A three-dimensional, numerical groundwater flow model of the Hualapai Plateau and Truxton Basin was developed to assist water-resource managers in understanding the potential effects of projected groundwater withdrawals on groundwater levels and storage in the basin. The Truxton Basin Hydrologic Model (TBHM) was developed using previously published data, as well as, new geophysical data collected as part of this investigation (Ball, 2020; Kennedy, 2020). TBHM is a transient model that simulates the hydrologic system between the years 1976–2140, including three hypothetical groundwater withdrawal scenarios between 2020–2140. The predevelopment (before 1976) groundwater system is simulated using a steady-state model. The TBHM study area encompasses 1,200 square miles (mi2), including the Truxton basin (approximately 75 mi2) and much of the surrounding Hualapai Plateau. Potential future pumping scenarios are simulated in Truxton Basin at the existing Truxton well field and at a hypothetical new pumping location in the northern portion of the basin. This USGS data release contains all of the input and output files for the simulations described in the associated model documentation report (https://doi.org/10.3133/sir20205017E).

A numerical groundwater flow model of the Hualapai Valley Basin, using MODFLOW-NWT, was developed to assist water-resource managers in understanding the potential effects of projected groundwater withdrawals on groundwater levels in the basin. Hualapai Valley Basin is a broad, internally drained, intermountain desert basin in Mohave County, northwestern Arizona. Basin-fill aquifers are the primary groundwater source for many desert communities, and the residents, commerce, and agriculture in and near to the Hualapai Valley Basin must rely on such groundwater to meet water needs. As in many parts of the western United States, population growth in this part of Arizona is substantial. From 2000 to 2018 the population of the City of Kingman, Arizona, grew from 20,069 to 30,314, an increase of 51 percent, whereas the population of Mohave County grew from 155,062 to 209,550, an increase of 35 percent. Water managers in Mohave County have raised concern about the potential for future groundwater development and additional stresses on the groundwater system in the Hualapai Valley Basin. In particular, the City of Kingman, Ariz., water supply is primarily groundwater withdrawn from the Kingman subbasin of the Hualapai Valley Basin, northeast of the city. The potential effects of future water development on the City of Kingman well field have become a top concern to regional water-resource managers. To address these concerns the Hualapai Valley Hydrologic Model (HVHM) simulates the hydrologic system for the years 1935 through 2219, including future withdrawal scenarios that simulate large-scale agricultural expansion with and without enhanced groundwater recharge from potential new infiltration basin projects. HVHM is a highly parameterized model (75,586 adjustable parameters) capable of simulating grid-scale variability in aquifer properties (for example, conductivity, specific yield, and specific storage) and system stresses (for instance, natural recharge and groundwater withdrawals). System stresses were partially adopted from a previously-published groundwater model (Tillman and others, 2013). Parameter estimation and uncertainty quantification were performed using an iterative ensemble smoother software (PESTPP-IES) to produce an ensemble of models fit to historical data. Two future scenarios were simulated with a subset of the posterior parameter ensemble comprising the 40 best-fit realizations. In scenario 1, future pumping was simulated to increase linearly from 2019 through 2029 and then held constant through 2219. Scenario 2 includes the same specified future pumping, but also simulates enhanced recharge at proposed infiltration basins throughout the Kingman subbasin beginning in 2019. This USGS data release contains all of the input and output files for the simulations described in the associated model documentation report (https://doi.org/10.3133/sir20215077).

