Richard G Niswonger (Former Employee)
Science and Products
Filter Total Items: 17
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Feedback of land subsidence on the movement and conjunctive use of water resources Feedback of land subsidence on the movement and conjunctive use of water resources
The dependency of surface- or groundwater flows and aquifer hydraulic properties on dewatering-induced layer deformation is not available in the USGS's groundwater model MODFLOW. A new integrated hydrologic model, MODFLOW-OWHM, formulates this dependency by coupling mesh deformation with aquifer transmissivity and storage and by linking land subsidence/uplift with deformation-dependent...
Authors
Wolfgang Schmid, Randall T. Hanson, Stanley A. Leake, Joseph D. Hughes, Richard G. Niswonger
Using heat as a tracer to estimate spatially distributed mean residence times in the hyporheic zone of a riffle-pool sequence Using heat as a tracer to estimate spatially distributed mean residence times in the hyporheic zone of a riffle-pool sequence
Biochemical reactions that occur in the hyporheic zone are highly dependent on the time solutes that are in contact with sediments of the riverbed. In this investigation, we developed a 2-D longitudinal flow and solute-transport model to estimate the spatial distribution of mean residence time in the hyporheic zone. The flow model was calibrated using observations of temperature and...
Authors
Ramon C. Naranjo
Appraising options to reduce shallow groundwater tables and enhance flow conditions over regional scales in an irrigated alluvial aquifer system Appraising options to reduce shallow groundwater tables and enhance flow conditions over regional scales in an irrigated alluvial aquifer system
Some of the world’s key agricultural production systems face big challenges to both water quantity and quality due to shallow groundwater that results from long-term intensive irrigation, namely waterlogging and salinity, water losses, and environmental problems. This paper focuses on water quantity issues, presenting finite-difference groundwater models developed to describe shallow...
Authors
Eric D. Morway, Timothy K. Gates, Richard G. Niswonger
Modeling variably saturated multispecies reactive groundwater solute transport with MODFLOW-UZF and RT3D Modeling variably saturated multispecies reactive groundwater solute transport with MODFLOW-UZF and RT3D
A numerical model was developed that is capable of simulating multispecies reactive solute transport in variably saturated porous media. This model consists of a modified version of the reactive transport model RT3D (Reactive Transport in 3 Dimensions) that is linked to the Unsaturated-Zone Flow (UZF1) package and MODFLOW. Referred to as UZF-RT3D, the model is tested against published...
Authors
Ryan T. Bailey, Eric D. Morway, Richard G. Niswonger, Timothy K. Gates
MODFLOW–USG version 1: An unstructured grid version of MODFLOW for simulating groundwater flow and tightly coupled processes using a control volume finite-difference formulation MODFLOW–USG version 1: An unstructured grid version of MODFLOW for simulating groundwater flow and tightly coupled processes using a control volume finite-difference formulation
A new version of MODFLOW, called MODFLOW–USG (for UnStructured Grid), was developed to support a wide variety of structured and unstructured grid types, including nested grids and grids based on prismatic triangles, rectangles, hexagons, and other cell shapes. Flexibility in grid design can be used to focus resolution along rivers and around wells, for example, or to subdiscretize...
Authors
Sorab Panday, Christian D. Langevin, Richard G. Niswonger, Motomu Ibaraki, Joseph D. Hughes
CRT--Cascade Routing Tool to define and visualize flow paths for grid-based watershed models CRT--Cascade Routing Tool to define and visualize flow paths for grid-based watershed models
The U.S. Geological Survey Cascade Routing Tool (CRT) is a computer application for watershed models that include the coupled Groundwater and Surface-water FLOW model, GSFLOW, and the Precipitation-Runoff Modeling System (PRMS). CRT generates output to define cascading surface and shallow subsurface flow paths for grid-based model domains. CRT requires a land-surface elevation for each...
