Jay Choi
Dr. Jay Choi is a Hydrologist in the Earth System Processes Division, USGS Water Resources Mission Area.
Dr. Jay Choi studies hydrologic numerical modeling and field investigation for contaminant transport processes, especially in coupled groundwater and surface-water systems and wetlands. His research has been focused on quantifying the interactions between groundwater and surface water from stream hyporheic zone to wetlands using field-tracer studies and the application of numerical models with statistical optimization and statistical sensitivity analysis, the development and modification of surface-water flow model for wetland system, and the management and development of hydrologic and biogeochemical database. Jay completed his Ph.D in Hydrology from University of Arizona in 1998, and since 2010, has focused his research on the Everglades wetlands restoration project, where he leads data collection efforts and scientific interpretations. In 2023, Jay became the project manager for the 5-year USACE CEPP-S (Central Everglades Planning Project) project. This project will evaluate the uncertainties associated with hydrologic restoration needed to restore a natural mosaic of wetland habitats in CEPP, active vegetation management within CEPP, and identification of the potential benefits and risks associated with restoring connectivity to the system.
Professional Experience
2017 - present: Hydrologist, Earth System Processes Division, Water Resources Mission Area, USGS, Reston
2014 – 2017: Hydrologist, National Research Program, USGS, Reston
2010 - 2014: Senior research associate, National Research Program, USGS, Reston
2001 – 2010: Project hydrologist at S.S. Papadopulos & Associates, Inc.
1998 -2001: Postdoctoral Fellow (Interagency Personnel Agreement), USGS, Reston
Education and Certifications
University of Arizona, Tucson, AZ, Hydrology, Ph.D. 1998
Shimane University, Matsue, Japan, Geology, M.S. 1989
Science and Products
River Corridor hot spots for biogeochemical processing: a continental scale synthesis
Rivers are the veins of the landscape, providing environmental benefits that are disproportionately high relative to their aerial extent; shedding flood waters, hosting aquatic ecosystems, transporting solutes and energy-rich materials, and storing and transforming pollutants into less harmful forms. From uplands to the coasts, rivers facilitate key biogeochemical reactions that cumulatively influ
Modeled transport components of daily chlorophyll-a in the Illinois River, 2018 through 2020 (version 1.1, April 2024)
TThis data release contains approximately three years of modeled chlorophyll-a—a proxy for planktonic algal biomass—transport through a 394-km portion of the Illinois River. Defined by four distinct reaches, model estimates include daily water balance, velocities, and algal biomass separated into its components of net growth, net loss, transported from upstream, and input from tributaries.
First
Hydrologic analysis of flow and transport for the Everglades DPM experiments
Flow and transport of sediment and phosphorus through the low-gradient wetlands of the Everglades, FL were characterized using hydrologic, biological, geomorphic, and biogeochemical data as inputs to several types of simulations. The data were collected in the DPM (Decompartmentalization Physical Model) experimental high-flow facility in the central Everglades, FL. The DPM includes wetlands, canal
RiverMET: Workflow and scripts for river metabolism estimation including Illinois River Basin application, 2005 - 2020
Ecosystem metabolism is a measure of energy flow in terrestrial and aquatic environments that quantifies a balance between the rate of biomass production by photosynthesizing plants and the rate of biomass oxidation by respiring plants and animals to maintain and build living biomass. It is therefore a fundamental measure of ecosystem function that quantifies the balance between the rate of produc
High-Flow Field Experiments to Inform Everglades Restoration: Experimental Data 2010 to 2022 (ver. 2.0, October 2023)
Data were collected between 2010 and 2022 in a research area of the Everglades known as the Decompartmentalization Physical Model (DPM), a wetland area in the central Everglades that includes canals and levees bordering Water Conservation Area 3A (WCA-3A) to the northwest and Water Conservation Area 3B (WCA-3B) to the southeast. During the twelve-year study period more than ten major controlled fl
Biophysical Data for Simulating Overland Flow in the Everglades
