. At MIT, he worked with Prof. Dara Entekhabi. He also completed his bachelor’s and master’s degrees in civil engineering from Drexel University in Philadelphia, PA in 2016.

The Ghost Valley - Sara Holger, Lead Interpretive Naturalist at Whitewater State Park

Please join us on Monday, November 14th for two events featuring Sara Holger: a panel discussion at 12:30pm and a Beyond the Lab Seminar at 3pm.

Sara Holger, Lead Interpretive Naturalist at Whitewater State Park in Minnesota

Panel discussion with Sara Holger, Prof. Andy Wickert & Jimmy Wood 

Monday, November 14th

In-person at St. Anthony Falls Laboratory at 12:30pm

Sara will be in conversation with SAFL collaborators Prof. Andy Wickert and Jimmy Wood, with the discussion moderated by Shanti Penprase. Panelists will discuss the benefits of collaboration between the University and state parks, balancing priorities amongst partners, funding interdisciplinary work and more. Panelists will also engage with audience members, so please bring your questions! Snacks will be provided.

Beyond the Lab Seminar - The Ghost Valley

Monday, November 14th

In-person and online at 3pm

Abstract: The Whitewater River Valley lies within portions of Olmsted, Wabasha and Winona counties in the Driftless area of southeast Minnesota. Once home to five towns, visitors to the valley today find several ghost towns and the footprints of nearly 100 farms that have vanished. This presentation will explore the fascinating history of the Whitewater River watershed and how human land use, erosion and destruction catastrophically altered human lives and the natural resources of the valley.

Sara Holger

About: Sara has been an environmental educator since 1994. She graduated from the University of Minnesota – Twin Cities campus in 1998 with an undergraduate degree in Natural Resources and Environmental Studies. Over the course of her career, she’s worked for various agencies and organizations including the US Forest Service, the Bell Museum of Natural History, the Minnesota Department of Natural Resources – Division of Fisheries, Eagle Bluff Environmental Learning Center, Olmsted County Parks, and Minnesota State Parks and Trails. Sara is the Lead Interpretive Naturalist at Whitewater State Park. She is also the Founder of a non-profit organization called Project Get Outdoors, working to connect low-income youth and Children of Color to the natural world. Sara farmed for 11 years in the Whitewater River watershed and is grateful to have learned through experience about the farming community and the incredible work our farmers do to feed the world. In her spare time she enjoys fishing, kayaking and exploring public lands in southeast Minnesota with her family.

Beyond the Lab Seminars

We love learning from prominent figures in environmental science and fluid mechanics through the SAFL Seminar Series, just as we recognize the value in examining any issue, idea, or area of study from a multitude of perspectives. Beyond the Lab seminars allow us to do just this: by bringing in experts from other fields and the community, we enrich our understanding of environmental science and fluid mechanics while situating research and other concepts in a holistic context. 

Do you have an idea for a Beyond the Lab Seminar? Email Clare at

Carbonate mineral reactions during geological carbon sequestration, and implications for induced seismicity - Charles Werth, UT-Austin

Charles Werth, Professor & Bettie Margaret Smith Chair of Environmental Health Engineering in the Department of Civil, Architecture, and Environmental Engineering at the University of Texas at Austin.

Abstract: Geologic carbon sequestration in deep saline aquifers results in a low pH brine plume that pushes into subsurface storage reservoirs and can access pre-existing or induced (micro)fractures and possibly induce shear slip.  To investigate this phenomenon, an artificial fracture was created in a Bandera Gray sandstone sample, and it was held under shear stress in a custom flow cell housed within an industrial CT scanner. Acidic (pH 4) or reservoir-simulated (pH 8.3) brine was pumped through the artificial fracture for seven days. CT imaging shows that acidic brine resulted in greater shear slip than reservoir-simulated brine, and fracture surfaces exposed to acidic brine had rougher surfaces and lower fracture toughness. SEM images of fracture surfaces indicate a loss by area of carbonate cementing crystals after exposure to the acidic brine, as well as a corresponding porosity increase. These results motivated more fundamental studies on carbonate mineral dissolution using freshly cleaved calcite.  The effects of solution pH, carbonic acid, and the presence of an anionic surfactant on calcite dissolution kinetics and etch pit morphology were probed in a high pressure and temperature reactor, and complemented with density functional theory calculations.  Results indicate that carbonic acid promotes much faster dissolution than protons or water, and that the anionic surfactant inhibits dissolution by competing with carbonic acid for calcium edge sites on the calcite surface.  Hence, addition of anionic surfactants to injected CO2 may inhibit calcite dissolution and slip along existing fractures. 

Charles Werth

AboutDr. Werth is a Professor and the Bettie Margaret Smith Chair in Environmental Health Engineering at the University of Texas at Austin. His research and teaching focus on the reactive transport of water pollutants in porous media, with applications in (electro)catalytic water treatment, groundwater remediation, and geological carbon sequestration. He is editor of Journal of Contaminant Hydrology, and previously served on the USEPA Science Advisory Board.  He received his BS degree in mechanical engineering from Texas A&M University, and MS and PhD degrees in environmental engineering from Stanford University.

