MODFLOW-LGR data sets for the Great Basin carbonate and alluvial aquifer system model version 3.0: Revisions in southwestern Utah and east central Nevada

A new version of previously published steady-state numerical groundwater flow models of the Great Basin 
carbonate and alluvial aquifer system (GBCAAS), and was developed in conjunction with U.S. Geological 
Survey (USGS) studies in Parowan, Pine, and Wah Wah Valleys, Utah. This version of the model is 
considered to be GBCAAS v. 3.0 and supersedes previous versions. This model added 15 transient 
calibration stress periods and 14 projection stress periods, aquifer storage properties, historical 
withdrawals in Parowan Valley, and observations of water-level changes in Parowan Valley to the 
previous steady-state versions. Recharge in Parowan Valley and withdrawal from wells in Parowan 
Valley and two nearby wells in Cedar City Valley vary for each calibration stress period representing 
conditions from March 1940 to November 2013. Stresses, including recharge, are the same in each 
stress period as in the steady-state stress period for all areas outside of Parowan Valley. This data 
release contains one calibration simulation and one projection simulation. The model is calibrated to 
transient conditions only in Parowan Valley. Simulated storage properties outside of Parowan Valley 
are set the same as the Parowan Valley properties and should not be considered calibrated. The 
projection simulation was used to estimate that reducing withdrawals in Parowan Valley from 35,000 
to about 22,000 acre-feet per year should stabilize groundwater levels in the valley if recharge varies 
as it did from about 1950 to 2012 and that withdrawals of 15,000 acre-feet per year from Pine Valley 
and 6,500 acre-feet per year from Wah Wah Valley could ultimately (long-term steady-state) cause 
water-level declines of about 1,900 feet near the withdrawal wells and more than 5 feet over about 
10,500 square miles. 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/sir20175072). This data 
release also contains source code needed to run the models. Model files presented in this data release 
were modified from an existing, calibrated, steady-state model of the Great Basin carbonate and alluvial 
aquifer system. SIR 2014-5213 (https://pubs.usgs.gov/sir/2014/5213/) and SIR 2017-5011 
(https://doi.org/10.3133/sir20175011) document the construction and calibration of the previous versions 
of this model. Modifications that were made to the input files and discussion of model results are 
documented in SIR2017-5072 (https://doi.org/10.3133/sir20175072), which is associated with this 
data release. The model consists of a parent and a child model and must be run using MODFLOW-LGR. 
The child model is far removed from the area considered for this project, but is being kept with the model 
so that one model version exists of the Great Basin carbonate and alluvial aquifer system that incorporates 
all refinements and improvements. The model files documented in this data release should be used instead 
of previous versions.

Tags: beaver-county, environment, geoscientificinformation, great-basin-carbonate-and-alluvial-aquifer-system, groundwater, groundwater-model, inlandwaters, iron-county, lincoln-county, millard-county, modflow-lgr, nevada, parowan-valley, pine-valley, ucode, usgs-27456b40-c7c8-4e18-bd76-4fa4032f6694, usgsgroundwatermodel, utah, wah-wah-valley, white-pine-county
Organization: Department of the Interior