This data release includes a polygon shapefile of grid cells attributed with values representing the simulated base-flow, evapotranspiration, and groundwater-storage depletions as a percentage of hypothetical well pumpage for the 2006-2055 time period. Depletions were simulated by the Phase-Two Elkhorn-Loup Model (ELM), constructed using MODFLOW-2005 (Harbaugh, 2005) with the Groundwater Vistas, version 5, software (Environmental Simulations, Inc., 2009). Each polygon represents one model grid cell. All values are estimates and approximations. The Phase-Two ELM simulated the High Plains aquifer in north-central Nebraska from predevelopment (pre-1895) through 2055 (Stanton and others, 2010). The simulation was calibrated using an automated parameter-estimation method to optimize the fit of simulation outputs to three sets of calibration targets: estimated 1939 groundwater levels and base flows (representing pre-1940 conditions), 1945-through-2005 decadal groundwater-level changes, and 1940-through-2005 annual base flows. The calibrated simulation was used to estimate volumetric ratios of the reductions in base flow, evapotranspiration, and groundwater storage to the total volume of water pumped from a hypothetical well for a 50-year future time period. Ratios were then multiplied by 100 to obtain percentages. The 50-year period was selected because base-flow depletion percentages for 40- to 50-year periods are the basis of groundwater and surface-water management decisions in Nebraska.

This data release includes a polygon shapefile of grid cells attributed with values representing the simulated base-flow, evapotranspiration, and groundwater-storage depletions as a percentage of hypothetical well pumpage for the 2011-2060 time period. Depletions were simulated by the Phase-Three Elkhorn-Loup Model (ELM), constructed using MODFLOW-NWT (Niswonger and others, 2011). Each polygon represents one model grid cell, with pumping specified from either layer one or layer two of the model. All values are estimates and approximations. The phase three ELM simulated the High Plains aquifer in north-central Nebraska from predevelopment (pre-1895) through 2060 (Flynn and Stanton, 2018). The simulation was calibrated using an automated parameter-estimation method to optimize the fit of simulation outputs to three sets of calibration targets: estimated 1940 groundwater levels and base flows (representing pre-1940 conditions), 1940-through-2010 monthly groundwater levels, and 1940 through 2010 monthly estimated base flows. The calibrated simulation was used to estimate volumetric ratios of the reductions in base flow, evapotranspiration, and groundwater storage to the total volume of water pumped from a hypothetical well for a 50-year future time period. Ratios were then multiplied by 100 to obtain percentages. The 50-year period was selected because base-flow depletion percentages for 40- to 50-year periods are the basis of groundwater and surface-water management decisions in Nebraska.

This data release includes a polygon shapefile of grid cells attributed with values representing the simulated base-flow, evapotranspiration, and groundwater-storage depletions as a percentage of hypothetical well pumpage for the 2006-2055 time period. Depletions were simulated by the Phase-Two Elkhorn-Loup Model (ELM), constructed using MODFLOW-2005 (Harbaugh, 2005) with the Groundwater Vistas, version 5, software (Environmental Simulations, Inc., 2009). Each polygon represents one model grid cell. All values are estimates and approximations. The Phase-Two ELM simulated the High Plains aquifer in north-central Nebraska from predevelopment (pre-1895) through 2055 (Stanton and others, 2010). The simulation was calibrated using an automated parameter-estimation method to optimize the fit of simulation outputs to three sets of calibration targets: estimated 1939 groundwater levels and base flows (representing pre-1940 conditions), 1945-through-2005 decadal groundwater-level changes, and 1940-through-2005 annual base flows. The calibrated simulation was used to estimate volumetric ratios of the reductions in base flow, evapotranspiration, and groundwater storage to the total volume of water pumped from a hypothetical well for a 50-year future time period. Ratios were then multiplied by 100 to obtain percentages. The 50-year period was selected because base-flow depletion percentages for 40- to 50-year periods are the basis of groundwater and surface-water management decisions in Nebraska.