A biophysical approach to modeling overland flow in the Everglades can help predict future outcomes for ecological habitat, water storage during droughts, and water conveyance during floods. The data provided include measurements of vegetation stem architecture, microtopography, and landscape pattern metrics. Stem architecture measurements present the opportunity to estimate flow roughness of dist
High-Flow Field Experiments to Inform Everglades Restoration: Experimental Data 2010 to 2018
Data Release from the High-Flow Field Experiments to Inform Everglades Restoration: Experimental Data 2010 to 2018. Data were obtained from field sites located in the Everglades between two canals (L-67A and L-67C) from 2010 to 2018. During this time, five major controlled flow releases occurred by opening the culvert S152 on canal L-67A. Data consist of water velocity (continuous and discrete), w
Filter Total Items: 15
Metabolism regimes in regulated rivers of the Illinois River basin, USA
Metabolism estimates organic carbon accumulation by primary productivity and removal by respiration. In rivers it is relevant to assessing trophic status and threats to river health such as hypoxia as well as greenhouse gas fluxes. We estimated metabolism in 17 rivers of the Illinois River basin (IRB) for a total of 15,176 days, or an average of 2.5 years per site. Daily estimates of gross primary
Authors
Judson Harvey, Jay Choi, Katherine Quion
River Metabolism Estimation Tools (RiverMET) with demo in the Illinois River Basin
Ecosystem metabolism quantifies the rate of production, maintenance, and decay of organic matter in terrestrial and aquatic systems. It is a fundamental measure of energy flow associated with biomass production by photosynthesizing organisms and biomass oxidation by respiring plants, animals, algae, and bacteria (Bernhardt et al., 2022) . Ecosystem metabolism also provides an understanding of ener
Authors
Jay Choi, Katherine Michelle Bernabe Quion, Ariel Reed, Judson Harvey
Biophysical methods and data analysis for simulating overland flow in the Everglades
The Everglades in south Florida supply fresh drinking water for more than 7 million people, host a National Park, and are classified as a Ramsar wetland of international distinction. Predicting trajectories of water flow and water storage changes in the future is important to managing the Congressionally authorized restoration of the Everglades. Here we describe the needed data sources and analysi
Authors
Judson Harvey, Jay Choi
How hydrologic connectivity regulates water quality in river corridors
Downstream flow in rivers is repeatedly delayed by hydrologic exchange with off‐channel storage zones where biogeochemical processing occurs. We present a dimensionless metric that quantifies river connectivity as the balance between downstream flow and the exchange of water with the bed, banks, and floodplains. The degree of connectivity directly influences downstream water quality — too little c
Authors
Judson Harvey, Jesus Gomez-Velez, Noah Schmadel, Durelle Scott, Elizabeth W. Boyer, Richard Alexander, Ken Eng, Heather E. Golden, Albert Kettner, Christopher Konrad, Richard Moore, Jim Pizzuto, Gregory E. Schwarz, Chris Soulsby, Jay Choi
On factors influencing air-water gas exchange in emergent wetlands
Knowledge of gas exchange in wetlands is important in order to determine fluxes of climatically and biogeochemically important trace gases and to conduct mass balances for metabolism studies. Very few studies have been conducted to quantify gas transfer velocities in wetlands, and many wind speed/gas exchange parameterizations used in oceanographic or limnological settings are inappropriate under
Authors
David T. Ho, Victor C. Engel, Sara Ferron, Benjamin Hickman, Jay Choi, Judson W. Harvey
Predicting outcomes of restored Everglades high flow: A model system for scientifically managed floodplains
Restoration of higher flows through the Everglades is intended to reestablish sheetflow to rebuild a well-functioning ridge and slough landscape that supports a productive and diverse ecosystem. Our objective of the study was to use hydrologic simulations and biophysical analysis to predict restoration outcomes for five major subbasins of the Everglades. Five different scenarios of restoration wer
Authors
Jay Choi, Judson Harvey
Relative significance of microtopography and vegetation as controls on surface water flow on a low-gradient floodplain
Surface water flow controls water velocities, water depths, and residence times, and influences sediment and nutrient transport and other ecological processes in shallow aquatic systems. Flow through wetlands is substantially influenced by drag on vegetation stems but is also affected by microtopography. Our goal was to use microtopography data directly in a widely used wetland model while retaini
Authors
Jungyill Choi, Judson W. Harvey
Directional connectivity in hydrology and ecology
