Hydraulic Characterization of Overpressured Tuffs in Central Yucca Flat, Nevada Test Site, Nye County, Nevada
By Keith J. Halford, Randell J. Laczniak, and Devin L. Galloway
Report availability: Portable Document Format (PDF).
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CONTENTS
- Abstract
- Introduction
- Purpose and Scope
- Acknowledgments
- Description of Study Area
- Hydraulic Characterization of Bedded Tuffs
- Ground-Water Levels
- Land-Surface Displacement
- Conceptual Model
- Numerical Models
- Common Model Approaches and Boundary Conditions
- Cross-Sectional Model
- Initial-Head Distribution
- Model Calibration
- Model Results
- Three-Dimensional Model
- Simulation of Detonation Effects
- Model Calibration
- Model Results
- Model and Conceptual Limitations
- Summary and Conclusions
- References Cited
- Appendix
FIGURES
- General area of study showing physiographic, hydrologic, geologic, and underground test features in the Yucca Flat area of the Nevada Test Site
- Generalized east-west geologic section across the overpressured area of central Yucca Flat
- Anomalous ground-water levels measured during and after period of underground nuclear testing in bedded tuffs within the overpressured area of central Yucca Flat
- InSAR-derived subsidence for three sequential time periods in overpressured area of central Yucca Flat
- Cumulative regional range displacement of land surface along three profiles across the overpressured area of central Yucca Flat, April 24, 1992 - June 16, 1997
- Average subsidence rate in central subsidence trough determined from three time-sequenced interferograms
- Location of cross-sectional and three-dimensional models used to estimate hydraulic properties of bedded tuffs in overpressured area of central Yucca Flat
- Time line showing water-level and subsidence measurements used as observations to calibrate cross-sectional and three-dimensional models, and detonations used to develop three-dimensional model
- Initial-head distribution estimated for model simulation using horizontal and vertical shape functions developed for cross-sectional model
- Comparison of observed water levels and water levels simulated with cross-sectional and three-dimensional models
- Comparison between observed subsidence and subsidence simulated with cross-sectional and three-dimensional models along cross-sectional model trace, April 24, 1992 - June 16, 1997
- Finite-difference grid, lateral model boundaries, and grid used for subsidence-rate observations
- Normalized linear and cube-root functions used to simulate initial hydraulic-head increases at radial distances from a nuclear detonation
- Comparison of observed subsidence rates and subsidence rates simulated with cross-sectional and three-dimensional models for different time periods between April 24, 1992, and June 16, 1997
- Simulated subsidence and general areas of greatest difference between simulated and measured values for period April 24, 1992 - June 16, 1997
- Simulated water-level change for period April 24, 1992 - June 16, 1997
- Simulated water-level changes in model layer 5
- Simulated cumulative discharge into water table and underlying carbonate rock, and water-level changes in water table and in overpressured tuffs at selected locations in model layer 8, 1962 - 2003
- Simulated and predicted cumulative discharge into water table and underlying carbonate rock, and water-level changes in water table and in overpressured tuffs at selected locations in model layer 8, 1962 - 2500
TABLES
- Hydraulic conductivity estimated by slug-test analysis of drilling-recovery data for wells completed in bedded tuffs in or near the overpressured area of central Yucca Flat
- Synthetic aperture radar (SAR) images and interferograms processed by differencing two SAR images of central Yucca Flat area
- Underground nuclear tests in or near the overpressured area of central Yucca Flat
- Shape function and hydraulic-property parameters estimated or evaluated by cross-sectional model
- Initial-rise and hydraulic-property parameters estimated or evaluated by three-dimensional model
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