Central Valley Aquifer, Chapters A and B - MAE Class Websites

GROUNDWATER RESOURCES PROGRAM
Groundwater Availability of the
Central Valley Aquifer, California
Professional Paper 1766
U.S. Department of the Interior
U.S. Geological Survey
Sacramento Valley
San Joaquin Valley

Generalized block diagrams showing post-development hydrologeology of the Sacramento and San Joaquin Valleys, California.

Groundwater Availability of the
Central Valley Aquifer, California
Edited by Claudia C. Faunt
Chapter A
Introduction, Overview of Hydrogeology, and Textural Model of
California’s Central Valley
By Claudia C. Faunt, Randall T. Hanson, and Kenneth Belitz
Chapter B
Groundwater Availability in California’s Central Valley
By Claudia C. Faunt, Kenneth Belitz, and Randall T. Hanson
Chapter C
Numerical Model of the Hydrologic Landscape and Groundwater
Flow in California’s Central Valley
By Claudia C. Faunt, Randall T. Hanson, Kenneth Belitz, Wolfgang Schmid,
Steven P. Predmore, Diane L. Rewis, and Kelly McPherson
Appendix 1
Supplemental Information—Modifications to
Modflow-2000 Packages and Processes
By Wolfgang Schmid and R.T. Hanson
Groundwater Resources Program
Professional Paper 1766
U.S. Department of the Interior
U.S. Geological Survey

U.S. Department of the Interior
KEN SALAZAR, Secretary
U.S. Geological Survey
Suzette M. Kimball, Acting Director
U.S. Geological Survey, Reston, Virginia: 2009
For more information on the USGS—the Federal source for science about the Earth, its natural and living resources,
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Government.
Although this report is in the public domain, permission must be secured from the individual copyright owners to
reproduce any copyrighted materials contained within this report.
Suggested citation:
Faunt, C.C., ed., 2009, Groundwater Availability of the Central Valley Aquifer, California: U.S. Geological Survey
Professional Paper 1766, 225 p.
ISBN 978-1-4113-2515-9

Foreword
An adequate supply of groundwater is essential for the Nation’s health and economic well
being. Increased use of groundwater resources and the effects of drought have led to concerns
about the future availability of groundwater to meet domestic, agricultural, industrial, and environmental
needs. The resulting effects of competition for groundwater from human and environmental
uses need to be better understood to respond to the following basic questions that are
being asked about the Nation’s ability to meet current and future demands for groundwater. Do
we have enough groundwater to meet the needs of the Nation? Where are these groundwater
resources? Is groundwater available where it is needed? To help answer these questions, the
U.S. Geological Survey’s (USGS) Groundwater Resources Program is conducting large-scale
multidisciplinary regional studies of groundwater availability, such as this study of the Central
Valley Aquifer System, California.
Regional groundwater availability studies quantify current groundwater resources, evaluate how
those resources have changed through time, and provide tools that decision makers can use
to forecast system responses to future development and climate variability and change. These
quantitative studies are, by design, large in scope, can include multiple aquifers, and address
critical groundwater issues. The USGS has previously identified the Nation’s principal aquifers
and they will be used as a framework to classify and study regional groundwater systems.
The groundwater availability studies being conducted for each regional groundwater flow system
emphasize the use of long-term groundwater monitoring data, in conjunction with groundwater
models, to improve understanding of the flow systems and assess the status and trends
in groundwater resources in the context of a changing water budget for the aquifer system. The
results of these individual groundwater availability studies will be used collectively as building
blocks towards a national assessment of groundwater availability. In addition, these studies will
provide the foundational information and modeling tools needed to help State and local resource
managers make water availability decisions based on the latest comprehensive quantitative
assessment given their regional water-management constraints and goals.
Matthew C. Larsen, Associate Director for Water
U.S. Geological Survey
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Contents
Chapter A
Introduction, Overview of Hydrogeology, and Textural Model of California’s Central Valley
Executive Summary .......................................................................................................................................1
Geographic Information System (GIS) ..............................................................................................1
Texture Modeling ..................................................................................................................................2
Hydrologic System Modeling ..............................................................................................................2
Introduction.....................................................................................................................................................3
Purpose and Scope ..............................................................................................................................4
Methods of Analyses............................................................................................................................6
Data Compilation ..........................................................................................................................6
Numerical Model .........................................................................................................................6
Previous Investigations........................................................................................................................7
Recent Regional Groundwater Models ....................................................................................7
Central Valley Regional Aquifer-System Analysis (CV-RASA) ....................................7
California Central Valley Groundwater-Surface-Water Simulation Model
(C2VSIM) ..............................................................................................................10
Study Area.....................................................................................................................................................10
Climate .................................................................................................................................................10
Sacramento Valley .............................................................................................................................10
Delta and Eastside Streams ..............................................................................................................15
San Joaquin Basin of the San Joaquin Valley ...............................................................................15
Tulare Basin of the San Joaquin Valley ..........................................................................................17
Water-Balance Subregions...............................................................................................................18
Geologic History and Setting .....................................................................................................................18
Hydrogeology................................................................................................................................................20
Aquifer Characteristics ......................................................................................................................20
Textural Analysis .................................................................................................................................23
Selection and Compilation of Existing Well Data .................................................................25
Classification of Texture from Drillers’ Logs and Regularization of Well Data ................26
Geostatistical Modeling Approach .........................................................................................26
Regions and Domains ......................................................................................................26
Geostatistical Model of Coarse-Grained Texture ........................................................27
3-D Model of Percentage of Coarse-Grained Texture ................................................29
Results of Texture Model ..........................................................................................................30
Sacramento Valley ............................................................................................................30
San Joaquin Valley ...........................................................................................................39
Hydrologic System ..............................................................................................................................40
Climate ........................................................................................................................................41
Surface Water ............................................................................................................................46
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Groundwater ..............................................................................................................................47
Predevelopment Recharge, Discharge, Water Levels, and Flows ...........................48
Groundwater/Surface-Water Interaction .....................................................................48
Aquifer-System Storage ..................................................................................................48
Water Budget ....................................................................................................................53
Acknowledgments .......................................................................................................................................53
References Cited..........................................................................................................................................54
Chapter B
Groundwater Availability in California’s Central Valley
Introduction ..................................................................................................................................................59
Development and the Hydrologic System ...............................................................................................59
Surface-Water and Groundwater Development History .............................................................59
Land Use ...............................................................................................................................................60
Agricultural Land Use ...............................................................................................................61
Urban Land Use ..........................................................................................................................61
Development and Changes to the Hydrologic Budget ..........................................................................62
Hydrologic Budget Components ......................................................................................................62
Recharge and Discharge ..........................................................................................................66
Aquifer-System Storage ...........................................................................................................67
Intra-Annual Variations in Typical, Dry, and Wet Years .......................................................70
Temporal Variation in the Hydrologic Budget ...............................................................................72
Spatial Variation in the Hydrologic Budget ....................................................................................79
Water Levels and Groundwater Flow .............................................................................................79
Land Subsidence.................................................................................................................................98
Surface Water and the Environment .............................................................................................101
Global Climate Change and Variability ...................................................................................................102
Past Climates .....................................................................................................................................102
Future Climate Projections ..............................................................................................................102
Groundwater Sustainability and Management ....................................................................................103
Groundwater Sustainability ............................................................................................................103
Groundwater Management ............................................................................................................104
Conjunctive Use .......................................................................................................................106
Water Banking ..........................................................................................................................107
Other Management Strategies ..............................................................................................108
Monitoring the Hydrologic System .........................................................................................................109
Groundwater ......................................................................................................................................110
Surface Water ...................................................................................................................................111
Subsidence ........................................................................................................................................112
Water Quality .....................................................................................................................................112
Land Use and Climate.......................................................................................................................114
Summary......................................................................................................................................................114
References Cited........................................................................................................................................116

Chapter C
Numerical Model of the Hydrologic Landscape and Groundwater Flow in
California’s Central Valley
Introduction ................................................................................................................................................121
Model Development ..................................................................................................................................121
Discretization ....................................................................................................................................123
Spatial Discretization and Layering ......................................................................................123
Temporal Discretization .........................................................................................................126
Boundary Conditions .......................................................................................................................126
Specified-Flow Boundaries ....................................................................................................128
Pumpage ...................................................................................................................................128
Agricultural Pumpage ....................................................................................................128
Urban Pumpage ..............................................................................................................130
Recharge from and Discharge to the Delta .........................................................................131
Recharge from and Discharge to Canals and Streams .....................................................132
Water-Table Simulation ...................................................................................................................132
Farm Process (FMP) .........................................................................................................................132
Delivery Requirement ..............................................................................................................134
Soils ..............................................................................................................................135
Land Use ...........................................................................................................................135
Virtual Crop Maps ..................................................................................................139
Crop-Type Data .......................................................................................................143
Climate Data ....................................................................................................................151
Reference Evapotranspiration (ETo) ...................................................................151
Precipitation ...........................................................................................................152
Surface-Water Supply ............................................................................................................152
Groundwater Supply ...............................................................................................................152
Net Recharge ...........................................................................................................................154
Hydraulic Properties.........................................................................................................................154
Hydraulic Conductivity ............................................................................................................156
Storage Properties ..................................................................................................................158
Hydrogeologic Units ...............................................................................................................160
Hydrogeologic Structures .....................................................................................................160
Initial Conditions................................................................................................................................160
Model Calibration and Sensitivity ...........................................................................................................161
Observations Used in Model Calibration ......................................................................................161
Water-Level Altitudes, Water-Level Altitude Changes, and
Water-Level Altitude Maps .......................................................................................163
Water-Table and Potentiometric-Surface Maps .......................................................167
Sacramento Valley .................................................................................................167
Delta .....................................................................................................................167
San Joaquin Valley ...............................................................................................170
Tulare Basin ............................................................................................................170
Streamflow Observations .......................................................................................................170
Boundary Flow Observations .................................................................................................173
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Subsidence Observations ......................................................................................................173
Pumpage Observations ...........................................................................................................179
Water-Use Observations ........................................................................................................179
Water-Delivery Observations.................................................................................................181
Model Parameters ...........................................................................................................................181
Sensitivity Analysis ..........................................................................................................................191
Simulation Results and Budget ...............................................................................................................191
Recharge and Discharge .................................................................................................................192
Aquifer-System Storage ..................................................................................................................197
Model Uncertainty and Limitations ........................................................................................................203
Future Work ................................................................................................................................................205
References Cited........................................................................................................................................207
Appendix 1
Supplemental Information—Modifications to Modflow-2000 Packages and Processes
Introduction.................................................................................................................................................213
Layer-Property Flow Package (LPF) .......................................................................................................213
Multiplier Package (MULT).......................................................................................................................213
Time-Series Package (HYDMOD) ............................................................................................................213
Streamflow Routing Package (SFR1) ......................................................................................................214
The Farm Process (FMP1) ........................................................................................................................214
Concepts and Input Instructions for New FMP1 Features ........................................................214
Data for each Simulation ........................................................................................................215
Data for each Stress Period ...................................................................................................216
Root Uptake Under Variably Saturated Conditions (PSI specified in Item 14) ........................217
Current Concept of Root Uptake from Unsaturated Conditions .......................................217
Expanded Concept of Root Uptake from Variably Saturated Conditions ........................217
Input Instructions .....................................................................................................................221
Matrix of On-Farm Efficiencies (OFE specified in Items 7 or 24) ...............................................221
Input Requirements .................................................................................................................221
Data Output ...............................................................................................................................221
Non-Irrigation Crops (NONIRR Specified in Items 15 or 27) ......................................................222
Consumptive Use Options (ICUFL Specified in Item 2; ETR Specified as New Item) ............222
Semi-Routed Delivery (ISRDFL in Item 2; REACH in Items 20 or 34) .........................................222
Semi-Routed Surface-Water Runoff-Return Flow (ISRRFL in Item 2 and ROW COLUMN
SEGMENT REACH Specified as New Item) ....................................................................223
Farm-Related Data List for Semi-Routed Runoff-Return Flow Locations
(New Item Added After Items 20 or 34): ........................................................223
Additional Auxiliary Variable (AUX NOCIRNOQ Specified in Item 2) .......................................224
Farm Budget Output Options (IFBPFL Specified in Item 2) ........................................................224
References Cited........................................................................................................................................225

Figures
Chapter A
Figure A1. Map of Central Valley major geomorphic provinces, alluvial fans of the
San Joaquin Basin, and extent and thickness of Corcoran Clay ....................................5
Figure A2. Diagram showing the relation and flow of information used in analyzing the
Central Valley Hydrogeologic system .................................................................................7
Figure A3. Diagram showing the diversity of data types and categories included in the
centralized geospatial database ..........................................................................................8
Figure A4. Diagram showing an example of the detail for compilation, integration, and
analysis for one data type (water-level nformation) .........................................................9
Figure A5. A, Map of surface-water inflows and average annual precipitation for
September 1961 through September 2003 throughout the Central Valley,
California. B, Map showing average annual reference evapotranspiration (ETo)
for September 1961 through September 2003 throughout the Central Valley,
California ................................................................................................................................12
Figure A6. Graph of average monthly precipitation for Redding, Davis, and
Bakersfield, California ..........................................................................................................14
Figure A7. Map of general features of the surface-water system in the Central
Valley, California ....................................................................................................................16
Figure A8. Map of distribution of water-balance subregions (WBSs) used for
surface-water delivery and estimation of groundwater pumpage ...............................19
Figure A9. Generalized cross-sections showing pre- and post-development of the
A, Sacramento Valley. B, Central part of the San Joaquin Valley,
California .................................................................................................................................21
Figure A10. A, Map of Central Valley showing groundwater basins and subbasins,
groupings of basins and subbasins into spatial provinces and domains for
textural analysis. B, Map showing distribution of wells used for mapping texture.
C, Graph showing count of wells for each depth increment by domains
through 1,200 feet .................................................................................................................24
Figure A11. Generalized hydrogeologic section (A–A’) indicating the vertical discretization
of the numerical model of the groundwater-flow system in the Central Valley,
California ................................................................................................................................29
Figure A12. Maps showing kriged distribution of coarse-grained deposits for layers 1, 3,
Corcoran Clay, 6, and 9 of the groundwater-flow model. A, Layer 1. B, Layer 3.
C, Corcoran Clay. D, Layer 6. E, Layer 9 .............................................................................31
Figure A13. Block diagram of kriged texture within groundwater-flow model ..............................36
Figure A14. Map showing distribution of coarse-grained deposits for the upper 50 feet
for part of the Central Valley...............................................................................................37
Figure A15. Graph of cumulative distributions of kriged sediment textures for model
layers in the A, Sacramento Valley. B, San Joaquin Valley and Tulare Basin ...........38
Figure A16. A, Bar chart of total inflow from 44 gaged streams flowing into the
Central Valley, California, water years 1962–2003. B, Graph of average annual
precipitation in the Central Valley, California, water years 1962–2003.
C, Pie chart of total surface-water flow into the Central Valley, California,
water years 1962–2003 .......................................................................................................42
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Figure A17. Graph of cumulative departure from average annual precipitation at
Redding, Davis, Fresno, and Bakersfield, California ......................................................44
Figure A18. Graph of cumulative departure of monthly precipitation (Parameter-
elevation Regressions on Independent Slopes Model (PRISM) data from Davis,
California), cumulative departure of the Pacific Decadal Oscillation (PDO)
index, and cumulative departure of the monthly reference evapotranspiration
(ETo) values (gridded values of California Irrigation Management Information
System’s (CIMIS) stations from Redding, Davis, and Bakersfield, 1960–2004) .........45
Figure A19. Graph of cumulative departure of streamflow diversions from the
Bear River by South Sutter Water District, California; cumulative annual
temperature from California Irrigation Management Information System’s
(CIMIS) stations at Davis and the Pacific Decadal Oscillation (PDO) index,
1960–2004 ..............................................................................................................................47
Figure A20. Map of pre-development groundwater map ....................................................................49
Figure A21. Maps of distribution of A, Pre-1900 land-use patterns. B, Land-use
patterns in 2000 for the Central Valley, California ...........................................................50
Figure A22. Map of distribution of selected streams and canals, and average
estimated gains and losses for selected segments .......................................................52
Figure A23. Diagrams of pre-development water budget and post-development
water budget .........................................................................................................................53
Chapter B
Figure B1. Diagram showing average water budget for water years 1962–2003 .........................63
Figure B2. Pie charts and histograms showing simulated landscape budget for the
Central Valley for typical (1975), dry (1990), and wet (1998) years ...............................64
Figure B3. Pie charts and histograms showing simulated groundwater budget for the
Central Valley for typical (1975), dry (1990), and wet (1998) years ...............................65
Figure B4. Maps of A, Estimated change in hydraulic head in upper part of the
aquifer system from 1860 to 1961. B, Simulated change in hydraulic head in
lower part of the aquifer system from spring 1962 to spring 2003 ...............................68
Figure B5. Graphs showing monthly groundwater budget for the Central Valley for a
dry year (1990), typical year (1975), and wet year (1998) ...............................................71
Figure B6. Graphs of annual A, Delivery requirement, landscape recharge,
surface-water deliveries, and agricultural pumpage. B, Groundwater
withdrawals for agricultural and urban use for the entire Central Valley
between 1962 and 2003 .......................................................................................................73
Figure B7. Stacked bar chart showing simulated groundwater budget changes between
water years 1962 and 2003 for the Central Valley, California ........................................75
Figure B8. Stacked bar chart showing simulated annual changes in aquifer-system
storage between water years 1962 and 2003 for the Central Valley, California .......76
Figure B9. Graph showing simulated cumulative annual changes in aquifer-system storage
between water years 1962 and 2003 for the Central Valley, California ......................77
Figure B10. Pie charts and histograms of average annual groundwater budget for the
A, Sacramento Valley. B, Delta and Eastside Streams. C, San Joaquin Valley.
D, Tulare Basin .....................................................................................................................80
Figure B11. Stacked bar chart of simulated flow through multi-zone wells ...................................84

