A MODFLOW-NWT model was used to simulate the water budget for Haskell Lake and Tower Creek in WI using the Lake, Streamflow Routing, and Unsaturated Zone Flow packages. Particle tracking was performed with the MODFLOW solution (using MODPATH 6). 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/sir20205024).

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 developed groundwater flow model (https://doi.org/10.5066/P9051RUT) was slightly modified to estimate the risk-based discrete relation between groundwater extraction and surface-water/groundwater exchange. Previously, the concept of a ''capture map'' has been put forward as a means to effectively summarize this relation for decision-making consumption. While capture maps have enjoyed success in the environmental simulation industry, they are deterministic, ignoring uncertainty in the underlying model. Furthermore, capture maps are not typically calculated in a manner that facilitates analysis of varying combinations of extraction locations and/or reaches. That is, they are typically constructed with focus on a single reach or group of reaches. The former of these limitations is important for conveying risk to decision makers, while the latter is important for decision-making support related to surface-water management, where future foci may include reaches that were not the focus of the original capture analysis. Herein, we use a MODFLOW-NWT groundwater/surface-water model of the lower San Antonio River, Texas, USA to demonstrate a technique to estimate risk-based and spatially discrete streamflow depletion potential. This USGS data release contains all of the input and output files for the simulations described in the associated journal article (https://doi.org/10.1111/gwat.13080)

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).

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).

A previously developed steady state three-dimensional groundwater flow (MODFLOW-2005) and advective transport (MODPATH6) model was used to examine subsurface nitrate transport to wells and receiving streams in two subcatchments contributing to the Upper Chester River, Maryland. Multiple scenarios of flow and transport parameter fields (recharge, hydraulic conductivity, and porosity) were previously calibrated against groundwater levels, stream discharge measurements, and atmospheric tracer measurements, as described in https://doi.org/10.1016/j.jhydrol.2018.02.006; those multiple scenarios are also available as a USGS data release (https://doi.org/10.5066/F7SN087R). Two of the flow and transport scenarios calibrated in Zell et al. (2018) were selected to simulate nitrate transport, with MODPATH6 files updated as necessary to represent advective transport from observation wells with subsurface nitrate measurements. The development of the model input and output files included in this data release and the application of the models to nitrate transport simulation are documented in the Journal of Environmental Quality article (https://doi.org/10.2134/jeq2018.11.0408).

A previously developed steady state three-dimensional groundwater flow (MODFLOW-2005) and advective transport (MODPATH6) model was used to examine subsurface nitrate transport to wells and receiving streams in two subcatchments contributing to the Upper Chester River, Maryland. Multiple scenarios of flow and transport parameter fields (recharge, hydraulic conductivity, and porosity) were previously calibrated against groundwater levels, stream discharge measurements, and atmospheric tracer measurements, as described in https://doi.org/10.1016/j.jhydrol.2018.02.006; those multiple scenarios are also available as a USGS data release (https://doi.org/10.5066/F7SN087R). Two of the flow and transport scenarios calibrated in Zell et al. (2018) were selected to simulate nitrate transport, with MODPATH6 files updated as necessary to represent advective transport from observation wells with subsurface nitrate measurements. The development of the model input and output files included in this data release and the application of the models to nitrate transport simulation are documented in the Journal of Environmental Quality article (https://doi.org/10.2134/jeq2018.11.0408).

Groundwater flow models have the potential to predict spatial groundwater discharge dynamics within river networks, but models are often not evaluated against discharge dynamics. The objective of this study was to understand the variation in simulated discharge dynamics (discharge location, flowpath depth, and subsurface travel time) for models with common, but varying frameworks and assumptions. The University of Connecticut in collaboration with the United States Geological Survey developed a groundwater flow model (MODFLOW-NWT) for the Farmington River Watershed (1,570 km2) in the northeastern United States and systematically varied the type of typical calibration data (well head and stream elevation); calibration parameters; parameters related to permeability of the surficial materials, bedrock, and riverbed sediments; control of river-aquifer exchange directionality; and model resolution. Each model variation has an associated particle tracking (MODPATH) model. Subsequent work, not described in this model archive, compared with simulated spatial patterns of groundwater discharge with patterns observed with hand-held thermal infrared imagery. This dataset contains model inputs and outputs, post-processing python scripts, and pest calibration input files for 12 model variations described in the associated journal article (https://doi.org/10.1029/2020WR028027)

Groundwater flow models have the potential to predict spatial groundwater discharge dynamics within river networks, but models are often not evaluated against discharge dynamics. The objective of this study was to understand the variation in simulated discharge dynamics (discharge location, flowpath depth, and subsurface travel time) for models with common, but varying frameworks and assumptions. The University of Connecticut in collaboration with the United States Geological Survey developed a groundwater flow model (MODFLOW-NWT) for the Farmington River Watershed (1,570 km2) in the northeastern United States and systematically varied the type of typical calibration data (well head and stream elevation); calibration parameters; parameters related to permeability of the surficial materials, bedrock, and riverbed sediments; control of river-aquifer exchange directionality; and model resolution. Each model variation has an associated particle tracking (MODPATH) model. Subsequent work, not described in this model archive, compared with simulated spatial patterns of groundwater discharge with patterns observed with hand-held thermal infrared imagery. This dataset contains model inputs and outputs, post-processing python scripts, and pest calibration input files for 12 model variations described in the associated journal article (https://doi.org/10.1029/2020WR028027)

A MODFLOW-6 groundwater flow model of the Shell Valley aquifer near the Turtle Mountain Band of the Chippewa Indians land area representation in northern North Dakota was constructed to improve the understanding and management of the water-supply resources. The model area included sub-watersheds containing the extent of the Shell Valley aquifer approximately between the towns of St. John, Belcourt, Wolford, Overly, and Dunseith, North Dakota. The model simulated groundwater flow in the Shell Valley aquifer and the adjacent overlying and underlying hydrogeologic units from 1980 through 2022. 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 combined steady-state and transient MODFLOW-6 groundwater flow model; (2) a version of the MODFLOW-6 groundwater flow model used to estimate model water-budget uncertainty; and, (3) a Soil-Water Balance (SWB) model used to estimate spatial and temporal variations of recharge and potential evapotranspiration.