Antolino, D.J. 20251203 groundwater model Reston, VA U.S. Geological Survey https://doi.org/10.5066/P9N3EQ86 Dominick J. Antolino Gerard Gonthier Georgina M. Sanchez 2025 Publication Scientific Investigations Report 2025-5087 Reston, VA U.S. Geological Survey Antolino, D.J., Gonthier, G., and Sanchez, G.M., 2025, Simulation of groundwater flow in Wake County, North Carolina, 2000 through 2070: U.S. Geological Survey Scientific Investigations Report 2025-5087, 77 p., https://doi.org/10.3133/sir20255087. https://doi.org/10.3133/sir20255087 The U.S. Geological Survey (USGS) and Wake County Environmental Services developed a collaborative study to assess the hydrogeologic setting and groundwater flow conditions for Wake County, North Carolina. A groundwater-flow model was developed to conceptualize the fractured-rock aquifer system in Wake County and to assess historic and future groundwater resource availability. The MODFLOW-NWT (version 1.3.0) model simulates transient groundwater flow across two layers, incorporating recharge estimates from a previously developed Soil-Water-Balance (SWB) model (Antolino, 2021) for 2000-2019 in 82 seasonal stress periods. Model calibration using manual and automated parameter estimation with PEST (Doherty and Hunt, 2010) resulted in simulated values with an acceptable fit against observed groundwater levels and stream base flow observations. Six forecast scenarios were simulated for 2020-2070 with projected recharge datasets that incorporate projected land cover change and three general climate models under two future emissions scenarios. As Wake County is experiencing rapid population growth and increased demand on drinking water resources, the study results are intended to provide a scientific foundation for the ongoing management and future planning of Wake County’s groundwater resources. This USGS data release contains all the input and output files for the transient simulations of the model described in the associated model documentation report (https://doi.org/10.3133/sir20255087). The readme.txt file contains information on model archive file structure and instructions for running the model simulations. References: -Antolino, D.J., 2021, Soil-Water-Balance (SWB) model data sets for the Greater Wake County area, North Carolina, 1981-2070: U.S. Geological Survey data release, accessed February 5, 2025, at https://doi.org/10.5066/P9MO793B. -Doherty, J.E., and Hunt, R.J., 2010, Approaches to highly parameterized inversion—A guide to using PEST for groundwater-model calibration: U.S. Geological Survey Scientific Investigations Report 2010–5169, 59 p., accessed February 5, 2025, at https://doi.org/10.3133/sir20105169. The MODFLOW-NWT groundwater flow model was developed by the U.S. Geological Survey for Wake County Environmental Services to assess historic and projected groundwater availability in the fractured-rock aquifer system in Wake County, North Carolina. The calibrated model simulates transient groundwater flow within the fractured-rock aquifer system from 2000-2019. Forecast scenarios were simulated for 2020-2070 using projected land cover change and three general climate models under two future emissions scenarios. The groundwater flow model is intended to provide foundational information that can be used by Wake County water-resource managers and other stakeholders to evaluate current and future groundwater stresses with projected climate and land cover scenarios. The development of the model input and output files included in this data release are documented in the U.S. Geological Survey Scientific Investigations Report 2025-5087 (https://doi.org/10.3133/sir20255087). Support is provided for correcting errors in the data release and clarification of the modeling conducted by the U.S. Geological Survey. Users are encouraged to review the model documentation report (https://doi.org/10.3133/sir20255087) to understand the purpose, construction, and limitations of this model. The models will run successfully only if the original directory structure is correctly restored. The model archive is broken into several pieces to reduce the likelihood of download timeouts. Instructions for reconstructing the original directory structure and running the models included in this data release and described in the model documentation report can be found in the readme.txt ASCII file which can be downloaded as part of this data release. Files in this data release include: -readme.txt: This ASCII text file describes the model data release including the archive folder structure and files contained within each subfolder. This file also includes instructions on how to run the models contained in this data release. -modelgeoref.txt: This ASCII text file defines the four corners of the model domain in decimal degrees. -bin.zip: This ZIP file contains the MODFLOW-NWT executable (version 1.3.0) used to run the simulations. -georef.zip: This ZIP file contains a polygon shapefile showing the active and inactive areas of the model domain. -model.zip: This ZIP file contains input files for the calibrated base model and six forecast scenarios. Detailed information about these simulations is provided in the model documentation report. -output.zip: This ZIP file contains output files for the calibrated base model and six forecast scenarios. Detailed information about this simulation is provided in the model documentation report. -source.zip: This ZIP file contains the source codes for MODFLOW-NWT (version 1.3.0) used to run the simulations. 20000101 20701231 publication date Complete Not planned -79.703838 -77.635908 36.686268 35.012686 USGS Thesaurus groundwater hydrology climate change none usgsgroundwatermodel MODFLOW-NWT InlandWaters Groundwater Model SWB soil-water-balance model general climate model fractured rock ISO 19115 Topic Category geoscientificInformation inlandWaters environment USGS Metadata Identifier USGS:654cf7fbd34ee4b6e05c2dae Geographic Names Information Systems Wake County North Carolina Atlantic Coastal Plain none Piedmont Physiographic Province Neuse River Basin Cape Fear River Basin None. Acknowledgement of the U.S. Geological Survey would be appreciated in products derived from this data release. These groundwater model input and output files are provided to support the analyses documented in the associated report (https://doi.org/10.3133/sir20255087). Although the information contained in the model files may be useful for other purposes, it is incumbent on the user to understand the purpose, construction, and limitations of this model. Data have been checked to ensure consistency with the accompanying report. If any errors are detected, please notify the originating office. Dominick J. Antolino U.S. Geological Survey mailing and physical