Authors
Wesley R. Henson, Rose L. Medina, C. Justin Mayers, Richard G. Niswonger, R.S. Regan
Science and Products
Filter Total Items: 17
No Result Found
Filter Total Items: 63
Feedback of land subsidence on the movement and conjunctive use of water resources Feedback of land subsidence on the movement and conjunctive use of water resources
The dependency of surface- or groundwater flows and aquifer hydraulic properties on dewatering-induced layer deformation is not available in the USGS's groundwater model MODFLOW. A new integrated hydrologic model, MODFLOW-OWHM, formulates this dependency by coupling mesh deformation with aquifer transmissivity and storage and by linking land subsidence/uplift with deformation-dependent...
Authors
Wolfgang Schmid, Randall T. Hanson, Stanley A. Leake, Joseph D. Hughes, Richard G. Niswonger
Using heat as a tracer to estimate spatially distributed mean residence times in the hyporheic zone of a riffle-pool sequence Using heat as a tracer to estimate spatially distributed mean residence times in the hyporheic zone of a riffle-pool sequence
Biochemical reactions that occur in the hyporheic zone are highly dependent on the time solutes that are in contact with sediments of the riverbed. In this investigation, we developed a 2-D longitudinal flow and solute-transport model to estimate the spatial distribution of mean residence time in the hyporheic zone. The flow model was calibrated using observations of temperature and...
Authors
Ramon C. Naranjo
Appraising options to reduce shallow groundwater tables and enhance flow conditions over regional scales in an irrigated alluvial aquifer system Appraising options to reduce shallow groundwater tables and enhance flow conditions over regional scales in an irrigated alluvial aquifer system
Some of the world’s key agricultural production systems face big challenges to both water quantity and quality due to shallow groundwater that results from long-term intensive irrigation, namely waterlogging and salinity, water losses, and environmental problems. This paper focuses on water quantity issues, presenting finite-difference groundwater models developed to describe shallow...
Authors
Eric D. Morway, Timothy K. Gates, Richard G. Niswonger
Modeling variably saturated multispecies reactive groundwater solute transport with MODFLOW-UZF and RT3D Modeling variably saturated multispecies reactive groundwater solute transport with MODFLOW-UZF and RT3D
A numerical model was developed that is capable of simulating multispecies reactive solute transport in variably saturated porous media. This model consists of a modified version of the reactive transport model RT3D (Reactive Transport in 3 Dimensions) that is linked to the Unsaturated-Zone Flow (UZF1) package and MODFLOW. Referred to as UZF-RT3D, the model is tested against published...
Authors
Ryan T. Bailey, Eric D. Morway, Richard G. Niswonger, Timothy K. Gates
MODFLOW–USG version 1: An unstructured grid version of MODFLOW for simulating groundwater flow and tightly coupled processes using a control volume finite-difference formulation MODFLOW–USG version 1: An unstructured grid version of MODFLOW for simulating groundwater flow and tightly coupled processes using a control volume finite-difference formulation
A new version of MODFLOW, called MODFLOW–USG (for UnStructured Grid), was developed to support a wide variety of structured and unstructured grid types, including nested grids and grids based on prismatic triangles, rectangles, hexagons, and other cell shapes. Flexibility in grid design can be used to focus resolution along rivers and around wells, for example, or to subdiscretize...
Authors
Sorab Panday, Christian D. Langevin, Richard G. Niswonger, Motomu Ibaraki, Joseph D. Hughes
CRT--Cascade Routing Tool to define and visualize flow paths for grid-based watershed models CRT--Cascade Routing Tool to define and visualize flow paths for grid-based watershed models
The U.S. Geological Survey Cascade Routing Tool (CRT) is a computer application for watershed models that include the coupled Groundwater and Surface-water FLOW model, GSFLOW, and the Precipitation-Runoff Modeling System (PRMS). CRT generates output to define cascading surface and shallow subsurface flow paths for grid-based model domains. CRT requires a land-surface elevation for each...
Authors
Wesley R. Henson, Rose L. Medina, C. Justin Mayers, Richard G. Niswonger, R.S. Regan