Hedeff Essaid is a Research Hydrologist with the USGS Water Resources Mission Area.
My research has involved the analysis of field data and simulation of groundwater systems and watersheds to characterize water and chemical mass balances and to study the relative importance of different hydrologic processes and flow pathways. The results of these studies provide an opportunity to compare and contrast groundwater transport, surface water-groundwater interactions and chemical fate in different hydrologic/environmental settings. This work has improved our understanding and quantification of processes and factors that control the magnitude and timing of environmental responses to contaminant loading and changing hydrology. I have used this approach to study: saltwater intrusion in layered coastal aquifer systems; the impact of heterogeneity and hysteresis on the distribution of crude oil at a spill site; the role of dissolution and biodegradation on the fate of hydrocarbon components in the subsurface; the impact of surface water-ground water interactions on stream flow, temperature, and water quality; the hydrology of natural and incised mountain meadows; and nutrient fate in diverse watersheds.
EDUCATION:
- Stanford University, Ph.D., 1987, Hydrogeology
- Stanford University, M.S., 1984, Hydrogeology
- University of Baghdad, Iraq, B.S., 1978, Geology-Geophysics
Science and Products
Daily streamflow performance benchmark defined by the standard statistical suite (v1.0) for the National Water Model Retrospective (v2.1) at benchmark streamflow locations (ver. 2.0, December 2022)
This data release contains the standard statistical suite (version 1.0) daily streamflow performance benchmark results for the National Water Model Retrospective (v2.1) at streamflow benchmark locations (version 1.0) as defined by Foks and others (2022). Modeled hourly timesteps were converted to mean daily timesteps. Model error was determined by evaluating predicted daily mean streamflow versus
Daily streamflow performance benchmark defined by the standard statistical suite (v1.0) for the National Hydrologic Model application of the Precipitation-Runoff Modeling System (v1 byObs Muskingum) at benchmark streamflow locations (ver. 2.0, December 20
This data release contains the standard statistical suite (version 1.0) daily streamflow performance benchmark results for the National Hydrologic Model Infrastructure application of the Precipitation-Runoff Modeling System (NHM-PRMS) version 1 "byObs" calibration with Muskingum routing computed at streamflow benchmark locations (version 1.0) as defined by Foks and others (2022).
Streamflow benchmark locations for hydrologic model evaluation within the conterminous United States (cobalt gages)
A list of stream gages within the conterminous United States that will serve as the initial list of sites (version 1.0) used for streamflow benchmarking of hydrologic models. Sites within this list were chosen based on their presence in the GAGES-II dataset, their availability of modeled streamflow data from the most recent version of the National Hydrologic Model application of Precipitation-Runo
MODFLOW, MT3D-USGS and VS2DH simulations used to estimate groundwater and nutrient inflow to Upper Klamath Lake, Oregon
One-dimensional vertical models of GW flow (MODFLOW-2005) and solute transport (MT3D-USGS) were calibrated (UCODE) to 2014 observed dissolved silica (Si, 0.2-micron filtered) porewater concentrations in the upper 0.1 m of lakebed sediment to estimate GW flow and Si exchange across the lakebed interface. The Si-based calibrated GW flow rates were then used in conjunction with observed dissolved pho
Filter Total Items: 33
Evaluating the dynamics of groundwater, lakebed transport, nutrient inflow and algal blooms in Upper Klamath Lake, Oregon, USA
Transport of nutrients to lakes can occur via surface-water inflow, atmospheric deposition, groundwater (GW) inflow and benthic processes. Identifying and quantifying within-lake nutrient sources and recycling processes is challenging. Prior studies in hypereutrophic Upper Klamath Lake, Oregon, USA, indicated that ~60% of the early summer phosphorus (P) load to the lake was internal and hypothesiz
Evaluating the impact of irrigation on surface water – groundwater interaction and stream temperature in an agricultural watershed
