Category: Research

Agricultural Assessment for the Apalachicola-Chattahoochee-Flint(ACF) River Basin

In this study, bias-corrected and spatio-temporally downscaled climate projections are analyzed to assess how the future climate in the Apalachicola-Chattahoochee-Flint (ACF) River Basin may impact agricultural production and irrigation demand for major crops in the coming decades. This agricultural assessment uses present-day (e.g. year 2023) crop acreages as delineated by the USDA Cropland Data Layer (USDA NASS, 2023) and subjects them to historical and projected daily climate from multiple downscaled and bias-corrected climate models. Climatic hindcasts and projections are based on the Joint Variable Bias Correction with Historical Analog (JVBC-HA) approach. Two Shared Socioeconomic Pathway (SSP) scenarios are considered, the SSP245 scenario featuring mild future greenhouse gas emissions heading into the end of the century, and the SSP585 aggressive emissions scenario. Assessments answer the science question: What kinds of yield and irrigation demand would materialize if present-day agricultural production practices were conditioned under both historical (dating back to year 1988) and projected (extending to year 2095) daily climate?

Research sponsored by the USGS/NIWR Water Resources Act Program 104b Grant (Fiscal Year 2023-2024)

Report Title

Agricultural Assessment for the Apalachicola-Chattahoochee-Flint (ACF) River Basin

Principal Investigator(s)/Authors and Affiliation

Husayn El Sharif
Aris Georgakakos
Georgia Water Resources Institute – Georgia Institute of Technology

Abstract

In this study, bias-corrected and spatio-temporally downscaled climate projections are analyzed to assess how the future climate in the Apalachicola-Chattahoochee-Flint (ACF) River Basin may impact agricultural production and irrigation demand for major crops in the coming decades. This agricultural assessment uses present-day (e.g. year 2023) crop acreages as delineated by the USDA Cropland Data Layer (USDA NASS, 2023) and subjects them to historical and projected daily climate from multiple downscaled and bias-corrected climate models. Climatic hindcasts and projections are based on the Joint Variable Bias Correction with Historical Analog (JVBC-HA) approach. Two Shared Socioeconomic Pathway (SSP) scenarios are considered, the SSP245 scenario featuring mild future greenhouse gas emissions heading into the end of the century, and the SSP585 aggressive emissions scenario. Assessments answer the science question: What kinds of yield and irrigation demand would materialize if present-day agricultural production practices were conditioned under both historical (dating back to year 1988) and projected (extending to year 2095) daily climate?

Report

Final-Draft-ACF-Agricultural-Assessment-v01Download

Climate Assessment for the Southeastern U.S.

In this study, bias-corrected climate projections are analyzed to assess how the future climate in the southeastern U.S. may change in the coming decades. These climatic projections are based on the Joint Variable Bias Correction with Historical Analog (JVBC-HA) approach (Georgakakos & El Sharif, 2024). Two Shared Socioeconomic Pathway (SSP) scenarios are considered, the SSP245 scenario featuring mild future greenhouse gas emissions, and the SSP585 aggressive emissions scenario.

Research sponsored by the USGS/NIWR Water Resources Act Program 104b Grant (Fiscal Year 2023-2024)

Report Title

Climate Assessment for the Southeastern U.S.

Principal Investigator(s)/Authors and Affiliation

Husayn El Sharif
Shivani Chougule
Aris Georgakakos
Georgia Water Resources Institute – Georgia Institute of Technology

Abstract

In this study, bias-corrected climate projections are analyzed to assess how the future climate in the southeastern U.S. may change in the coming decades. These climatic projections are based on the Joint Variable Bias Correction with Historical Analog (JVBC-HA) approach (Georgakakos & El Sharif, 2024). Two Shared Socioeconomic Pathway (SSP) scenarios are considered, the SSP245 scenario featuring mild future greenhouse gas emissions, and the SSP585 aggressive emissions scenario.

