A three-dimensional MODFLOW-NWT model was constructed to better understand the effects of drought stress on the Cedar River alluvial aquifer, the principal source of municipal water for the City of Cedar Rapids, Iowa. Historically, the aquifer supported the production needs of the City of Cedar Rapids and surrounding area but between July 2011 and February 2013, Iowa experienced severe drought conditions that affected water availability for communities that relied on alluvial aquifers for their production needs. During that time, the City of Cedar Rapids observed water level declines in their horizontal collector wells (HCW) of as much as about 11 meters. Pumping from affected production wells had to be halted to prevent damage to the pumps and wells and caused concern about the reliability of the alluvial aquifer under future drought conditions. In 2013, the U.S. Geological Survey (USGS), in cooperation with the City of Cedar Rapids, began a study to better understand the effects of drought stress on the Cedar River alluvial aquifer using a numerical groundwater flow model which combined published hydrogeologic data with airborne, waterborne, down-hole, and land-based geophysical survey data collected from 2015 to 2017. The model (1) provided a detailed three-dimensional lithologic model of the Cedar River alluvial aquifer and surrounding area, (2) improved the conceptual model for the groundwater flow system, and (3) evaluated hydrogeologic characteristics of aquifer materials. Two models were constructed for this study. A steady-state model of mean hydrologic conditions for November 2015 and a transient model to simulate conditions from October 1, 2016, to August 31, 2018 (calibration period), and from October 1, 2011, to April 30, 2013 (simulation period). Additional scenarios using the transient model simulate drought conditions from October 2011 to April 2013 and evaluate the transient drought conditions with modifications to the riverbed. The numerical models were developed as a tool for use by water managers to better understand the potential effects of drought and increased demand on production wells. 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/sir20215065).

The U.S. Geological Survey constructed a steady-state numerical groundwater flow model in cooperation with Des Moines Water Works (DMWW) to simulate groundwater flow conditions in the Des Moines River alluvial aquifer (DMRA) during winter low-flow conditions typical of December 2018-2020. The Des Moines River alluvial aquifer (DMRA) is an important source of water for Des Moines Water Works (DMWW), the municipal water utility that serves residential and commercial water needs in the city of Des Moines, Iowa and surrounding municipalities. A comprehensive understanding of groundwater flow processes in the DMRA is needed for DMWW to make decisions related to the management of this water resource. A three-layered model was constructed using MODFLOW-NWT to simulate an area of about 15 square kilometers near Prospect Park in Des Moines, Iowa. The model has 130 rows and 130 columns of cells within the model boundary. Parameter ESTimation software (PEST) was used for model calibration to assess and optimize performance of individual parameters including the horizontal and vertical hydraulic conductivity of the various units, evapotranspiration rate, and recharge rate. 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/ofr20211110).

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, finite-difference MODFLOW 2005 groundwater model using the Newton formulation solver (MODFLOW-NWT) was created for the Cimarron River alluvial aquifer in Payne County, north-central Oklahoma to assess the impacts of current groundwater withdrawal rates with respect to current and future groundwater availability and the impacts to baseflow to the Cimarron River. To better understand current (2021) water resources and possible future water availability in the Pawnee Nation Tribal jurisdictional area, the U.S. Geological Survey, in cooperation with the Bureau of Indian Affairs and the Pawnee Nation of Oklahoma, compiled available hydrogeologic data and developed conceptual and numerical groundwater-flow models. The numerical model consists of a single layer representing alluvium and terrace deposits within the alluvial aquifer model area. The calibrated model contains one steady-state stress period and 24 monthly, transient stress periods for 2016-17. Streamflow-capture analysis was applied to the steady-state simulation to identify areas of the aquifer where base flows in the Cimarron River were most sensitive to groundwater withdrawals. 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/sir20215073).

Des Moines Water Works (DMWW) is a regional municipal water utility that supplies residential and commercial water resources to about 600,000 customers in Des Moines, Iowa, and surrounding municipalities in central Iowa. DMWW has identified a need for increased water supply and is exploring the potential for expanding groundwater production capabilities in the Des Moines River alluvial aquifer, where it operates two radial collector wells (RCWs). The U.S. Geological Survey, in cooperation with DMWW, completed a study of the Des Moines River alluvial aquifer and the interactions of the RCWs with the aquifer; no previously published model has included the existing well locations, which is the focus of this model. A numerical groundwater flow model has been developed to characterize the Des Moines River alluvial aquifer based on a conceptual model under historical conditions, to simulate water levels observed in the DMWW RCWs, and to provide a tool that potentially can be used in the future to evaluate groundwater production scenarios. The data release directories contain ancillary, bin, georef, model, output, and source folders for the following model: tr_mf6_sim: A calibrated transient MODFLOW 6 groundwater flow model of the Des Moines River alluvial aquifer near Des Moines, Iowa.

Des Moines Water Works (DMWW) is a regional municipal water utility that supplies residential and commercial water resources to about 600,000 customers in Des Moines, Iowa, and surrounding municipalities in central Iowa. DMWW has identified a need for increased water supply and is exploring the potential for expanding groundwater production capabilities in the Des Moines River alluvial aquifer, where it operates two radial collector wells (RCWs). The U.S. Geological Survey, in cooperation with DMWW, completed a study of the Des Moines River alluvial aquifer and the interactions of the RCWs with the aquifer; no previously published model has included the existing well locations, which is the focus of this model. A numerical groundwater flow model has been developed to characterize the Des Moines River alluvial aquifer based on a conceptual model under historical conditions, to simulate water levels observed in the DMWW RCWs, and to provide a tool that potentially can be used in the future to evaluate groundwater production scenarios. The data release directories contain ancillary, bin, georef, model, output, and source folders for the following model: tr_mf6_sim: A calibrated transient MODFLOW 6 groundwater flow model of the Des Moines River alluvial aquifer near Des Moines, Iowa.

A MODFLOW-NWT model was used to simulate the groundwater/surface-water interactions in the Partridge River Basin, MN using the Streamflow Routing and Unsaturated Zone Flow packages. The base model represents 2011-2013 average mining conditions and was used to build five mining scenario models, as described in the report. The base model and mining scenarios were used to estimate the base flow at 6 stream locations, pit inflows rates for the new hypothetical pits, and the average depth to water in twelve wetlands. PEST utilities were used to estimate an uncertainty with each of these forecasts. Particle tracking was performed with the MODFLOW solution (using MODPATH 7) and Monte Carlo techniques to create probabilistic capture zones. 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/sir20215038).

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).

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 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).