Quantifying hydrologic and ecological connectivity has contributed to understanding transport and dispersal processes and assessing ecosystem degradation or restoration potential. However, there has been little synthesis across disciplines. The growing field of ecohydrology and recent recognition that loss of hydrologic connectivity is leading to a global decline in biodiversity underscore the nee
Authors
Laurel G. Larsen, Jungyill Choi, Martha K. Nungesser, Judson W. Harvey
Surface-Water and Ground-Water Interactions in the Central Everglades, Florida
Recharge and discharge are hydrological processes that cause Everglades surface water to be exchanged for subsurface water in the peat soil and the underlying sand and limestone aquifer. These interactions are thought to be important to water budgets, water quality, and ecology in the Everglades. Nonetheless, relatively few studies of surface water and ground water interactions have been conducted
Authors
Judson W. Harvey, Jessica T. Newlin, James M. Krest, Jungyill Choi, Eric A. Nemeth, Steven L. Krupa
Interactions between surface water and ground water and effects on mercury transport in the north-central Everglades
The hydrology of the north-central Everglades was altered substantially in the past century by canal dredging, land subsidence, ground-water pumping, and levee construction. Vast areas of seasonal and perennial wetlands were converted to uses for agriculture, light industry, and suburban development. As the catchment area for the Everglades decreased, so did the sources of water from local precipi
Authors
Judson W. Harvey, Steven L. Krupa, Cynthia Gefvert, Robert H. Mooney, Jungyill Choi, Susan A. King, Jefferson B. Giddings
Quantifying time-varying ground-water discharge and recharge in wetlands of the northern Florida Everglades
Developing a more thorough understanding of water and chemical budgets in wetlands depends in part on our ability to quantify time-varying interactions between ground water and surface water. We used a combined water and solute mass balance approach to estimate time-varying ground-water discharge and recharge in the Everglades Nutrient Removal project (ENR), a relatively large constructed wetland
Authors
Jungyill Choi, Judson W. Harvey
Characterizing multiple timescales of stream and storage zone interaction that affect solute fate and transport in streams
The fate of contaminants in streams and rivers is affected by exchange and biogeochemical transformation in slowly moving or stagnant flow zones that interact with rapid flow in the main channel. In a typical stream, there are multiple types of slowly moving flow zones in which exchange and transformation occur, such as stagnant or recirculating surface water as well as subsurface hyporheic zones.
Authors
Jungyill Choi, Judson W. Harvey, Martha H. Conklin
Non-USGS Publications**
Choi, J., M.H. Conklin, R.C. Bales, and R.A. Sommerfeld. 2000. Processes Controlling SO2 Uptake in Snowpacks: Atmospheric Environment. 34, no. 5: 793-801.
Bales, R.C., and J. Choi. 1997. Conceptual Framework for Interpretation of Exchange Processes. In Processes of Chemical Exchange between Polar Snow and Atmosphere. Wolff, E., and R. Bales, editors. NATO ASI Series 1. Springer-Verlag. 319-338.
Choi, J., T. Tokuoka, and K. Yu. 1993. Late Paleozoic -Early Mesozoic Sandstone Petrology of the Maizuru and Akiyoshi -Nishiki Terranes in Southwest Japan. Journal of Geological Society of Korea. 29, no. 2: 188-198.
Choi, J., K. Yu, and T. Tokuoka. 1991. Significance of Volcanogenic Sediments in the Nogam Formation of the Pyeongan Group in Korea (South). Journal of the Geological Society of Japan. 97, no. 7: 557-559.
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
River Corridor hot spots for biogeochemical processing: a continental scale synthesis
Rivers are the veins of the landscape, providing environmental benefits that are disproportionately high relative to their aerial extent; shedding flood waters, hosting aquatic ecosystems, transporting solutes and energy-rich materials, and storing and transforming pollutants into less harmful forms. From uplands to the coasts, rivers facilitate key biogeochemical reactions that cumulatively influ
Modeled transport components of daily chlorophyll-a in the Illinois River, 2018 through 2020 (version 1.1, April 2024)
TThis data release contains approximately three years of modeled chlorophyll-a—a proxy for planktonic algal biomass—transport through a 394-km portion of the Illinois River. Defined by four distinct reaches, model estimates include daily water balance, velocities, and algal biomass separated into its components of net growth, net loss, transported from upstream, and input from tributaries.