Report

Final-Draft-SE-Climate-Assessment-v01Download

2023 Biennial Georgia Water Resources Conference – Year 2 (Final Report)

Since its inception in 1989, the biennial Georgia Water Resources Conference has provided an open forum for the discussion of water policies, research, and management strategies within the state of Georgia and surrounding states. The high-profile meeting attracts diverse attendance from government, private, academic and non-profit sectors. The 2023 meeting was the largest ever, with 400 total registrants, 130 oral presentations, 10 panels and 47 posters. The meeting attracted 27 sponsors in addition to GWRI (the lead sponsor); these additional sponsors contributed a total of $30,350. A total of 116 students (mostly graduate and undergraduate, plus a few high school students) attended the meeting.

Research sponsored by the USGS/NIWR Water Resources Act Program 104b Grant (Fiscal Year 2023-2024)

Report Title

2023 Biennial Georgia Water Resources Conference – Year 2 (Final Report)

Principal Investigator(s)/Authors and Affiliation

Dr. Seth Wenger
University of Georgia

Abstract

Since its inception in 1989, the biennial Georgia Water Resources Conference has provided an open forum for the discussion of water policies, research, and management strategies within the state of Georgia and surrounding states. The high-profile meeting attracts diverse attendance from government, private, academic and non-profit sectors. The 2023 meeting was the largest ever, with 400 total registrants, 130 oral presentations, 10 panels and 47 posters. The meeting attracted 27 sponsors in addition to GWRI (the lead sponsor); these additional sponsors contributed a total of $30,350. A total of 116 students (mostly graduate and undergraduate, plus a few high school students) attended the meeting.

Report

2024-GWRC-Final-ReportDownload

Evaluating longitudinal declines in water quality in the Conasauga River using aquatic macroinvertebrates

The Conasauga River in Northwest Georgia is nationally recognized for its aquatic biodiversity, much of which is imperiled. The river supports five federally listed fish and seven federally listed mussel species and has been identified as a top priority watershed for conservation in the southeastern USA (Elkins et al. 2019). As many as 30% of the native mussel species in the Conasauga may be extirpated (Evans 2001, Walters et al. 2003), and numerous fish species have declined precipitously in abundance since 2000 (Nagy et al. 2024), including the federally endangered Amber Darter (Percina antesella) and the federally threatened Frecklebelly Madtom (Noturus munitus; Freeman et al. 2017, Stowe et al. 2020). The mechanisms contributing to declining aquatic species have yet to be identified.

Research sponsored by the USGS/NIWR Water Resources Act Program 104b Grant (Fiscal Year 2023-2024)

Report Title

Evaluating longitudinal declines in water quality in the Conasauga River using aquatic macroinvertebrates

Principal Investigator(s)/Authors and Affiliation

Dr. Seth Wenger
University of Georgia

Abstract

The Conasauga River in Northwest Georgia is nationally recognized for its aquatic biodiversity, much of which is imperiled. The river supports five federally listed fish and seven federally listed mussel species and has been identified as a top priority watershed for conservation in the southeastern USA (Elkins et al. 2019). As many as 30% of the native mussel species in the Conasauga may be extirpated (Evans 2001, Walters et al. 2003), and numerous fish species have declined precipitously in abundance since 2000 (Nagy et al. 2024), including the federally endangered Amber Darter (Percina antesella) and the federally threatened Frecklebelly Madtom (Noturus munitus; Freeman et al. 2017, Stowe et al. 2020). The mechanisms contributing to declining aquatic species have yet to be identified.

The headwaters of the Conasauga River lie in the Chattahoochee National Forest in the Blue Ridge Mountains, but the river quickly enters a highly productive agricultural valley after exiting the national forest (Fig. 1; Bumpers et al. 2019). Shortly downstream of the National Forest boundary agricultural land use increases to ~ 19% of the entire watershed (Figure 1; Bumpers et al. 2019). Nitrogen (N) and phosphorus (P) concentrations in the Conasauga River are consistently high compared to EPA reference conditions, and episodically spike to very high levels (Sharpe and Nichols 2007, Lasier et al. 2016, Bumpers and Freeman 2017). Nutrients, contaminants, and sediment from agricultural activities may negatively affect water quality and impair the habitat of aquatic species in the river.