Figure B12. Map of altitude of the A, Water table in the unconfined part of the aquifer
system. B, Potentiometric surface of the confined part of the aquifer system for
1961. C, Unconfined part of the aquifer system. D, Potentiometric surface of
the confined part of the aquifer system for 1976. E, Unconfined part of
the aquifer system. F, Potentiometric surface of the confined part of the
aquifer system, for 2000 .....................................................................................................86
Figure B13. Map showing hydrographs for representative wells in the Central Valley,
California ................................................................................................................................92
Figure B14. Map of estimated depth to water table in spring 2000 ...................................................96
Figure B15. A, Map of areal extent of land subsidence in the Central Valley and
locations of extensometers. B, Graph of compaction data from selected
extensometers and total simulated pumpage in the Central Valley ............................99
Figure B16. Graph of measured compaction in relation to head decline in the
San Joaquin Valley .............................................................................................................101
Figure B17. Graph showing streamflow gains and losses in the Central Valley
between 1962 and 2003 .....................................................................................................105
Figure B18. Diagram of relationship of water-level changes and critical heads to
subsidence and inelastic compaction ...........................................................................109
Chapter C
Figure C1. Map of Central Valley Hydrologic Model grid: A, Extent of San Joaquin
Formation, Corcoran Member of the Tulare Formation, crystalline bedrock,
and horizontal flow barriers. B, Upper-most active layer............................................124
Figure C2. Map of distribution of general-head boundary cells and major streams
and canals with streamflow-routing cells (including location of inflows and
diversions) ...........................................................................................................................127
Figure C3. Map of distribution of urban and agricultural wells simulated in the
Central Valley Hydrologic Model ....................................................................................129
Figure C4. Graph of urban pumpage from U.S. Geological Survey and California
Department of Water Resources data ............................................................................131
Figure C5. Flow chart of water inflows to and outflows from a “farm” as simulated
by the Farm Process (FMP) .............................................................................................133
Figure C6. Map of agricultural soils for the Central Valley, California, derived from
STATSGO data ....................................................................................................................136
Figure C7. Graph showing cumulative departure of precipitation, Pacific Decadal
Oscillation (PDO) Index, climate windows, and time frame land-use maps
were applied .......................................................................................................................137
Figure C8. Map showing virtual crops for 1960 (modified with 2000 data), including
pie chart of percentage of different virtual crops ........................................................140
Figure C9. Map showing virtual crops for 1973, including pie chart of percentage of
different virtual crops ........................................................................................................141
Figure C10. Map showing virtual crops for 1992, including pie chart of percentage of
different virtual crops .......................................................................................................142
Figure C11. Map showing virtual crops for 1998, including pie chart of percentage of
different virtual crops .......................................................................................................144
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Figure C12. Map showing virtual crops for 2000, including a pie chart of percentage of
different virtual crops .......................................................................................................145
Figure C13. Graphs showing monthly crop coefficients for virtual crops in the
Central Valley, California ..................................................................................................147
Figure C14. Graph showing relation between hydraulic conductivity and percentage
coarse-grained deposits based on hydraulic conductivity end members and
exponent of the power mean ..........................................................................................155
Figure C15. Map of distribution of calibration data (groundwater levels, gains and
losses of streamflow, and subsidence observations)................................................162
Figure C16. Map of distribution of wells with water-level-altitude data for the
simulation period 1961–2003, and location of wells selected for model
calibration ..........................................................................................................................164
Figure C17. Graph of plots of simulated water-level altitude values compared with the
measured water-level altitudes for the A, Entire modeled area (and with inset
with histogram of residuals). B, Sacramento Valley. C, Delta and Eastside.
D, San Joaquin Basin. E, Tulare Basin ..........................................................................165
Figure C18. Maps of the simulated A, Water-table altitude in spring 1976.
B, Potentiometric-surface altitude in spring 1976 for the calibrated transient
groundwater-flow model of the Central Valley ............................................................168
Figure C19. Map showing distribution of stream gain/loss segments used for model
calibration A, Measured gaining and losing reaches for selected stream
reaches for 1961–1977. B, Simulated gaining and losing reaches for
selected stream reaches for 1961–1977 for the Central Valley, California ..............171
Figure C20. Map of distribution of historical subsidence, estimated from 1961 to
1977 extensometer data, Central Valley, California .....................................................174
Figure C21. A, Map of distribution of total simulated subsidence for water years
1962 through 2003, and locations of subsidence measurements. B, Graph
of aggregate compaction measured at, and simulated subsidence for,
selected extensometer locations, Central Valley, California .....................................175
Figure C22. Graph of agricultural pumpage from 1961–77 estimated from power
records compared to Central Valley Hydrologic Model simulated agricultural
pumpage for the Central Valley, California ...................................................................180
Figure C23. Graph showing A, Annual water deliveries. B, Monthly water deliveries
from the mid 1970s to mid 1980s for water-balance subregion 14 ............................182
Figure C24. Graph showing single and double cropped crop coefficient values for
truck crops .........................................................................................................................183
Figure C25. Graph showing original and adjusted crop coefficient values for truck and
cotton crops .......................................................................................................................184
Figure C26. Map showing distribution of cells used for streams, colored by streambed
hydraulic conductivity values for cells estimated during calibration ......................190
Figure C27. Graph showing relative composite sensitivity of computed water-level
altitudes, flows, and subsidence information at calibration points to changes
in parameters .....................................................................................................................192

Figure C28. Pie chart and histograms showing average annual components of farm
budget for water years 1962–2003 .................................................................................193
Figure C29. Stacked bar chart showing farm budget changes through time for the
Central Valley, California ..................................................................................................194
Figure C30. Graphs showing farm budget changes through time for water-balance
subregion 13, western San Joaquin Valley, Central Valley, California.
A, Water years 1962–2003. B, Water years 1977–1985 ...............................................195
Figure C31. Stacked bar chart showing groundwater budget changes through time
for the Central Valley. A, All values. B, Net values ......................................................197
Appendix
Figure 1-1. Diagram of evaluation of active and inactive parts of a variably
saturated root zone in FMP .............................................................................................218
Figure 1-2. Diagram of conceptualization to the change of transpiration uptake
from a saturated root zone with varying water level ..................................................220
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Tables
Chapter A
Table A1. Water-balance subregions within the Central Valley, California ...................................11
Table A2. Distribution of statistical properties for the percentage of coarse-grained
deposits for the Central Valley, Calfornia, by domain, including variogram and
variogram models ....................................................................................................................28
Table A3. Central Valley, California, groundwater flow model layer thicknesses and depths ....29
Chapter B
Table B1. Summary of the simulated landscape budget for average (water years
1962-2003), typical (1975), dry (1990), and wet (1998) years for the Central Valley,
California ..................................................................................................................................66
Table B2. Summary of the simulated groundwater budget for average (water years
1962-2003), typical (1975), dry (1990), and wet (1998) years for the Central Valley,
California ..................................................................................................................................66
Table B3. Selected average annual hydrologic budget components for water years
1962–2003 for each of the 21 water balance areas in the Central Valley,
California ..................................................................................................................................78
Chapter C
Table C1. MODFLOW-2000 packages and processes used with the hydrologic flow
model of the Central Valley, California ...............................................................................122
Table C2. Coordinates of the Central Valley Hydrologic Model grid ..............................................126
Table C3. Land-use periods with acreage in square miles and percentage of
different virtual crop categories .........................................................................................138
Table C4. Summary of Central Valley, California, virtual crop categories and properties .........146
Table C5. Summary of fractions of transpiration and evaporation by month for
Central Valley, California, virtual crops .............................................................................150
Table C6. Average area-weighted composite efficiency for each water-balance
subregion of the Central Valley, California, through the simulation period .................151
Table C7. Average reference evapotranspiration (ETo) by month for the Central Valley,
California, for 1961–2003 based on temperature data using the Hargreaves–
Samani equation ....................................................................................................................153
Table C8. Measured and simulated hydraulic properties ................................................................157
Table C9. Estimated and Central Valley Hydrologic Model-simulated average and unit
evapotranspiration of applied water (ETaw) for the Central Valley, California ..........180
Table C10. Parameter values estimated for the Central Valley Hydrologic Model ........................185
Table C11. Simulated farm budget for the Central Valley, California, in acre-feet per year ........199
Table C12. Simulated groundwater budget for the Central Valley, California,
in acre-feet per year ............................................................................................................200

Conversion Factors
Inch/Pound to SI
Multiply By To obtain
Length
inch (in.) 2.54 centimeter (cm)
inch (in.) 25.4 millimeter (mm)
foot (ft) 0.3048 meter (m)
mile (mi) 1.609 kilometer (km)
mile, (mi) 1.609 kilometer (km)
Area
acre 4,047 square meter (m 2 )
acre 0.4047 hectare (ha)
acre 0.4047 square hectometer (hm 2 )
acre 0.004047 square kilometer (km 2 )
square foot (ft 2 ) 929.0 square centimeter (cm 2 )
square foot (ft 2 ) 0.09290 square meter (m 2 )
square inch (in 2 ) 6.452 square centimeter (cm 2 )
section (640 acres or 1 square mile) 259.0 square hectometer (hm 2 )
square mile (mi 2 ) 259.0 hectare (ha)
square mile (mi 2 ) 2.590 square kilometer (km 2 )
Volume
acre-foot (acre-ft) 1,233 cubic meter (m 3 )
acre-foot (acre-ft) 0.001233 cubic hectometer (hm 3 )
Flow rate
acre-foot per day (acre-ft/d) 0.01427 cubic meter per second (m 3 /s)
acre-foot per year (acre-ft/yr) 1,233 cubic meter per year (m 3 /yr)
acre-foot per year (acre-ft/yr) 0.001233 cubic hectometer per year (hm 3 /yr)
Hydraulic conductivity
foot per day (ft/d) 0.3048 meter per day (m/d)
Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:
°F=(1.8×°C)+32
Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929
(NGVD 29).
Altitude, as used in this report, refers to distance above or below the NGVD 29.
NGVD 29 can be converted to the North American Vertical Datum of 1988 (NAVD 88) by using the
National Geodetic Survey conversion utility available at URL http://www.ngs.noaa.gov/TOOLS/
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Well-Numbering System
-
-
-
TOWNSHIP
T13N
T12N
T11N
T10N
T9N
R2W
RANGE
R1W R1E
Mt. Diablo Meridian
R2E R3E
T11N
R1E
6 5 4 3 2
7 8 9 10 11
18 17 16 15 14 13
19 20 21 22 23
30 29 28 27 26 25
31 32 33 34 35 36
D C B A
E F G H
M
SECTION 24
L
K
J
N P Q R
11N/1E-24Q8
Well-numbering diagram (Note: maps in this report use abbreviated well numbers such as "24Q8")
1
12
24

Chapter A. Introduction, Overview of Hydrogeology, and Textural
Model of California’s Central Valley
By Claudia C. Faunt, Randall T. Hanson, and Kenneth Belitz
Executive Summary
-
its aquifers.
-
Geographic Information System (GIS)
-
-
resampled to produce spatial and temporal data sets needed for

2 Groundwater Availability of the Central Valley Aquifer, California
Texture Modeling
-
-
-
-
-
-
Hydrologic System Modeling
-
-
-
-
-
20,000 model cells of 1-mi 2
-
-

-
-
precipitation.
-
-
-
-
Introduction 3
-
also could be used as a platform to connect the simulation
-
Introduction
-
-
-
-
-
to continue.

4 Groundwater Availability of the Central Valley Aquifer, California
ties,
industries, and ecosystems that depend directly or indi-
nia
(
-
source of supply is a function of many factors—both natural
and human—that control its use. Natural factors include
-
-
Purpose and Scope
-
-
report. Included in are descriptions of the effects of
-
.
1.
2.
3.
“
-
-
in
model that is described in . describes the
-

40°
39°
38°
37°
36°
35°
Klamath Mts
Carquinez
Straits
C o a s t
San Francisco
Bay
Selected faults
A A'
Line of section (figure A11)
Extent of San Joaquin Basin
fluvial fans
Major streams and selected
canals
Davis Population centers
0
124°
123°
122°
S a c r a m e n t o V a l l e y
Pacific Ocean
EXPLANATION
Geomorphic province—
Basin
Delta
Dissected uplands
Sacramento River flood plains
Sutter Buttes
Younger fan deposits
Historical lakes
Extent of Corcoran Clay
Redding
Red Bluff
Sacramento River
Davis
Cascade Range
0 100 200 Kilometers
Shaded relief derived from U.S. Geological Survey National Elevation Dataset, 2006.
Albers Equal Area Conic Projection
Sutter
Buttes
121°
Sacramento
Stockton
Modesto
San Joaquin River
R a n g e s
S i e r r a N e v a d a
Stockton
Fault
S a n J o a q u i n V a l l e y
San Joaquin Basin
Kettleman
Hills
Tulare
Lake bed
100 200 Miles
120°
San
Francisco
Central
Valley
A
C A L I
Pacific Ocean
F O R N I A
Fresno
Kings River
Tulare
Basin
119°
NEVADA
CALIFORNIA
Visalia
A'
Introduction 5
Bakersfield
Tehachapi Mts
Figure A1. Central Valley major geomorphic provinces (modified from Davis and others, 1959; Olmstead and Davis, 1961; and
Jennings,1977), alluvial fans of the San Joaquin Basin (Weissmann and others, 2005), and extent and thickness of Corcoran Clay
(modified from Page,1986 and Burow and others, 2004).

6 Groundwater Availability of the Central Valley Aquifer, California
Methods of Analyses
-
-
-
-
-
-
ity.
The results, conclusions, and limitations discussed in this
Data Compilation
-
-
-
-
of this report.
-
-
-
( and
in
compilation, and analysis of information for the hydraulic
properties database is described in the “”
section of this chapter.
-
-
(and
-
-
processed, and (or) re-sampled to produce spatial and temporal
-
).
Numerical Model
-
-
of this report.
in a sand-silt-clay aquifer system. The system has been

Texture
Model
DATA
Centralized
Geospatial
Database
VISUALIZATION
Groundwater
Levels
and Flows
Hydrogeologic
Properties
Introduction 7
Flow Model
CVHM
Figure A2. The relation and flow of information used in analyzing the Central Valley Hydrogeologic system. Both interpretive and
modeling data flow in and out of the centralized geospatial database. The texture model, data in the geospatial database, and modeling
results are visualized throughout the data gathering, analysis, and modeling stages of the project.
Previous Investigations
-
-
-
-
Recent Regional Groundwater Models
Central Valley Regional Aquifer-System Analysis
(CV-RASA)
-
-
-
-
2 , and the
about 500 mi 2
often are smaller than 500 mi 2

8 Groundwater Availability of the Central Valley Aquifer, California
Soils Topography Remote Sensing
Soil Surveys (STATSGO)
Soil Properties Data
Digital Elevation Models
Topographic Maps
Geology Vegetation & Land Use
Geologic Maps
Geologic Cross Sections
Drillers Logs
Centralized
Geospatial
Database
Satellite Imagery
MoDIS
Land Use/Land Cover Maps (DWR)
Agricultural Data
Crop Data
Original Data Types
Climate Geophysics
Precipitation Data
Temperature Data
Humidity
Evapotranspiration
Hydrology Chemistry Anthropogenic Controls
Water Well Information
Aquifer Tests
Aquifer Properites
Surface Water Data
Aquifer Chemistry
Spring Chemistry
SU Chemistry
Redox Chemistry
Gravity
Seismic/Earthquake
Magnetics/Resistivity
Surface Water Delivery
Surface Water Diversions
Environmental Requirements
Figure A3. The diversity of data types and categories included in the centralized geospatial database. Data types in bold were used
specifically in this study.
-
-
-

Hydrology
Water Well Information
Aquifer Tests
Aquifer Properites
Surface Water Data
DWR USGS
Water Levels
Locations
Construction
Hydrographs
Combined
Water-Level
Database
21,417 wells
873,073 water levels
Data
Analysis
CVHM
Subset
206 wells
19,725 water levels
Water Levels
Locations
Construction
Overlapping records
Missing information
Location discrepancies
Construction
Measurement discrepancies
Temporal distribution
Specific time periods
Climate control
Continuous record
Spatial distribution
Water balance areas
Basin to foothills
Calibration
Observations
Water levels
Water-level gradients
Change in water levels
Figure A4. An example of the detail for compilation, integration, and analysis for one data type (water-level nformation).
Introduction 9

10 Groundwater Availability of the Central Valley Aquifer, California
California Central Valley Groundwater-Surface-Water
Simulation Model (C2VSIM)
-
-
-
2 .
-
-
system and calculate stream accretions and depletions for use
2006).
Study Area
2 and is one of the more
-
-
-
-
-
is about 1,700 ft.
( and
Climate
-
Sacramento Valley
-
-
).