A previously published MODFLOW-NWT groundwater-flow model for the Rush Springs aquifer in western Oklahoma (using 1 steady state stress period followed by 444 monthly stress periods representing 1979-2015; Ellis, 2018a) was used as the basis of several groundwater-use scenarios. The model is a 3-layer model including the Cloud Chief formation (confining unit of the Rush Springs aquifer), alluvial and terrace deposits, and the Rush Springs aquifer. The scenarios were used to assess the effects of increasing groundwater withdrawals from the Rush Springs aquifer on base flows to streams that flow into Fort Cobb Reservoir to address concerns over groundwater use reducing inflows to the lake. The effects of groundwater use on base flow were assessed using four scenarios: (1) scaling the equal-proportionate-share rate estimated by Ellis (2018a), (2) scaling historical groundwater withdrawals, (3) scaling historical groundwater withdrawals using zones, and (4) base flow depletion simulations. This USGS data release contains all input and output files for the groundwater-flow simulations and streamflow and base-flow statistics described in the associated model documentation report (https://doi.org/10.3133/sir20245002). Supporting geospatial data are provided that were used to help construct the scenarios and used to display model outputs.

In 2018 The U.S. Geological Survey, in cooperation with the U.S. Bureau of Reclamation and 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 Rush Springs aquifer in western 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 evaluate the maximum annual yield of groundwater from the Rush Springs aquifer in Oklahoma. 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 conceptual model was necessary to provide 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 Rush Springs 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 Rush Springs aquifer had 1,362 rows, 1,083 columns, about 554,000 active cells of 500 by 500 ft, and 3 convertible layers. The top layer (layer 1) represented the Permian-age Cloud Chief Formation. The Rush Springs aquifer is composed of Permian-age Whitehorse Group. The second layer (layer 2) represented the undifferentiated Quaternary-age alluvium and terrace deposits, as well as the upper 30 ft of the Whitehorse Group. The bottom layer (layer 3) represented the remainder of the Rush Springs Formation. The model active area was modified from Neel and others (2018). The numerical model was temporally discretized into 444 monthly transient stress periods representing the period 1979-2015. 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/sir20185136)

A three-dimensional groundwater flow model was developed to characterize groundwater resources of the uppermost principal aquifers in the Williston structural basin in parts of Montana, North Dakota, and South Dakota in the United States and of Manitoba and Saskatchewan in Canada as part of a detailed assessment of the groundwater availability of the area. The uppermost principal aquifers are comprised of the glacial, lower Tertiary, and Upper Cretaceous aquifer systems. The model was developed as a part of the U.S. Geological Survey Water Availability and Use Science Program's effort to conduct large-scale multidisciplinary regional studies of groundwater availability. The numerical model was used to (1) simulate hydrologic scenarios of interest to groundwater managers and to advance the understanding of groundwater budgets and components including recharge, discharge, and aquifer storage for the entire system, (2) compute historical and projected system response to natural and anthropogenic stresses, and (3) evaluate potential hydrologic monitoring programs at a scale relevant to basin-wide water-management decisions. This model was previously published by the U.S. Geological Survey in a Scientific Investigations Report (https://doi.org/10.3133/sir20175158) and the model input and output files are available in a data release (https://doi.org/10.5066/F75B01CZ). The underlying directories contain all of the input and output files for predictive simulations of groundwater response to selected scenarios for the uppermost principal aquifer systems in the Williston Basin, United States and Canada. The predictive simulations were created using base model files from a model developed by Davis and Long and documented in the U.S. Geological Survey Scientific Investigations Report 2017-5158 (https://doi.org/10.3133/sir20175158). Model archive files are documented and are available in an online data release (https://doi.org/10.5066/F75B01CZ). The three-dimensional groundwater-flow model was developed using the numerical modeling software, MODFLOW-NWT. For this study, the numerical groundwater-flow model was used to simulated three predictive scenarios: scenario 1 was focused on flowing artesian wells, and was used to simulate 1960‒2035 hydraulic-head changes that would result if none of the flowing artesian wells in the model area were capped or plugged during this period and other conditions remained constant; scenario 2 simulated 10-year drought for 2006‒15, with no increases in groundwater pumping after 2005; and scenario 3 was identical to scenario 2, except that it also applied the increased groundwater withdrawals necessary to fill the needs of energy-resource production for 2006‒15. A data-worth analysis for evaluation of potential hydrologic monitoring networks was also accomplished using the numerical model. 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/pp1841). This data release also includes MODFLOW-NWT (version 1.0.9) source code.

