Libby Wildermuth Jeffrey R. Kennedy 2022 groundwater model Reston, VA, USA U.S. Geological Survey https://doi.org/10.5066/P9575C61 Jeffrey R. Kennedy Libby Wildermuth Jacob E. Knight Joshua Larsen 2021 Journal article Westerville, OH, USA Groundwater https://doi.org/10.1111/gwat.13167 A numerical model was developed using MODFLOW-NWT and FloPy to simulate groundwater flow and demonstrate a practical method for incorporating repeat microgravity observations (i.e., small changes in the acceleration due to Earth’s gravity) as a new type of calibration target for groundwater-flow models. The single-layer, 250-m cell size model was kept relatively simple to focus on the value of repeat microgravity data in the East Mesa area of the Imperial Valley, in the vicinity of the All American Canal, southeast California, USA. The method is demonstrated with repeat microgravity data collected over a 10-year period following the lining of the All American Canal with concrete. This lining of the canal resulted in the removal of a large source of seepage (recharge) causing groundwater levels, groundwater storage, and gravity all to declined considerably. The study area and field data are used to demonstrate a novel forward gravity modeling application linked to MODFLOW input and output files. The analysis demonstrates that including gravity data, compared to drawdown data alone, improves model parameter identifiability and reduces uncertainty in parameter estimates. 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.13167). A MODFLOW-NWT groundwater-flow model was created to demonstrate the application of repeat microgravity data as flux calibration targets. The development of the model input and output files included in this data release are documented in the article published in the journal Groundwater (https://doi.org/10.1111/gwat.13167) 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 accompanying journal article (https://doi.org/10.1111/gwat.13167) to understand the purpose, construction, and limitations of this model. The model 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 model 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. Please note: this model is not intended to be an accurate simulation of groundwater conditions in the Imperial Valley or Mexicali Valleys. Importantly, substantial groundwater pumping outside the model boundaries was not simulated. Optimal parameter values may be different for different models of the same groundwater-flow system. 19400501 20190501 publication date Complete Not planned -115.3400 -114.6039 33.0823 32.5700 ISO 19115 Topic Category geoscientificInformation location environment USGS Thesaurus usgsgroundwatermodel MODFLOW-NWT Groundwater InlandWaters Groundwater Model PEST++ None Southwest Gravity Program repeat microgravity Arizona Water Science Center USGS Metadata Identifier USGS:79e2e22d-b0cb-4b3b-a9a5-d9f32f679d22 Geographic Names Information System Imperial Valley California Colorado River Algodones Dunes Imperial County None. Acknowledgement of the U.S. Geological Survey would be appreciated in products derived from this data release. none Jeffrey Kennedy U.S. Geological Survey, Arizona Water Science Center mailing and physical

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Flagstaff AZ 86001 USA 928-556-7087 jkennedy@usgs.gov https://water.usgs.gov/GIS/browse/kennedy2021_groundwaterThumbnail.jpg Image of the model domain and active area of the model. jpg City of Needles Parameter values were determined using PEST++ (pestpp-glm). Drawdown at 29 wells and repeat microgravity data at 12 stations were used for calibration. Final parameter values are presented as distributions with accompanying uncertainty rather than a single, optimal parameter set. Parameter uncertainty is the topic of the accompanying journal article (https://doi.org/10.1111/gwat.13167). 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 journal article (https://doi.org/10.1111/gwat.13167) 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 associated journal article (https://doi.org/10.1111/gwat.13167). 2021 Raster pixel WGS_1984_UTM_Zone_11N 0.9996 -117.0 0.0 500000.0 0.0 row and column 250 250 meters North American Vertical Datum of 1988 1.0 meters Attribute values kennedy2021_groundwater.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/10.1111/gwat.13167 usgsgroundwatermodel Delineation of active and inactive areas in the model. https://doi.org/10.1111/gwat.13167 Wildermuth, L., Kennedy, J.R., 2022, MODFLOW-NWT groundwater model demonstrating groundwater model calibration with repeat microgravity measurements: U.S. Geological Survey data release https://doi.org/10.5066/P9575C61 U.S. Geological Survey Michael Ierardi IT Specialist mailing

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Reston VA 20192 1-888-275-8747 (1-888-ASK-USGS) mierardi@usgs.gov The data have been approved for release by the U.S. Geological Survey (USGS). 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. Although the data, software, and related material have been processed successfully on a computer system at 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. 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, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. readme.txt 1.0 ASCII text file This ASCII text file describes the model data release. This file also includes instructions on how to run the models contained in this data release. 0.021 https://water.usgs.gov/GIS/dsdl/gwmodels/kennedy2021_groundwater/readme.txt modelgeoref.txt 1.0 ASCII text file This ASCII text file defines the four corners of the model domain in decimal degrees. Model data files are in the WGS_1984_UTM_Zone_11N projection. 0.008 https://water.usgs.gov/GIS/dsdl/gwmodels/kennedy2021_groundwater/modelgeoref.txt ancillary.zip none ZIP This ZIP file contains ancillary data including the PEST control files for PEST++ GLM calibration, and Slurm scripts for running PEST++ GLM on the USGS Denali supercomputer cluster. 94.3 https://water.usgs.gov/GIS/dsdl/gwmodels/kennedy2021_groundwater/ancillary.zip bin.zip none ZIP file ZIP file containing the MODFLOW_NWT executable used to run the model, the PEST++ executables used for model analysis, and an executable ("Heavy") for calculating gravity change from the MODFLOW output. All are compiled for linux on the USGS Denali cluster. 10.9 https://water.usgs.gov/GIS/dsdl/gwmodels/kennedy2021_groundwater/bin.zip georef.zip none ZIP file ZIP file containing a shapefile which defines the active and active portions of the model. 0.007 https://water.usgs.gov/GIS/dsdl/gwmodels/kennedy2021_groundwater/georef.zip model.zip none ZIP file This ZIP file contains the input files for the MODFLOW-NWT model documented in this data release. 3.24 https://water.usgs.gov/GIS/dsdl/gwmodels/kennedy2021_groundwater/model.zip output.zip none ZIP file This ZIP file contains the output files for the MODFLOW-NWT model documented in this data release. 2.82 https://water.usgs.gov/GIS/dsdl/gwmodels/kennedy2021_groundwater/output.zip source.zip 1.0 ZIP file ZIP file containing source files of MODFLOW-NWT, PEST++, and the forward-gravity model used to run model simulations included in the data release. 66.3 https://water.usgs.gov/GIS/dsdl/gwmodels/kennedy2021_groundwater/source.zip None 20220105 U.S. Geological Survey Ask USGS -- Water Webserver Team mailing

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Reston VA 20192 1-888-275-8747 (1-888-ASK-USGS) mierardi@usgs.gov FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998