Edward Silberman Award Ceremony & Distinguished Lecture by Prof. Anna Trugman

Presentation of the 2022 Edward Silberman Fellowship to Reyhaneh Rahimi

Distinguished Lecture: Plant functional traits in terrestrial hydrological and carbon cycles

Distinguished SpeakerAnna Trugman, Assistant Professor in the Department of Geography at the University of California, Santa Barbara

AbstractClimate change has the potential to massively disrupt terrestrial ecosystem productivity, impacting biodiversity, and driving Earth’s forests to release carbon into the atmosphere, which would further exacerbate climate change and modify the hydrological cycle. Plant functional traits, such as those that determine tree drought vulnerability, and the diversity in traits within a forest, modulate surface water, carbon, and energy fluxes. Yet, we do not know how species composition and their accompanying traits will change with climate change. In this talk, I leverage plant physiological observations, large observational databases, and trait-based ecosystem models to understanding the extent to which plant trait diversity can impact ecosystem resilience to drought events, and the subsequent effects on ecosystem carbon and water fluxes. Using a trait-based vegetation model and observed maps of hydraulic traits, I generated maps of plant water status and hydraulic stress and examine the extent to which trait acclimation and turnover can ameliorate future climate stress. Importantly observed trait velocities (changes in forest community trait compositions over time) are not keeping pace with the required compositional shifts to mitigate increases in hydraulic stress.

Anna Trugman

AboutAnna Trugman is an Assistant Professor in the Department of Geography at the University of California, Santa Barbara. Her research is focused on the biogeochemical and hydrological consequences of forest physiological and ecological responses to climate change through combined observational and modeling approaches. Anna is a recipient of the New Phytologist Tansley Medal for outstanding research in plant sciences, the Ecological Society of America Early Career Award, and the American Geophysical Union Global Environmental Change Early Career Award.

Award recipient: Reyhaneh Rahimi, Department of Civil, Environmental and Geo- Engineering

Abstract: Precipitation nowcasting, the high-resolution forecasting of precipitation up to 6 hours ahead, supports the real-world socioeconomic needs of many sectors reliant on weather-dependent decision-making. Today’s weather predictions are driven by powerful numerical weather prediction (NWP) systems. By solving physical equations, NWPs provide essential planet-scale predictions several days ahead. However, they struggle to generate high-resolution predictions for short lead times. On the other hand, current remotely sensed precipitation products have a few hours of latency, associated with the acquisition and processing of satellite data. In my research I want to reduce this latency and improve their applicability, value, and impact by applying a robust nowcasting system to these products. However, the development of such a system is complicated by the chaotic nature of the atmosphere, and the consequent rapid changes that can occur in the structures of precipitation systems. Using Recurrent and Convolutional deep neural network structures to I tried to address the challenge of precipitation nowcasting and develop a model that can provide precipitation estimation for up to four hours ahead. The results demonstrate that the performance of the deep learning-based forecasting model can outperform the numerical weather prediction models.

Reyhaneh Rahimi

About the recipient: Reyhaneh Rahimi is a Ph.D. candidate in Civil Engineering (Water Resources Management) at the St. Anthony Falls Laboratory studying under Prof. Ardeshir Ebtehaj. Reyhaneh holds a Bachelor of Science and Master of Science in Civil Engineering from the University of Tehran. Her research interests include remote sensing of land-atmosphere interactions, statistical hydrology and analysis of uncertainties, satellite hydrology and precipitation retrievals, and hydrological modeling and optimization.


Microwave remote sensing of plant water stress - Alexandra Konings, Stanford University

Alexandra Konings, Assistant Professor in the Department of Earth System Science at Stanford University

Abstract: Understanding how vegetation responds to changes in hydrological conditions is a fundamental prerequisite for characterizing the response of ecosystems to a changing hydroclimate. However, doing so is challenging because of the large diversity of relevant vegetation traits (including root, xylem, and stomatal properties) within species, within ecosystems, and across the globe. In this talk, I will describe how microwave remote sensing of vegetation – which naturally integrates over these sources of variability and provides data across the globe - may be a useful tool for better understanding plant water stress response. In this talk, I will discuss active and passive microwave observations and their sensitivity to vegetation water content. I will further discuss evidence that ecosystem-scale variations in vegetation water content are not just sensitive to biomass - as commonly used - but also carry the signature of variations in leaf water potential, the physiological variable that most directly influences plant water stress response. I will discuss how this signature can be used for several applications, including determining ecosystem-scale plant hydraulic traits (including isohydricity, stomatal closure, P50, and xylem closure) and their link to spatial variability in photosynthesis responses to water stress, estimating drought-driven tree mortality rates, and characterizing wildfire risk.

Alex Konings

About: Alexandra 'Alex' Konings is an assistant professor in the department of Earth System Science at Stanford University. She also has a courtesy appointment in the Stanford Department of Geophysics and is a center fellow, by courtesy, of the Stanford Woods Institute of the Environment. Her research is focused on interactions between the global carbon and water cycles, especially as related to plant hydraulics and to the effects of small-scale trait variability on regional-scale ecosystem behavior. She received the NASA New (Early Career) Investigator Award in 2018, the NSF CAREER in 2020, and the AGU Global Environmental Change Early Career Award in 2021.