Changes in groundwater discharge to streams caused by irrigation practices can influence stream temperature. Observations along two currently flood-irrigated reaches in the 640-square-kilometer upper Smith River watershed, an important agricultural and recreational fishing area in west-central Montana, showed a downstream temperature decrease resulting from groundwater discharge to the stream. A w
Contrasting nitrogen fate in watersheds using agricultural and water quality information
Surplus nitrogen (N) estimates, principal component analysis (PCA), and end-member mixing analysis (EMMA) were used in a multisite comparison contrasting the fate of N in diverse agricultural watersheds. We applied PCA-EMMA in 10 watersheds located in Indiana, Iowa, Maryland, Nebraska, Mississippi, and Washington ranging in size from 5 to 1254 km2 with four nested watersheds. Watershed Surplus N w
The role of dynamic surface water-groundwater exchange on streambed denitrification in a first-order, low-relief agricultural watershed
The role of temporally varying surface water-groundwater (SW-GW) exchange on nitrate removal by streambed denitrification was examined along a reach of Leary Weber Ditch (LWD), Indiana, a small, first-order, low-relief agricultural watershed within the Upper Mississippi River basin, using data collected in 2004 and 2005. Stream stage, GW heads (H), and temperatures (T) were continuously monitored
Organic contaminant transport and fate in the subsurface: evolution of knowledge and understanding
Toxic organic contaminants may enter the subsurface as slightly soluble and volatile nonaqueous phase liquids (NAPLs) or as dissolved solutes resulting in contaminant plumes emanating from the source zone. A large body of research published in Water Resources Research has been devoted to characterizing and understanding processes controlling the transport and fate of these organic contaminants and
Watershed-scale modeling of streamflow change in incised montane meadows
Land use practices have caused stream channel incision and water table decline in many montane meadows of the Western United States. Incision changes the magnitude and timing of streamflow in water supply source watersheds, a concern to resource managers and downstream water users. The hydrology of montane meadows under natural and incised conditions was investigated using watershed simulation for
Design of Cycle 3 of the National Water-Quality Assessment Program, 2013-23: Part 2: Science plan for improved water-quality information and management
This report presents a science strategy for the third decade of the National Water-Quality Assessment (NAWQA) Program, which since 1991, has been responsible for providing nationally consistent information on the quality of the Nation's streams and groundwater; how water quality is changing over time; and the major natural and human factors that affect current water quality conditions and trends.
VS2DI: Model use, calibration, and validation
VS2DI is a software package for simulating water, solute, and heat transport through soils or other porous media under conditions of variable saturation. The package contains a graphical preprocessor for constructing simulations, a postprocessor for displaying simulation results, and numerical models that solve for flow and solute transport (VS2DT) and flow and heat transport (VS2DH). Flow is desc
Crude oil at the Bemidji Site: 25 years of monitoring, modeling, and understanding
The fate of hydrocarbons in the subsurface near Bemidji, Minnesota, has been investigated by a multidisciplinary group of scientists for over a quarter century. Research at Bemidji has involved extensive investigations of multiphase flow and transport, volatilization, dissolution, geochemical interactions, microbial populations, and biodegradation with the goal of providing an improved understandi
Effects of upstream dams versus groundwater pumping on stream temperature under varying climate conditions
The relative impact of a large upstream dam versus in‐reach groundwater pumping on stream temperatures was analyzed for humid, semiarid, and arid conditions with long dry seasons to represent typical climate regions where large dams are present, such as the western United States or eastern Australia. Stream temperatures were simulated using the CE‐QUAL‐W2 water quality model over a 110 km model gr
Design of Cycle 3 of the National Water-Quality Assessment Program, 2013-2022: Part 1: Framework of Water-Quality Issues and Potential Approaches
