CONTENTS
- Abstract
- Introduction
- Purpose and Scope
- Study Area
- History of Land Subsidence in Las Vegas Valley
- Previous Investigations
- Acknowledgments
- Hydrogeology
- Lorenzi Site
- Mechanics of Vertical Aquifer-System Deformation
- Principle of Effective Stress
- Theory of Hydrodynamic Consolidation
- Numerical Model
- Conceptual Model
- Discretization
- Boundary Conditions
- Initial Head and Compaction Conditions
- Transient Progression
- Hydraulic Properties
- Model Calibration
- Observation Data
- Sensitivity
- Model Fit
- Estimated Parameter Values
- Simulated Conditions
- Model and Regression Limitations
- Summary and Conclusions
- References Cited
FIGURES
- Maps showing the location of Las Vegas Valley and the Lorenzi site, Nevada
- Map showing land-subsidence contours for 1963-2000, benchmarks used to help
estimate historic compaction trends, wells used to help estimate historic water-level
trends, selected faults, and the Lorenzi site, Las Vegas Valley, Nevada
3-5. Schematic diagram showing:
- A simplified hydrogeologic cross section of the Las Vegas Valley aquifer
system, Nevada
- The generalized hydrogeology, piezometers, and extensometer at the Lorenzi site,
Las Vegas, Nevada
- The generalized hydrogeology of the conceptual model and model grid, including
a close-up of the model grid showing variable cell spacing, for the Lorenzi model,
Las Vegas, Nevada
- Graph showing the initial, starting preconsolidation, and 1992 conceptual heads
for the Lorenzi model, Las Vegas, Nevada
- Hydrographs showing (A) heads for P.J. Goumond and SNMRE wells, used to estimate
historic specified heads, and historic specified heads used in the Lorenzi model and
(B) daily average heads for USGS-PZS, USGS-PZM, and USGS-PZD, used as recent
specified heads in the Lorenzi model, Las Vegas, Nevada
8-18. Graphs showing:
- (A) Daily average water levels from USGS-PZD, (B) daily deformation
from USGS-EXT1, and (C) stress-deformation data from USGS-PZD and
USGS-EXT1, Lorenzi site, Las Vegas, Nevada
- USGS-PZD water levels and USGS-EXT1 deformation for July 17-26, 1999,
a period of diurnal pumping with an extensometer record contaminated by
thermal effects, Lorenzi site, Las Vegas, Nevada
- Estimated, interpolated, and extrapolated compaction data used as historic
observations in the Lorenzi model (1901-95), compaction measured at
selected benchmarks, relative to 1963, and an InSAR-derived compaction
estimate (1963-98), Las Vegas, Nevada
- (A) daily deformation measured at USGS-EXT1 and (B) time spans for
recent-period observations, by observation type, for the Lorenzi model,
Las Vegas, Nevada
- Composite scaled sensitivities for the estimated parameters of the Lorenzi
model, Las Vegas, Nevada
- (A) historic simulated and estimated and (B) recent simulated and measured
deformation data for the Lorenzi model, Las Vegas, Nevada
- Simulated deformation versus observed deformation for (A) the historic period
and (B) the recent period of the Lorenzi model, Las Vegas, Nevada
- Weighted residuals versus time for the (A) entire model and (B) recent period
of the Lorenzi model, Las Vegas, Nevada
- Simulated heads for selected years of the Lorenzi model, Las Vegas, Nevada
- Simulated deformation, by aquifer system and aquifer-system unit, for
(A) the entire model and (B) the recent period, and (C) USGS-PZD specified heads,
for the recent period of the Lorenzi model, Las Vegas, Nevada
- Initial heads and simulated head profiles for the calibrated model and an
intermediate model, for 2000, the Lorenzi model, Las Vegas, Nevada
TABLES
- Well-construction data for piezometers and the extensometer at the Lorenzi site,
Las Vegas, Nevada
- Historic observations and weight-related statistics used with the Lorenzi model,
Las Vegas, Nevada
- Reasonable ranges and optimal estimates for the hydraulic parameters estimated with the
Lorenzi model, Las Vegas, Nevada
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