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.

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)

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)

This model archive provides the necessary documentation of the numerical models developed for the Central Sands Lake study in central Wisconsin and will be included as a technical appendix (Appendix C) in the report to the Wisconsin State Legislature by the Wisconsin Department of Natural Resources (WDNR) in response to 2017 Wisconsin Act 10. This legislation directed DNR to determine whether existing and potential groundwater withdrawals are causing or are likely to cause significant reduction of mean seasonal water levels at Pleasant Lake, Long Lake, and Plainfield Lake (s. 281.34(7m)(2)(b), Wis. Stats.) in Waushara County, Wisconsin. To evaluate the potential hydrologic connection between groundwater withdrawals and the nearby study lakes, hydrologic models were created that focused on the lakes of interest and yet were large enough to cover a broad enough region to extend to the major hydrologic boundaries of the natural flow system. The areas near the lakes require finer-scale grid discretization (or spacing) to better represent the lakes and streams in the model, but also need to cover a large enough area to include the groundwater withdrawal locations that have the potential to cause reduction in water levels in the lakes. To accomplish these goals, three groundwater models were created: a regional model extending to major hydrologic boundaries; and two inset models, inheriting boundaries from the regional model but focused near the lakes. Each of the inset models, in turn, included a detailed area close to the lakes surrounded by an area at the same spatial scale as the regional model. To support WDNR in evaluating the connection between groundwater withdrawals and lake levels, a representative time period was required over which to compare land use with and without irrigated agriculture and for WDNR to evaluate potential lake stage and flux changes related to irrigated agriculture. WDNR chose the climate period of 1981-2018 to be representative of a typical period and provided two land use scenarios—one with no irrigated agriculture and one with assumed crop rotations similar to current conditions—to simulate with groundwater models to, then, compare lake responses with. As a result, simulations over this climate record are not intended to recreate the history of 1981-2018 because land use changed over that time. These runs are, instead, intended to provide a basis on which to compare land use with and without irrigation-related groundwater withdrawals based on the current arrangement of land use and a varied climatic record. Groundwater withdrawals focused on irrigated-agriculture-related water use because greater than 95% of groundwater withdrawal in the two inset models around the study lakes is for irrigated agriculture water use. The period of 2012-2018 was used for parameter estimation (synonymously referred to as “history matching”) for the groundwater models. This time period was chosen because it includes the most complete water use records to simulate groundwater withdrawals. History matching was performed using groundwater elevations, lake stages, and streamflow observations over the 2012-2018 time period and processed observations derived from those raw data. Climatic data were incorporated into the model using a soil-water balance approach. A soil water balance model (Westenbroek and others, 2021) was constructed at the scale of the regional groundwater model to both calculate recharge based on land use and climate, and in the long-term climate-period runs, to estimate water use required by irrigated agriculture to apply as well boundary conditions in the groundwater model in the absence of reported water use values over that period. The model archive presents all the inputs needed to run the models, the model software, information on history matching to estimate parameters of the model, model scenario files, and model outputs that the user should be able to recreate using the model files in this archive.

This model archive provides the necessary documentation of the numerical models developed for the Central Sands Lake study in central Wisconsin and will be included as a technical appendix (Appendix C) in the report to the Wisconsin State Legislature by the Wisconsin Department of Natural Resources (WDNR) in response to 2017 Wisconsin Act 10. This legislation directed DNR to determine whether existing and potential groundwater withdrawals are causing or are likely to cause significant reduction of mean seasonal water levels at Pleasant Lake, Long Lake, and Plainfield Lake (s. 281.34(7m)(2)(b), Wis. Stats.) in Waushara County, Wisconsin. To evaluate the potential hydrologic connection between groundwater withdrawals and the nearby study lakes, hydrologic models were created that focused on the lakes of interest and yet were large enough to cover a broad enough region to extend to the major hydrologic boundaries of the natural flow system. The areas near the lakes require finer-scale grid discretization (or spacing) to better represent the lakes and streams in the model, but also need to cover a large enough area to include the groundwater withdrawal locations that have the potential to cause reduction in water levels in the lakes. To accomplish these goals, three groundwater models were created: a regional model extending to major hydrologic boundaries; and two inset models, inheriting boundaries from the regional model but focused near the lakes. Each of the inset models, in turn, included a detailed area close to the lakes surrounded by an area at the same spatial scale as the regional model. To support WDNR in evaluating the connection between groundwater withdrawals and lake levels, a representative time period was required over which to compare land use with and without irrigated agriculture and for WDNR to evaluate potential lake stage and flux changes related to irrigated agriculture. WDNR chose the climate period of 1981-2018 to be representative of a typical period and provided two land use scenarios—one with no irrigated agriculture and one with assumed crop rotations similar to current conditions—to simulate with groundwater models to, then, compare lake responses with. As a result, simulations over this climate record are not intended to recreate the history of 1981-2018 because land use changed over that time. These runs are, instead, intended to provide a basis on which to compare land use with and without irrigation-related groundwater withdrawals based on the current arrangement of land use and a varied climatic record. Groundwater withdrawals focused on irrigated-agriculture-related water use because greater than 95% of groundwater withdrawal in the two inset models around the study lakes is for irrigated agriculture water use. The period of 2012-2018 was used for parameter estimation (synonymously referred to as “history matching”) for the groundwater models. This time period was chosen because it includes the most complete water use records to simulate groundwater withdrawals. History matching was performed using groundwater elevations, lake stages, and streamflow observations over the 2012-2018 time period and processed observations derived from those raw data. Climatic data were incorporated into the model using a soil-water balance approach. A soil water balance model (Westenbroek and others, 2021) was constructed at the scale of the regional groundwater model to both calculate recharge based on land use and climate, and in the long-term climate-period runs, to estimate water use required by irrigated agriculture to apply as well boundary conditions in the groundwater model in the absence of reported water use values over that period. The model archive presents all the inputs needed to run the models, the model software, information on history matching to estimate parameters of the model, model scenario files, and model outputs that the user should be able to recreate using the model files in this archive.