The density and biomass of aquatic insects can be measured to assess water quality impairment. Changes in community composition versus changes in total community biomass can provide insights into potential effects on higher trophic levels. For instance, fish communities may not be affected by water quality impairment if the quantity of prey does not change, even if the taxonomic composition does. However, if water quality results in overall declines in prey biomass, fish could become resource-limited and thus have their carrying capacity reduced as a result of indirect effects of water quality. We estimated invertebrate abundance, biomass, and species composition in the Conasauga River along a longitudinal gradient in landuse to assess if the Conasauga River has depressed invertebrate biomass. We evaluated if 1) invertebrate populations and communities differed along this longitudinal gradient and 2) if invertebrate biomass in the Conasauga is lower than expected compared to similar rivers. Here we summarize findings from year 1 of a two-year project.

Report

GA_2023_Wenger_GWRI-tech-reportDownload

Uncertainty Analysis of Flooding Drivers in the City of Savannah by an Urban Flooding Model

This study assesses flood variability during different hurricane events along the Savannah River’s fluvial system. To achieve real-time estimations of water surface elevations (WSE) across river channels and reaches, we developed a Physics-Informed Geostatistics Approach (PIGA) that combines reduced spatial correlations derived from a fluvial hydrodynamic model with a Reduced Geostatistical Approach (RGA) based on observational data. A 1D-2D HEC-RAS model was constructed as the physical model for the Savannah River Basin, an area highly susceptible to riverine flooding during hurricane seasons. The performance of the PIGA was compared to the HEC-RAS model across multiple hurricane events, including Hurricanes Matthew, Irma, Dorian, and Idalia. Our study explores the transferability and variability of reduced spatial correlations across different hurricane events, assessing the capability of one event’s spatial data to predict WSE during other events. Results indicate that spatial correlations derived from one hurricane event can reliably predict WSE for other events, with the correlations from Hurricane Irma demonstrating the greatest versatility for our study site. However, significant variability in spatial correlations between hurricane events was also observed, underscoring the need to carefully select the optimal reference event to achieve accurate predictions.

Research sponsored by the USGS/NIWR Water Resources Act Program 104b Grant (Fiscal Year 2023-2024)

Report Title

Uncertainty Analysis of Flooding Drivers in the City of Savannah by an Urban Flooding Model

Principal Investigator(s)/Authors and Affiliation

Dr. Jian Luo
School of Civil and Environmental
Georgia Institute of Technology

Abstract

This study assesses flood variability during different hurricane events along the Savannah River’s fluvial system. To achieve real-time estimations of water surface elevations (WSE) across river channels and reaches, we developed a Physics-Informed Geostatistics Approach (PIGA) that combines reduced spatial correlations derived from a fluvial hydrodynamic model with a Reduced Geostatistical Approach (RGA) based on observational data. A 1D-2D HEC-RAS model was constructed as the physical model for the Savannah River Basin, an area highly susceptible to riverine flooding during hurricane seasons. The performance of the PIGA was compared to the HEC-RAS model across multiple hurricane events, including Hurricanes Matthew, Irma, Dorian, and Idalia. Our study explores the transferability and variability of reduced spatial correlations across different hurricane events, assessing the capability of one event’s spatial data to predict WSE during other events. Results indicate that spatial correlations derived from one hurricane event can reliably predict WSE for other events, with the correlations from Hurricane Irma demonstrating the greatest versatility for our study site. However, significant variability in spatial correlations between hurricane events was also observed, underscoring the need to carefully select the optimal reference event to achieve accurate predictions.

Report

Final-Report_FY23_LUODownload

Spatial changes in trace element water chemistry across Piedmont rivers of Georgia with applications for native fish species conservation

Anthropogenic changes to freshwater river systems have impacted native fish and mussel distribution and abundance. Disruptions in movement and migration have led to the declines of many important species in Georgia, including several threatened and endangered species. Furthermore, anthropogenic barriers, physical stream alterations, and reservoir construction may facilitate invasive species expansion and colonization, thereby impacting native species through displacement, disease, and hybridization. The impacts of these human activities – and their relative degrees of influence – vary among river basins and among distinct segments within systems. To help assess the impacts anthropogenic effects have on native species, fish microchemistry can be used to help decipher large scale movement patterns, natal origins and introductions, and habitat use. Trace elements, such as strontium and barium are incorporated into calcified structures of fishes relative to water concentrations. Therefore, quantifying trace element concentrations within and among river systems is a conduit for examining fish behaviors, such as movement and dispersal. The Piedmont ecoregion is an ideal place to study microchemistry as it has unique geologic features and human population centers that can influence water chemistry. Furthermore, there is a diverse fish assemblage containing a mix of native species in need of conservation and introduced or invasive fishes.

