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Groundwater-flow model for the Wood River Valley aquifer system, south-central Idaho

Scientific Investigations Report 2016-5080

Prepared in cooperation with the Idaho Department of Water Resources
By:
, , , , and
DOI:10.3133/sir20165080

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Abstract

A three-dimensional numerical model of groundwater flow was developed for the Wood River Valley (WRV) aquifer system, Idaho, to evaluate groundwater and surface-water availability at the regional scale. This mountain valley is located in Blaine County and has a drainage area of about 2,300 square kilometers (888 square miles). The model described in this report can serve as a tool for water-rights administration and water-resource management and planning. The model was completed with support from the Idaho Department of Water Resources, and is part of an ongoing U.S. Geological Survey effort to characterize the groundwater resources of the WRV. A highly reproducible approach was taken for constructing the WRV groundwater-flow model. The collection of datasets, source code, and processing instructions used to construct and analyze the model was distributed as an R statistical-computing and graphics package.

Flow in the WRV aquifer was simulated using the MODFLOW-USG groundwater flow model. The transient flow model simulates groundwater flow between 1995 and 2010. The model uses a 100-meter (328-feet) uniform grid spacing with 54,922 active model cells distributed over three model layers. A confining unit in the south-central part of the Bellevue fan necessitated the use of a multi-layer model. Specified-flow boundaries were used to simulate the groundwater inflows from each of the major tributary basins (also known as tributary basin underflow) and the areal recharge of precipitation and applied irrigation. Head‑dependent flow boundaries were used to simulate the stream-aquifer flow exchange in river reaches and the groundwater discharge at the outlet boundaries of Stanton Crossing and Silver Creek. The model was calibrated by adjusting aquifer hydraulic properties to match simulated and measured water levels and stream-aquifer flow exchange, using the parameter-estimation program PEST. The model reasonably simulated the measured water-table elevation, orientation, and gradients. Stream-aquifer flow exchange along river reaches also was reasonably simulated by the model.

Inflow into the WRV aquifer system originates from three sources (from largest to smallest):

  1. Streamflow loss from the Big Wood River and Silver Creek,
  2. Areal recharge of precipitation and applied irrigation, and
  3. Tributary basin underflow.

Outflow from the WRV aquifer system originates from five sources (from largest to smallest):

  1. Aquifer discharge into the Big Wood River and Silver Creek,
  2. Production-well pumping,
  3. Discharge across the water table into the vadose zone,
  4. Subsurface outflow beneath Silver Creek near Picabo, and
  5. Subsurface outflow beneath the Big Wood River near Stanton Crossing.

Temporal changes in aquifer storage are most affected by areal recharge and groundwater pumping, and also contribute to changes in streamflow gains.

Suggested Citation

Fisher, J.C., Bartolino, J.R., Wylie, A.H., Sukow, Jennifer, and McVay, Michael, 2016, Groundwater-flow model of the Wood River Valley aquifer system, south-central Idaho: U.S. Geological Survey Scientific Investigations Report 2016–5080, 71 p., http://dx.doi.org/10.3133/sir20165080.

ISSN: 2328-0328 (online)

Study Area

Table of Contents

  • Abstract
  • Introduction
  • Description of Groundwater-Flow System
  • Calibrated Groundwater Flow Model
  • Model Limitations and Suggestions for Future Work
  • Summary
  • References Cited
  • Appendixes A-H

Additional publication details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Groundwater-flow model for the Wood River Valley aquifer system, south-central Idaho
Series title:
Scientific Investigations Report
Series number:
2016-5080
DOI:
10.3133/sir20165080
Year Published:
2016
Language:
English
Publisher:
U.S. Geological Survey
Publisher location:
Reston, VA
Contributing office(s):
Idaho Water Science Center
Description:
Report: viii, 71 p.; Appendixes A-H; Model Archive; Data Repository
Country:
United States
State:
Idaho
Other Geospatial:
Wood River Valley
Online Only (Y/N):
Y
Additional Online Files (Y/N):
N