Table A1. Water-balance subregions within the Central Valley, California.
Regions
Site
identifier
General
description
DWR DSA
number
Total
area
(mi 2 )
Routed
surface-
water
deliveries
Study Area 11
-
2 ,
square mile]
Non-routed
surface-
water
deliveries
1 611 2 None
2
1,163 3 None
3
1,112 4 None
4
560 1 None
5
957 2 6
6
1,044 4 None
7
534 4 4
8
1,362 6 None
9
1,026 1 None
10 1,083 1 7
11 664 6 None
12 540 5 None
13 1,648 6 2
14 1,071 None 3
15 1,423 4 5
16 478 2 1
17 569 2 1
18 1,358 4 4
19
1,365 2 3
20 705 2 3
21
area)
1,105 3 2
— — — 20,378 64 41
-

12 Groundwater Availability of the Central Valley Aquifer, California
A
Average annual
precipitation,
in inches per year—
6 to 8
9 to 10
11 to 12
13 to 14
15 to 16
17 to 18
19 to 20
21 to 22
23 to 24
25 to 26
27 to 28
29 to 30
31 to 32
33 to 34
35 to 36
37 to 38
39 to 40
41 to 42
43 to 44
45 to 46
Red Bluff
0 50 100 Miles
0 50 100 Kilometers
Sacramento River
Davis
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
San Joaquin River
Los Gatos
Creek
Feather
River
Yuba
River
Bear
River
American
River
Cosumnes
River
Mokelumne
River
Calaveras
River
Stanislaus
River
Fresno
Slough
Davis
EXPLANATION
Average annual inflow,
in thousands of acre-feet per year—
Tuolumne
River
Merced
River
Less than 100
100.1 to 500
500.1 to 1,000
1,000.1 to 2,000
2,000.1 to 3,000
3,000.1 to 4,000
4,000.1 to 5,000
Greater than 5,000
Selected streams
and rivers
Precipitation station
and identifier
San Joaquin
River
Kings
River
Kaweah
River
Tule
River
White
River
Kern
River
Bakersfield
Figure A5. A, Surface-water inflows and average annual precipitation for September 1961 through September 2003 throughout the Central Valley,
California. B, Average annual reference evapotranspiration (ETo) for September 1961 through September 2003 throughout the Central Valley, California.
ETo data were calculated from PRISM temperature data (Climate Source, 2006). The surface-water inflows are from U.S. Geological Survey files and
California Department of Water Resources (C. Brush, written commun., February 21, 2007). Precipitation data are from Parameter-Elevation Regressions
on Independent Slopes Model (PRISM) data (Climate Source, 2006).

B
Red Bluff
0 50 100 Miles
0 50 100 Kilometers
Davis
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
Figure A5. Continued.
Davis
EXPLANATION
Selected streams
and rivers
Precipitation station
and identifier
Bakersfield
Study Area 13
Average annual reference evapotranspiration,
in inches per year—
45.5 to 46
46.1 to 47
47.1 to 48
48.1 to 49
49.1 to 50
50.1 to 51
51.1 to 52
52.1 to 53
53.1 to 54
54.1 to 55
55.1 to 56

14 Groundwater Availability of the Central Valley Aquifer, California
AVERAGE PRECIPITATION, IN INCHES
5
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
-
MONTH
EXPLANATION
Monthly average precipitation (1961 to 2003) at—
Red Bluff
Davis
Bakersfield
Figure A6. Average monthly precipitation for Redding, Davis, and Bakersfield, California (Climate Source, 2006).
ecosystem protection and restoration efforts are needed
purposes.

Delta and Eastside Streams
).
-
2 of estuary.
-
-
times
are curtailed. This focus on ecosystem restoration often
-
Study Area 15
-
-
-
-
-
San Joaquin Basin of the San Joaquin Valley
).
-
-
the summers are particularly hot and dry, the area has been
-
rapid shift to other crops, particularly almond orchards. On the
nated
by deciduous fruit and nut orchards. The remainder of

16 Groundwater Availability of the Central Valley Aquifer, California
Shasta Lake
Corning
Canal
Red Bluff
Tehama
Co
Glenn
Co
Colusa
Co
Napa
Co
0 50 100 Miles
0 50 100 Kilometers
Shasta
Co
Yolo
Co
Davis
Solano
Co
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
Tehama-Colusa
Canal
Glenn-Colusa
Canal
Lake Oroville
Folsom Lake
Folsom South Canal
Camanche Reservoir
Pardee Lake
California
Mokelumne
Aqueduct
Kern
Water Bank
Figure A7. General features of the surface-water system in the Central Valley, California.
Butte
Co
Sutter
Co
Yuba
Co
Sacramento
Co
Nevada
Co
Placer
Co
San Joaquin
Co
Stanislaus
Co
El Dorado Co
Amador Co
Calaveras
Co
Merced
Co
Tuolumne
Co
Mariposa
Co
Hetch Hetchy
Aqueduct
Madera
Co
Fresno
Co
Aqueduct
Kings
Co
EXPLANATION
Historic lakes
Reservoir
State Water Project
Federal Water Project
Davis
Tulare
Co
Local Canal/
Aqueduct Projects
Selected streams
and rivers
County boundary
Precipitation station
and identifier
Kern
Co
Friant-Kern
Canal
Cross Valley
Canal
Bakersfield

for about 30 percent of the annual supply of both types of
-
-
-
Tulare Basin of the San Joaquin Valley
-
-
-
Study Area 17
-
-
ter
often is used to replace much of the shortfall in surface-
-
-
-
as for recreation.

18 Groundwater Availability of the Central Valley Aquifer, California
Water-Balance Subregions
-
and ).
).
Geologic History and Setting
-
-
-
(last 10 million years). The only prominent non-sedimentary
-
materials—mostly clay and silt—compose as much as
and Williams, 1995).
-
-
-
-
-
). The

0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
1
2
3
6
4
5
9
7
8
11
12
10
12
14
13
EXPLANATION
16
15
19
17
Geologic History and Setting 19
California Department of Water Resources
water-balance subregion and identifier. Water-
balance subregion identifier with red highlight
indicates subregion receiving deliveries not
shown by arrows
Major streams and canals
Diversion locations
Direction of water movement
from diversion location, and
water-balance subregion affected.
Length of arrow does not relate
to volume of diversion
Figure A8. Distribution of water-balance subregions (WBSs) used for surface-water delivery and estimation of groundwater
pumpage. These areas are based on areas defined by the California Department of Water Resources and are used as “virtual farms”
for accounting by the Farm Process in the simulation of the hydrologic system of the Central Valley with MODFLOW-2000. WBSs 5, 7, 10,
and 13-21 receive surface-water that is not shown in the stream network (non-routed deliveries).
18
20
21

20 Groundwater Availability of the Central Valley Aquifer, California
). They determined that the character
turn, resulted in thinner depositional sequences and no incised
” section
model in more detail.
Hydrogeology
-
Aquifer Characteristics
-
). The chief source of
-
thick, marine sedimentary rocks (-
-
-
-
-
-
-
-
).
others, 1993) (
-

A
Coast Ranges
Clayey
lenses
Fault
Marine
deposits
River
Potentiometric surface for the
lower part of the aquifer system
Old saline water
Pumping wells
Slough
-
-
constitute more than 50 percent of the total thickness of the
-
2
Water
movement
Sierra Nevada
Fresh-water
recharge
Lower part
of the aquifer
system
Upper part
of the aquifer
system
Bedrock
Hydrogeology 21
Figure A9. Pre- and post-development of the A, Sacramento Valley. B, Central part of the San Joaquin Valley, California. (Modified
from Belitz and Heimes, 1990; and Galloway and others, 1999).
Water
table
lacustrine deposit (Johnson and others, 1968) as much as 200
). This

22 Groundwater Availability of the Central Valley Aquifer, California
B
Coast Ranges
Clayey
lenses
Corcoran Clay
(confining layer)
Marine
deposits
Figure A9. Continued.
River
Potentiometric surface of the
lower part of the aquifer system
Old saline water
Pumping wells
Slough
Subsidence area
(
Water
table
Water
movement
Lower part
of the aquifer
system
Sierra Nevada
Fresh-water
recharge
Upper part
of the aquifer
system
(Sierran
deposits)
Bedrock

-
the distribution of these properties are more important than are
1991).
ments
of hydraulic properties of the aquifer system are scarce,
).
” section.
Textural Analysis
nitude
and distribution of aquifer-system compaction, mani-
-
Hydrogeology 23
-
-
-
2
-
500 to 1,000 mi 2
a 1,000-mi 2
2
tribution
of sedimentary hydrofacies in a nearly 6.5-mi 2 study
area
(cies
model in a 19-mi 2
of the 64-mi 2
-
-
-
().

24 Groundwater Availability of the Central Valley Aquifer, California
A B
10
S a c r a m e n t o V a l l e y
11
Sacramento River
12
EXPLANATION
Textural analysis spatial
provinces and domains
Number Name
10
11
12
20
21
22
23
24
30
Redding
Western Sacramento
Eastern Sacramento
Tracy/Delta-Mendota
Westside
Northern San Joaquin
Chowchilla-Madera
Kings
Tulare/Kern
Stream or river
Orestimba
Creek
S a n J o a q u i n V a l l e y
San Joaquin River
20
22
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
Merced River
Bear
Creek
21
23
24
Kings River
30
10
11
12
20
21
22
23
24
30
0 50
EXPLANATION
Textural analysis spatial
provinces and domains
Number Name
Redding
Western Sacramento
Eastern Sacramento
Tracy/Delta-Mendota
Westside
Northern San Joaquin
Chowchilla-Madera
Kings
Tulare/Kern
Well used for
texture analysis
0 50 100 Kilometers
100 Miles
Figure A10. A, Central Valley showing groundwater basins and subbasins, groupings of basins and subbasins into spatial provinces
and domains for textural analysis. B, Distribution of wells used for mapping texture. C, Count of wells for each depth increment by
domains through 1,200 feet. Because less than 1 percent of the logs extend past 1,200 feet, increments below 1,200 feet were not shown.
Detailed description of the spatial provinces and domains are in .

C
DEPTH TO MIDPOINT OF INCREMENT, IN FEET BELOW LAND SURFACE
0
50
100
150
200
250
300
350
400
450
500
550
600
650
700
750
800
850
900
950
1,000
1,050
1,100
1,150
Selection and Compilation of Existing Well Data
-
-
ated
on the basis of the amount of detail in the descriptions
-
NUMBER OF WELLS USED FOR TEXTURE ANALYSIS
EXPLANATION
Number of wells,
colored by basin
Number Name
10 Redding
Hydrogeology 25
-
-
-
-
11
12
20
21
22
23
24
30
Western Sacramento
Eastern Sacramento
Tracy/Delta-Mendota
Westside
Northern San Joaquin
Chowchilla-Madera
Kings
Tulare/Kern
1,200
0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 5,000 5,500 6,000 6,500 7,000 7,500
Figure A10. Continued.

26 Groundwater Availability of the Central Valley Aquifer, California
2
2
Classification of Texture from Drillers’ Logs and
Regularization of Well Data
-
-
surface to the bottom of the borehole. Thus, none of the depth
-
-
Geostatistical Modeling Approach
tistics
is a set of applications and statistical techniques used
-
-
methods are based on an assumed spatial correlation structure.
models.
Regions and Domains
-
-
south (
-

). The southern part, referred
, includes the
2003).
cally
(
).
and ).
Geostatistical Model of Coarse-Grained Texture
-
-
-
-
-
165 to 820 ft (
directions.
Hydrogeology 27
-
-
points, rather than by the spatial dimensions of the search
-
-
-
used is a function of both distance and direction.
-

28 Groundwater Availability of the Central Valley Aquifer, California
Table A2. Distribution of statistical properties for the percentage of coarse-grained deposits for the Central Valley, Calfornia, by domain, including variogram and variogram
models.
-
Spatial
Spatial
Valley
province
province
number2 Variogram Variogram models
Area
Domain (square
miles)
3
Model 1 - Exponential Model 2 - Gaussian
Num-
Anisotropy/
ber of Mean Variance rotation Nugget
Directional scales
Directional scales
Sill
Sill
samples
(degrees)
1 2 3 1 2 3
10 597 1,010 39 1,348 0 1,300 2,400 5,000 15,000 500 800 98,000 328,000 700
Western 11 3,524 6,423 25 820 10 1,100 1,200 16,000 21,000 400 300 131,000 656,000 2,300
12 2,588 4,632 32 1,069 15 1,300 1,600 20,000 28,000 400 500 164,000 492,000 500
20 1,198 1,466 45 1,029 20 1,000 2,300 16,000 59,000 800
508 433 29 820 20 0 2,700 16,000 8,000 200
Westside 21 - 844 1,343 30 982 47 1,000 2,200 20,000 30,000 500
384 481 33 1,012 47 1,300 2,000 17,000 39,000 500
absent
22 865 4,470 51 876 31 1,600 1,200 459,000 33,000 600
Joaquin
2,373 8,931 34 936 31 300 2,100 3,000 4,000 200 600 66,000 164,000 300
375 330 37 691 35 0 2,200 30,000 20,000 200
488 1,119 36 878 35 1,100 1,500 21,000 21,000 600
498 1,157 46 577 30 1,000 900 26,000 39,000 200
1,027 1,560 47 837 30 1,000 1,600 39,000 30,000 500
2,788 2,562 43 1,042 28 500 2,100 11,000 8,000 300 900 164,000 295,000 2,000
2,500 2,775 41 1,314 28 1,200 2,000 16,000 25,000 700
6,568 374 26 874 33 0 2,900 20,000 20,000 0 9,800 197,000 656,00 197,000
6,568 4,685 35 1,138 33 900 1,400 6,000 4,000 400 1,400 180,000 558,000 400
23
24
absent
30
-
-

3-D Model of Percentage of Coarse-Grained Texture
1 mi 2
).
layers 4 and 5 (). In order to complete this representa-
ALTITUDE, IN FEET
1,000
500
NGVD 29
-500
-1,000
-1,500
-2,000
Layer
Thickness
(feet)
Depth to
base outside
Corcoran Clay
(feet)
Hydrogeology 29
Table A3. Central Valley, California, groundwater flow model
layer thicknesses and depths.
Texture
figure
1 50 50
2 100 150 —
3 150 300
4 301
5 302
6 198 500
7 250 750 —
8 300 1,050 —
9 350 1,400
10 400 1,800 —
A Cross section along row 355
A'
Layer 1
Layer 2
Layer 3
Land surface
Corcoran Clay
Layer 6
Layer 7
Layer 8
Layer 9
Layer 10
Not in model
-2,500
0 30,000 60,000 90,000 120,000 150,000 180,000 210,000 240,000 270,000 300,000
DISTANCE ALONG SECTION, IN FEET
Figure A11. Generalized hydrogeologic section (A–A’) indicating the vertical discretization of the numerical model of the groundwaterflow
system in the Central Valley, California. Line of section shown on (altitudes are along row 355; layer numbers indicate
model layer).

30 Groundwater Availability of the Central Valley Aquifer, California
-
).
Results of Texture Model
-
-
model (
and
and
because of the data density, is the most detailed layer in the
model (
the land surface ( and -
(
and ).
sediments ( and
( and
. It also can be related to
domains.
Sacramento Valley
-
-
and
-
-
and
-
).
and).
-
in

A
Layer 1
EXPLANATION
Central Valley boundary
Percentage of coarse-grained
material > is greater than.
0 to 10
>10 to 20
>20 to 30
>30 to 40
>40 to 50
>50 to 60
>60 to 70
>70 to 80
>80 to 90
>90 to 100
7,263 wells have logged data
Wells having logged data
11
Western
Sacramento
0 50 100 Miles
0 50 100 Kilometers
Layer 1
Land surface
Not in model
10
Redding
20
Tracy/Delta-
Mendota
Enlarged area
shown
on figure 14
12
Eastern
Sacramento
21
Westside
22
Northern
San Joaquin
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
23
Chowchilla-
Madera
Well locations
24
Kings
Hydrogeology 31
30
Tulare/Kern
Enlarged area
shown
on figure 14
Figure A12. Kriged distribution of coarse-grained deposits for layers 1, 3, Corcoran Clay, 6, and 9 of the groundwater-flow model. Inset
shows distribution of wells used in that depth interval.