First
Hydrologic analysis of flow and transport for the Everglades DPM experiments
Flow and transport of sediment and phosphorus through the low-gradient wetlands of the Everglades, FL were characterized using hydrologic, biological, geomorphic, and biogeochemical data as inputs to several types of simulations. The data were collected in the DPM (Decompartmentalization Physical Model) experimental high-flow facility in the central Everglades, FL. The DPM includes wetlands, canal
RiverMET: Workflow and scripts for river metabolism estimation including Illinois River Basin application, 2005 - 2020
Ecosystem metabolism is a measure of energy flow in terrestrial and aquatic environments that quantifies a balance between the rate of biomass production by photosynthesizing plants and the rate of biomass oxidation by respiring plants and animals to maintain and build living biomass. It is therefore a fundamental measure of ecosystem function that quantifies the balance between the rate of produc
High-Flow Field Experiments to Inform Everglades Restoration: Experimental Data 2010 to 2022 (ver. 2.0, October 2023)
Data were collected between 2010 and 2022 in a research area of the Everglades known as the Decompartmentalization Physical Model (DPM), a wetland area in the central Everglades that includes canals and levees bordering Water Conservation Area 3A (WCA-3A) to the northwest and Water Conservation Area 3B (WCA-3B) to the southeast. During the twelve-year study period more than ten major controlled fl
Biophysical Data for Simulating Overland Flow in the Everglades
A biophysical approach to modeling overland flow in the Everglades can help predict future outcomes for ecological habitat, water storage during droughts, and water conveyance during floods. The data provided include measurements of vegetation stem architecture, microtopography, and landscape pattern metrics. Stem architecture measurements present the opportunity to estimate flow roughness of dist
High-Flow Field Experiments to Inform Everglades Restoration: Experimental Data 2010 to 2018
Data Release from the High-Flow Field Experiments to Inform Everglades Restoration: Experimental Data 2010 to 2018. Data were obtained from field sites located in the Everglades between two canals (L-67A and L-67C) from 2010 to 2018. During this time, five major controlled flow releases occurred by opening the culvert S152 on canal L-67A. Data consist of water velocity (continuous and discrete), w
Filter Total Items: 15
Metabolism regimes in regulated rivers of the Illinois River basin, USA
Metabolism estimates organic carbon accumulation by primary productivity and removal by respiration. In rivers it is relevant to assessing trophic status and threats to river health such as hypoxia as well as greenhouse gas fluxes. We estimated metabolism in 17 rivers of the Illinois River basin (IRB) for a total of 15,176 days, or an average of 2.5 years per site. Daily estimates of gross primary
Authors
Judson Harvey, Jay Choi, Katherine Quion
River Metabolism Estimation Tools (RiverMET) with demo in the Illinois River Basin
Ecosystem metabolism quantifies the rate of production, maintenance, and decay of organic matter in terrestrial and aquatic systems. It is a fundamental measure of energy flow associated with biomass production by photosynthesizing organisms and biomass oxidation by respiring plants, animals, algae, and bacteria (Bernhardt et al., 2022) . Ecosystem metabolism also provides an understanding of ener
Authors
Jay Choi, Katherine Michelle Bernabe Quion, Ariel Reed, Judson Harvey
Biophysical methods and data analysis for simulating overland flow in the Everglades
The Everglades in south Florida supply fresh drinking water for more than 7 million people, host a National Park, and are classified as a Ramsar wetland of international distinction. Predicting trajectories of water flow and water storage changes in the future is important to managing the Congressionally authorized restoration of the Everglades. Here we describe the needed data sources and analysi
Authors
Judson Harvey, Jay Choi
How hydrologic connectivity regulates water quality in river corridors
Downstream flow in rivers is repeatedly delayed by hydrologic exchange with off‐channel storage zones where biogeochemical processing occurs. We present a dimensionless metric that quantifies river connectivity as the balance between downstream flow and the exchange of water with the bed, banks, and floodplains. The degree of connectivity directly influences downstream water quality — too little c
Authors
Judson Harvey, Jesus Gomez-Velez, Noah Schmadel, Durelle Scott, Elizabeth W. Boyer, Richard Alexander, Ken Eng, Heather E. Golden, Albert Kettner, Christopher Konrad, Richard Moore, Jim Pizzuto, Gregory E. Schwarz, Chris Soulsby, Jay Choi
On factors influencing air-water gas exchange in emergent wetlands
Knowledge of gas exchange in wetlands is important in order to determine fluxes of climatically and biogeochemically important trace gases and to conduct mass balances for metabolism studies. Very few studies have been conducted to quantify gas transfer velocities in wetlands, and many wind speed/gas exchange parameterizations used in oceanographic or limnological settings are inappropriate under