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).

A previously calibrated MODFLOW-NWT groundwater-flow model (https://doi.org/10.3133/sir20205118) was used to determine the effects of climate variability under a range of future climatic conditions on groundwater resources in the reach 1 of the Washita River alluvial aquifer in western Oklahoma. The study area focuses on reach 1 of the Washita River alluvial aquifer; the entire Washita River alluvial aquifer consists of four administrative sections, or reaches, that are designated as reaches 1–4 by the Oklahoma Water Resources Board (OWRB, 2012). To approximate a range in future base-flow conditions in reach 1 of the Washita River alluvial aquifer and base-flow into Foss Reservoir, the Coupled Model Intercomparison Project Phase 5 Global Climate Model climate data were downscaled to watershed scale using monthly Bias-Correction Spatial Disaggregation techniques. A time series of scaling factors was developed and spatially interpolated for three climate scenarios (central tendency, warmer/drier, and less warm-wetter) representing a range of future climate conditions for the period 2050–2079. These scaling factors were then applied to an existing soil-water-balance model (https://doi.org/10.3133/sir20205118) with climate data for the baseline period 1985–2014 to produce recharge and evapotranspiration estimations for this future period. The downscaled climate data were applied to the groundwater-flow model of the reach 1 of the Washita River alluvial aquifer using MODFLOW-NWT. This data release contains the input and output files for the scenarios described in the associated model documentation report (https://doi.org/10.3133/sir20245082).

A previously calibrated MODFLOW-NWT groundwater-flow model (https://doi.org/10.3133/sir20205118) was used to determine the effects of climate variability under a range of future climatic conditions on groundwater resources in the reach 1 of the Washita River alluvial aquifer in western Oklahoma. The study area focuses on reach 1 of the Washita River alluvial aquifer; the entire Washita River alluvial aquifer consists of four administrative sections, or reaches, that are designated as reaches 1–4 by the Oklahoma Water Resources Board (OWRB, 2012). To approximate a range in future base-flow conditions in reach 1 of the Washita River alluvial aquifer and base-flow into Foss Reservoir, the Coupled Model Intercomparison Project Phase 5 Global Climate Model climate data were downscaled to watershed scale using monthly Bias-Correction Spatial Disaggregation techniques. A time series of scaling factors was developed and spatially interpolated for three climate scenarios (central tendency, warmer/drier, and less warm-wetter) representing a range of future climate conditions for the period 2050–2079. These scaling factors were then applied to an existing soil-water-balance model (https://doi.org/10.3133/sir20205118) with climate data for the baseline period 1985–2014 to produce recharge and evapotranspiration estimations for this future period. The downscaled climate data were applied to the groundwater-flow model of the reach 1 of the Washita River alluvial aquifer using MODFLOW-NWT. This data release contains the input and output files for the scenarios described in the associated model documentation report (https://doi.org/10.3133/sir20245082).

A three-dimensional groundwater flow model was developed to characterize groundwater resources and the interaction of groundwater with streams and other hydrologic features in the Northern High Plains aquifer. The Northern High Plains aquifer is generally unconfined; most of the water withdrawn from the aquifer is used for irrigation. A modified version of a previously published soil-water-balance (SWB) model estimates recharge using climatic, soils, land cover data, in addition to data for groundwater withdrawals for irrigation. The SWB output was adjusted in areas where surface water is used for irrigation. The groundwater flow model results were calibrated using parameter estimation to measured groundwater levels and estimated stream base flows. 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. 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/sir20165153). This data release also includes (1) MODFLOW-NWT (version 1.0.9) source code, and (2) SWB source code in two formats.

A previously developed model (https://doi.org/10.3133/sir20175098) was coupled with downscaled climate model data to determine the impact of climate variability on base flow and groundwater storage in the North Fork Red River aquifer, Oklahoma. The North Fork Red River aquifer is an alluvial aquifer that discharges groundwater to the North Fork Red River, which provides inflow to Lake Altus, an important water source for the surrounding communities. The impact of climate variability on hydrologic systems and the resulting effects on basins has become an important topic in assessing future water resources. Global climate projections from general circulation models, including the Coupled Model Intercomparison Project Phase 5 (CMIP5), have been developed to improve the understanding of climate science and forecast future climatic conditions. Due to the impact of climate variations on groundwater resources, it is important to communicate the ranges of results with water resource managers. To approximate a range in future base flow conditions and flow into Lake Altus, the Coupled Model Intercomparison Project Phase 5 climate data was downscaled to watershed scale using monthly Bias-Correction Spatial Disaggregation techniques. A time-series of scaling factors were developed and interpolated for three climate scenarios (central tendency, warmer/drier, and less warm-wetter) representing a range of future climate conditions for the period 2045–2074. These scaling factors were then applied to an existing soil-water-balance model dataset with climate data for the baseline period 1980–2009 to produce recharge and evapotranspiration estimations for this future period. The downscaled climate data was applied to the finite-difference numerical groundwater-flow model of the North Fork Red River aquifer using MODFLOW-2005 with the Newton formulation solver (MODFLOW-NWT) which was temporally discretized into 373 monthly transient stress periods representing the period 1980–2010. Three climate scenarios (central tendency, warmer/drier, and less warm/wetter) representing a range of future climate conditions for the period 2045–2074 were simulated. This USGS data release contains all of the input and output files for the simulations described in the associated journal article (http://doi.org/10.1007/s10040-020-02230-x).