MODFLOW-2005 model used to estimate paleo-recharge volumes and project future water-level changes in Ash Meadows groundwater basin, southwest Nevada, based on Devils Hole paleo-water-table record

This data release documents a modified version of the Death Valley version 3 steady-state (DV3-SS)
model described in U.S. Geological Survey Professional Paper 1863 (https://doi.org/10.3133/pp1863).
The DV3-SS model was modified by conversion into a superposition model with initial heads of 0 ft (0 m).
Simulated water-level changes are relative to modern, predevelopment (pre-1950) conditions, where
modern levels have a reference datum of 0 ft (0 m). The modified DV3-SS model is a three-dimensional,
groundwater model (MODFLOW-2005) that was used to estimate paleo-recharge in the Ash Meadows
groundwater basin, southwest Nevada, using the Devils Hole (cave 2) water-table record that spans the
last 350,000 years. Two steady-state (paleo-recharge) scenarios were developed. Scenario 1 simulates
paleo-recharge during peak glaciation when the Devils Hole water-table elevation was +31.2 ft (+9.5 m)
above the modern level. Scenario 2 simulates the peak interglacial when the Devils Hole water-table
elevation was below the modern level but above -5.25 ft (-1.6 m). Two transient (future recharge) scenarios
were developed by running the modified DV3-SS model as a transient model. Transient scenarios 1 and 2
simulate 10 and 20 percent decreases in modern recharge, respectively. Transient scenarios are used to
estimate future water-level declines in Devils Hole and the time period for equilibration to changes in future
recharge. Input and output files for the paleo-recharge and future scenarios are in the model and output
directories, respectively. The modified DV3-SS model and transient model used the calibrated hydraulic
properties and recharge distribution from the original DV3-SS model (https://doi.org/10.3133/pp1863). The
ancillary directory includes (1) 151 MODFLOW-2005 recharge files used to simulate 151 paleo-recharge
scenarios (Appendix A); (2) batch files, executables, and post-processing utilities to sequentially run the
151 paleo-recharge scenarios and process results (Appendix B); and (3) a transient version of the modified
DV3-SS model to determine the timescale for equilibration to steady-state conditions assuming modern
recharge is reduced by 10 or 20 percent (Appendix C).