Authors
David T. Ho, Victor C. Engel, Sara Ferron, Benjamin Hickman, Jay Choi, Judson W. Harvey
Predicting outcomes of restored Everglades high flow: A model system for scientifically managed floodplains
Restoration of higher flows through the Everglades is intended to reestablish sheetflow to rebuild a well-functioning ridge and slough landscape that supports a productive and diverse ecosystem. Our objective of the study was to use hydrologic simulations and biophysical analysis to predict restoration outcomes for five major subbasins of the Everglades. Five different scenarios of restoration wer
Authors
Jay Choi, Judson Harvey
Relative significance of microtopography and vegetation as controls on surface water flow on a low-gradient floodplain
Surface water flow controls water velocities, water depths, and residence times, and influences sediment and nutrient transport and other ecological processes in shallow aquatic systems. Flow through wetlands is substantially influenced by drag on vegetation stems but is also affected by microtopography. Our goal was to use microtopography data directly in a widely used wetland model while retaini
Authors
Jungyill Choi, Judson W. Harvey
Directional connectivity in hydrology and ecology
Quantifying hydrologic and ecological connectivity has contributed to understanding transport and dispersal processes and assessing ecosystem degradation or restoration potential. However, there has been little synthesis across disciplines. The growing field of ecohydrology and recent recognition that loss of hydrologic connectivity is leading to a global decline in biodiversity underscore the nee
Authors
Laurel G. Larsen, Jungyill Choi, Martha K. Nungesser, Judson W. Harvey
Surface-Water and Ground-Water Interactions in the Central Everglades, Florida
Recharge and discharge are hydrological processes that cause Everglades surface water to be exchanged for subsurface water in the peat soil and the underlying sand and limestone aquifer. These interactions are thought to be important to water budgets, water quality, and ecology in the Everglades. Nonetheless, relatively few studies of surface water and ground water interactions have been conducted
Authors
Judson W. Harvey, Jessica T. Newlin, James M. Krest, Jungyill Choi, Eric A. Nemeth, Steven L. Krupa
Interactions between surface water and ground water and effects on mercury transport in the north-central Everglades
The hydrology of the north-central Everglades was altered substantially in the past century by canal dredging, land subsidence, ground-water pumping, and levee construction. Vast areas of seasonal and perennial wetlands were converted to uses for agriculture, light industry, and suburban development. As the catchment area for the Everglades decreased, so did the sources of water from local precipi
Authors
Judson W. Harvey, Steven L. Krupa, Cynthia Gefvert, Robert H. Mooney, Jungyill Choi, Susan A. King, Jefferson B. Giddings
Quantifying time-varying ground-water discharge and recharge in wetlands of the northern Florida Everglades
Developing a more thorough understanding of water and chemical budgets in wetlands depends in part on our ability to quantify time-varying interactions between ground water and surface water. We used a combined water and solute mass balance approach to estimate time-varying ground-water discharge and recharge in the Everglades Nutrient Removal project (ENR), a relatively large constructed wetland
Authors
Jungyill Choi, Judson W. Harvey
Characterizing multiple timescales of stream and storage zone interaction that affect solute fate and transport in streams
The fate of contaminants in streams and rivers is affected by exchange and biogeochemical transformation in slowly moving or stagnant flow zones that interact with rapid flow in the main channel. In a typical stream, there are multiple types of slowly moving flow zones in which exchange and transformation occur, such as stagnant or recirculating surface water as well as subsurface hyporheic zones.
Authors
Jungyill Choi, Judson W. Harvey, Martha H. Conklin
Non-USGS Publications**
Choi, J., M.H. Conklin, R.C. Bales, and R.A. Sommerfeld. 2000. Processes Controlling SO2 Uptake in Snowpacks: Atmospheric Environment. 34, no. 5: 793-801.
Bales, R.C., and J. Choi. 1997. Conceptual Framework for Interpretation of Exchange Processes. In Processes of Chemical Exchange between Polar Snow and Atmosphere. Wolff, E., and R. Bales, editors. NATO ASI Series 1. Springer-Verlag. 319-338.
Choi, J., T. Tokuoka, and K. Yu. 1993. Late Paleozoic -Early Mesozoic Sandstone Petrology of the Maizuru and Akiyoshi -Nishiki Terranes in Southwest Japan. Journal of Geological Society of Korea. 29, no. 2: 188-198.
Choi, J., K. Yu, and T. Tokuoka. 1991. Significance of Volcanogenic Sediments in the Nogam Formation of the Pyeongan Group in Korea (South). Journal of the Geological Society of Japan. 97, no. 7: 557-559.
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.