32 Groundwater Availability of the Central Valley Aquifer, California
B
Layer 3
EXPLANATION
Central Valley boundary
Percentage of coarse-grained material
> is greater than.
0 to 10
>10 to 20
>20 to 30
>30 to 40
>40 to 50
>50 to 60
>60 to 70
>70 to 80
>80 to 90
>90 to 100
5,952 wells have logged data
13,235 depth increments intercepted
Wells having logged data
11
Western
Sacramento
0 50 100 Miles
0 50 100 Kilometers
Land surface
Layer 3
Figure A12. Continued.
Not in model
10
Redding
20
Tracy/Delta-
Mendota
12
Eastern
Sacramento
21
Westside
22
Northern
San Joaquin
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
23
Chowchilla-
Madera
Well locations
24
Kings
30
Tulare/Kern

C
Layer Corcoran Clay
EXPLANATION
Central Valley boundary
Percentage of coarse-grained material
> is greater than.
0 to 10
>10 to 20
>20 to 30
>30 to 40
>40 to 50
>50 to 60
>60 to 70
>70 to 80
>80 to 90
>90 to 100
1,306 wells have logged data
1,534 depth increments intercepted
Wells having logged data
0 50 100 Miles
0 50 100 Kilometers
Corcoran Clay
Land surface
Figure A12. Continued.
11
Western
Sacramento
Not in model
10
Redding
20
Tracy/Delta-
Mendota
12
Eastern
Sacramento
21
Westside
22
Northern
San Joaquin
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
23
Chowchilla-
Madera
24
Kings
Hydrogeology 33
Well locations
30
Tulare/Kern

34 Groundwater Availability of the Central Valley Aquifer, California
D
Layer 6 10
EXPLANATION
Central Valley boundary
Percentage of coarse-grained material
> is greater than.
0 to 10
>10 to 20
>20 to 30
>30 to 40
>40 to 50
>50 to 60
>60 to 70
>70 to 80
>80 to 90
>90 to 100
2,007 wells have logged data
8,312 depth increments intercepted
Wells having logged data
0 50 100 Miles
0 50 100 Kilometers
Land surface
Figure A12. Continued.
11
Western
Sacramento
Layer 6
Not in model
Redding
20
Tracy/Delta-
Mendota
12
Eastern
Sacramento
21
Westside
22
Northern
San Joaquin
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
23
Chowchilla-
Madera
Well locations
24
Kings
30
Tulare/Kern

E
Layer 9
EXPLANATION
Central Valley boundary
Percentage of coarse-grained material
> is greater than.
0 to 10
>10 to 20
>20 to 30
>30 to 40
>40 to 50
>50 to 60
>60 to 70
>70 to 80
>80 to 90
>90 to 100
79 wells have logged data
309 depth increments intercepted
Wells having logged data
0 50 100 Miles
0 50 100 Kilometers
Land surface
Figure A12. Continued.
11
Western
Sacramento
Layer 9
Not in model
10
Redding
20
Tracy/Delta-
Mendota
12
Eastern
Sacramento
21
Westside
22
Northern
San Joaquin
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
23
Chowchilla-
Madera
Well locations
24
Kings
Hydrogeology 35
30
Tulare/Kern

36 Groundwater Availability of the Central Valley Aquifer, California
Corcoran
Clay
Figure A13. Kriged texture within groundwater-flow model.
EXPLANATION
Percent coarse-grained material—
> is greater than.
0 to 10
>10 to 20
>20 to 30
>30 to 40
>40 to 50
>50 to 60
>60 to 70
>70 to 80
>80 to 90
>90 to 100
Approximate extent
of Tulare Lake bed
Inactive in model
Box encompassing
extent of model
Line of cross section
shown on figure 11
(Row 355)

Geomorphic province—
Basin
Delta
Dissected uplands
Sacramento River
flood plains
Fan deposits
Orestimba
Creek
EXPLANATION
Percent coarse-grained
material—
> is greater than.
San Joaquin River
0 to 10
0 50 Miles
0 50 Kilometers
>10 to 20
>20 to 30
>30 to 40
>40 to 50
>50 to 60
>60 to 70
>70 to 80
>80 to 90
>90 to 100
Mokelumne
River
Calaveras
River
Stanislaus River
Major stream
or canal
San Joaquin Basin
fluvial-fan boundaries
Tuolumne River
Merced River
Bear Creek
Chowchilla River
Fresno River
Sacramento River
Kings
River
Kaweah
River
Hydrogeology 37
Sacramento River
flood plains
Figure A14. Distribution of coarse-grained deposits for the upper 50 feet for part of the Central Valley. The map is overlain with the
major geomorphic provinces of the Central Valley and the fluvial fans of the San Joaquin Basin (modified from Davis and others, 1959;
Olmstead and Davis, 1961; Jennings, 1977; and Weissmann and others, 2005).

38 Groundwater Availability of the Central Valley Aquifer, California
A
COARSE-GRAINED MATERIAL, IN PERCENT
B
COARSE-GRAINED MATERIAL, IN PERCENT
100
80
60
40
20
0
0.0 0.2 0.4 0.6 0.8 1.0
100
80
60
40
20
0
San Joaquin Valley
Sacramento Valley
0.0 0.2 0.4 0.6 0.8 1.0
CUMULATIVE PROBABILITY
Layer 1
Layer 2
Layer 3
Corcoran Clay
EXPLANATION
Layer 6
Layer 7
Layer 8
Layer 9
Layer 10
Figure A15. Cumulative distributions of kriged sediment textures for model layers in the A, Sacramento Valley. B, San Joaquin Valley
and Tulare Basin.

San Joaquin Valley
),
(
and ). In this
the mountain front.
and
and -
and
Hydrogeology 39
-
-
from north to south because of the differences in tectonic basin
outlet ( and ) is not
-
-
-
-

40 Groundwater Availability of the Central Valley Aquifer, California
).
and
).
and
, , and
(, and -
and ).
). This is especially true in comparison to
(
-
Hydrologic System
-
). These dams capture

-
Water supplied from aquifers is a less formal and less
-
.
-
Climate
-
Hydrogeology 41
(
months.
-
-
(
and -
). Under the current climatic
-
). Wet periods represent
median periods and drier-than-median periods since the
-
(
).
departure is less in the south ( and
) also

42 Groundwater Availability of the Central Valley Aquifer, California
A
FLOW RATE, IN THOUSANDS OF ACRE-FEET PER YEAR
B
MEAN PRECIPITATION, IN INCHES PER YEAR
80,000
70,000
60,000
50,000
40,000
30,000
20,000
10,000
0
30
25
20
15
10
5
0
"Normal"
to
Dry
"Normal"
to
Dry
Representative Water Year
"Variable"
to
Wet
"Variable"
to
Wet
Dry Wet Dry
Wet
WATER YEAR
EXPLANATION
75 th percentile
(38,200)
Median
(26,300)
Dry Wet Dry
Wet
WATER YEAR
"Variable"
to
Dry
1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002
Sacramento River
Feather River
American River
Representative Water Year
Typical
1975
Yuba River
Cottonwood Creek
Other Sacramento Valley streams
Typical
1975
25 th percentile
(18,800)
Kings River
Tuolumne River
Stanislaus River
75 th percentile
(16.8)
Median
(13.0)
Merced River
Kern River
Other San Joaquin Valley streams
25 th percentile
(11.0)
"Variable"
to
Dry
1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002
Figure A16. A, Total inflow from 44 gaged streams flowing into the Central Valley, California, water years 1962–2003.
B, Average annual precipitation in the Central Valley, California, water years 1962–2003. C, Total surface-water flow into the Central
Valley, California, water years 1962–2003.
Dry
1990
Dry
1990
Wet
1998
Wet
1998

C
Figure A16. Continued.
3.54%
5.45%
S a n J o a q u i n V a l l e y R i v e r s
6.00%
3.24%
2.42%
Sacramento River
Feather River
American River
Yuba River
16.54%
Cottonwood Creek
7.85%
2.17%
6.12%
EXPLANATION
-
20 th
24.03%
8.95%
S a c r a m e n t o V a l l e y R i v e r s
Kings River
Tuolumne River
Stanislaus River
Merced River
Kern River
13.69%
Other Sacramento Valley streams Other San Joaquin Valley streams
Hydrogeology 43
.
There are some notable spatial differences in the cumula-
-
-
precipitation.

44 Groundwater Availability of the Central Valley Aquifer, California
CUMULATIVE DEPARTURE OF PRECIPITATION, IN INCHES PER YEAR
50
40
30
20
10
0
-10
-20
-30
-40
-50
-60
-70
-80
"Variable"
"Variable" "Variable"
Dry Wet to
Wet Dry Wet Dry Wet Dry
to to Dry Wet Dry Wet
Dry
Dry Wet
1875 1885 1895 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005
Red Bluff
Davis
Fresno
( and
TIME, IN YEARS
EXPLANATION
Annual cumulative departure of precipition—
Bakersfield
Pacific Decadal Oscillation (PDO) Index-24 month moving average
Figure A17. Cumulative departure from average annual precipitation at Redding, Davis, Fresno, and Bakersfield, California. For
reference, a 24-month moving average of the Pacific Decadal Oscillation Index is also plotted.
"Variable"
to
Dry
-1.0
-2.0
-3.0
and ).
3.0
2.0
1.0
0.0
PACIFIC DECADAL OSCILLATION (PDO) INDEX, UNITLESS

CUMULATIVE DEPARTURE OF PRECIPITATION AND
REFERENCE EVAPOTRANSPIRATION, IN INCHES PER YEAR
10
0
-10
-20
-30
-40
"Variable"
to
Dry
"Variable"
to
Wet
) and is directly dependent on a combina-
-
).
Dry Wet Dry
Wet
TIME, IN YEARS
Hydrogeology 45
-50
-1.5
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
EXPLANATION
Annual cumulative departure of
reference evapotranspiration (ETo)—
Red Bluff
Davis
Bakersfield
Annual cumulative departure of precipitation
from PRISM data
Davis
Pacific Decadal Oscillation (PDO) average annual value
"Variable"
to
Dry
Figure A18. Cumulative departure of monthly precipitation (Parameter-elevation Regressions on Independent Slopes Model (PRISM)
data from Davis, California), cumulative departure of the Pacific Decadal Oscillation (PDO) index, and cumulative departure of the
monthly reference evapotranspiration (ETo) values (gridded values of California Irrigation Management Information System’s (CIMIS)
stations from Redding, Davis, and Bakersfield, 1960–2004).
-0.5
-1.0
-
2.0
1.5
1.0
0.5
0.0
PACIFIC DECADAL OSCILLATION (PDO) INDEX, UNITLESS

46 Groundwater Availability of the Central Valley Aquifer, California
Surface Water
-
(
-
). North
much smaller (
-
-
acre-ft/yr (
).
-
-
).
).
-
-
-
-
-
but also is controlled by other factors. These factors may

CUMULATIVE DEPARTURE OF STREAMFLOW DIVERSION, IN ACRE-FEET PER YEAR
300
200
100
0
-100
-200
Cool (Negative) Warm (Positive)
Cool
(Negative)
"Variable"
to
Dry
"Variable"
to
Wet
-
). In addition,
Dry Wet
Dry
TIME, IN YEARS
Groundwater
Hydrogeology 47
"Variable"
to
Dry
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Cool
(Negative)
EXPLANATION
Periods of Pacific Decadal Oscillation [PDO]
(Mantua, 2006)
Bear River Diversion cumulative departure average
Cumulative annual temperature difference, 1964-2003
Pacific Decadal Oscillation (PDO) average annual value
Figure A19. Cumulative departure of streamflow diversions from the Bear River by South Sutter Water District, California; cumulative
annual temperature from California Irrigation Management Information System’s (CIMIS) stations at Davis and the Pacific Decadal
Oscillation (PDO) index, 1960–2004.
Wet
-2.0
-4.0
-6.0
-
6.0
4.0
2.0
0.0
CUMULATIVE ANNUAL TEMPERATURE DIFFERENCE, IN DEGREES FAHRENHEIT
PDO-INDEX, UNITLESS

48 Groundwater Availability of the Central Valley Aquifer, California
Predevelopment Recharge, Discharge,
Water Levels, and Flows
-
and
basin.
-
-
-
-
). Other
(
Groundwater/Surface-Water Interaction
-
-
-
-
-
).
Aquifer-System Storage
-
-
-
-
-
-
-
serious consequences. Therefore, this type of calculation of

700
500
600
400
200
160
0 50 100 Miles
240
360
320
120
280
40
240
160
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
0
40
40
160
80
200
200
160
160
240
160
120
240
280
400
200
240
320
400
500
700
320
200
360
EXPLANATION
Predevelopment water levels
Water-level altitude,
in feet above NGVD 29
Figure A20. Pre-development groundwater map (modified from Williamson and others, 1989).
360
360
280
360
360
0
1 to 50
51 to 100
101 to 200
201 to 400
401 to 800
Historical lakes
Central Valley boundary
320
360
400
400
400
500
Hydrogeology 49

50 Groundwater Availability of the Central Valley Aquifer, California
A
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
EXPLANATION
Vegetation types—
Alkali desert scrub
Major streams
Figure A21. Distribution of A, Pre-1900 land-use patterns (modified from California State University, Chico, 2003), B, land-use patterns
in 2000 (California Department of Water Resources, 2000) for the Central Valley, California.
Aquatic
Grassland
Other floodplain habitat
Riparian
Valley/Foothill hardwood
Wetland
Central Valley boundary

B
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
Figure A21. Continued.
Alfalfa
Almond and pistachio
Corn
Cotton
Cucurbits
Dry beans
Fallow and idle
Grain
EXPLANATION
Land use or vegetation types—
Native classes
Not surveyed
Onions and garlic
Other decidious
Major streams
Hydrogeology 51
Other field
Other truck
Pasture
Potatoes
Rice
Safflower
Subtropical
Sugar beets
Tomatoes
Urban
Vineyard
Water
Central Valley boundary

52 Groundwater Availability of the Central Valley Aquifer, California
Stony Creek
Sacramento
Cache Creek
Putah Cr ek
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
1
2
3
6
4
5
Feather
9
American
Mokelumne
Calaveras
Stanislaus
Tuolumne
San Joaquin
San Joaquin
Kaweah River
Figure A22. Distribution of selected streams and canals, and average estimated gains and losses for selected segments (Mullen and
Nady, 1985).
Merced
STREAMFLOW
7 7
8
11
12
10
Deadman's Creek
14
13
GAIN
LOSS
Fresno
Fresno Slough
EXPLANATION
Central Valley boundary
Selected streams and canals
Groundwater/surface-water interaction,
in acre-feet per year
16
-54.97 to -44.42
-44.39 to -14.81
-14.78 to -1.48
-1.45 to 0
0.03 to 1.48
1.51 to 14.81
14.84 to 44.42
44.45 to 113.07
Kings River
15
19
17
18
20
Kern River
21
Out of groundwater
system
Into groundwater
system
California Department of Water Resources
water-balance subregion and identifier.

Water Budget
per year (
-
-
-
-
pired
by plants (
Precipitation
(12.4)
(1.5)
(10.9)
Central Valley
Surface Processes
Evapotranspiration
(12.6)
Central Valley
Aquifer
(1.7)
Acknowledgments 53
-
-
Acknowledgments
-
others.
Surface-Water
Gain (0.3)
[sw out]
Surface-Water
Loss (0.5)
[sw in]
Figure A23. Pre-development water budget and post-development water budget. Values are in millions of acre-feet per year.

54 Groundwater Availability of the Central Valley Aquifer, California
References Cited
-
-
-
44 p.
-
-
-
-
-
-
16, 2009, at
2009, at
-
-

References Cited 55
-
-
http://
-
-
-
-
at
-
-
-
-
-
-

56 Groundwater Availability of the Central Valley Aquifer, California
-
-
-
-
561 p.
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
974 p.
1497, 287 p.
-
-
24 p.
-
54 p.

References Cited 57
-
-
2009, at
-
-
-
-
-
-
-

Chapter B. Groundwater Availability in
California’s Central Valley
By Claudia C. Faunt, Kenneth Belitz, and Randall T. Hanson
Introduction
-
, this report). The
-
Development and the
Hydrologic System
in. in places (
-
-
help rectify the imbalance.
Surface-Water and Groundwater
Development History
-
-

60 Groundwater Availability of the Central Valley Aquifer, California
-
basins (
-
-
-
season.
-
-
).
-
).
-
Land Use
-

Agricultural Land Use
-
-
19 th
tomatoes, melons, squash and lettuce) crops. The tomato
Water, soils, microclimate, pests, economic and historical
ley
(
-
-
-
Development and the Hydrologic System 61
-
Urban Land Use
-
-
-
threefold from about 0.6 to nearly 2 million acre-ft/yr, despite

62 Groundwater Availability of the Central Valley Aquifer, California
-
Development and Changes to the
Hydrologic Budget
and ).
-
-
-
-
system.
-
paction
and associated land subsidence.
-
system (
-
study (). Where necessary, the results of simulations
Hydrologic Budget Components
-
and and tabulated in and
components pertain to both systems (). The landscape
( and and and
-
-
-

Groundwater
Pumpage
(9.3)
Agricultural
(8.6)
Municipal
(1.1)
Flow through
Boreholes
(0.4)
Precipitation
(15.8)
Central Valley
Surface Processes
Groundwater Recharge from
Irrigation and Precipitation
(7.8)
Central Valley
Aquifer
Change in Storage
(including Subsidence)
(1.4)
—Indicates loss of storage in aquifer system
Development and Changes to the Hydrologic Budget 63
Evapotranspiration
(25.6)
INFLOW
(26.3)
Surface-Water
Deliveries (10.2)
Runoff
(1.1)
Surface-Water
System
Groundwater
Flow to Delta (0.1)
Surface-Water
Gain from
Groundwater
System (2.2)
Surface-Water
Loss from
Groundwater
System (2.5)
OUTFLOW
to DELTA
(27.2)
Figure B1. Average water budget for water years 1962–2003. This budget includes the landscape and groundwater components and
their linkages. Values in millions of acre-ft/yr. A diagram showing the pre-development water budget is shown in .

