Skip to main content
U.S. flag

An official website of the United States government

Richard G Niswonger

Richard Niswonger is a Research Hydrologist with the USGS Water Resources Mission Area.

Our research aims to better understand local and regional hydrologic processes affecting humans and the environment. Our focus is on the development of numerical software for simulating coupled hydrologic and anthropogenic effects on water resources. An example of the software we develop is the integrated groundwater and surface water model, GSFLOW that can simulate all of the important terrestrial hydrologic processes in watersheds. We combine GSFLOW with other software and diverse data types, including satellite imagery, geo-spatial data sets, hydrologic tracers and age dating, and many other quantitative and qualitative information that provides skill for hydrologic prediction. 

An important challenge of the 21st century is the global water challenge that is exacerbated by recent droughts and rapid population growth. Water shortages have led to increased reliance on groundwater and broad reductions in groundwater resources. As demands for water resources increase, our understanding of interconnections between the hydrologic cycle and our environment increasingly become more important. Moving into the future, approaches are needed for sustainable management of water resources in order to maintain robust water-dependent systems on earth. 

 

We use our tools to better understand the effects of climate change on water resources, and to develop collaborative solutions to surface and groundwater pollution caused by unsustainable withdrawals of water from aquifers, rivers and lakes. We develop and apply tools to increase efficiency of water and energy in agricultural systems using innovative scientific solutions. 


Download CV

Science and Products

link
View downstream, Carson River, Nevada

Water for the Seasons

Water for the Seasons (WftS) is a four year study funded by the National Science Foundation and the U.S. Department of Agriculture. WtfS uses the Truckee-Carson River System (TCRS) as a pilot study to learn how to best link science with decision-making in snow-fed arid-land river systems. By working collaboratively with stakeholders, WftS aims to create a model for improving community climate...
By
Nevada Water Science Center
link

Water for the Seasons

Water for the Seasons (WftS) is a four year study funded by the National Science Foundation and the U.S. Department of Agriculture. WtfS uses the Truckee-Carson River System (TCRS) as a pilot study to learn how to best link science with decision-making in snow-fed arid-land river systems. By working collaboratively with stakeholders, WftS aims to create a model for improving community climate...
Learn More
link
USGS

Water Resources Discipline Research Seminar Series

The Water Resources Discipline (predecessor of the Water Mission Area) Research Seminar Series hosted a wide range of speakers on a diverse array of water research topics.  Archived videos of many seminars are available for viewing.

link

Water Resources Discipline Research Seminar Series

The Water Resources Discipline (predecessor of the Water Mission Area) Research Seminar Series hosted a wide range of speakers on a diverse array of water research topics.  Archived videos of many seminars are available for viewing.

Learn More

GSFLOW and MODSIM-GSFLOW model used to evaluate the potential effects of increased temperature on the Carson Valley watershed and agricultural system in eastern California and western Nevada

The USGS developed an integrated river operations-groundwater model using GSFLOW and MODSIM GSFLOW to simulate streamflow derived from snowmelt, the distribution of surface water based on the existing prior appropriations water doctrine, supplemental pumping in response to surface water shortfalls, and the resulting surface water-groundwater interactions in the Carson Valley in California and Neva
By
Nevada Water Science Center
Filter Total Items: 49

Integrated hydrologic model development and postprocessing for GSFLOW using pyGSFLOW

pyGSFLOW is a python package designed to create new GSFLOW integrated hydrologic models, read existing models, edit model input data, run GSFLOW models, process output, and visualize model data.
By
Water Resources, California Water Science Center

Integrated hydrology and operations modeling to evaluate climate change impacts in an agricultural valley irrigated with snowmelt runoff

Applying models to developed agricultural regions remains a difficult problem because there are no existing modeling codes that represent both the complex physics of the hydrology and anthropogenic manipulations to water distribution and consumption. We apply an integrated groundwater – surface water and hydrologic river operations model to an irrigated river valley in northwestern Nevada/northern
By
Ecosystems, Water Resources, Alaska Science Center, Nevada Water Science Center, Oklahoma-Texas Water Science Center

Baseflow age distributions and depth of active groundwater flow in a snow‐dominated mountain headwater basin

Deeper flows through bedrock in mountain watersheds could be important, but lack of data to characterize bedrock properties limits understanding. To address data scarcity, we combine a previously published integrated hydrologic model of a snow‐dominated, headwater basin of the Colorado River with a new method for dating baseflow age using dissolved gas tracers SF6, CFC‐113, N2, and Ar. The origina
By
Geology, Geophysics, and Geochemistry Science Center

An agricultural water use package for MODFLOW and GSFLOW

The Agricultural Water Use (AG) Package was developed for simulating demand-driven and supply-constrained agricultural water use in MODFLOW and GSFLOW models. The AG Package uses pre-existing hydrologic simulation provided by MODFLOW and GSFLOW. Three options are available for simulating water use for agriculture: (1) user-specified demands, (2) demands determined by a user-specified irrigation tr
By
Water Resources

Managed aquifer recharge in snow-fed river basins: What, why and how?