3916 Sunset Ridge Rd

Raleigh NC 27607 USA 919-571-4094 dantolin@usgs.gov Wake County Environmental Services–Water Quality Division None Unclassified None Dominick J. Antolino 2022 Soil-Water-Balance (SWB) model U.S. Geological Survey data release 1 Reston, VA U.S. Geological Survey https://doi.org/10.5066/P95XKK5V Dominick J. Antolino Laura N. Gurley 2022 Publication Scientific Investigations Report 2022-5041 Reston, VA U.S. Geological Survey https://doi.org/10.3133/sir20225041 John E. Doherty Randall J. Hunt 2010 Publication Scientific Investigations Report 2010–5169 Reston, VA U.S. Geological Survey https://doi.org/10.3133/sir20105169 Gerard J. Gonthier Dominick J. Antolino 2023 Comma-separated text file, Microsoft Excel file, portable network graphic file, joint photographic experts group file, zip file, and tabular digital data U.S. Geological Survey data release 1 Reston, VA U.S. Geological Survey https://doi.org/10.5066/P9UC8F3Z Arlen W. Harbaugh 1990 publication Open-file report 90-3921 Reston, VA U.S. Geological Survey https://doi.org/10.3133/ofr90392 Richard G. Niswonger Sorab Panday Motomu Ibaraki 2011 publication Techniques and Methods 6-A37 Reston, Virginia US Geological Survey https://doi.org/10.3133/tm6A37 S. M. Westenbroek V. A. Kelson W. R. Dripps R. J. Hunt K. R. Bradbury 2010 publication Reston, Virginia US Geological Survey https://doi.org/10.3133/tm6A31 S. M. Westenbroek J. A. Engott V. A. Kelson R. J. Hunt 2018 publication Reston, Virginia US Geological Survey https://doi.org/10.3133/tm6A59 The model contained 308 parameter values that were included in the calibration process from 6 parameter groups: hydraulic conductivity, horizontal anisotropy and vertical anisotropy (directional variation in hydraulic conductivity within and between model layers), specific yield, specific storage, and drain conductance. Horizontal hydraulic conductivity values were represented by using pilot points with 44 points in layer 1 and 251 points in layer 2, that were interpolated within zones via kriging for each of the three major rock types: crystalline rock, Triassic sedimentary basin rock, and Coastal Plain sediments. The groundwater-flow model parameters were calibrated to groundwater-level observations from 1941 to 2019 and base-flow observations, derived from streamflow data, from 1980 to 2019. Model calibration using manual and automated parameter estimation with PEST (Doherty and Hunt, 2010) resulted in simulated values with an acceptable fit against observed groundwater levels and stream base flow observations. No formal logical accuracy tests were conducted Data set is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record and the associated model documentation report (https://doi.org/10.3133/sir20255087) for additional details. No formal positional accuracy tests were conducted No formal positional accuracy tests were conducted The process used to develop, calibrate, and apply the model is fully described in the model documentation report (https://doi.org/10.3133/sir20255087). 2025 raster pixel Lambert_Conformal_Conic 34.33333333333334 36.16666666666666 -79.0 33.75 2000000.002616666 0 row and column 500 500 feet North American Vertical Datum of 1988 1.0 feet Attribute values modelarea.shp ESRI Polygon shapefile U.S. Geological Survey Area Text string indicating is polygon area is active or inactive in the model. https://doi.org/10.3133/sir20255087 usgsgroundwatermodel Delineation of active and inactive areas in the model. https://doi.org/10.3133/sir20255087 This model application data release contains all the model input and output files needed to replicate the simulations described in the associated model documentation report (https://doi.org/10.3133/sir20255087). https://doi.org/10.3133/sir20255087 Detailed descriptions of the MODFLOW-NWT model input and output files can be found in the model documentation (https://doi.org/10.3133/tm6A37) and online at: https://water.usgs.gov/ogw/modflow-nwt/MODFLOW-NWT-Guide/index.html, accessed February 5, 2025. https://doi.org/10.3133/tm6A37 Detailed descriptions of the PEST model input and output files can be found in the model documentation (https://doi.org/10.3133/sir20105169) and online at: https://pesthomepage.org/, accessed February 5, 2025. https://doi.org/10.3133/sir20105169 Detailed descriptions of the ZoneBudget model input and output files can be found in the model documentation (https://doi.org/10.3133/ofr90392) and online at: https://www.usgs.gov/software/zonebudget-program-computing-subregional-water-budgets-modflow-groundwater-flow-models, accessed February 5, 2025. https://doi.org/10.3133/ofr90392 Detailed descriptions of the SWB model input and output files can be found in the model documentation (https://doi.org/10.3133/tm6A31) and online at: https://www.usgs.gov/centers/upper-midwest-water-science-center/science/soil-water-balance-swb-a-modified-thornthwaite, accessed February 5, 2025. https://doi.org/10.3133/tm6A31 GS ScienceBase U.S. Geological Survey mailing and physical

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Denver CO 80225 United States 1-888-275-8747 sciencebase@usgs.gov Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although the data, software, and related material have been processed successfully on a computer system at the U.S. Geological Survey (USGS), reviewed for accuracy and completeness, and approved for release by the USGS, no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. Although the data have been subjected to rigorous review and are substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, the data are released on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from authorized or unauthorized use. The USGS or the U.S. Government shall not be held liable for improper or incorrect use of the data described and/or contained herein. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Digital datasets None 34.7 GB (all zip files size totaled) https://doi.org/10.5066/P9N3EQ86 None. No fees are applicable for obtaining the dataset. 20251203 Dominick J. Antolino U.S. Geological Survey mailing and physical

3916 Sunset Ridge Rd

Raleigh NC 27607 USA 919-571-4094 dantolin@usgs.gov Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998