New Mexico Geological Society Annual Spring Meeting — Abstracts

The U.S. Geological Survey in cooperation with the City of Alamogordo, New Mexico and Holloman Air Force Base investigated the hydrology of the basin-fill aquifer in the Tularosa Basin through construction and calibration of a steady-state three-dimensional ground-water-flow model using the U.S. Geological Survey finite-difference modular ground-water flow computer software MODFLOW-96. The model was calibrated by matching simulated water levels to available pre-development ground-water-Ievel measurements. The distribution of pre-development water-level data restricts the wellcalibrated area of the model to the eastern side of the Tularosa Basin. The root mean square error of the model in the well-calibrated area was 6.3 meters.

Estimates made through model calibration indicate that an amount equal to approximately 143,000 cubic meters per day (42,300 acre-feet per year) of recharge enters the basin-fill aquifer from sub-basins that rim the Tularosa Basin. An amount equal to approximately 4-5 percent of annual precipitation in most sub-basins is simulated to enter the basin-fill aquifer as recharge. Approximately 88 percent of recharge left the basin-fill aquifer as simulated evapotranspiration under pre-development conditions. The remaining 12 percent was simulated either at land surface splings or across the southern model boundary as ground-water flow into the Hueco Bolson. Generalized directions of simulated predevelopment ground-water flow are dominantly west to southwest away from recharge areas in the Sacramento Mountains.