Hydrus-3D unsaturated-zone flow model for simulating recharge at the Southeast Houghton Artificial Recharge Project (SHARP), Tucson, Arizona, 2020-2022

A three-dimensional unsaturated-zone flow model was developed using Hydrus-3D (PC-Progress, Inc.) to simulate managed aquifer recharge at the Southeast Houghton Artificial Recharge Project (SHARP) in Tucson, AZ. Recharge, up to about 4,000 acre-feet per year, takes place at three surface basins. The model simulates variable-saturated flow in the unsaturated zone and groundwater mounding. The local-scale model (2 km x 2 km) does not simulate regional groundwater flow. The model was calibrated using groundwater-level data, repeat microgravity data, and PEST++ model calibration software. Additional information about the model and results is in the U.S. Geological Survey Scientific Investigations report 2025-5017 (https://doi.org/10.3133/sir20255017). Running the model requires a (paid) license for Hydrus-3D software.