Scientific Investigations Report 2007–5009
U.S. GEOLOGICAL SURVEY
Scientific Investigations Report 2007–5009
Simulation of Multiscale Ground-Water Flow in Part of the Northeastern
San Joaquin Valley, California
By Steven P. Phillips, Christopher T. Green, Karen R. Burow, Jennifer L. Shelton,
and Diane L. Rewis
Table of Contents
Datums Used
Well-Numbering System
Abstract
Introduction
Conceptual
Understanding of Ground-Water System
Ground-Water
Flow Simulations
Summary
Acknowledgments
References
Figures
Figure
1. Locations of San Joaquin regional and local study areas within the Central
Valley, California.
Figure
2. Land use and description of U.S. Geological Survey (USGS) wells in Modesto,
San Joaquin regional study area, California.
Figure
3. Land use and description of U.S. Geological Survey (USGS) transect wells,
San Joaquin local study area, California.
Figure
4. Selected geologic units, San Joaquin regional study area, California.
Figure
5. Two-dimensional slices through three-dimensional model of percentage coarse-grained
sediments, San Joaquin regional study area, California.
Figure
6. Vertical transition probabilities used to constrain vertical sequences
of hydrofacies, San Joaquin local study area, California.
Figure
7. Conceptual diagram of (A) regional lateral ground-water flow and (B) vertical
flow influenced by agricultural practices and natural discharge zones.
Figure
8. Contours of measured water-level altitudes in the unconfined to semiconfined
aquifer, spring 2000, San Joaquin regional study area, California.
Figure
9. Hydrographs of measured water-level altitudes for selected irrigation
wells from 1960 to 2001, San Joaquin regional study area, California.
Figure
10. Hydrographs of water-level altitudes measured hourly in U.S. Geological
Survey monitoring wells in urban Modesto from December 2003 to July 2005,
San Joaquin regional study area, California.
Figure
11. Hydrographs of water-level altitudes measured hourly in U.S. Geological
Survey monitoring-well transect from June 2003 to May 2005, San Joaquin local
study area, California.
Figure
12. Subareas of regional model used for water-budget calculations, San Joaquin
regional study area, California.
Figure
13. Estimated rates of recharge for subareas of regional model, water year
2000, San Joaquin regional study area, California.
Figure
14. Estimated rates of ground-water pumping for subareas of regional model,
water year 2000, San Joaquin regional study area, California.
Figure
15. Model extent, boundary conditions, and extent of the downslope, midslope,
and upslope areas for the regional model, San Joaquin regional study area,
California.
Figure
16. Vertical discretization of regional model along row 73, San Joaquin regional
study area, California.
Figure
17. Extent of active area and boundary conditions for the local model, San
Joaquin local study area, California.
Figure
18. Estimated rates of recharge for the local model, water year 2000, San
Joaquin local study area, California.
Figure
19. Frequency of estimated horizontal and vertical hydraulic conductivity
for the upslope (eastern) and downslope (western) alluvial deposits, San
Joaquin regional study area, California.
Figure
20. Vertical section roughly parallel to the Merced River showing distribution
of hydrofacies used in calibrated local model, San Joaquin local study area,
California.
Figure
21. Error surfaces used to calibrate, and calibration results for, the regional
model, San Joaquin regional study area, California.
Figure
22. Simulated hydraulic heads at the water table and in layer 9, and errors
between measured water levels and simulated hydraulic heads at wells used
to calibrate the regional model, San Joaquin regional study area, California.
Figure
23. Relation between simulated hydraulic head and measured water levels for
regional model, San Joaquin regional study area, California.
Figure
24. Relative composite sensitivity of computed hydraulic head at calibration
points to changes in the horizontal and vertical hydraulic conductivities
of the defined hydrofacies, local model, San Joaquin local study area, California.
Figure
25. Relative sensitivity of computed hydraulic head at calibration points
to changes in hydraulic parameters, local model, San Joaquin local study
area, California.
Figure
26. Relation between simulated hydraulic head and measured water levels for
the local model, San Joaquin local study area, California.
Figure
27. Simulated water-table altitudes for the local model, San Joaquin local
study area, California.
Tables
Table
1. Proportions and mean lengths of hydrofacies used in local model, San Joaquin
local study area, California.
Table
2. Soft-conditioning probabilities assigned to hydrofacies for non-U.S. Geological
Survey well log descriptions, San Joaquin local study area, California.
Table
3. Calibrated and specified hydraulic conductivity values for the local model,
San Joaquin local study area, California.
Table
4. Measured concentrations of sulfur hexafluoride (SF6) along the U.S. Geological Survey well transect and concentrations estimated
using simulated travel time and historical atmospheric concentrations of
SF6, San Joaquin local study area, California.
Table
5. Changes in key hydraulic conductivity parameters with alternate three-dimensional
distributions of hydrofacies in the local model, San Joaquin local study
area, California.
Table
6. Simulated water budget for the regional model, San Joaquin regional study
area, California.
Table
7. Simulated water budget for the local model, San Joaquin local study area,
California.
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Send questions or comments about this report to the author, S.P. Phillips, (916) 278-3002.
For more information about USGS activities in California, visit the USGS
California Water Science Center home page.
U.S.
Department of the Interior | U.S. Geological Survey
