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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...
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).
This data release contains three groundwater-flow models of northeastern Wisconsin, USA, that were developed with differing levels of complexity to provide a framework for subsequent evaluations of the effects of process-based model complexity on estimates of groundwater age distributions for withdrawal wells and streams. Preliminary assessments, which focused on the effects of model complexity on simulated water levels in the glacial aquifer system, illustrate that simulation of vertical gradients using multiple model layers improves simulated heads more in relatively low-permeability units than in high-permeability units. Moreover, simulation of heterogeneous hydraulic conductivity fields in both coarse-grained...
A new groundwater flow model for western Chippewa County, Wisconsin has been developed by the Wisconsin Geological and Natural History Survey (WGNHS) and the U.S. Geological Survey (USGS). An analytic element GFLOW model was constructed and calibrated to generate hydraulic boundary conditions for the perimeter of the more detailed three-dimensional MODFLOW-NWT model. This three-dimensional model uses the USGS MODFLOW-NWT finite difference code, a standalone version of MODFLOW-2005 that incorporates the Newton (NWT) solver. The model conceptualizes the hydrogeology of western Chippewa County as a six-layer system which includes several hydrostratigraphic units. The model explicitly simulates groundwater-surface-water...
This groundwater-flow model archive contains all of the input and output files for an inset MODFLOW-NWT model extracted from the northern (Wisconsin) half of a published USGS steady-state regional model of the Upper Fox River Basin in the U.S. Upper Midwest. The construction and details of the published USGS steady-state model of the Upper Fox River Basin is outlined in the U.S. Geological Survey Scientific Investigations Report 2018-5038 (https://doi.org/10.3133/sir20185038). The regional model is archived in the data release at https://doi.org/10.5066/F76D5R5V. The extracted model was used to demonstrate an innovative new method for delinating fen distribution and discharge using the MODFLOW UZF package. The extracted...
A three-dimensional, numerical groundwater flow model of the Hualapai Plateau and Truxton Basin was developed to assist water-resource managers in understanding the potential effects of projected groundwater withdrawals on groundwater levels and storage in the basin. The Truxton Basin Hydrologic Model (TBHM) was developed using previously published data, as well as, new geophysical data collected as part of this investigation (Ball, 2020; Kennedy, 2020). TBHM is a transient model that simulates the hydrologic system between the years 1976–2140, including three hypothetical groundwater withdrawal scenarios between 2020–2140. The predevelopment (before 1976) groundwater system is simulated using a steady-state model....
In the Chenango River Basin, New York, glacial valley-fill unconfined and confined aquifers are an important source of drinking-water supplies. The U.S. Geological Survey developed three-dimensional groundwater-flow models (MODFLOW-NWT code) of three study areas in the basin to improve understanding of groundwater flow and delineate areas contributing recharge to 16 production wells as part of an effort to protect the source of water to these wells. The modeled areas were the Cortland study area in Cortland County (CCSA), Greene study area (GSA), and the Cincinnatus study area (CSA). Production wells in CCSA tap unconfined aquifers, whereas the production wells in GSA and CSA are screened in confined aquifers. The...
A previously developed three-dimensional steady-state groundwater flow model (https://doi.org/10.3133/sir20205091) is used to assist resource managers and planners in developing informed strategies to address nitrogen loading to coastal water bodies of Long Island, New York. Coastal water bodies of Long Island are important economic and recreational resources for the region. Therefore, the U.S. Geological Survey and New York State Department of Environmental Conservation initiated a program to delineate a comprehensive dataset of CAs (or areas contributing groundwater), travel times, and groundwater discharges to streams, lakes, marine-surface waters, and subsea discharge boundaries. The 25-layer regional groundwater-flow...