Research sponsored by the USGS/NIWR Water Resources Act Program 104b Grant (Fiscal Year 2023-2024)

Report Title

Spatial changes in trace element water chemistry across Piedmont rivers of Georgia with applications for native fish species conservation

Principal Investigator(s)/Authors and Affiliation

Dr. Martin Hamel
University of Georgia, Associate Professor

Dr. James Shelton
University of Georgia, Associate Professor

Abstract

Anthropogenic changes to freshwater river systems have impacted native fish and mussel distribution and abundance. Disruptions in movement and migration have led to the declines of many important species in Georgia, including several threatened and endangered species. Furthermore, anthropogenic barriers, physical stream alterations, and reservoir construction may facilitate invasive species expansion and colonization, thereby impacting native species through displacement, disease, and hybridization. The impacts of these human activities – and their relative degrees of influence – vary among river basins and among distinct segments within systems. To help assess the impacts anthropogenic effects have on native species, fish microchemistry can be used to help decipher large scale movement patterns, natal origins and introductions, and habitat use. Trace elements, such as strontium and barium are incorporated into calcified structures of fishes relative to water concentrations. Therefore, quantifying trace element concentrations within and among river systems is a conduit for examining fish behaviors, such as movement and dispersal. The Piedmont ecoregion is an ideal place to study microchemistry as it has unique geologic features and human population centers that can influence water chemistry. Furthermore, there is a diverse fish assemblage containing a mix of native species in need of conservation and introduced or invasive fishes.

The objective of our study is to develop a comprehensive data set of environmental levels of trace elements among major river systems and their tributaries in the Piedmont region of Georgia. Assessments of water chemistry throughout a network of rivers in the Piedmont ecoregion will provide a baseline for future changes in water chemistry due to land use changes resulting from urbanization, agriculture, or other sources of change, and a mechanism for understanding fish movement dynamics.

Report

Final-report_HamelDownload

Development of a New Green Infrastructure by Using Biochar Amended Topsoil for on-site Stormwater Runoff Treatment-Phase II

The proposed objectives of this Phase II research project are to 1) To continually operate,
maintain, sample and test the Test Site treating the Runoff; 2) To continually investigate and
determine performance of the Test Site on removal efficiencies of the pollutants under different
weather conditions including frequencies of rainfall events and dry and wet seasons; and 3) To
develop guidelines for operation and maintenance for the Green Infrastructure (GI) by Using
Biochar Amended Topsoil for On-Site Stormwater Runoff Treatment. The major pollutants
from raw stormwater runoff and its treated effluent from the Test Site were total suspended
solid (TSS), nutrients including nitrogen and phosphorous, heavy metals including lead (Pb),
zinc (Zn) and copper (Cu) and oil and grease etc. Their removal efficiencies were determined
and evaluated. The goal of this research project, including Phase I and Phase II, is to investigate
the feasibility of using biochar-amended topsoil as a new GI solution for on-site treating
stormwater runoff in urban areas. Based on this assessment, guidelines will be developed for
the implementation of similar systems in urban areas. The findings of this study will contribute
to the understanding of biochar application in GI which is cost-effective and broadens the
spectrum of sustainable stormwater treatment strategies.

Research sponsored by the USGS/NIWR Water Resources Act Program 104b Grant (Fiscal Year 2023-2024)

Report Title

Development of a New Green Infrastructure by Using Biochar Amended Topsoil for on-site Stormwater Runoff Treatment- Phase II

Principal Investigator(s)/Authors and Affiliation

George Yuzhu Fu, Ph.D., P.E., Professor
Ayesha Sadia, Master Student
Department of Civil Engineering and Construction
Georgia Southern University
September 2024