What does climate change mean for snow-fed river basins?Climate change poses unique challenges in snow-fed river basins across the western United States because the majority of water supply originates as snow (Dettinger, Udall, & Georgakakos, 2015). In the Sierra Nevada, recent observations include changes in snow accumulation and snowmelt, and shifts in peak streamflow timing (Barnhart et al., 20
By
Water Resources, Nevada Water Science Center

Linkages between hydrology and seasonal variations of nutrients and periphyton in a large oligotrophic subalpine lake

Periphyton is important to lake ecosystems, contributing to primary production, nutrient cycling, and benthic metabolism. Increases in periphyton growth in lakes can be indicative of changes in water quality, shifts in ecosystem structure, and increases in nutrient fluxes. In oligotrophic lakes, conservationists are interested in characterizing the influence of hydrological drivers on excessive pe
By
Water Resources, Nevada Water Science Center

GSFLOW-GRASS v1.0.0: GIS-enabled hydrologic modeling of coupled groundwater–surface-water systems

The importance of water moving between the atmosphere and aquifers has led to efforts to develop and maintain coupled models of surface water and groundwater. However, developing inputs to these models is usually time-consuming and requires extensive knowledge of software engineering, often prohibiting their use by many researchers and water managers, thus reducing these models' potential to promo
By
Geology, Minerals, Energy, and Geophysics Science Center

Input data processing tools for the integrated hydrologic model GSFLOW

Integrated hydrologic modeling (IHM) encompasses a vast number of processes and specifications, variable in time and space, and development of models can be arduous. Model input construction techniques have not been formalized or made easily reproducible. Creating the input files for integrated hydrologic models requires complex GIS processing of raster and vector datasets from various sources. De
By
Water Resources, Nevada Water Science Center

Documentation for the MODFLOW 6 Groundwater Flow Model

This report documents the Groundwater Flow (GWF) Model for a new version of MODFLOW called MODFLOW 6. The GWF Model for MODFLOW 6 is based on a generalized control-volume finite-difference approach in which a cell can be hydraulically connected to any number of surrounding cells. Users can define the model grid using one of three discretization packages, including (1) a structured discretization pac
By
Water Resources, Groundwater and Streamflow Information Program

Managed aquifer recharge through off-season irrigation in agricultural regions

Options for increasing reservoir storage in developed regions are limited and prohibitively expensive. Projected increases in demand call for new long-term water storage to help sustain agriculture, municipalities, industry, and ecological services. Managed aquifer recharge (MAR) is becoming an integral component of water resources around the world. However, MAR faces challenges, including infrast
By
Water Resources

Nutrient processes at the stream-lake interface for a channelized versus unmodified stream mouth

Inorganic forms of nitrogen and phosphorous impact freshwater lakes by stimulating primary production and affecting water quality and ecosystem health. Communities around the world are motivated to sustain and restore freshwater resources and are interested in processes controlling nutrient inputs. We studied the environment where streams flow into lakes, referred to as the stream-lake interface (
By
Water Resources

Evaluating mountain meadow groundwater response to Pinyon-Juniper and temperature in a great basin watershed

This research highlights development and application of an integrated hydrologic model (GSFLOW) to a semiarid, snow-dominated watershed in the Great Basin to evaluate Pinyon-Juniper (PJ) and temperature controls on mountain meadow shallow groundwater. The work used Google Earth Engine Landsat satellite and gridded climate archives for model evaluation. Model simulations across three decades indica
By
Water Resources

pyGSFLOW v1.0.0

Python package software release for pyGSFLOW. pyGSFLOW is a python package to create, read, write, edit, and visualize GSFLOW models. Source code, examples, installation instructions, and documentation can be found at https://github.com/pygsflow/pygsflow
By
California Water Science Center

GSFLOW: Coupled Groundwater and Surface-Water Flow Model

Groundwater and Surface-water FLOW (GSFLOW) was developed to simulate coupled groundwater and surface-water resources. The model is based on the integration of the U.S. Geological Survey Precipitation-Runoff Modeling System (PRMS) and the U.S. Geological Survey Modular Groundwater Flow Model (MODFLOW).

By
Water Resources

GSFLOW: Coupled Groundwater and Surface-Water Flow Model, version 2.1.0

GSFLOW is a coupled Groundwater and Surface-water FLOW model based on the integration of the USGS Precipitation-Runoff Modeling System (PRMS-V) and the USGS Modular Groundwater Flow Model (MODFLOW-2005 and MODFLOW-NWT). GSFLOW was developed to simulate coupled groundwater/surface-water flow in one or more watersheds by simultaneously simulating flow across the land surface, within subsurface satur

MODFLOW-NWT: A Newton Formulation for MODFLOW-2005

MODFLOW-NWT is a Newton-Raphson formulation for MODFLOW-2005 to improve solution of unconfined groundwater-flow problems. MODFLOW-NWT is a standalone program that is intended for solving problems involving drying and rewetting nonlinearities of the unconfined groundwater-flow equation.

By
Water Resources, Water Resources

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. 

By
California Water Science Center

Science and Products