64 Groundwater Availability of the Central Valley Aquifer, California
21%
10%
30%
39%
Simulated landscape water budget
INPUT OUTPUT
Typical Year 1975
Dry Year 1990
35%
10%
MILLIONS OF ACRE-FEET
MILLIONS OF ACRE-FEET
30
25
20
15
10
5
0
25
20
15
10
5
0
14.53
11.28
7.93
3.93
30 30
Wet Year 1998
7%
10%
19%
25%
30%
64%
Precipitation
Surface-water
deliveries
MILLIONS OF ACRE-FEET
30
25
20
15
10
5
0
10.12
30.18
8.36
8.95
Groundwater
pumpage
11.69
4.54
Evapotranspiration
from ground water
3.19
1%
EXPLANATION
3%
29%
21%
40%
5%
68%
78%
55%
MILLIONS OF ACRE-FEET
MILLIONS OF ACRE-FEET
MILLIONS OF ACRE-FEET
30
25
20
15
10
5
0
25
20
15
10
5
0
30
25
20
15
10
5
0
Evapotranspiration Runoff
Deep percolation
Figure B2. Simulated landscape budget for the Central Valley for typical (1975), dry (1990), and wet (1998) years.
3.33
25.52
25.99
25.85
1.02
0.49
2.14
10.99
6.92
18.65

Simulated groundwater budget
INPUT OUTPUT
EXPLANATION
Development and Changes to the Hydrologic Budget 65
Typical Year 1975
51%
2%
32%
6% 0%
9%
Dry Year 1990
55%
Wet Year 20.86
1998
0%
38%
4%
15%
25%
43%
3%
10%
1%
5%
0%
MILLIONS OF ACRE-FEET
MILLIONS OF ACRE-FEET
MILLIONS OF ACRE-FEET
20
16
12
Specific yield and
compressibility of water
Elastic and inelastic
matrix storage
8
4
0
20
16
12
8
4
0
20
16
12
8
4
0
6.50
2.78
0.03
0.06
0.01
1.13
0.58
1.47
1.90
1.11
7.46
10.19
6.29
18.14
Surface-water loss to
groundwater system
Recharge from
landscape system
Intra-borehole flow
0.44
0.39
37%
43%
27%
11%
13%
9%
18%
33%
7% 0%
10%
6%
32%
10%
38%
4% 2%
0%
Specific yield and
compressibility of water
Elastic and inelastic
matrix storage
MILLIONS OF ACRE-FEET
MILLIONS OF ACRE-FEET
20
16
12
8
4
0
20
16
12
8
4
0
7.67
9.43
0.11
0.03
Groundwater lost
to streams
Evapotranspiration from
groundwater
Pumpage
Figure B3. Simulated groundwater budget for the Central Valley for typical (1975), dry (1990), and wet (1998) years.
0.31
MILLIONS OF ACRE-FEET
20
16
12
8
4
0
8.83
0.45
1.66
2.99
1.00
2.36
1.64
4.12
3.05
2.00
2.65
8.72
12.60
6.18

66 Groundwater Availability of the Central Valley Aquifer, California
Table B1. Summary of the simulated landscape budget for average (water years 1962-2003), typical (1975), dry (1990), and wet (1998)
years for the Central Valley, California.
Precip-
itation
Input to landscape system Output from landscape system
Surface
surface-water
deliveries
Groundwater
pumpage
Evapotranspiration
from
groundwater
Evapotranspiration
Runoff
Deep percolation
Ground-
water
recharge
15.8 10.2 8.6 3.7 25.6 1.1 11.4 7.7
Typical 14.5 11.3 7.9 3.9 25.5 1 11 7.0
10.1 8.4 11.7 3.3 26 0.5 6.9 3.6
Wet 30.2 8.9 4.5 3.2 25.8 2.1 18.6 15.4
Table B2. Summary of the simulated groundwater budget for average (water years 1962-2003), typical (1975), dry (1990), and wet (1998)
years for the Central Valley, California.
-
]
Storage from
specific yield and
compressibility of
water
Elastic and inelastic
storage
Input to the groundwater system
Stream leakage to
groundwater
Recharge from
landscape process
Intra-borehole
flow
General head
boundaries
8.1 1 2.6 10.7 0.4 0.0
Typical 6.5 1.1 1.9 10.2 0.4 0.0
2.8 0.6 1.1 6.3 0.4 0.1
Wet 20.9 1.5 7.5 18.1 0.3 0.0
Output from the groundwater system
Storage
(specific yield and
compressibility
of water)
Storage
(elastic and
inelastic
compaction)
Groundwater
inflow to
streams
Discharge
from landscape
process
Pumpage
General head
boundaries
8.5 2 2.2 3. 9.7 0.1
Typical 7.7 1.7 2.4 3.1 8.7 0.1
8.8 3 1.6 2.6 12.6 0
Wet 18.9 1 4.1 2.6 6.2 0.5
Net in relation to groundwater availability
Storage from
specific yield and
compressibility of
water
Elastic and inelastic
storage
Stream
interaction
Recharge
from landscape
process
Pumpage
General head
boundaries
0.3 7.8
Typical 7.1
3.7 0
Wet 12 0.5 3.3 15.5
Recharge and Discharge
-
times (Williamson and others, 1989).
(

and
-
mechanisms.
-
-
-
-
and -
-
-
-
and .
10.2 million acre-ft/yr ( and
Development and Changes to the Hydrologic Budget 67
-
proportion increases.
Aquifer-System Storage
-
system ( and and
-
). The principal areas of historical
.
-
-
-
-

68 Groundwater Availability of the Central Valley Aquifer, California
A
S a c r a m e n t o V a l l e y
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
Delta
S a n J o a q u i n V a l l e y
EXPLANATION
Estimated change in hydraulic head,
predevelopment to 1961, in feet—
Rise of 0 to 40
Decline from 0 to 40
Decline from 40 to 80
Decline from 80 to 120
Decline from 120 to 200
Decline from 200 to 300
Decline from 300 to 400
Decline of more than 400
Central Valley boundary
Water-balance subregion
Tulare
Basin
Figure B4. A, Estimated change in hydraulic head in upper part of the aquifer system from 1860 to 1961 (modified from Williamson and
others, 1989; Bertoldi and others, 1991). B, Simulated change in hydraulic head in lower part of the aquifer system from spring 1962 to
spring 2003.

B
01_01645
03b06329
02_05172
04_07807
06b12975
06_14809
Delta
07_13870
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
Figure B4. Continued.
05_10854
08_14958
09_19824
11_21412
10_25517
12_22972
14_28350
Development and Changes to the Hydrologic Budget 69
13_25144
14_30806
15_29737
Simulated change in hydraulic head,
1961 to 2003, in feet—
11_21412
16_30057
15_34255
18_33084
19_37289
19_38742
EXPLANATION
Tulare
Basin
Rise of greater than 400
Rise of 300 to 400
Rise of 200 to 300
Rise of 120 to 200
Rise of 80 to 120
Rise of 40 to 80
Rise of 0 to 40
Decline from 0 to 40
Decline from 40 to 80
Decline from 80 to 120
Decline from 120 to 200
Decline from 200 to 300
Decline from 300 to 400
Central Valley boundary
Water-balance subregion
Hydrograph well and identifier
See figure 13 for hydrographs
20_37212

70 Groundwater Availability of the Central Valley Aquifer, California
-
-
aquifer system.
-
permanent compaction and land subsidence, can accompany
-
This is discussed in more detail in the section of this report
entitled “.”
and
and
).
1.4 million acre-ft. In dry years, about 9.0 million acre-ft of
).
Intra-Annual Variations in Typical, Dry, and Wet
Years
-
-
),
().
(
-
-
(
-
Water pumped from the aquifer system may not be
-
from precipitation and streams. In other areas, replenishment
).

NET MONTHLY CHANGE IN GROUNDWATER BUDGET, IN MILLIONS OF ACRE-FEET PER YEAR
5
4
3
2
1
0
-1
-2
-3
-4
-5
5
4
3
2
1
0
-1
-2
-3
-4
-5
25
20
15
10
5
0
-5
Typical Year - 1975
OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP
Dry Year - 1990
OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP
Wet Year - 1998 (Note scale change)
OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP
MONTH
Development and Changes to the Hydrologic Budget 71
Figure B5. Monthly groundwater budget for the Central Valley for a dry year (1990), typical year (1975), and wet year (1998). Values are
relative to water availability. Hence, an increase in storage is shown as a positive value.
A
B
C
EXPLANATION
Net groundwater budget
Specific yield and
compressibility of water
Elastic and inelastic
matrix storage
Groundwater recharge from
landscape
Stream interaction
Pumpage

72 Groundwater Availability of the Central Valley Aquifer, California
Temporal Variation in the Hydrologic Budget
-
tation
(
the same climatic pattern as the precipitation (
and
). -
-
). This partly is a result of an
(
-
-
-
( and
-
-
( and
and
-
(
-
-
).

A
MILLIONS OF ACRE-FEET PER YEAR
30
25
20
15
10
5
0
Figure C8
4/61-3/68
"Variable"
to
Dry
Representative water year
Figure C9
4/68-3/78
"Variable"
to
Wet
Time frame land-use maps were applied, from Chapter C
Typical
Development and Changes to the Hydrologic Budget 73
Figure C10
4/78-3/93
Dry Wet Dry
Wet
Agricultural pumping
WATER YEAR
EXPLANATION
Surface-water deliveries
Delivery requirement
Landscape recharge
Figure C11
4/93-3/99
Dry Wet
Figure C12
4/99-9/03
"Variable"
to
Dry
1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002
Figure B6. A, Annual delivery requirement, landscape recharge, surface-water deliveries, and agricultural pumpage. B, Annual
groundwater withdrawals for agricultural and urban use for the entire Central Valley between 1962 and 2003. Other than urban
pumpage, all values are simulated by the Central Valley Hydrologic Model (CVHM) (). Urban pumpage compiled by California
Department of Water Resources (C. Brush, California Department of Water Resources, written commun., February 21, 2007).
represents a steady increase from less than 5 percent in 1962 to
-
urban uses ( and and ).

74 Groundwater Availability of the Central Valley Aquifer, California
B
SIMULATED PUMPAGE, IN MILLIONS OF ACRE-FEET PER YEAR
20
15
10
5
"Variable"
to
Dry
"Variable"
to
Wet
system.
-
and inelastic compaction.
and
Dry Wet
Dry
Wet
"Variable"
to
Dry
0
1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002
Figure B6. Continued.
WATER YEAR
EXPLANATION
Simulated pumpage—
Total
Urban
Agricultural
( and
-
and ).

ANNUAL CHANGE IN GROUNDWATER AVAILABILITY, IN MILLIONS OF ACRE-FEET PER YEAR
30
20
10
0
-10
-20
-30
"Variable"
to
Dry
mal
precipitation () (fourth driest and the driest year
-
Development and Changes to the Hydrologic Budget 75
Period of
Period of growth of water supplies Period of abundance Period of reduced supplies
drought
Representative water year
"Variable"
to
Wet
Typical
Available water resources
Dry Wet Dry
Wet
WATER YEAR
EXPLANATION
Net groundwater budget
Dry
Wet
"Variable"
to
Dry
1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002
Specific yield and
compressibility of water
Groundwater flow
to Delta
Elastic and inelastic
matrix storage
Stream interaction
Landscape recharge
Pumpage
Figure B7. Simulated groundwater budget changes between water years 1962 and 2003 for the Central Valley, California.
(

76 Groundwater Availability of the Central Valley Aquifer, California
NET ANNUAL CHANGE IN STORAGE, IN MILLIONS OF ACRE-FEET PER YEAR
15
10
5
0
-5
-10
-15
"Variable"
to
Dry
Representative water year
"Variable"
to
Wet
Typical
Figure B8. Simulated annual changes in aquifer-system storage between water years 1962 and 2003 for the Central Valley, California.
-
).
Dry Wet Dry
Wet
WATER YEAR
EXPLANATION
Dry Wet
"Variable"
to
Dry
1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002
Specific yield and
compressibility of water
Elastic and inelastic
matrix storage
).
-
and -

CUMULATIVE CHANGE IN GROUNDWATER STORAGE, IN MILLIONS OF ACRE-FEET
20
0
-20
-40
-60
-80
"Variable"
to
Dry
Representative water year
"Variable"
to
Wet
Typical
-
and
-
and
, , and
acre-ft in the mid-1990s ().
Dry
Development and Changes to the Hydrologic Budget 77
Wet Wet
WATER YEAR
EXPLANATION
Dry
Dry Wet
"Variable"
to
Dry
1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002
Sacramento
Central Valley Overall
By region
Delta and Eastside Streams
San Joaquin Basin
Tulare Basin
Figure B9. Simulated cumulative annual changes in aquifer-system storage between water years 1962 and 2003 for the Central Valley,
California.
-
-
about 5.7 million acre-ft/yr (
-

78 Groundwater Availability of the Central Valley Aquifer, California
Table B3. Selected average annual hydrologic budget components for water years 1962–2003 for each of the 21 water balance areas
in the Central Valley, California.
Water-balance subregion
Area
(square
miles)
Net storage
from spe-
cific yield and
compressibility
of
water 1
Net elastic
and
inelastic storage
1
rates in the simulation period of 3.4 million acre-ft/year in
2001 ( and
-
and
-
Net
stream
leakage 2
Net
pumpage
Net
recharge
from landscape
3
Precip-
itation
Evapo-
trans-
piration
Surface-
water
deliveries
1 611 36,000 13,000 45,000 453,000 1,063,000 547,000 46,000
2 1,163 23,000 557,000 768,000 1,496,000 1,269,000 129,000
3 1,112 3,000 49,000 508,000 1,125,000 1,300,000 717,000
4 560 0 6,000 562,000 635,000 78,000
5 957 65,000 466,000 1,200,000 1,101,000 439,000
6 1,044 10,000 34,000 506,000 522,000 1,137,000 1,315,000 329,000
7 534 2,000 4,000 186,000 222,000 590,000 512,000 172,000
Sacramento Valley 5,981 –99,000 52,000 1,348,000 1,414,000 2,920,000 7,173,000 6,6799,000 1,910,000
Eastside Streams (8) 1,362 –26,000 7,000 95,000 850,000 721,000 1,365,000 1,444,000 205,000
Delta (9) 1,026 –218,000 3,000 705,000 467,000 –200,000 975,000 1,603,000 64,000
10 1,083 29,000 64,000 60,000 89,000 588,000 1,465,000 983,000
11 664 0 85,000 251,000 509,000 901,000 643,000
12 540 1,000 39,000 45,000 131,000 384,000 702,000 440,000
13 1,648 43,000 67,000 163,000 754,000 474,000 1,092,000 2,233,000 936,000
San Joaquin Basin 3,935 –70,000 97,000 168,000 944,000 945,000 2,573,000 5,301,000 3,002,000
14 1,071 179,000 165,000 6,000 934,000 418,000 432,000 1,631,000 716,000
15 1,423 26,000 146,000 239,000 1,603,000 708,000 607,000 2,225,000 757,000
16 478 89,000 35,000 33,000 202,000 212,000 299,000 518,000 358,000
17 569 54,000 28,000 170,000 445,000 348,000 358,000 852,000 442,000
18 1,358 158,000 198,000 104,000 1,135,000 710,000 715,000 2,237,000 821,000
19 1,365 85,000 133,000 0 754,000 334,000 494,000 1,275,000 367,000
20 705 74,000 92,000 19,000 252,000 240,000 295,000 892,000 610,000
21 1,105 83,000 81,000 130,000 324,000 272,000 414,000 1,333,000 1,096,000
Tulare Basin 8,074 748,000 878,000 701,000 5,649,000 3,188,000 3,614,000 10,963,000 5,167,000
Total 20,378 300,000 1,000,000 300,000 9,300,000 7,600,000 15,700,000 25,900,000 10,300,000
1
2
3
system ( and ).
declines (
indicates a net loss of 57.7 million acre-ft from aquifer-system
, ).

Spatial Variation in the Hydrologic Budget
tially
( and , and
(
-
-
( andand
-
() ( and
( and and
and ). In the mid-1970s, there
-
.
Development and Changes to the Hydrologic Budget 79
Water Levels and Groundwater Flow
-
-
-
-
-
tions
(

80 Groundwater Availability of the Central Valley Aquifer, California
A
3%
21%
MILLIONS OF ACRE-FEET
Sacramento
45%
MILLIONS OF ACRE-FEET
1.0
0.5
0.0
-0.5
-1.0
MILLIONS OF ACRE-FEET
5% 0%0%
1.0
0.5
0.0
-0.5
-1.0
26%
1.0
0.5
0.0
-0.5
-1.0
MILLIONS OF ACRE-FEET
4
3
2
1
0
-1
-2
-3
-4
-5
-0.29
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
2
1
3
0
MILLIONS OF ACRE-FEET
1.0
0.5
0.0
-0.5
-1.0
-0.03
-1.66
1
2
3
2.88
6
4
-1.37
5
6
7
MILLIONS OF ACRE-FEET
-0.18
1.0
0.5
0.0
-0.5
-1.0
MILLIONS OF ACRE-FEET
EXPLANATION
Net annual groundwater budget,
water years 1962-2003
Specific yield and
compressibility of water
Flow of groundwater
to Delta
Elastic and inelastic
matrix storage
Stream interaction
Landscape recharge
MILLIONS OF ACRE-FEET
1.0
0.5
0.0
-0.5
-1.0
1
1.0
0.5
0.0
-0.5
-1.0
Pumpage
Flow between regions or
water-balance subregion
Central Valley boundary
Water-balance subregion
boundary and identifier
Figure B10. Average annual groundwater budget for the A, Sacramento Valley. B, Delta and Eastside Streams. C, San Joaquin Valley.
D, Tulare Basin. Schematic bar charts of average annual groundwater budget for the 21 water-balance subregions (WBSs) in the
Central Valley also are shown.
4
7
5

B
MILLIONS OF ACRE-FEET
Delta and
Eastside Streams
1.0
0.5
45%
2%
13%
3%
26%
11%
0%
MILLIONS OF ACRE-FEET
4
3
2
1
0
-1
-2
-3
-4
-5
0.05
-0.09
9
0.0 0.5
-0.5
-1.0
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
Figure B10. Continued.
9
0.00
0.65
8
Development and Changes to the Hydrologic Budget 81
0.28
-1.12
0.32
MILLIONS OF ACRE-FEET
1.0
0.0
-0.5
-1.0
EXPLANATION
Net annual groundwater budget,
water years 1962-2003
8
Specific yield and
compressibility of water
Flow of groundwater
to Delta
Elastic and inelastic
matrix storage
Stream interaction
Landscape recharge
Pumpage
Flow between regions or
water-balance subregion
Central Valley boundary
Water-balance subregion
boundary and identifier
8

