Simulation of Groundwater-Level Changes from Projected Groundwater Withdrawals in the Truxton Basin, Northern Arizona

Scientific Investigations Report 2020-5017-E
Prepared in cooperation with the Bureau of Reclamation
Edited by: Jon P. Mason



A three-dimensional, numerical groundwater flow model of the Hualapai Plateau and Truxton basin was developed to assist water-resource managers in understanding the potential effects of projected groundwater withdrawals on groundwater levels and storage in the basin. The Truxton Basin Hydrologic Model (TBHM) is a transient model that simulates the hydrologic system for the years 1976 through 2139, including hypothetical low-, medium-, and high-groundwater withdrawal scenarios beginning in 2020. The simulated effects of these withdrawal scenarios are presented as groundwater-level changes from the year 2020 to 2070, and from 2020 to 2140. Hydrologic properties in the TBHM are derived from calibration of a steady-state model of the predevelopment (before 1976) groundwater system. The future pumping scenarios are each simulated with three different interpretations of basin depth supported by geophysical data. For each of the resulting nine transient models, a Monte Carlo approach is used to produce a range of possible and probable groundwater-level changes at points throughout the basin given probabilistic ranges of hydrologically reasonable aquifer property values supported by the model calibration results. The ensemble of models that simulate the future pumping scenarios include pumping from the existing well field (three wells) plus additional pumping from a proposed new well. Simulated high future pumping increases progressively to 1,840 acre-feet per year in 2120 and produces a range of drawdowns between 20 and 39 feet (ft) near the pumping center, with a median drawdown of 28 ft. The low future pumping scenario, which increases progressively to 650 acre-ft per year in 2120, produces a range of drawdowns between 5 and 15 ft, with a median drawdown of 10 ft at the same location over the same period of time.

Suggested Citation

Knight, J.E., 2020, Simulation of groundwater-level changes from projected groundwater withdrawals in the Truxton basin, northwestern Arizona, chap. E of Mason, J.P., ed., Geophysical surveys, hydrogeologic characterization, and groundwater flow model for the Truxton basin and Hualapai Plateau, northwestern Arizona: U.S. Geological Survey Scientific Investigations Report 2020–5017, 39 p.,

ISSN: 2328-0328 (online)

Study Area

Table of Contents

  • Abstract
  • Introduction
  • Conceptual Model of the Groundwater-Flow System
  • Simulation of Groundwater Flow
  • Forecasting Simulations and Uncertainty Analysis
  • Discussion and Model Limitations
  • Summary
  • References Cited
  • Appendixes

Publication type Report
Publication Subtype USGS Numbered Series
Title Simulation of groundwater-level changes from projected groundwater withdrawals in the Truxton basin, northwestern Arizona
Series title Scientific Investigations Report
Series number 2020-5017
Chapter E
DOI 10.3133/sir20205017E
Year Published 2020
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Arizona Water Science Center
Description Report: viii, 39 p.; Data Release
Country United States
State Arizona
Other Geospatial Truxton basin
Online Only (Y/N) Y
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