In 1991, the U.S. Congress established the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program to develop long-term, nationally consistent information on the quality of the Nation's streams and groundwater. Congress recognized the critical need for this information to support scientifically sound management, regulatory, and policy decisions concerning the increasingly
In situ measurements of volatile aromatic hydrocarbon biodegradation rates in groundwater
Benzene and alkylbenzene biodegradation rates and patterns were measured using an in situ microcosm in a crude-oil contaminated aquifer near Bemidji, Minnesota. Benzene-D6, toluene, ethylbenzene, o-, m- and p-xylenes and four pairs of C3- and C4-benzenes were added to an in situ microcosm and studied over a 3-year period. The microcosm allowed for a mass-balance approach and quantification of hydr
Science and Products
- Data
Daily streamflow performance benchmark defined by the standard statistical suite (v1.0) for the National Water Model Retrospective (v2.1) at benchmark streamflow locations (ver. 2.0, December 2022)
This data release contains the standard statistical suite (version 1.0) daily streamflow performance benchmark results for the National Water Model Retrospective (v2.1) at streamflow benchmark locations (version 1.0) as defined by Foks and others (2022). Modeled hourly timesteps were converted to mean daily timesteps. Model error was determined by evaluating predicted daily mean streamflow versusDaily streamflow performance benchmark defined by the standard statistical suite (v1.0) for the National Hydrologic Model application of the Precipitation-Runoff Modeling System (v1 byObs Muskingum) at benchmark streamflow locations (ver. 2.0, December 20
This data release contains the standard statistical suite (version 1.0) daily streamflow performance benchmark results for the National Hydrologic Model Infrastructure application of the Precipitation-Runoff Modeling System (NHM-PRMS) version 1 "byObs" calibration with Muskingum routing computed at streamflow benchmark locations (version 1.0) as defined by Foks and others (2022).Streamflow benchmark locations for hydrologic model evaluation within the conterminous United States (cobalt gages)
A list of stream gages within the conterminous United States that will serve as the initial list of sites (version 1.0) used for streamflow benchmarking of hydrologic models. Sites within this list were chosen based on their presence in the GAGES-II dataset, their availability of modeled streamflow data from the most recent version of the National Hydrologic Model application of Precipitation-RunoMODFLOW, MT3D-USGS and VS2DH simulations used to estimate groundwater and nutrient inflow to Upper Klamath Lake, Oregon
One-dimensional vertical models of GW flow (MODFLOW-2005) and solute transport (MT3D-USGS) were calibrated (UCODE) to 2014 observed dissolved silica (Si, 0.2-micron filtered) porewater concentrations in the upper 0.1 m of lakebed sediment to estimate GW flow and Si exchange across the lakebed interface. The Si-based calibrated GW flow rates were then used in conjunction with observed dissolved pho - Publications
Filter Total Items: 33
Evaluating the dynamics of groundwater, lakebed transport, nutrient inflow and algal blooms in Upper Klamath Lake, Oregon, USA
Transport of nutrients to lakes can occur via surface-water inflow, atmospheric deposition, groundwater (GW) inflow and benthic processes. Identifying and quantifying within-lake nutrient sources and recycling processes is challenging. Prior studies in hypereutrophic Upper Klamath Lake, Oregon, USA, indicated that ~60% of the early summer phosphorus (P) load to the lake was internal and hypothesizEvaluating the impact of irrigation on surface water – groundwater interaction and stream temperature in an agricultural watershed
Changes in groundwater discharge to streams caused by irrigation practices can influence stream temperature. Observations along two currently flood-irrigated reaches in the 640-square-kilometer upper Smith River watershed, an important agricultural and recreational fishing area in west-central Montana, showed a downstream temperature decrease resulting from groundwater discharge to the stream. A wContrasting nitrogen fate in watersheds using agricultural and water quality information
Surplus nitrogen (N) estimates, principal component analysis (PCA), and end-member mixing analysis (EMMA) were used in a multisite comparison contrasting the fate of N in diverse agricultural watersheds. We applied PCA-EMMA in 10 watersheds located in Indiana, Iowa, Maryland, Nebraska, Mississippi, and Washington ranging in size from 5 to 1254 km2 with four nested watersheds. Watershed Surplus N wThe role of dynamic surface water-groundwater exchange on streambed denitrification in a first-order, low-relief agricultural watershed