82 Groundwater Availability of the Central Valley Aquifer, California
C
MILLIONS OF ACRE-FEET
MILLIONS OF ACRE-FEET
13%
37%
1.0
0.5
0.0
-0.5
-1.0
1.0
0.5
0.0
-0.5
-1.0
San Joaquin
3%
0%
1% 2%
44%
Figure B10. Continued.
MILLIONS MILLIONS OF OF ACRE-FEET
ACRE-FEET
4
33
22
11
00
-1 -1
-2 -2
-3 -3
-4 -4
-5 -5
-0.04
0 50 100 Miles
11
10
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
0
11
-0.02
12
10
0.04
13
0.71
-0.60
MILLIONS OF ACRE-FEET
1.0
0.5
0.0
-0.5
-1.0
-0.21
MILLIONS OF ACRE-FEET
EXPLANATION
Net annual groundwater budget,
water years 1962-2003
1.0
0.5
0.0
-0.5
-1.0
11
Specific yield and
compressibility of water
Flow of groundwater
to Delta
Elastic and inelastic
matrix storage
Stream interaction
Landscape recharge
Pumpage
Flow between regions or
water-balance subregion
Central Valley boundary
Water-balance subregion
boundary and identifier
12
13

D
MILLIONS OF ACRE-FEET
1.0
0.5
0.0
-0.5
-1.0
50%
MILLIONS OF ACRE-FEET
1%
MILLIONS OF ACRE-FEET
Tulare
1.0
0.5
0.0
-0.5
-1.0
-1.5
1.0
0.5
0.0
-0.5
-1.0
8%
31%
Figure B10. Continued.
0%
5%
5%
19
MILLIONS OF ACRE-FEET
MILLIONS OF ACRE-FEET
4
3
2
1
0
-1
-2
-3
-4
-5
-6
1.0
0.5
0.0
-0.5
-1.0
-0.88
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
15
14
0
-0.49
14
21
0.50
16
15
MILLIONS OF ACRE-FEET
Development and Changes to the Hydrologic Budget 83
19
1.0
0.5
0.0
-0.5
-1.0
3.26
17
18
-5.20
20
21
0.06
MILLIONS OF ACRE-FEET
1.0
0.5
0.0
-0.5
-1.0
20
EXPLANATION
Net annual groundwater budget,
water years 1962-2003
Specific yield and
compressibility of water
Flow of groundwater
to Delta
Elastic and inelastic
matrix storage
Stream interaction
Landscape recharge
MILLIONS OF ACRE-FEET
MILLIONS OF ACRE-FEET
15
1.0
0.5
0.0
-0.5
-1.0
1.0
0.5
0.0
-0.5
-1.0
Pumpage
Flow between regions or
water-balance subregion
Central Valley boundary
Water-balance subregion
boundary and identifier
16
17
18

84 Groundwater Availability of the Central Valley Aquifer, California
depth of permeable aquifer material and by the quality of the
-
-
-
NET ANNUAL PUMPAGE AND FLOW THROUGH MULTI-NODE WELLS,
IN MILLIONS OF ACRE-FEET PER YEAR
1.0
0
-1.0
-2.0
-3.0
-4.0
"Variable"
to Dry
Representative water year
Figure B11. Simulated flow through multi-zone wells.
unit (-
2 (Williamson and others, 1989). If
"Variable"
to Wet Dry Wet Dry
Wet
Typical
WATER YEAR
Dry Wet
"Variable"
to Dry
-5.0
1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002
EXPLANATION
Intra-borehole flow
Pumpage

-
-
(-
-
-
). The
this study (-
-
conditions. When compared, these potentiometric-surface
time .
-
-
().
Development and Changes to the Hydrologic Budget 85
-
-
-
(
,
remain fairly constant
-
and ).
-
-
). In addition,
2003 and
, ,
and )
-
). The
.

86 Groundwater Availability of the Central Valley Aquifer, California
A
700
500
400
320
360
280
120
240
120
160
0
0 50 100 Miles
80
200
40
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
40
120
0
160
40
120
120
120
120
80
240
120
80
200
240
160
200
120
500
600
200
320
200
280
400
EXPLANATION
Spring 1961
Water-level altitude
(from Williamson and others, 1989),
in feet above NGVD 29—
240
360
280
400
320
320
160
360
280
320
280
0
1 to 50
51 to 100
101 to 200
201 to 400
401 to 800
Central Valley boundary
Major streams and canals
Direction of flow
Figure B12. Altitude of the A, Water table in the unconfined part of the aquifer system (Williamson and others, 1989). B, Potentiometric surface of the confined
part of the aquifer system for 1961 (Williamson and others, 1989). C, Unconfined part of the aquifer system (Williamson and others, 1989). D, Potentiometric
surface of the confined part of the aquifer system for 1976 (Williamson and others, 1989. E, Unconfined part of the aquifer system (simulated, ).
F, Potentiometric surface of the confined part of the aquifer system, for 2000 (simulated, ).
400
240
360
360
400
320
500

B
Figure B12. Continued.
600
400
320
240
280
200
80
160
120
120
80
40
40
120
40
0
40
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
80
0
160
80
40
120
80
80
-80
80
-160
Development and Changes to the Hydrologic Budget 87
-120
-160
400
40
0
0
240
-80
160
-40
280
500
400
160
500
280
-40
EXPLANATION
320
Spring 1961
Potentiometric surface of the lower part of the
aquifer system (from Williamson and others, 1989),
in feet above NGVD 29—
360
120
280
280
320
-200 to -100
-99 to 0
240
200
1 to 100
101 to 250
251 to 500
501 to 750
Central Valley boundary
Major streams and canals
Direction of flow
240
200
280
160
280
280
240
160
280

88 Groundwater Availability of the Central Valley Aquifer, California
C
Figure B12. Continued.
600
500
240
400
280
200
80
160
40
120
0
120
40
0
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
120
40
80
120
160
240
120 320
80
200
320
400
700
320
200
280 240
EXPLANATION
Spring 1976
Water-level altitude
(from Williamson and others, 1989),
in feet above NGVD 29—
320
160
120
280
240
320
400
320
0
1 to 50
51 to 100
101 to 200
201 to 400
401 to 800
Central Valley boundary
Major streams and canals
Direction of flow
400

D
Figure B12. Continued.
500
400 320
280
240
200
160
80
40
0
40
80
120
120
40
0
-40
-40
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
0
40
80
0
80
40
80
80
120
-40
Development and Changes to the Hydrologic Budget 89
-80
240
160 80
-80
400
0
160
-40
0
EXPLANATION
Spring 1976
Potentiometric surface of the lower part
of the aquifer system (from Williamson and others, 1989),
in feet above NGVD 29—
40
200
400
-200 to -100
-99 to 0
160
280
200
40
1 to 100
101 to 250
251 to 500
Central Valley boundary
Major streams and canals
Direction of flow
0
200
360
320
280
320
280
200
320
240
160
160
120
80
200

90 Groundwater Availability of the Central Valley Aquifer, California
E
Figure B12. Continued.
480
360
320
120
160
440
280
200
400
160
240
0 50 100 Miles
120
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
80
40
80
40
80
80
120
80
160
120
40
120
200
240
160
EXPLANATION
200
Spring 2000
Simulated water-level altitude,
in feet above NGVD 29—
240
240
280
200
80
160
200
40
80
120
160
200
240
280
320
360
400
440
480
Central Valley boundary
Major streams and canals
Direction of flow
120
280

F
Figure B12. Continued.
400
440
360
320
120
120
80
0
440
280
240
200
160
40
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
40
80
Development and Changes to the Hydrologic Budget 91
160
120
80
40
0
480
160
240
440
400
120
280
240
80
40
EXPLANATION
Spring 2000
Simulated potentiometric surface of the lower part
of the aquifer system, in feet above NGVD 29—
280
240
200
160
Central Valley boundary
Major streams and canals
120
120
280
80
240
80
200
280
0
40
80
120
160
200
240
280
320
360
400
440
480
Direction of flow
160

92 Groundwater Availability of the Central Valley Aquifer, California
WATER-LEVEL ALTITUDE, IN FEET ABOVE NGVD 29
500
450
400
350
300
250
Layer 2
200
1960 1970 1980 1990 2000
250
200
150
100
50
NGVD
29
Well 01_01645
Note scale change
Well 03b06329
Layer 6
Layer 7
-50
1960 1970 1980 1990 2000
250
200
150
100
50
NGVD
29
Well 05_10854
Layer 1
Layer 2
-50
1960 1970 1980
WATER YEAR
1990 2000
250
200
150
100
NGVD
29
250
200
150
100
50
NGVD
29
EXPLANATION
Well 02_05172
Layer 2
Layer 3
Layer 6
-50
1960 1970 1980 1990 2000
Well 04_07807
Layer 1
Layer 2
-50
1960 1970 1980 1990 2000
250
200
150
100
50
NGVD
29
Well 06_14809
Layer 2
Layer 3
-50
1960 1970 1980
WATER YEAR
1990 2000
Land-surface elevation at well Simulated water-level elevation from model for—
Measured head of well
Layer 1
Layer 5
Layer 9
Layer 2
Layer 6
Layer 10
Layer 3
Layer 7
Layer 4
Layer 8
Figure B13. Hydrographs for representative wells in the Central Valley, California (locations shown in ).
50

WATER-LEVEL ALTITUDE, IN FEET ABOVE NGVD 29
250
200
150
100
50
NGVD
29
250
200
150
100
50
NGVD
29
-50
1960 1970 1980 1990 2000
250
200
150
100
50
NGVD
29
Well 06b12975
Layer 2
Layer 3
Layer 6
Layer 7
-50
1960 1970 1980 1990 2000
Well 08_14958
Layer 2
EXPLANATION
Development and Changes to the Hydrologic Budget 93
-50
1960 1970 1980 1990 2000
-50
1960 1970 1980 1990 2000
-50
-50
1960 1970 1980 1990 2000
1960 1970 1980 1990 2000
WATER YEAR WATER YEAR
250
200
150
100
NGVD
29
250
200
150
100
NGVD
29
Well 10_25517 Well 11_21412
Layer 1
Layer 2
Layer 3
Figure B13. Continued.
Land-surface elevation at well Simulated water-level elevation from model for—
Measured head of well
Layer 1
Layer 5
Layer 9
Layer 2
Layer 6
Layer 10
Layer 3
Layer 7
Layer 4
Layer 8
50
50
250
200
150
100
50
NGVD
29
Well 07_13870
Layer 2
Well 09_19824
Layer 1
Layer 1
Layer 2
Layer 3
Layer 4
Layer 5
Layer 5

94 Groundwater Availability of the Central Valley Aquifer, California
WATER-LEVEL ALTITUDE, IN FEET ABOVE NGVD 29
250
200
150
100
50
NGVD
29
NGVD
29
-100
250
200
150
100
NGVD
29
1960 1970 1980 1990 2000 1960 1970 1980 1990 2000
50
Well 12_22972
-50
1960 1970 1980 1990 2000
200
100
-200
-300
-400
-500
-600
Layer 1
Layer 2
Well 14_30806
Land-surface elevation 266 feet
Note scale change
Well 15_34255
-50
-50
1960 1970 1980 1990 2000
1960 1970 1980 1990 2000
WATER YEAR WATER YEAR
Figure B13. Continued.
Layer 2
Layer 3
Layer 4
Layer 5
Layer 6
Layer 7
Layer 8
Layer 9
Layer 10
250
200
150
100
NGVD
29
250
200
150
100
NGVD
29
EXPLANATION
-50
1960 1970 1980 1990 2000
Land-surface elevation at well Simulated water-level elevation from model for—
Measured head of well
Layer 1
Layer 5
Layer 9
Layer 2
Layer 6
Layer 10
Layer 3
Layer 7
Layer 4
Layer 8
50
200
100
NGVD
29
-100
-200
-300
-400
-500
-600
50
Well 13_25144
Layer 6
Layer 7
Well 14_28350
Land-surface elevation 348 feet
Note scale change
Well 15_29737
Layer 3
Layer 4
Layer 5
Layer 6
Layer 7
Layer 8
Layer 9
Layer 10
Layer 6
Layer 7

WATER-LEVEL ALTITUDE, IN FEET ABOVE NGVD 29
250
200
150
100
50
NGVD
29
350
300
250
250
200
150
100
50
Well 16_30057
Land-surface elevation 213 feet
Layer 3
Layer 4
Layer 5
Layer 6
-50
1960 1970 1980 1990 2000
Well 19_38742
Land-surface elevation 269 feet
Layer 2
Layer 3
EXPLANATION
Development and Changes to the Hydrologic Budget 95
250
200
150
100
NGVD
29
-50
1960 1970 1980 1990 2000
NGVD
29
50
Well 20_37212
Land-surface elevation 590 feet
Note scale change
-50
NGVD 29
1960 1970 1980 1990 2000 1960 1970 1980 1990 2000
WATER YEAR WATER YEAR
Land-surface elevation at well Simulated water-level elevation from model for—
Measured head of well
Layer 1
Layer 5
Layer 9
Layer 2
Layer 6
Layer 10
Layer 3
Layer 7
Layer 4
Layer 8
50
Well 18_33084
Layer 5
Layer 6
Layer 7
200
-100
-200
150 Well 18c33884
Note scale change
-300
Layer 3
Layer 4
100
Layer 2
-400
Layer 5
50
NGVD 29
Layer 3
Layer 6
-500
-600
Well 19_37289
Land-surface elevation 279 feet
Note scale change
Layer 6
Layer 7
Layer 8
1960 1970 1980 1990 2000 1960 1970 1980 1990 2000
Figure B13. Continued.
200
100
NGVD 29
350
300
250
200
150
100
Layer 6
Layer 7
Layer 8

96 Groundwater Availability of the Central Valley Aquifer, California
100
100
100
50
50
50
100
150
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
Figure B14. Estimated depth to water table in spring 2000.
50
50
100
150
100
100
50
50
100
100
50
150
100
EXPLANATION
Area with depth-to-water
less than 50 feet
Central Valley boundary
Line of equal depth-to-water,
Spring 2000, in feet.
Contour interval is 50 feet
Depth-to-water, by well,
in feet below land surface
0 to 50
50 to 100
100 to 150
150 to 200
200 to 500
50
100
150
50
200

-
and
(
-
-
-
1960s ( and ).
, , and ). The combined
the aquifer system ( and ). In some parts of the
-
( and ).
Development and Changes to the Hydrologic Budget 97
-
and ). Williamson and others (1989)
(
-
and ,
and terns
in the aquifer system are the same from the mid-1970s to
2003.
-
others, 1993) ( and
(

98 Groundwater Availability of the Central Valley Aquifer, California
-
and ). The increased
-
Land Subsidence
-
others (1999) compiled a summary on the phenomena of land
-
1991) (
-
-
-
other four processes (Williamson and others, 1989).
-
-
2
(
others, 1975).
2
2 in the
2
Ireland and others, 1984) (-
caused inelastic compaction of the clayey beds and resulted
( and
fraction of the total simulated aquifer-system compaction in
affected by subsidence (mented
that as much as 4 ft of subsidence has occurred in the
feet in the early 1990s (Ikehara, 1995).

A
11N/1E-24Q8
0 50 100Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
A
14S/12E-12H1
18S/16E-33A1
Development and Changes to the Hydrologic Budget 99
EXPLANATION
Area of subsidence due to compaction
of peat and based on field surveys in 1952
Area of subsidence due to compaction
of peat, more than 10 feet as of 1981
Area of subsidence due to hydrocompaction
Area of subsidence due to water-level
decline, more than 1 foot as of 2000
Historic lakes
Major land-subsidence area from Ireland, 1984.
Simulated subsidence 1962-2003, in feet
5
10
Central Valley boundary
Subsidence measurement locations
(extensometers)—Data for labeled
sites shown on figure 15B
13S/15E-31J3
B
17S/15E-14Q1
C
23S/25E-16N3
32S/28E-20Q1
Figure B15. A, Areal extent of land subsidence in the Central Valley (modified from figure 9 Thomas and Phoenix, 1976; figure 11
Bertoldi and others, 1991) and locations of extensometers. Contours show simulated subsidence for water years 1962-2003.
B, Compaction data from selected extensometers and total simulated pumpage in the Central Valley.

100 Groundwater Availability of the Central Valley Aquifer, California
GROUND MOVEMENT, IN FEET
B
Rebound
Subsidence
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
"Variable"
to
Dry
Figure B15. Continued.
"Variable"
to
Wet
1960 1970 1980
-
and subsidence (
(, , and
Dry Wet
Dry
YEAR
11N/1E-24Q8 17S/15E-14Q1
23S/25E-16N3
EXPLANATION
18S/16E-33A1
14S/12E-12H1 13S/15E-31J3
32S/28E-20Q1
Wet
1990 2000
Total simulated
pumpage for the
Central Valley
"Variable"
to
Dry
and ).
-
-
most areas (
20
15
10
5
0
SIMULATED PUMPAGE, IN MILLIONS OF ACRE-FEET PER YEAR

compaction and land subsidence in some areas (
and
). In some areas,
2004) (
-
-
-
” subsection
of the “” section.
Surface Water and the Environment
-
-
When water levels recover,
compaction and land subsidence can abate.
DEPTH-TO-WATER,
IN FEET BELOW LAND SURFACE
COMPACTION,
IN INCHES
200
400
600
12
0
Deep well
No data
1960 1970 1980
YEAR
Drought Drought
No data
1990
Development and Changes to the Hydrologic Budget 101
-
nation
of and
-
().
-
During the droughts of 1976-77 and
1987-91, deliveries of imported water
to the west side of the San Joaquin
Valley were cut back. More groundwater
was pumped to meet the demand, resulting
in a drop in the water table and
consequent compaction.
Some elastic expansion of the aquifer
system has occured but the compacted
materials can never return to their
pre-compacted thickness.
Figure B16. Measured compaction in relation to head decline in the San Joaquin Valley. The effects of drought on groundwater levels
and associated subsidence also are evident. (Modified from Galloway and others, 1999; and Swanson, 1998.)

