Hydraulic characterization of volcanic rocks in Pahute Mesa using an integrated analysis of 16 multiple-well aquifer tests, Nevada National Security Site, 2009–14
Links
- Document: Report (3.2 MB pdf)
- Appendix: Appendixes 1-3 (28 MB zip)
- Data Releases:
- USGS data release - MODFLOW-2005 and PEST models used to simulate multiple-well aquifer tests and characterize hydraulic properties of volcanic rocks in Pahute Mesa, Nevada
- USGS data release - Supplemental data from: Hydraulic characterization of volcanic rocks in Pahute Mesa using an integrated analysis of 16 multiple-well aquifer tests, Nevada National Security Site, 2009–14
- Read Me: Appendix readme (415 KB pdf)
- Download citation as: RIS | Dublin Core
Abstract
An improved understanding of groundwater flow and radionuclide migration downgradient from underground nuclear-testing areas at Pahute Mesa, Nevada National Security Site, requires accurate subsurface hydraulic characterization. To improve conceptual models of flow and transport in the complex hydrogeologic system beneath Pahute Mesa, the U.S. Geological Survey characterized bulk hydraulic properties of volcanic rocks using an integrated analysis of 16 multiple-well aquifer tests. Single-well aquifer-test analyses provided transmissivity estimates at pumped wells. Transmissivity estimates ranged from less than 1 to about 100,000 square feet per day in Pahute Mesa and the vicinity. Drawdown from multiple-well aquifer testing was estimated and distinguished from natural fluctuations in more than 200 pumping and observation wells using analytical water-level models. Drawdown was detected at distances greater than 3 miles from pumping wells and propagated across hydrostratigraphic units and major structures, indicating that neither faults nor structural blocks noticeably impede or divert groundwater flow in the study area.
Consistent hydraulic properties were estimated by simultaneously interpreting drawdown from the 16 multiple-well aquifer tests with an integrated groundwater-flow model composed of 11 well-site models—1 for each aquifer test site. Hydraulic properties were distributed across volcanic rocks with the Phase II Pahute Mesa-Oasis Valley Hydrostratigraphic Framework Model. Estimated hydraulic-conductivity distributions spanned more than two orders of magnitude in hydrostratigraphic units. Overlapping hydraulic conductivity ranges among units indicated that most Phase II Hydrostratigraphic Framework Model units were not hydraulically distinct. Simulated total transmissivity ranged from 1,600 to 68,000 square feet per day for all pumping wells analyzed. High-transmissivity zones exceeding 10,000 square feet per day exist near caldera margins and extend along the northern and eastern Pahute Mesa study area and near the southwestern edge of the study area. The estimated hydraulic-property distributions and observed hydraulic connections among geologic structures improved the characterization and representation of groundwater flow at Pahute Mesa.
Suggested Citation
Garcia, C.A., Jackson, T.R., Halford, K.J., Sweetkind, D.S., Damar, N.A., Fenelon, J.M., and Reiner, S.R., 2017, Hydraulic characterization of volcanic rocks in Pahute Mesa using an Integrated Analysis of 16 multiple-well aquifer tests, Nevada National Security Site, 2009–14: U.S. Geological Survey Scientific Investigations Report 2016-5151, 62 p., https://doi.org/10.3133/sir20165151.
ISSN: 2328-0328 (online)
Study Area
Table of Contents
- Acknowledgments
- Abstract
- Introduction
- Well Network and Data Collection
- Drawdown Observations
- Integrated Aquifer-Test Analysis
- Hydraulic Characterization of Volcanic Rocks
- Summary
- References Cited
- Appendixes 1-3
Publication type | Report |
---|---|
Publication Subtype | USGS Numbered Series |
Title | Hydraulic characterization of volcanic rocks in Pahute Mesa using an integrated analysis of 16 multiple-well aquifer tests, Nevada National Security Site, 2009–14 |
Series title | Scientific Investigations Report |
Series number | 2016-5151 |
DOI | 10.3133/sir20165151 |
Year Published | 2017 |
Language | English |
Publisher | U.S. Geological Survey |
Publisher location | Reston, VA |
Contributing office(s) | Nevada Water Science Center |
Description | Report: x, 61 p.; Appendixes 1-3; Data Releases; Read Me |
Country | United States |
State | Nevada |
Other Geospatial | Nevada National Security Site |
Online Only (Y/N) | Y |
Additional Online Files (Y/N) | Y |
Google Analytic Metrics | Metrics page |