The role of temporally varying surface water-groundwater (SW-GW) exchange on nitrate removal by streambed denitrification was examined along a reach of Leary Weber Ditch (LWD), Indiana, a small, first-order, low-relief agricultural watershed within the Upper Mississippi River basin, using data collected in 2004 and 2005. Stream stage, GW heads (H), and temperatures (T) were continuously monitoredOrganic contaminant transport and fate in the subsurface: evolution of knowledge and understanding
Toxic organic contaminants may enter the subsurface as slightly soluble and volatile nonaqueous phase liquids (NAPLs) or as dissolved solutes resulting in contaminant plumes emanating from the source zone. A large body of research published in Water Resources Research has been devoted to characterizing and understanding processes controlling the transport and fate of these organic contaminants andWatershed-scale modeling of streamflow change in incised montane meadows
Land use practices have caused stream channel incision and water table decline in many montane meadows of the Western United States. Incision changes the magnitude and timing of streamflow in water supply source watersheds, a concern to resource managers and downstream water users. The hydrology of montane meadows under natural and incised conditions was investigated using watershed simulation forDesign of Cycle 3 of the National Water-Quality Assessment Program, 2013-23: Part 2: Science plan for improved water-quality information and management
This report presents a science strategy for the third decade of the National Water-Quality Assessment (NAWQA) Program, which since 1991, has been responsible for providing nationally consistent information on the quality of the Nation's streams and groundwater; how water quality is changing over time; and the major natural and human factors that affect current water quality conditions and trends.VS2DI: Model use, calibration, and validation
VS2DI is a software package for simulating water, solute, and heat transport through soils or other porous media under conditions of variable saturation. The package contains a graphical preprocessor for constructing simulations, a postprocessor for displaying simulation results, and numerical models that solve for flow and solute transport (VS2DT) and flow and heat transport (VS2DH). Flow is descCrude oil at the Bemidji Site: 25 years of monitoring, modeling, and understanding
The fate of hydrocarbons in the subsurface near Bemidji, Minnesota, has been investigated by a multidisciplinary group of scientists for over a quarter century. Research at Bemidji has involved extensive investigations of multiphase flow and transport, volatilization, dissolution, geochemical interactions, microbial populations, and biodegradation with the goal of providing an improved understandiEffects of upstream dams versus groundwater pumping on stream temperature under varying climate conditions
The relative impact of a large upstream dam versus in‐reach groundwater pumping on stream temperatures was analyzed for humid, semiarid, and arid conditions with long dry seasons to represent typical climate regions where large dams are present, such as the western United States or eastern Australia. Stream temperatures were simulated using the CE‐QUAL‐W2 water quality model over a 110 km model grDesign of Cycle 3 of the National Water-Quality Assessment Program, 2013-2022: Part 1: Framework of Water-Quality Issues and Potential Approaches
In 1991, the U.S. Congress established the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program to develop long-term, nationally consistent information on the quality of the Nation's streams and groundwater. Congress recognized the critical need for this information to support scientifically sound management, regulatory, and policy decisions concerning the increasinglyIn situ measurements of volatile aromatic hydrocarbon biodegradation rates in groundwater
Benzene and alkylbenzene biodegradation rates and patterns were measured using an in situ microcosm in a crude-oil contaminated aquifer near Bemidji, Minnesota. Benzene-D6, toluene, ethylbenzene, o-, m- and p-xylenes and four pairs of C3- and C4-benzenes were added to an in situ microcosm and studied over a 3-year period. The microcosm allowed for a mass-balance approach and quantification of hydr