A previously developed three-dimensional groundwater flow model (https://doi.org/10.3133/sir20125183) of the three primary aquifers in the region north of Aberdeen, South Dakota, was revised to assist the City of Aberdeen with water-resource planning. The principal aquifers are the Elm, Middle James, and Deep James. The numerical model is intended to be 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, (2) compute historical and projected system response to natural and anthropogenic stresses, and (3) evaluate potential withdrawal scenarios to assist with water-management decisions. The three-dimensional groundwater-flow model was developed using the USGS's numerical modeling software, MODFLOW-NWT. The model included both steady-state (mean) and transient (temporally varying) conditions. Steady-state data were from October 1, 1974 to September 30, 2009, and the transient time period included data from October 1, 1974 to September 30, 2015. The model was calibrated by attempting to match simulated and measured or estimated hydraulic heads, differences in hydraulic heads between aquifers, and stream base flow. Water budgets for the model's layers area were produced with ZONEBUDGET. This USGS data release contains all of the input and output files for the model described in the associated model documentation report (http://doi.org/10.3133/sir20185137). The data release also includes (1) MODFLOW-NWT (version 1.1.4) source code, and (2) ZONEBUDGET (3.01) source code.

A MODFLOW-6 groundwater flow model of the Big Sioux aquifer near Sioux Falls, South Dakota, was constructed to improve the understanding and management of the water supply resources for the City of Sioux Falls. The model area included the Big Sioux River drainage basin between Del Rapids and Sioux Falls, South Dakota, and simulated groundwater flow in the Big Sioux aquifer and underlying hydrogeologic units. The data release directories contain ancillary, bin, georef, model, output, and source folders with the necessary executable and input files for the following models: (1) a transient MODFLOW-6 groundwater flow model; (2) a steady-state MODFLOW-6 model used for eventual streamflow capture analysis; (3) a modified transient MODFLOW-6 model used for timing-of-capture analysis at three hypothetical well sites; and (4) a Soil-Water Balance (SWB) model used to estimate spatial and temporal variations of recharge and potential evapotranspiration. 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/sir20195117).

A MODFLOW-6 groundwater flow model of the Big Sioux aquifer near Sioux Falls, South Dakota, was constructed to improve the understanding and management of the water supply resources for the City of Sioux Falls. The model area included the Big Sioux River drainage basin between Del Rapids and Sioux Falls, South Dakota, and simulated groundwater flow in the Big Sioux aquifer and underlying hydrogeologic units. The data release directories contain ancillary, bin, georef, model, output, and source folders with the necessary executable and input files for the following models: (1) a transient MODFLOW-6 groundwater flow model; (2) a steady-state MODFLOW-6 model used for eventual streamflow capture analysis; (3) a modified transient MODFLOW-6 model used for timing-of-capture analysis at three hypothetical well sites; and (4) a Soil-Water Balance (SWB) model used to estimate spatial and temporal variations of recharge and potential evapotranspiration. 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/sir20195117).

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 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.

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 three-dimensional groundwater flow model was developed to characterize groundwater resources 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 is intended to be 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. The three-dimensional groundwater-flow model was developed using the numerical modeling software, MODFLOW-NWT. The steady-state (mean) hydrological conditions included data from 1981 to 2005, and transient (temporally-varying) conditions included a combination of a steady state period with data prior to 1960, and a transient period from 1961 to 2005. The model was calibrated by attempting to match simulated and measured or estimated hydraulic heads, differences in hydraulic heads between aquifers, stream base flow, and measured flow at flowing artesian wells. Sub-regional water budgets for the model area were produced with ZONEBUDGET. 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/sir201755158). This data release also includes (1) MODFLOW-NWT (version 1.0.9) source code, and (2) ZONEBUDGET source code.

Five MODFLOW-NWT inset models were extracted from the Lake Michigan Basin (LMB) regional model (https://pubs.usgs.gov/sir/2010/5109/). These inset models were designed to serve as a training ground for metamodels of groundwater age in glacial wells. The study areas of the inset models correspond to HUC8 basins. Two of the basins are tributary to Lake Michigan from the east, two are tributary to the lake from the west, and one is located outside the western boundary of the Lake Michigan topographic basin. The inset models inherit many of the inputs to the parent LMB model, such as its hydrostratigraphy and layering scheme, the hydraulic conductivity assigned bedrock layers, the recharge distribution, and water use in the form of pumping rates from glacial and bedrock wells. The construction of the inset models entails modifying some inputs, most notably the grid spacing (reduced from cells 5000-ft on a side in the parent model to 500-ft on a side in the inset models). The refined grid spacing allowed more precise location of pumping wells and more detailed simulation of groundwater/surface-water interactions. Also modified are the glacial hydraulic conductivity values, the top bedrock surface elevation, and the surface-water network input to the inset models. The inset models are solved using the MODFLOW-NWT code which allows for more robust handling of conditions in unconfined aquifers than previous versions of MODFLOW. The particle-tracking code MODPATH was used to simulate the distribution of age of groundwater discharging to wells pumping from glacial deposits. This USGS data release contains all of the input and output files for the simulation of the inset models of the Lake Michigan Basins model as described in the associated model documentation report (https://doi.org/10.3133/sir20185038).

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.

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).