A numerical groundwater flow model of the Hualapai Valley Basin, using MODFLOW-NWT, was developed to assist water-resource managers in understanding the potential effects of projected groundwater withdrawals on groundwater levels in the basin. Hualapai Valley Basin is a broad, internally drained, intermountain desert basin in Mohave County, northwestern Arizona. Basin-fill aquifers are the primary groundwater source for many desert communities, and the residents, commerce, and agriculture in and near to the Hualapai Valley Basin must rely on such groundwater to meet water needs. As in many parts of the western United States, population growth in this part of Arizona is substantial. From 2000 to 2018 the population of the City of Kingman, Arizona, grew from 20,069 to 30,314, an increase of 51 percent, whereas the population of Mohave County grew from 155,062 to 209,550, an increase of 35 percent. Water managers in Mohave County have raised concern about the potential for future groundwater development and additional stresses on the groundwater system in the Hualapai Valley Basin. In particular, the City of Kingman, Ariz., water supply is primarily groundwater withdrawn from the Kingman subbasin of the Hualapai Valley Basin, northeast of the city. The potential effects of future water development on the City of Kingman well field have become a top concern to regional water-resource managers. To address these concerns the Hualapai Valley Hydrologic Model (HVHM) simulates the hydrologic system for the years 1935 through 2219, including future withdrawal scenarios that simulate large-scale agricultural expansion with and without enhanced groundwater recharge from potential new infiltration basin projects. HVHM is a highly parameterized model (75,586 adjustable parameters) capable of simulating grid-scale variability in aquifer properties (for example, conductivity, specific yield, and specific storage) and system stresses (for instance, natural recharge and groundwater withdrawals). System stresses were partially adopted from a previously-published groundwater model (Tillman and others, 2013). Parameter estimation and uncertainty quantification were performed using an iterative ensemble smoother software (PESTPP-IES) to produce an ensemble of models fit to historical data. Two future scenarios were simulated with a subset of the posterior parameter ensemble comprising the 40 best-fit realizations. In scenario 1, future pumping was simulated to increase linearly from 2019 through 2029 and then held constant through 2219. Scenario 2 includes the same specified future pumping, but also simulates enhanced recharge at proposed infiltration basins throughout the Kingman subbasin beginning in 2019. This USGS data release contains all of the input and output files for the simulations described in the associated model documentation report (https://doi.org/10.3133/sir20215077).

The U.S. Geological Survey (USGS), in cooperation with the Oklahoma Water Resources Board (OWRB), constructed a finite-difference numerical groundwater-flow model of the Washita River aquifer by using MODFLOW-2005 (Harbaugh, 2005) with the Newton formulation solver (MODFLOW-NWT). The 1973 Oklahoma Groundwater Law requires that the OWRB conduct hydrologic investigations of the State’s aquifers to determine the maximum annual yield (MAY) for each groundwater basin. The MAY is defined as the total amount of fresh groundwater that can be annually withdrawn while allowing a minimum 20-year life of that groundwater basin. For alluvium and terrace groundwater basins, the life requirement is satisfied if, after 20 years of MAY withdrawals, 50 percent of the groundwater basin (hereinafter referred to as an “aquifer”) retains a saturated thickness of at least 5 ft. Once a MAY has been established, the amount of land owned or leased by a groundwater-use permit applicant determines the annual volume of water allocated to that groundwater-use permit applicant. The annual volume of groundwater allocated per acre of land is known as the equal-proportionate-share (EPS) pumping rate. The OWRB issued a final order on November 13, 1990, that established the MAY (81,840 and 46,935 acre-feet per year [acre-ft/yr]) and EPS pumping rate (1.5 and 1.0 acre-foot per acre per year) for reaches 3 and 4, respectively, of the Washita River aquifer in southern Oklahoma. Because more than 20 years have elapsed since the final order was issued, the USGS, in cooperation with the OWRB, conducted an updated hydrologic investigation and evaluated the effects of potential groundwater withdrawals on groundwater flow and availability in the Washita River aquifer in southern Oklahoma. Reach 3 extends from near Anadarko, Okla., to Alex, Okla., and reach 4 extends from near Alex to south of Davis, Okla. Twenty-four simulations are included in this data release: a simulation for the calibrated numerical groundwater-flow model, 18 scenario simulations to evaluate the EPS pumping rate, 4 scenario simulations to evaluate groundwater storage over a 50-year period, and 1 scenario simulation to evaluate effects of a hypothetical drought. This USGS data release contains all of the input and output files for the simulations described in the associated model documentation report (https://doi.org/10.3133/sir20235072).