102 Groundwater Availability of the Central Valley Aquifer, California
-
-
-
ter
resources.
Global Climate Change and Variability
-
Past Climates
-
-
-
-
north to south (
of total precipitation in the north as compared to the south,
Future Climate Projections
-
21 st -
to increase. Other indirect effects of a temperature increase
more than one crop in a season, and reduced milk production

-
in the 21 st
-
-
and drier at times, could place more stress on the reliability
-
(24 million people).
-
humidity could help offset some of the effects of an increase in
-
-
-
Groundwater Sustainability and Management 103
be affected.
Groundwater Sustainability and
Management
-
-
-
Groundwater Sustainability
sustainable is based, in part, on social and philosophical
that limit sustainability include physical, chemical, economic,
ter
sustainability.
(
-

104 Groundwater Availability of the Central Valley Aquifer, California
-
These related effects may constitute the primary constraint to
-
(
-
-
-
users (
-
by 50 percent as measured in tons of crops per acre foot of
-
-
-
-
Groundwater Management
-
-
-
(described in
options.

STREAMFLOW LEAKAGE, IN MILLIONS OF ACRE-FEET PER YEAR
9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0
-1.0
-2.0
-3.0
"Variable"
to
Dry
Representative water year
"Variable"
to
Wet
Typical
Figure B17. Streamflow gains and losses in the Central Valley between 1962 and 2003.
Groundwater Sustainability and Management 105
Dry Wet Dry
Wet
WATER YEAR
Dry Wet
"Variable"
to
Dry
-4.0
1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002
EXPLANATION
Surface-water loss to
groundwater system
Surface-water gain from
groundwater system

106 Groundwater Availability of the Central Valley Aquifer, California
-
-
to meet demand.
-
-
-
-
-
-
-
-
-
-
-
decadal to century timeframes to assess policy and capital
-
-
Conjunctive Use
-

-
-
-
-
-
-
considered.
-
-
-
Groundwater Sustainability and Management 107
The report states that a peripheral canal is a necessary compo-
Water Banking
-
-
-
-
-
). These

108 Groundwater Availability of the Central Valley Aquifer, California
-
habitat.
-
subsidence.
) and the
suitable. Other factors that need to be considered include local
-
compaction in these units.
Other Management Strategies
-
-
-
ability to monitor soil moisture and other crop-related data
ence
that has already occurred, additional subsidence can be
aquifer system compact inelastically and the land subsidence
becomes permanent (-
-
-
identify areas that most likely are susceptible to subsidence
others, 1999).

When long-term pumping
lowers ground water levels
and stresses on the aquitards
beyond the preconsolidationstress
thresholds, the
aquitards compact and the
land surface subsides
permanently.
CH 1 Critical head at time, t 1
CH 2 Critical head at time, t 2
h 1
h 2
h
t2 greater than t 1
Head in well at t1 Head in well at t2 b Total land subsidence,
which equals compressibility
times h
Difference in head,
(h2 minus h1) Water table
Monitoring the Hydrologic System
h
-
-
-
t 1
Land surface
Clay and silt
(aquitards)
Granular aquitard
skeleton defining
fluid-filled pore spaces
storing groundwater
h 1
CH 1
Land
surface
b
h2=CH2 Rearranged, compacted granular
aquitard skeleton with reduced
porosity and groundwater
storage capacity
Monitoring the Hydrologic System 109
Depth
to
water
When h 1 is greater than CH 1 , sediments are
overconsolidated with compression, and land
subsidence is predominately elastic and recoverable
When h 2 is equal to CH 2 , sediments are
normally consolidated with additional head
decline causing inelastic and nonrecoverable
land subsidence
Compaction of the aquifer system
is concentrated in the aquitards
Figure B18. Relationship of water-level changes and critical heads to subsidence and inelastic compaction.
t 2
Time
Long-term decline in water level
modulated by the seasonal cycles
of groundwater pumping
-

110 Groundwater Availability of the Central Valley Aquifer, California
-
-
of an aquifer system as it is affected by land use, climate, and
-
-
Groundwater
-
-
2001).
information used to constrain the model. These measure-
-
-

-
1.
2.
personnel to enter the property and measure the
3.
-
-
the subsurface and, in some cases, construction
4.
reach the end of their usefulness because the
-
-
analysis from different parts of the aquifer system. These data
formities
can cause permeability contrasts that tend to isolate
-
Monitoring the Hydrologic System 111
-
-
-
-
-
section of
this report.
Surface Water
-
-
)
-
-

112 Groundwater Availability of the Central Valley Aquifer, California
-
-
Subsidence
-
(
-
-
-
-
ence
from 1994 to 2007.
-
-
-
-
-
Water Quality
-
-
-
-

oron, nitrate, and pesticides are of concern and monitored
-
-
-
-
-
-
soil leaches selenium from the soil and transports it to shal-
-
is found in concentrations potentially harmful to plants in the
-
Williams, 1995). The source of the nitrate is attributed to
Monitoring the Hydrologic System 113
-
-
depth.
-
-
quality to the public.

114 Groundwater Availability of the Central Valley Aquifer, California
Land Use and Climate
-
to measure, it is commonly not measured or tabulated in the
-
-
-
-
-
-
-
(K
number of studies report K -
-
users.
Summary
-
upon to help rectify the imbalance.
-
-
aquifer-system compaction and associated land subsidence.

Summary 115
-
-
about 8.7 million acre-ft/yr.
-
-
-
-
-
-
-
-
declines.
-
-
5,200 mi 2
been affected by subsidence.

116 Groundwater Availability of the Central Valley Aquifer, California
-
-
-
-
-
has had substantial related consequences. These consequences
perature,
and land subsidence. In turn, these consequences
-
-
References Cited
-
-
15, 2009, at

-
-
-
http://
-
44 p.
-
p. 112-130.
-
-
-
References Cited 117
-
-
-
2009, at
http://www.
16, 2009, at
2009, at
2009, at
-
-
-

118 Groundwater Availability of the Central Valley Aquifer, California
-
-
http://
-
-
-
-
http://
-
-
at
-
-

References Cited 119
77 p.
-
2009, at
-
http://pubs.er.usgs.gov/usgspubs/pp/
-
-
-
-
-
-
-
-
-
-
2008, at
-
-
at

120 Groundwater Availability of the Central Valley Aquifer, California
-
16 p.
-
-
-
-
ley,
updated to 1995, -
-
-
-
, .
-

Chapter C. Numerical Model of the Hydrologic Landscape and
Groundwater Flow in California’s Central Valley
By Claudia C. Faunt, Randall T. Hanson, Kenneth Belitz, Wolfgang Schmid, Steven P. Predmore, Diane L.
Rewis, and Kelly McPherson
Introduction
-
Model Development
-
-
) has
made it possible to do more detailed and realistic simulations
2
model cells to 1 mi 2
-
10 layers and the uppermost layer is 50 ft thick. This more
-
monthly stress periods facilitate representation of the cyclical
-
-
-
described in more detail in (). The

122 Groundwater Availability of the Central Valley Aquifer, California
Table C1. MODFLOW-2000 packages and processes used with the hydrologic flow model of the Central Valley, California.
Table C1. MODFLOW-2000 packages and processes used with the hydrologic flow model of the Central Valley, California.—Continued
Computer program
(packages, processes,
parameter estimation)
Function Reference
-
Processes and Solver
- -
-
Files
Discretization
-
ary conditions of the model.
Aquifer Parameters
centers.
land subsidence
Boundary Conditions
Recharge and Discharge
others (2000)
multiple layers.
Output, Observations and Sensitivity
each time-step for subsidence, heads, and stream-
-

-
mated
parameter estimation. The parameter estimation code
-
-
-
of this report and in the
release notes and online documentation of the source code for
these model components.
Discretization
().
model cell.
Spatial Discretization and Layering
2
layers (
Model Development 123
). The top layer (layer 1) has an upper
-
described in more detail in .
-
-
-
deep.
(
than the model bottom and may be as much as 2,500 ft deep

124 Groundwater Availability of the Central Valley Aquifer, California
A
0
STUDY
AREA
C A L I F O R N I A
San
Francisco
Central
Valley
Pacific Ocean
Sierra Nevada
50 100 Miles
0 50 100 Kilometers
1
3
2
Stockton
Fault
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
Cascade Range
6
4
5
9
7
Coast Range
8
11
10
Sutter
Buttes
Sierra Nevada
12
13
A
A
14
EXPLANATION
Model cells representing—
12
16
15
A'
Active areas
General-head boundary in layers 1 and 2
Bedrock in some layers
San Joaquin Formation in some layers
Corcoran Clay in layers 4 and 5
Corcoran Clay over
San Joaquin Formation
Potential horizontal flow
barrier
Active model grid boundary
California Department of Water Resources
water-balance subregions and identifier. See
table A1 for names
Geologic section along model row 355
(See figure A11)
19
17
18
20
21
A'
Tehachapi Mts
White Wolf
Fault
Figure C1. Central Valley Hydrologic Model grid: A, Extent of San Joaquin Formation, Corcoran Member of the Tulare Formation,
crystalline bedrock, and horizontal flow barriers. B, Upper-most active layer.

B
0
50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
Figure C1. Continued.
Cascade Range
Coast Range
Sierra Nevada
EXPLANATION
Uppermost active layer—
1
2
3
6
Active model grid boundary
Model Development 125
California Department of Water Resources
water-balance subregions
Tehachapi Mts

126 Groundwater Availability of the Central Valley Aquifer, California
Table C2. Coordinates of the Central Valley Hydrologic Model grid.
Corner of
model grid
Model
coordinates
X (column)
-
-
-
for purposes of this study, are less critical. In addition, to
-
patterns simulated.
(
Temporal Discretization
Model
coordinates
Y (row)
Latitude
(DMS)
-
Longitude
(DMS)
-
Boundary Conditions
Albers coordinates
X (easting)
(meters)
Albers coordinates
Y (northing)
(meters)
1 1 1,890,733
Northeast 98 1 1,969,734
1 441 38,818 1,280,164
98 441 173,410 1,359,209
-
-
-
-
this chapter.

0
Suisun
Bay
50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
1
3
2
6
4
5
9
7
8
11
10
12
13
12
14
EXPLANATION
Model stream cell
Model general-head boundary cell
Active model boundary
Water-balance subregion receiving
non-routed deliveries
Diversion location
Inflow location
Model Development 127
California Department of Water Resources
water-balance subregions and identifier
Figure C2. Distribution of general-head boundary cells and major streams and canals with streamflow-routing cells (including location
of inflows and diversions). The water-balance subregions are described in .
16
15
19
17
18
20
21

128 Groundwater Availability of the Central Valley Aquifer, California
Specified-Flow Boundaries
). Where bedrock
-
).
Pumpage
-
Agricultural Pumpage
-
-
can be no direct determination of the accuracy of the different
-
-
-
-
-
-

0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
EXPLANATION
Area of Corcoran Clay
Model grid boundary
California Department of Water Resources
water-balance subregion
Pumping wells—
Perforated in layers 2 and/or 3
Model Development 129
Perforated in upper and lower parts of system
Perforated in all or parts of layers 6 through 9
Multi-node irrigation wells perforated in layers
2 and/or 3 and all or parts of layers 6 through 9
Multi-node urban wells perforated in layers
2 and/or 3 and all or parts of layers 6 through 9
Figure C3. Distribution of urban and agricultural wells simulated in the Central Valley Hydrologic Model.

130 Groundwater Availability of the Central Valley Aquifer, California
-
-
-
). In addition,
).
Urban Pumpage
1983) (
-
-
-
-
-

REPORTED URBAN GROUNDWATER PUMPAGE, IN THOUSANDS OF ACRE-FEET PER YEAR
2,000
1,800
1,600
1,400
1,200
1,000
800
600
400
200
0
1961
1964
1967
Recharge from and Discharge to the Delta
(
1970
1973
Tulare Basin
San Joaquin Valley
Sacramento Valley and Delta
1976
1979
Pumpage reported by U.S. Geological Survey
[Williams and others, 1989](1961 to 1977) for—
1982
YEAR
EXPLANATION
1985
1988
1991
Model Development 131
and remained constant for the entire simulation period. The
1994
Pumpage reported by California Department of
Water Resources (1961 to 2003) for—
Tulare Basin
San Joaquin Valley
Sacramento Valley and Delta
Figure C4. Urban pumpage from U.S. Geological Survey and California Department of Water Resources data (C. Brush, California
Department of Water Resources, written commun., February 21, 2007).
1997
2000
2003

132 Groundwater Availability of the Central Valley Aquifer, California
Recharge from and Discharge to Canals and
Streams
others, 2004) (-
,
-
).
Water-Table Simulation
table is deeper than 50 ft (
” sec-
(
-
Farm Process (FMP)
-
-
anced
for each simulation time step (-
.

nrd
wells
p
nrd
srdin
wells
egwin
tgwin
egwout
egwin
Precipitation
Non-routed deliveries
into farm
Semi-routed deliveries
into farm
Groundwater well pumping
deliveries into farm
Evaporation from groundwater
into the farm
Transpiration from groundwater
into the farm
Farm
Figure C5. Flow chart of water inflows to and outflows from a “farm” as simulated by the Farm Process (FMP).
ei
ep
ei
ep
egwout
ti
tp
p
dp
Aquifer
tp
EXPLANATION
ti
Evaporation from irrigation
out of the farm
Evaporation from precipitation
out of the farm
Evaporation from groundwater
out of the farm
Transpiration from irrigation
out of the farm
tgwout
tgwin
Transpiration from precipitation
out of the farm
srdout
srdin
tgwout
run
dp
srdout
Model Development 133
run
Transpiration from groundwater
out of the farm
Overland runoff out
of the farm
Deep percolation out
of the farm
Semi-routed deliveries
out of the farm
INFLOW
Streams
OUTFLOW
contains many optional simulation features, only some of the

134 Groundwater Availability of the Central Valley Aquifer, California
others, 2006a). In contrast to the micro-scale application in
-
-
-
-
cussed
in
-
-
-
-
-
-
-
Delivery Requirement
components estimated from both the landscape (predominantly
crop.

Soils
). The
-
Land Use
-
-
-
-
in the model on a cell-by-cell basis and include urban and
2 model
Model Development 135
-
-
-
).
(
detailed (-
-
1973, 1992, 1998, and 2000 (
simplicity, the land-use maps are named for the year the map
,
,
more permanent or more established crop types mapped more
in the earlier maps on the basis of the most recent land-use
period (2000 land use).

136 Groundwater Availability of the Central Valley Aquifer, California
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
EXPLANATION
Agricultural soil classes and (capillary fringe)
used in Farm Process—
Sandy loam (9.1 feet)
Silty clay (7.1 feet)
Silt (9.3 feet)
Active model boundary
California Department of Water Resources
water-balance subregion
Figure C6. Agricultural soils for the Central Valley, California, derived from STATSGO data (U.S. Department of Agriculture Natural
Resources Conservation Service, 2005b).