Abstract

The proposed objectives of this Phase II research project are to 1) To continually operate,
maintain, sample and test the Test Site treating the Runoff; 2) To continually investigate and
determine performance of the Test Site on removal efficiencies of the pollutants under different
weather conditions including frequencies of rainfall events and dry and wet seasons; and 3) To
develop guidelines for operation and maintenance for the Green Infrastructure (GI) by Using
Biochar Amended Topsoil for On-Site Stormwater Runoff Treatment. The major pollutants
from raw stormwater runoff and its treated effluent from the Test Site were total suspended
solid (TSS), nutrients including nitrogen and phosphorous, heavy metals including lead (Pb),
zinc (Zn) and copper (Cu) and oil and grease etc. Their removal efficiencies were determined
and evaluated. The goal of this research project, including Phase I and Phase II, is to investigate
the feasibility of using biochar-amended topsoil as a new GI solution for on-site treating
stormwater runoff in urban areas. Based on this assessment, guidelines will be developed for
the implementation of similar systems in urban areas. The findings of this study will contribute
to the understanding of biochar application in GI which is cost-effective and broadens the
spectrum of sustainable stormwater treatment strategies.

The Phase II project started in September 2023 and concluded in August 2024. Throughout the Phase II project, one-year continual operation, maintaining, monitoring, collecting and testing the water samples were performed. In this research project water quality (WQ) parameters of concern were suspended solids, nutrients (i.e., nitrogen and phosphorus), heavy metals (i.e., Pb, Zn, and Cu), oil and grease, and chemical oxygen demand (COD). Also, new monitoring and testing as well as improvement were added including Turf Tech infiltrometer was used to monitor the infiltration rate, while the HOBO moisture logger was used to monitor the moisture content at the Field Test Site. In order to identify the surface morphology and elemental composition of the biochar samples, scanning electron microscopy (SEM) was performed. Adenosine Triphosphate (ATP) testing was also performed to monitor the active biofilm/biomass in the Field Test Site. During Phase II Project about 507 gallons of the Veazy Hall Parking Lot stormwater runoff were treated by each Test Cell and Control Cell during Fall 2023, Spring 2024, and Summer 2024. Finally, the removal efficiencies are summarized as follows: TSS: 58.97% for Control Cell versus 87.77% for Test Cell; NH3-N: 62.62% vs. 89.41%, NO3–N: -37.2% vs 82.68%, TKN: 63.13% vs 89.35%; TN: 64.70% vs 88.25%; TP: -276.19% vs 90.25%; Oil and grease: 35.51% vs 87.09%, Total Cu: 23.80% vs 80%, Total Zn: 30.67% vs 70.41% and Total Pb: 22.80% vs 61.07%. The removal efficiencies during Phase II Project for this 1-year duration are quite similar to those of preliminary results during Phase I.

Report

Final-Report-for-Project-ID-GA_2023_Fu-Biochar-Phase-II-Download

Land cover classification and wetland inundation mapping using MODIS

Sponsors: National Science Foundation

Students: Courtney Di Vittorio

Description:

Hydrologic models of wetlands enable hydrologists and water resources managers to appreciate the environmental and societal roles of wetlands and manage them in ways that preserve their integrity and sustain their valuable services. However, wetland model reliability and accuracy are often unsatisfactory due to the complexity of the underlying processes and the lack of adequate in-situ data. In this research, we demonstrate how MODIS satellite imagery can be used to characterize wetland flooding over time and to support the development of more reliable wetland models. We apply this method to the Sudd, a seasonal wetland in South Sudan that is part of the Nile River Basin.

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Sponsors: National Science Foundation

Students: Courtney Di Vittorio

Description:

Hydrologic models of wetlands enable hydrologists and water resources managers to appreciate the environmental and societal roles of wetlands and manage them in ways that preserve their integrity and sustain their valuable services. However, wetland model reliability and accuracy are often unsatisfactory due to the complexity of the underlying processes and the lack of adequate in-situ data. In this research, we demonstrate how MODIS satellite imagery can be used to characterize wetland flooding over time and to support the development of more reliable wetland models. We apply this method to the Sudd, a seasonal wetland in South Sudan that is part of the Nile River Basin.