Coal combustion by-products (CCBs, in the form of ash) produced at the coal-fired San Juan Generating Station in San Juan County, New Mexico, have been buried in former surface-mine pits at the San Juan Coal Mine since power-generation operations began in the early 1970s. A groundwater flow model was developed by the USGS to estimate the timing of groundwater recovery after the cessation of mining and to identify potential pathways and advective travel times for groundwater transport of metals that may be leached from stored CCBs to arrive at hydrologic receptors after mining operations cease. The USGS numerical modeling package MODFLOW-NWT with MODPATH particle-tracking software was used. This USGS data release...
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...
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...
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...
A groundwater-flow model was developed for the Bad River Watershed and surrounding area by using the U.S. Geological Survey (USGS) finite-difference code MODFLOW–NWT. The model simulates steady-state groundwater-flow and base flow in streams by using the streamflow routing (SFR) package. The model was calibrated to groundwater levels and base flows obtained from the USGS National Water Information System (NWIS) database, and groundwater levels obtained from the Wisconsin Department of Natural Resources and Bad River Band well-construction databases. Calibration was performed via nonlinear regression by using the parameter-estimation software suite PEST.
A three-dimensional groundwater flow model, MODFLOW-NWT with the SWI2 module, was developed to provide a better understanding of the fresh groundwater system of Assateague Island, Maryland and Virginia. Groundwater flow on Assateague Island was simulated to evaluate the effects of sea-level rise and changes in recharge on the depth to freshwater below the land surface, changes in freshwater discharge, and the depth of the freshwater/saltwater interface. The model was calibrated to average 2014-15 hydrologic conditions and vegetation. The model also simulated the movement of the freshwater- seawater interface for three sea-level rise scenarios.This USGS data release contains all of the input and output files for...
The U.S. Geological Survey, in cooperation with the Oklahoma Water Resources Board, constructed a finite-difference numerical groundwater-flow model of the Washita River alluvial aquifer using MODFLOW-2005 with the Newton formulation solver (MODFLOW-NWT). The 1973 Oklahoma Water Law (82 OK Stat § 82-1020.5) 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. A permanent MAY and EPS have not been established for the Washita River alluvial aquifer; thus, the U.S. Geological Survey, in cooperation with the Oklahoma Water Resources Board, conducted calibration and simulations...
The U.S. Geological Survey, in cooperation with the Southwest Florida Water Management District, calibrated a model to quantify the inflows and outflows in the Floral City, Inverness, and Hernando pools of the Tsala Apopka Lake basin in Citrus County, Florida. The calibrated model, which uses MODFLOW-NWT version 1.1.2, simulates hydrologic changes in pool stages, groundwater levels, spring flows, and streamflows caused by the diversion of streamflow from the Withlacoochee River to the Tsala Apopka Lake basin through water-control structures. A surface-water/groundwater flow model was developed using hydraulic parameters for lakes, streams, the unsaturated zone, and the underlying surficial and Upper Floridan aquifers...
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...
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).
A MODFLOW-NWT groundwater flow model was developed to simulate groundwater movement in the area around Anvil Lake, and groundwater inputs and outputs from the lake from 1980 to 2014. Surface-water hydrology was simulated using the lake package. The MODFLOW model was first calibrated for steady-state conditions, or "average" conditions corresponding to January 1, 1980, to December 31, 2014 to estimate spatial hydrogeologic properties. Following the steady-state calibration, the model was applied in transient mode to estimate average monthly hydrologic conditions (groundwater inputs and outputs) for each year from 1980 to 2014.
A series of three-dimensional, hypothetical, groundwater models (MODFLOW-NWT) were developed to investigate the effects of a variety of factors on the flow of arsenic-containing water into a well. The well is of novel design with a constructed aquifer providing storage. The models simulate a hillslope with till overlying a fractured bedrock aquifer as is common in New England. Backwards particle tracking using MODPATH was used to track the particles from the constructed aquifer to the recharge location. A new program, EndPoint Analyzer, was used to determine the fraction of the flow that passed through the bedrock. The bedrock is assumed to be the source of arsenic contamination so the fraction of the flow passing...
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