The U.S. Geological Survey (USGS), in cooperation with the Oklahoma Water Resources Board (OWRB), constructed a finite-difference numerical groundwater-flow model of the Washita River aquifer by using MODFLOW-2005 (Harbaugh, 2005) with the Newton formulation solver (MODFLOW-NWT). The 1973 Oklahoma Groundwater Law requires that the OWRB conduct hydrologic investigations of the State’s aquifers to determine the maximum annual yield (MAY) for each groundwater basin. The MAY is defined as the total amount of fresh groundwater that can be annually withdrawn while allowing a minimum 20-year life of that groundwater basin. For alluvium and terrace groundwater basins, the life requirement is satisfied if, after 20 years of MAY withdrawals, 50 percent of the groundwater basin (hereinafter referred to as an “aquifer”) retains a saturated thickness of at least 5 ft. Once a MAY has been established, the amount of land owned or leased by a groundwater-use permit applicant determines the annual volume of water allocated to that groundwater-use permit applicant. The annual volume of groundwater allocated per acre of land is known as the equal-proportionate-share (EPS) pumping rate. The OWRB issued a final order on November 13, 1990, that established the MAY (81,840 and 46,935 acre-feet per year [acre-ft/yr]) and EPS pumping rate (1.5 and 1.0 acre-foot per acre per year) for reaches 3 and 4, respectively, of the Washita River aquifer in southern Oklahoma. Because more than 20 years have elapsed since the final order was issued, the USGS, in cooperation with the OWRB, conducted an updated hydrologic investigation and evaluated the effects of potential groundwater withdrawals on groundwater flow and availability in the Washita River aquifer in southern Oklahoma. Reach 3 extends from near Anadarko, Okla., to Alex, Okla., and reach 4 extends from near Alex to south of Davis, Okla. Twenty-four simulations are included in this data release: a simulation for the calibrated numerical groundwater-flow model, 18 scenario simulations to evaluate the EPS pumping rate, 4 scenario simulations to evaluate groundwater storage over a 50-year period, and 1 scenario simulation to evaluate effects of a hypothetical drought. This USGS data release contains all of the input and output files for the simulations described in the associated model documentation report (https://doi.org/10.3133/sir20235072).

A three-dimensional, groundwater flow model (MODFLOW-NWT) was developed to examine groundwater storage changes in the Quincy Basin, Washington. The model was calibrated to conditions from 1920 to 2013. The model was used to (1) determine the change in groundwater storage from 1920 to 2013 , and (2) simulate the potential effects of increases in pumping, decrease in irrigation recharge, and increases in streamflow in Crab Creek by 100 cubic feet per second and 500 cubic feet per second. This USGS data release contains all of the input and output files for the simulations described in the associated model documentation report (https://doi.org/10.3133/sir20185162).

A three-dimensional, groundwater flow model (MODFLOW-NWT) was developed to examine groundwater storage changes in the Quincy Basin, Washington. The model was calibrated to conditions from 1920 to 2013. The model was used to (1) determine the change in groundwater storage from 1920 to 2013 , and (2) simulate the potential effects of increases in pumping, decrease in irrigation recharge, and increases in streamflow in Crab Creek by 100 cubic feet per second and 500 cubic feet per second. This USGS data release contains all of the input and output files for the simulations described in the associated model documentation report (https://doi.org/10.3133/sir20185162).

In 2017 the U.S. Geological Survey, in cooperation with the Oklahoma Water Resources Board, published a calibrated numerical groundwater-flow model and associated model documentation report that evaluated the effects of potential groundwater withdrawals on groundwater flow and availability in the North Fork Red River aquifer in southwest Oklahoma. The results of groundwater-availability scenarios run on the calibrated numerical groundwater-flow model could be used by the Oklahoma Water Resources Board to reevaluate the maximum annual yield of groundwater from the North Fork Red River aquifer in Oklahoma. The numerical groundwater-flow model was built on a hydrogeologic framework and a conceptual groundwater-flow model derived from previously published and newly collected hydrologic data. A hydrogeologic framework is a three-dimensional representation of the aquifer and the surrounding geologic units at a scale that captures the regional controls on groundwater flow. The hydrogeologic framework for the North Fork Red River aquifer included a definition of the aquifer extent and potentiometric surface, as well as a description of the textural and hydraulic properties of aquifer materials. A conceptual groundwater-flow model is a simplified description of the major inflow and outflow sources (hydrologic boundaries) of a groundwater-flow system as well as an accounting of the estimated mean flows from those sources (water budget) for a specified period of time. The hydrogeologic framework and conceptual model are necessary constraints used in the construction and calibration of a scientifically defensible numerical groundwater-flow model that reasonably represents the groundwater-flow system. A finite-difference numerical groundwater-flow model of the North Fork Red River aquifer was constructed by using MODFLOW-2005 with the Newton formulation solver (MODFLOW-NWT). Data inputs for each package were specified in machine-readable text files. The numerical model of the North Fork Red River aquifer had 385 rows, 460 columns, about 27,600 active cells of 886 by 886 ft (270 by 270 meters), and 2 convertible layers. The top layer (layer 1) represented the undifferentiated Quaternary alluvium and terrace deposits with variable thickness determined from the hydrogeologic framework, and the bottom layer (layer 2) represented the Permian bedrock with a nominal thickness of about 100 feet. The model active area was created from the North Fork Red River aquifer extent and expanded in some areas to ensure that each active cell was in connection with at least one other active cell. One terrace lobe in northern Beckham County was not included in the model active area because it was almost separated spatially and hydraulically from the rest of the North Fork Red River aquifer. The numerical model was temporally discretized into 408 monthly transient stress periods (each with 2 time steps) representing the period 1980–2013. An initial steady-state stress period, in which the groundwater-flow equation had no storage component, represented mean annual inflows to and outflows from the aquifer and produced a solution that was used as the initial condition for subsequent transient stress periods. The numerical model was constructed in units of meters and days. This USGS data release contains all of the input and output files for the simulations described in the associated model documentation report (https://doi.org/10.3133/sir20175098).