The database consists of 16 years of 8-day composite ground surface reflectance data with a 500-m spatial resolution. After masking poor quality pixels, monthly distributions of wetness and vegetation indices were extracted. Based on literature and personal accounts describing the Sudd as well as Google Earth imagery, a set of ground truth locations were identified for nine land classes. Using the ground truth locations, a novel classification procedure was developed that uses the empirical monthly distributions of each individual pixel. This procedure allows pixels to be classified as mixed pixels (or mixels) if their distributions share properties with two different classes. Once the full area of interest was classified, each pixel was evaluated on a monthly scale to determine if, when, and how long it was flooded using a procedure that incorporates spatial information and monthly precipitation data. The result is a set of monthly inundation maps for the full period of interest (2000–2015). An independent set of ground truth locations were selected to validate the land cover classification procedure, which demonstrated a high level of accuracy. The derived monthly inundation series agrees well with existing literature, limited ground observations, and estimated water fluxes into the wetland. This information is currently being used to develop a wetland model as part of a comprehensive modeling system for the Nile River Basin. This novel procedure is general and has many advantages over those in existing research for applications in data scare areas.

Publications:

C. A. Di Vittorio & A. P. Georgakakos. Land cover classification and wetland inundation mapping using MODIS. Remote Sensing of Environment 204, 1-17 (2018). https://doi.org/10.1016/j.rse.2017.11.001 

Acknowledgements:

We are grateful to the Ministries of Water and Irrigation in Uganda, Sudan, and Egypt for the provision of in-situ river flow and other hydrologic data.  Moreover, we are grateful to Dr. Georg Petersen for sharing his ground measurements on the Sudd Wetland. This research was supported in part by the National Science Foundation Graduate Research Fellowship Program under Grant No. DGE-1650044. Any opinions, findings, and conclusions or recommendations expressed in this article are those of the authors and do not necessarily reflect the views of the National Science Foundation or other organizations.

Adjustment of Ensemble Streamflow Predictions for Upstream Water Use and Regulation

In watersheds with appreciable water use and regulation (including storage reservoirs, in-stream withdrawals, and/or inter-basin water transfers), the development of reliable ensemble streamflow predictions (ESP) at downstream locations requires characterization and incorporation of the expected streamflow alterations from natural conditions and their associated uncertainty.  Streamflow alterations can be incorporated if, as part of the ESP forecast generation process, water use and regulation activities are represented with sufficient accuracy. 

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Streamflow Predictions for Upstream Water Use and Regulation

Effects of Water Use and Regulation

In watersheds with appreciable water use and regulation (including storage reservoirs, in-stream withdrawals, and/or inter-basin water transfers), the development of reliable ensemble streamflow predictions (ESP) at downstream locations requires characterization and incorporation of the expected streamflow alterations from natural conditions and their associated uncertainty.  Streamflow alterations can be incorporated if, as part of the ESP forecast generation process, water use and regulation activities are represented with sufficient accuracy.  This approach can be effective in watersheds where flow alterations occur due to large, main stem river projects and well documented water use activities, but it becomes impractical where flow alterations result from many small and/or medium scale storage projects and water use activities distributed throughout the watershed.  In the latter cases, comprehensive information on reservoir filling and depletion, water withdrawals and returns, and/or water transfers is both not readily available and subject to change from year to year, adding bias and uncertainty to the flow forecasts. This research project develops and demonstrates procedures to characterize the aggregate flow alteration biases and uncertainty in watersheds in the latter category and incorporate them in ensemble streamflow predictions at downstream points.

Project Scope and Activities

This research project develops and demonstrates a new method to characterize the aggregate flow alteration biases and associated uncertainty in watersheds with important but largely undocumented water use and regulation activities.

The approach includes procedures to (a) detect the presence of significant upstream regulation and water use influences; (b) correct the ensemble streamflow predictions and associated uncertainty for any biases during periods when upstream regulation and water use influences are detected; and (c) assess the forecast reliability improvements. Validation results are reported for three California watersheds. The forecast adjustment approach has been developed for operational use in routine forecast operations of the U.S. National Weather Service River Forecast Centers.  

Related Publications

1.    Georgakakos, A.P., H. Yao, and K.P. Georgakakos, “Upstream Regulation Effects on Ensemble Streamflow Prediction,” Journal of Hydrology, in press, 2014.

Acknowledgements

This project was funded by the Hydrologic Research Laboratory of the National Weather Service and was carried out jointly by the Hydrologic Research Center (HRC; California) and the Georgia Water Resources Institute (GWRI; Georgia) in collaboration with the NWS River Forecast Centers.