There is a growing interest in incorporating higher-resolution groundwater modeling within the framework of large-scale land surface models (LSMs), including new processes such as three-dimensional flow, variable soil saturation, and surface water/groundwater interactions. Conversely, complex groundwater models (e.g., the U.S. Geological Survey Groundwater-Flow Model, MODFLOW) often use simpler representations of land surface dynamics (e.g., surface vegetation, evapotranspiration, recharge) and may benefit from higher process fidelity and temporal resolutions in these inputs. This Data Release includes the model inputs used for the MODFLOW 6 models developed for the simulation of groundwater-flow dynamics in the U.S. Northern High Plains using recharge from four different Land Surface Models. Each model included the same MODFLOW 6 groundwater-flow model of the Northern High Plains aquifer which simulated transient recharge, irrigation pumping, groundwater evapotranspiration, changes in groundwater storage, routing of base flow through stream networks for irrigation and non-irrigation time periods from 1979 through 2015. The only difference in each groundwater-flow model is the source of recharge which came from the following Land Surface Models: (1 USGS Soil-Water-Balance (SWB), (2), coupled Weather Research and Forecasting (WRF) and Noah-MP, (3) U.S. National 122 Oceanic and Atmospheric Administration (NOAA) National Water Model (NWM) configuration 123 of the WRF-Hydro, and (4) the Community Land Model.

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 Salt Fork Arkansas River and Chikaskia River alluvial aquifers by using MODFLOW-2005 with the Newton formulation solver (MODFLOW-NWT). The model included the Chikaskia River alluvial aquifer, which is classified as a minor aquifer by the OWRB and is hydrologically connected to the Salt Fork Arkansas River alluvial aquifer. 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 feet. 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. At the time of this publication (2025), a hydrologic investigation and determination of the MAY for the Salt Fork Arkansas River alluvial aquifer had not been completed. The U.S. Geological Survey, in cooperation with the OWRB, conducted a hydrologic investigation and evaluated the simulated effects of potential groundwater withdrawals on groundwater flow and availability in the Salt Fork Arkansas River alluvial aquifer in northern Oklahoma for a study period spanning 1980–2020. Fifteen simulations are included in this data release: a simulation for the calibrated numerical groundwater-flow model, 9 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 the input and output files for the simulations described in the associated model documentation report (https://doi.org/10.3133/sir20255043).

The U.S. Geological Survey, in cooperation with the Oklahoma Water Resources Board, constructed a finite-difference numerical groundwater-flow model of the Salt Fork Red River aquifer using MODFLOW with the Newton formulation solver (MODFLOW-NWT). The 1973 Oklahoma Water Law requires the Oklahoma Water Resources Board to conduct hydrologic investigations of the State’s aquifers to support a determination of the maximum annual yield (MAY) for each groundwater basin. The MAY is defined as the amount of fresh groundwater that can be withdrawn annually while ensuring a minimum 20-year life of the groundwater basin. For alluvium and terrace aquifers, the groundwater-basin-life requirement is satisfied if, after 20 years of MAY withdrawals, 50 percent of the groundwater basin retains a saturated thickness of at least 5 ft. When a MAY has been established, the amount of land owned or leased by a permit applicant determines the annual volume of water allocated to that permit applicant. The annual volume of water allocated per acre of land is known as the equal-proportionate-share (EPS) pumping rate. Because the MAY and EPS have not yet been established for the Salt Fork Red River aquifer, the U.S. Geological Survey, in cooperation with the Oklahoma Water Resources Board, conducted a hydrologic investigation and developed a calibrated numerical groundwater-flow model to evaluate the effects of potential groundwater withdrawals on groundwater availability in the Salt Fork Red River aquifer. The results of groundwater-availability scenarios run on the calibrated numerical groundwater-flow model could be used by the Oklahoma Water Resources Board to evaluate the maximum annual yield of groundwater from the Salt Fork Red River aquifer in Oklahoma. The numerical model was temporally discretized into 1 initial steady-state stress period representing average conditions during 1980-2015 and 432 monthly transient stress periods representing the period 1980-2015. This U.S. Geological Survey 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/sir20215003).

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 Boone and Roubidoux aquifers in northeastern Oklahoma by using MODFLOW-NWT (version 1.1.4) with the Newton formulation solver to simulate groundwater flow and account for the drying and rewetting of cells within the groundwater-flow model. The numerical groundwater-flow model was discretized into four layers consisting of 354 rows by 261 columns with a 2,000-feet by 2,000-feet cell size. The model layers were used to simulate the Western Interior Plains confining system, the Boone aquifer, the Ozark confining unit, and the Roubidoux aquifer. The model was temporally discretized into one steady-state stress period followed by 456 monthly transient stress periods spanning from January 1980 to December 2017. The steady-state stress period typically consisted of mean annual inputs from January 1980 to December 2017, but inputs from 1979 were included for some of the simulations.