In 2017 the U.S. Geological Survey, in cooperation with the Oklahoma Water Resources Board, published a calibrated numerical groundwater-flow model and associated model documentation report that evaluated the effects of potential groundwater withdrawals on groundwater flow and availability in the North Fork Red River aquifer in southwest Oklahoma. The results of groundwater-availability scenarios run on the calibrated numerical groundwater-flow model could be used by the Oklahoma Water Resources Board to reevaluate the maximum annual yield of groundwater from the North Fork Red River aquifer in Oklahoma. The numerical groundwater-flow model was built on a hydrogeologic framework and a conceptual groundwater-flow model derived from previously published and newly collected hydrologic data. A hydrogeologic framework is a three-dimensional representation of the aquifer and the surrounding geologic units at a scale that captures the regional controls on groundwater flow. The hydrogeologic framework for the North Fork Red River aquifer included a definition of the aquifer extent and potentiometric surface, as well as a description of the textural and hydraulic properties of aquifer materials. A conceptual groundwater-flow model is a simplified description of the major inflow and outflow sources (hydrologic boundaries) of a groundwater-flow system as well as an accounting of the estimated mean flows from those sources (water budget) for a specified period of time. The hydrogeologic framework and conceptual model are necessary constraints used in the construction and calibration of a scientifically defensible numerical groundwater-flow model that reasonably represents the groundwater-flow system. A finite-difference numerical groundwater-flow model of the North Fork Red River aquifer was constructed by using MODFLOW-2005 with the Newton formulation solver (MODFLOW-NWT). Data inputs for each package were specified in machine-readable text files. The numerical model of the North Fork Red River aquifer had 385 rows, 460 columns, about 27,600 active cells of 886 by 886 ft (270 by 270 meters), and 2 convertible layers. The top layer (layer 1) represented the undifferentiated Quaternary alluvium and terrace deposits with variable thickness determined from the hydrogeologic framework, and the bottom layer (layer 2) represented the Permian bedrock with a nominal thickness of about 100 feet. The model active area was created from the North Fork Red River aquifer extent and expanded in some areas to ensure that each active cell was in connection with at least one other active cell. One terrace lobe in northern Beckham County was not included in the model active area because it was almost separated spatially and hydraulically from the rest of the North Fork Red River aquifer. The numerical model was temporally discretized into 408 monthly transient stress periods (each with 2 time steps) representing the period 1980–2013. An initial steady-state stress period, in which the groundwater-flow equation had no storage component, represented mean annual inflows to and outflows from the aquifer and produced a solution that was used as the initial condition for subsequent transient stress periods. The numerical model was constructed in units of meters and days. This USGS data release contains all of the input and output files for the simulations described in the associated model documentation report (https://doi.org/10.3133/sir20175098).

This groundwater flow model used a previously developed three-dimensional groundwater flow model (https://doi.org/10.3133/sir20165153) was used to assess future groundwater availability in the Northern High Plains aquifer in Colorado, Kansas, Nebraska, South Dakota, and Wyoming. In this groundwater flow model, a modified version of a previously published soil-water-balance (SWB) model (https://doi.org/10.3133/sir20165153) estimates recharge and groundwater withdrawals for irrigation using climatic, soils, land-cover data. For this groundwater flow model, the SWB output was adjusted in areas where surface water is used for irrigation and adjusted the same as was done through calibration of the previously-developed groundwater flow model. The model was designed as a tool for regional evaluations of groundwater resources and of groundwater interactions with streams and other hydrologic features resulting from current or forecasted conditions. For this study, five forecast scenarios are included, a baseline forecast, two forecasts evaluating the effects of land use changes, and two forecast evaluating the effects of climatic changes. This USGS data release also includes MODFLOW-NWT (version 1.0.5) source code and SWB source code. This USGS data release contains all of the input and output files for the model described in the associated model documentation report (https://doi.org/10.3133/pp1864).