Richard G Niswonger
Richard Niswonger is a Research Hydrologist with the USGS Water Resources Mission Area.
We study local and regional water resources to aid water management decisions by developing software and constructing models that simulate both natural hydrologic processes and human water usage.
In my current role as the national water use research manager, I lead teams in the development of nationally consistent models with three key features: automated data retrieval, monthly simulation at the USGS 12-digit Watershed Boundary Dataset (HUC12) resolution, and periodic updates for current and forecasted results. These models help identify data gaps, enhance data collection, and refine water use predictions. They facilitate frequent reporting, synthesis, and interpretation of data that support communities making informed water resources decisions.
Science and Products
Surface-groundwater interactions in hard rocks in Sardon Catchment of western Spain: an integrated modeling approach
Feedback of land subsidence on the movement and conjunctive use of water resources
Collaborative modelling and integrated decision support system analysis of a developed terminal lake basin
A method for estimating spatially variable seepage and hydrualic conductivity in channels with very mild slopes
Using heat as a tracer to estimate spatially distributed mean residence times in the hyporheic zone of a riffle-pool sequence
Modeling variably saturated multispecies reactive groundwater solute transport with MODFLOW-UZF and RT3D
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
Modeling variably saturated subsurface solute transport with MODFLOW-UZF and MT3DMS
Approaches to the simulation of unconfined flow and perched groundwater flow in MODFLOW
Role of surface-water and groundwater interactions on projected summertime streamflow in snow dominated regions : An integrated modeling approach
Simulating the effect of climate extremes on groundwater flow through a lakebed
The use of multiobjective calibration and regional sensitivity analysis in simulating hyporheic exchange
Science and Products
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Filter Total Items: 52
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 18 yearsAuthorsS.M. Tanvir Hassan, Maciek W. Lubczynski, Richard G. Niswonger, Su ZhongboFeedback 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 flows thatAuthorsWolfgang Schmid, Randall T. Hanson, Stanley A. Leake, Joseph D. Hughes, Richard G. NiswongerCollaborative 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 route forAuthorsRichard G. Niswonger, Kip K. Allander, Anne E. JetonA 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 for infilAuthorsMargaret Shanafield, Richard G. Niswonger, David E. Prudic, Greg Pohll, Richard Susfalk, Sorab PandayUsing 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 pressure, andAuthorsRamon C. NaranjoModeling 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 analytical bAuthorsRyan T. Bailey, Eric D. Morway, Richard G. Niswonger, Timothy K. GatesMODFLOW–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 individual layerAuthorsSorab Panday, Christian D. Langevin, Richard G. Niswonger, Motomu Ibaraki, Joseph D. HughesModeling 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 was tested aAuthorsEric D. Morway, Richard G. Niswonger, Christian D. Langevin, Ryan T. Bailey, Richard W. HealyApproaches 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-saturated, groundwAuthorsVivek Bedekar, Richard G. Niswonger, Kenneth Kipp, Sorab Panday, Matthew TonkinRole 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 annual grouAuthorsJustin L. Huntington, Richard G. NiswongerSimulating the effect of climate extremes on groundwater flow through a lakebed
Groundwater exchanges with lakes resulting from cyclical wet and dry climate extremes maintain lake levels in the environment in ways that are not well understood, in part because they remain difficult to simulate. To better understand the atypical groundwater interactions with lakes caused by climatic extremes, an original conceptual approach is introduced using MODFLOW-2005 and a kinematic-waveAuthorsMakhan L. Virdi, Terrie M. Lee, Amy Swancar, Richard G. NiswongerThe use of multiobjective calibration and regional sensitivity analysis in simulating hyporheic exchange
We describe an approach for calibrating a two-dimensional (2-D) flow model of hyporheic exchange using observations of temperature and pressure to estimate hydraulic and thermal properties. A longitudinal 2-D heat and flow model was constructed for a riffle-pool sequence to simulate flow paths and flux rates for variable discharge conditions. A uniform random sampling approach was used to examineAuthorsRamon C. Naranjo, Richard G. Niswonger, Mark Stone, Clinton Davis, Alan McKay - Science
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