Richard G Niswonger (Former Employee)
Science and Products
Filter Total Items: 17
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Surface-groundwater interactions in hard rocks in Sardon Catchment of western Spain: an integrated modeling approach Surface-groundwater interactions in hard rocks in Sardon Catchment of western Spain: an integrated modeling approach
The structural and hydrological complexity of hard rock systems (HRSs) affects dynamics of surface–groundwater interactions. These complexities are not well described or understood by hydrogeologists because simplified analyses typically are used to study HRSs. A transient, integrated hydrologic model (IHM) GSFLOW (Groundwater and Surface water FLOW) was calibrated and post-audited using...
Authors
S.M. Tanvir Hassan, Maciek W. Lubczynski, Richard G. Niswonger, Su Zhongbo
Collaborative modelling and integrated decision support system analysis of a developed terminal lake basin Collaborative modelling and integrated decision support system analysis of a developed terminal lake basin
A terminal lake basin in west-central Nevada, Walker Lake, has undergone drastic change over the past 90 yrs due to upstream water use for agriculture. Decreased inflows to the lake have resulted in 100 km2 decrease in lake surface area and a total loss of fisheries due to salinization. The ecologic health of Walker Lake is of great concern as the lake is a stopover point on the Pacific...
Authors
Richard G. Niswonger, Kip K. Allander, Anne E. Jeton
A method for estimating spatially variable seepage and hydrualic conductivity in channels with very mild slopes A method for estimating spatially variable seepage and hydrualic conductivity in channels with very mild slopes
Infiltration along ephemeral channels plays an important role in groundwater recharge in arid regions. A model is presented for estimating spatial variability of seepage due to streambed heterogeneity along channels based on measurements of streamflow-front velocities in initially dry channels. The diffusion-wave approximation to the Saint-Venant equations, coupled with Philip's equation...
Authors
Margaret Shanafield, Richard G. Niswonger, David E. Prudic, Greg Pohll, Richard Susfalk, Sorab Panday
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
Modeling variably saturated subsurface solute transport with MODFLOW-UZF and MT3DMS Modeling variably saturated subsurface solute transport with MODFLOW-UZF and MT3DMS
The MT3DMS groundwater solute transport model was modified to simulate solute transport in the unsaturated zone by incorporating the unsaturated-zone flow (UZF1) package developed for MODFLOW. The modified MT3DMS code uses a volume-averaged approach in which Lagrangian-based UZF1 fluid fluxes and storage changes are mapped onto a fixed grid. Referred to as UZF-MT3DMS, the linked model...
Authors
Eric D. Morway, Richard G. Niswonger, Christian D. Langevin, Ryan T. Bailey, Richard W. Healy
Approaches to the simulation of unconfined flow and perched groundwater flow in MODFLOW Approaches to the simulation of unconfined flow and perched groundwater flow in MODFLOW
Various approaches have been proposed to manage the nonlinearities associated with the unconfined flow equation and to simulate perched groundwater conditions using the MODFLOW family of codes. The approaches comprise a variety of numerical techniques to prevent dry cells from becoming inactive and to achieve a stable solution focused on formulations of the unconfined, partially...
Authors
Vivek Bedekar, Richard G. Niswonger, Kenneth Kipp, Sorab Panday, Matthew Tonkin
Role of surface-water and groundwater interactions on projected summertime streamflow in snow dominated regions : An integrated modeling approach Role of surface-water and groundwater interactions on projected summertime streamflow in snow dominated regions : An integrated modeling approach
Previous studies indicate predominantly increasing trends in precipitation across the Western United States, while at the same time, historical streamflow records indicate decreasing summertime streamflow and 25th percentile annual flows. These opposing trends could be viewed as paradoxical, given that several studies suggest that increased annual precipitation will equate to increased...
Authors
Justin L. Huntington, Richard G. Niswonger
Science and Products
Filter Total Items: 17
No Result Found
Filter Total Items: 66
Surface-groundwater interactions in hard rocks in Sardon Catchment of western Spain: an integrated modeling approach Surface-groundwater interactions in hard rocks in Sardon Catchment of western Spain: an integrated modeling approach
The structural and hydrological complexity of hard rock systems (HRSs) affects dynamics of surface–groundwater interactions. These complexities are not well described or understood by hydrogeologists because simplified analyses typically are used to study HRSs. A transient, integrated hydrologic model (IHM) GSFLOW (Groundwater and Surface water FLOW) was calibrated and post-audited using...
Authors
S.M. Tanvir Hassan, Maciek W. Lubczynski, Richard G. Niswonger, Su Zhongbo
Collaborative modelling and integrated decision support system analysis of a developed terminal lake basin Collaborative modelling and integrated decision support system analysis of a developed terminal lake basin
A terminal lake basin in west-central Nevada, Walker Lake, has undergone drastic change over the past 90 yrs due to upstream water use for agriculture. Decreased inflows to the lake have resulted in 100 km2 decrease in lake surface area and a total loss of fisheries due to salinization. The ecologic health of Walker Lake is of great concern as the lake is a stopover point on the Pacific...
Authors
Richard G. Niswonger, Kip K. Allander, Anne E. Jeton
A method for estimating spatially variable seepage and hydrualic conductivity in channels with very mild slopes A method for estimating spatially variable seepage and hydrualic conductivity in channels with very mild slopes
Infiltration along ephemeral channels plays an important role in groundwater recharge in arid regions. A model is presented for estimating spatial variability of seepage due to streambed heterogeneity along channels based on measurements of streamflow-front velocities in initially dry channels. The diffusion-wave approximation to the Saint-Venant equations, coupled with Philip's equation...
Authors
Margaret Shanafield, Richard G. Niswonger, David E. Prudic, Greg Pohll, Richard Susfalk, Sorab Panday
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
Modeling variably saturated subsurface solute transport with MODFLOW-UZF and MT3DMS Modeling variably saturated subsurface solute transport with MODFLOW-UZF and MT3DMS
The MT3DMS groundwater solute transport model was modified to simulate solute transport in the unsaturated zone by incorporating the unsaturated-zone flow (UZF1) package developed for MODFLOW. The modified MT3DMS code uses a volume-averaged approach in which Lagrangian-based UZF1 fluid fluxes and storage changes are mapped onto a fixed grid. Referred to as UZF-MT3DMS, the linked model...
Authors
Eric D. Morway, Richard G. Niswonger, Christian D. Langevin, Ryan T. Bailey, Richard W. Healy
Approaches to the simulation of unconfined flow and perched groundwater flow in MODFLOW Approaches to the simulation of unconfined flow and perched groundwater flow in MODFLOW
Various approaches have been proposed to manage the nonlinearities associated with the unconfined flow equation and to simulate perched groundwater conditions using the MODFLOW family of codes. The approaches comprise a variety of numerical techniques to prevent dry cells from becoming inactive and to achieve a stable solution focused on formulations of the unconfined, partially...
Authors
Vivek Bedekar, Richard G. Niswonger, Kenneth Kipp, Sorab Panday, Matthew Tonkin
Role of surface-water and groundwater interactions on projected summertime streamflow in snow dominated regions : An integrated modeling approach Role of surface-water and groundwater interactions on projected summertime streamflow in snow dominated regions : An integrated modeling approach
Previous studies indicate predominantly increasing trends in precipitation across the Western United States, while at the same time, historical streamflow records indicate decreasing summertime streamflow and 25th percentile annual flows. These opposing trends could be viewed as paradoxical, given that several studies suggest that increased annual precipitation will equate to increased...
Authors
Justin L. Huntington, Richard G. Niswonger