CUMULATIVE DEPARTURE OF PRECIPITATION, IN INCHES PER YEAR
50
40
30
20
10
0
-10
-20
-30
-40
-50
-60
-70
-80
Red Bluff
Davis
Fresno
TIME, IN YEARS
Bakersfield
Pacific Decadal Oscillation (PDO) Index
24 month moving average
Figure C8
4/61-3/68
EXPLANATION
Annual cumulative departure of precipitation—
Model Development 137
Time frame land-use maps were applied
Figure C9
4/68-3/78
Figure C10
4/78-3/93
"Variable"
"Variable"
Dry W to
Wet Dry Wet Dry Wet Dry
to Wet D Wet Dry Wet
et
ry
Dry
Dry
Figure C11 Figure C12
4/93-3/99 4/99-9/03
3.0
1875 1885 1895 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005
Figure C7. Cumulative departure of precipitation, Pacific Decadal Oscillation (PDO) Index, climate windows, and time frame land-use
maps were applied.
"Variable"
to
Dry
2.0
1.0
0.0
-1.0
-2.0
-3.0
PACIFIC DECADAL OSCILLATION (PDO) INDEX, UNITLESS

138 Groundwater Availability of the Central Valley Aquifer, California
Table C3. Land-use periods with acreage in square miles and percentage of different virtual crop categories.
Area (square miles) Percentage of active model area Grouping of
other classes1 1961 1973 1992 1998 2000 1961 1973 1992 1998 2000
Irrigated
Description
1. Water No 105 124 160 347 162 1 1 1 2 1 n/a
2 . Urban No 641 765 1,043 894 1,528 3 4 5 4 7 n/a
2 No 7,355 4,809 6,237 5,102 6,639 36 23 30 25 32 n/a
Yes n/a 312 553 263 n/a n/a 2 3 1 n/a 10,12,16
Yes n/a n/a 1,799 589 n/a n/a n/a 9 3 n/a 13,14
Yes n/a n/a 1,265 n/a n/a n/a n/a 6 n/a n/a 9,11,18
Yes n/a n/a 634 n/a n/a n/a n/a 3 n/a n/a 11,14,17
2 Yes 241 104 1 n/a 372 1 1

Virtual Crop Maps
(“1960” land-use map,
sented
in the simulation period from 1961 to 1968) uses
-
-
(
Model Development 139
-
-
spatial patterns of land use, there are discrepancies across
-
-
1973 to 1992 land-use maps.
map,
-
-
-
-
-

140 Groundwater Availability of the Central Valley Aquifer, California
16
15
17
14
18
13
12
19
11
1 2
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
10
Fraction of total area by land-use type
1
9
2
3
8
6
4
3
5
9
7
8
11
12
10
14
13
EXPLANATION
Land use—1961-68
Land use type—
1 Water
2 Urban
3 Native vegetation
4 Orchard, groves and vineyards (none shown)
5 Pasture/Hay (none shown)
6 Row crops (none shown)
7 Small grains (none shown)
8 Idle/fallow
9 Truck, nursery and berry crops
10 Citrus and subtropical
11 Field crops
12 Vineyards
13 Pasture
14 Grain and hay
15 Feed lots and diaries
16 Deciduous fruits and nuts
17 Rice
18 Cotton
19 Developed
20 Cropland and pasture (none shown)
21 Cropland (none shown)
22 Irrigated row and field crops (none shown)
16
15
19
Water-balance subregion boundaries
and identifier—See table C1
Active model grid boundary—
See figure C1
Figure C8. Virtual crops for 1960 (modified with 2000 data), including pie chart of percentage of different virtual crops (sources:
California Department of Water Resources, 2000; California State University, Chico, 2003;). The water-balance subregions are described
in .
17
18
20
21

18
17
16
20
14
13
1 2
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
12
1
11
2
3
10
Fraction of total area by land-use type
9
6
4
4
8
5
3
9
7
8
Model Development 141
EXPLANATION
Land use—1968-78
Land use type—
1 Water
2 Urban
3 Native vegetation
4 Orchard, groves and vineyards
5 Pasture/Hay (none shown)
6 Row crops (none shown)
7 Small grains (none shown)
8 Idle/fallow
9 Truck, nursery and berry crops
10 Citrus and subtropical
11 Field crops
12 Vineyards
13 Pasture
14 Grain and hay
15 Feed lots and diaries (none shown)
16 Deciduous fruits and nuts
17 Rice
18 Cotton
19 Developed (none shown)
20 Cropland and pasture
21 Cropland (none shown)
22 Irrigated row and field crops (none shown)
Water-balance subregion boundaries
and identifier—See table C1
Active model grid boundary—
See figure C1
Figure C9. Virtual crops for 1973, including pie chart of percentage of different virtual crops (sources: U.S. Geological Survey, 1990;
California Department of Water Resources, 2000). The water-balance subregions are described in .
11
12
10
14
13
16
15
19
17
18
20
21

142 Groundwater Availability of the Central Valley Aquifer, California
14
13
12
16
11
10
17
9
7
18
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
6
1 2
Fraction of total area by land-use type
1
5
2
3
4
6
4
5
3
9
7
8
EXPLANATION
Land use—1978-93
1
Land use type—
Water
2 Urban
3 Native vegetation
4 Orchard, groves and vineyards
5 Pasture/Hay
6 Row crops
7 Small grains
8 Idle/fallow (none shown)
9 Truck, nursery and berry crops
10 Citrus and subtropical
11 Field crops
12 Vineyards
13 Pasture
14 Grain and hay
15 Feed lots and diaries (none shown)
16 Deciduous fruits and nuts
17 Rice
18 Cotton
19 Developed (none shown)
20 Cropland and pasture (none shown)
21 Cropland (none shown)
22 Irrigated row and field crops (none shown)
Water-balance subregion boundaries
and identifier—See table C1
Active model grid boundary—
See figure C1
Figure C10. Virtual crops for 1992, including pie chart of percentage of different virtual crops (sources: Gilliom and others, 2006;
California Department of Water Resources, 2000). The water-balance subregions are described in table A1.
11
12
10
14
13
16
15
19
17
18
20
21

land-use map,
-
-
-
crop maps.
use map,
-
from the late 1990s, this type of map also lacks the temporal
terns,
there are some discrepancies across county boundaries.
-
urban (
-
In contrast, 11 percent of the crop land, predominantly on
Model Development 143
the southeast side, is planted in deciduous fruit and nut trees,
-
Crop-Type Data
-
-
-
-
. There is
-
). The
-
-
-

144 Groundwater Availability of the Central Valley Aquifer, California
18
17
16
21
22
1 2
9
14
10
13 12 11
Fraction of total area by land-use type
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
1
2
3
6
4
3
5
5
4
9
7
8
11
12
10
14
13
16
15
19
EXPLANATION
Land use—1993-99
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
17
Land use type—
Water
Urban
Native vegetation
Orchard, groves and vineyards
Pasture/Hay
Row crops (none shown)
Small grains (none shown)
Idle/fallow (none shown)
Truck, nursery and berry crops
Citrus and subtropical
Field crops
Vineyards
Pasture
Grain and hay
Feed lots and diaries (none shown)
Deciduous fruits and nuts
Rice
Cotton
Developed (none shown)
Cropland and pasture (none shown)
Cropland
Irrigated row and field crops
Water-balance subregion boundaries
and identifier—See table C1
Active model grid boundary—
See figure C1
Figure C11. Virtual crops for 1998, including pie chart of percentage of different virtual crops (sources: Davis and others, 1998;
California Department of Water Resources, 2000). The water-balance subregions are described in .
18
20
21

14
16
13
17
12
18
11
1 2
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
10
Fraction of total area by land-use type
9
1
2
8
3
6
4
5
3
9
7
8
11
12
10
14
13
16
15
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
19
EXPLANATION
Land use—1999-2003
Land use type—
Model Development 145
Water
Urban
Native vegetation
Orchard, groves and vineyards (none shown)
Pasture/Hay (none shown)
Row crops (none shown)
Small grains (none shown)
Idle/fallow
Truck, nursery and berry crops
Citrus and subtropical
Field crops
Vineyards
Pasture
Grain and hay
Feed lots and diaries (none shown)
Deciduous fruits and nuts
Rice
Cotton
Developed (none shown)
Cropland and pasture (none shown)
Cropland (none shown)
Irrigated row and field crops (none shown)
Water-balance subregion boundaries
and identifier—See table C1
Active model grid boundary—
See figure C1
Figure C12. Virtual crops for 2000, including a pie chart of percentage of different virtual crops (California Department of Water
Resources, 2000). The water-balance subregions are described in
17
18
20
21

146 Groundwater Availability of the Central Valley Aquifer, California
Table C4. Summary of Central Valley, California, virtual crop categories and properties.
Virtual-crop
crop category
(number)
Root depth,
in feet
Anoxia
).
-
-
pears, apricots, cherries, and other miscellaneous deciduous
trees.
Root uptake pressure heads, in feet Fraction of
surface-water
Lower optimal
range
Upper optimal
range
Wilting
runoff from
precipitation
/irrigation
(dimensionless)
Water (1) 3.6 1.6 0.3 0.05/0.01
Urban (2) 2.0 0.01/0.01
10.6 1.6 0.4 0.21/0.01
6.0 0.10/0.01
5.3 0.10/0.02
8.3 0.10/0.06
4.0 0.10/0.04
5.3 0.06/0.01
Truck, nursery, and berry crops (9) 6.3 0.10/0.10
4.0 0.10/0.01
4.0 0.10/0.08
5.0 0.01/0.01
5.3 0.0 0.10/0.02
4.0 0.10/0.04
3.6 0.32/0.35
poultry farms) (15)
6.0 0.11/0.05
5.3 1.6 0.4 0.01/0.03
9.3 0.10/0.10
5.3 0.10/0.08
4.9 0.10/0.08
6.3 0.10/0.08
4.9 0.10/0.07
-
-
-
-
-
months of the year ().

CROP COEFFICIENT BY LAND-USE TYPE, UNITLESS
A
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
in the simulations tabulated in
Model Development 147
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
Land use type—
Water
Urban
Native vegetation
Orchard, groves and vineyards
MONTH
EXPLANATION
Pasture/hay
Row crops
Small grains
Idle/fallow
Figure C13. Monthly crop coefficients for virtual crops in the Central Valley, California (sources: Brouwer and others, 1985; Brouwer
and Heibloem, 1986; Snyder and others, 1987a; Snyder and others, 1987b; Allen and others, 1998; Brush and others, 2004).

148 Groundwater Availability of the Central Valley Aquifer, California
CROP COEFFICIENT BY LAND-USE TYPE, UNITLESS
B
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
Figure C13. Continued.
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
Land use type—
time period in .
-
-
MONTH
EXPLANATION
Truck, nursery and berry crops
Citrus and subtropical
Field crops
Vineyards
Pasture
Grain and hay
Feed lots and dairies
-

1.40
1.20
1.00
0.80
0.60
0.40
CROP COEFFICIENT BY LAND-USE TYPE, UNITLESS C
0.20
0.00
Figure C13. Continued.
-
-
Model Development 149
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
Land use type—
Deciduous fruits and nuts
Rice
Cotton
Developed
MONTH
EXPLANATION
Cropland and pasture
Cropland
Irrigated row and field crops
-
-

150 Groundwater Availability of the Central Valley Aquifer, California
Table C5. Summary of fractions of transpiration and evaporation by month for Central Valley, California, virtual crops.
Table C5. Summary of fractions of transpiration and evaporation by month for Central Valley virtual crops.—Continued
Virtual-crop
crop category
(number)
January
(Ftr/Fep/Fei)
February
(Ftr/Fep/Fei)
March
(Ftr/Fep/Fei)
April
(Ftr/Fep/Fei)
May
(Ftr/Fep/Fei)
June
(Ftr/Fep/Fei)
Water (1) 0.00/1.00/1.00 0.00/1.00/1.00 0.00/1.00/1.00 0.00/1.00/1.00 0.00/1.00/1.00 0.00/1.00/1.00
Urban (2) 0.25/0.75/0.02 0.25/0.75/0.02 0.25/0.75/0.02 0.25/0.75/0.02 0.25/0.75/0.02 0.25/0.75/0.02
0.28/0.72/0.72 0.28/0.72/0.72 0.66/0.34/0.34 0.66/0.34/0.34 0.66/0.34/0.34 0.66/0.34/0.34
0.20/0.80/0.80 0.20/0.80/0.80 0.37/0.63/0.63 0.23/0.77/0.77 0.46/0.54/0.54 0.47/0.53/0.53
0.50/0.50/0.50 0.50/0.50/0.50 0.50/0.50/0.50 0.50/0.50/0.50 0.72/0.28/0.28 0.88/0.12/0.12
0.11/0.89/0.89 0.11/0.89/0.89 0.11/0.89/0.89 0.09/0.91/0.91 0.36/0.64/0.64 0.46/0.54/0.54
0.00/1.00/1.00 0.00/1.00/1.00 0.00/1.00/1.00 0.00/1.00/1.00 0.00/1.00/1.00 0.00/1.00/1.00
0.00/1.00/0.00 0.00/1.00/0.00 0.00/1.00/0.00 0.00/1.00/0.00 0.00/1.00/0.00 0.00/1.00/0.00
Truck, nursery, and berry crops (9) 0.80/0.20/0.18 0.80/0.20/0.18 0.39/0.61/0.61 0.44/0.56/0.36 0.42/0.58/0.38 0.80/0.20/0.18
0.27/0.73/0.73 0.27/0.73/0.73 0.46/0.54/0.14 0.46/0.54/0.14 0.46/0.54/0.14 0.46/0.54/0.14
0.01/0.99/0.99 0.01/0.99/0.99 0.01/0.99/0.99 0.15/0.85/0.85 0.15/0.85/0.85 0.94/0.06/0.06
0.00/1.00/0.03 0.00/1.00/0.03 0.28/0.72/0.22 0.40/0.60/0.10 0.38/0.62/0.12 0.36/0.64/0.14
0.18/0.82/0.82 0.15/0.85/0.85 0.46/0.64/0.64 0.91/0.09/0.03 0.91/0.09/0.03 0.91/0.09/0.03
0.46/0.54/0.54 0.92/0.08/0.08 0.92/0.08/0.08 0.92/0.08/0.08 0.23/0.77/0.77 0.00/1.00/1.00
0.00/1.00/1.00 0.00/1.00/1.00 0.00/1.00/1.00 0.00/1.00/1.00 0.00/1.00/1.00 0.00/1.00/1.00
0.10/0.90/0.90 0.10/0.90/0.90 0.10/0.90/0.90 0.50/0.50/0.50 0.50/0.50/0.50 0.97/0.03/0.03
0.20/0.80/0.50 0.20/0.80/0.50 0.20/0.80/0.50 0.75/0.25/0.25 0.75/0.25/0.25 0.80/0.20/0.10
0.75/0.25/0.25 0.75/0.25/0.25 0.75/0.25/0.25 0.43/0.57/0.17 0.75/0.25/0.20 0.75/0.25/0.20
0.30/0.70/0.67 0.30/0.70/0.67 0.22/0.78/0.78 0.16/0.84/0.84 0.42/0.58/0.38 0.85/0.15/0.15
0.00/1.00/1.00 0.00/1.00/1.00 0.00/1.00/1.00 0.00/1.00/1.00 0.20/0.80/0.80 0.30/0.70/0.70
0.05/0.95/0.85 0.05/0.95/0.85 0.05/0.95/0.55 0.05/0.95/0.55 0.05/0.95/0.95 0.05/0.95/0.85
0.05/0.95/0.55 0.05/0.95/0.55 0.05/0.95/0.75 0.05/0.95/0.75 0.20/0.80/0.78 0.85/0.15/0.10
Virtual-crop
crop category
(number)
July
(Ftr/Fep/Fei)
August
(Ftr/Fep/Fei)
September
(Ftr/Fep/Fei)
October
(Ftr/Fep/Fei)
November
(Ftr/Fep/Fei)
December
(Ftr/Fep/Fei)
Water (1) 0.00/1.00/1.00 0.00/1.00/1.00 0.00/1.00/1.00 0.00/1.00/1.00 0.00/1.00/1.00 0.00/1.00/1.00
Urban (2) 0.25/0.75/0.02 0.25/0.75/0.02 0.25/0.75/0.02 0.25/0.75/0.02 0.25/0.75/0.02 0.25/0.75/0.02
0.66/0.34/0.34 0.66/0.34/0.34 0.66/0.34/0.34 0.66/0.34/0.34 0.66/0.34/0.34 0.28/0.72/0.72
0.47/0.53/0.53 0.47/0.53/0.53 0.47/0.53/0.53 0.47/0.53/0.53 0.45/0.55/0.55 0.20/0.80/0.80
0.95/0.05/0.05 0.96/0.04/0.04 0.96/0.04/0.04 0.96/0.04/0.04 0.96/0.04/0.04 0.96/0.04/0.04
0.95/0.05/0.05 0.87/0.13/0.13 0.12/0.88/0.88 0.11/0.89/0.89 0.11/0.89/0.89 0.11/0.89/0.89
0.20/0.80/0.80 0.50/0.50/0.50 0.90/0.10/0.10 0.90/0.10/0.10 0.00/1.00/1.00 0.50/0.50/0.50
0.00/1.00/0.00 0.00/1.00/0.00 0.00/1.00/0.00 0.00/1.00/0.00 0.00/1.00/0.00 0.00/1.00/0.00
Truck, nursery, and berry crops (9) 0.80/0.20/0.18 0.80/0.20/0.18 0.80/0.20/0.18 0.80/0.20/0.18 0.80/0.20/0.18 0.80/0.20/0.18
0.46/0.54/0.14 0.46/0.54/0.14 0.46/0.54/0.14 0.46/0.54/0.14 0.46/0.54/0.14 0.46/0.54/0.14
0.94/0.06/0.06 0.94/0.06/0.06 0.90/0.10/0.10 0.01/0.99/0.99 0.01/0.99/0.99 0.01/0.99/0.99
0.36/0.64/0.14 0.36/0.64/0.14 0.36/0.64/0.14 0.36/0.64/0.14 0.36/0.64/0.14 0.38/0.62/0.12
0.96/0.04/0.04 0.91/0.09/0.03 0.91/0.09/0.03 0.46/0.64/0.64 0.15/0.85/0.85 0.15/0.85/0.85
0.00/1.00/1.00 0.00/1.00/1.00 0.00/1.00/1.00 0.00/1.00/1.00 0.16/0.84/0.84 0.35/0.65/0.65
0.00/1.00/1.00 0.00/1.00/1.00 0.00/1.00/1.00 0.00/1.00/1.00 0.00/1.00/1.00 0.00/1.00/1.00
0.97/0.03/0.03 0.97/0.03/0.03 0.97/0.03/0.03 0.10/0.90/0.90 0.10/0.90/0.90 0.10/0.90/0.90
0.75/0.25/0.25 0.60/0.40/0.27 0.20/0.80/0.50 0.20/0.80/0.50 0.20/0.80/0.50 0.20/0.80/0.50
0.75/0.25/0.20 0.75/0.25/0.20 0.47/0.53/0.33 0.36/0.64/0.44 0.75/0.25/0.25 0.75/0.25/0.25
0.90/0.10/0.10 0.90/0.10/0.10 0.90/0.10/0.10 0.50/0.50/0.50 0.30/0.70/0.70 0.30/0.70/0.67
0.85/0.15/0.15 0.95/0.05/0.05 0.90/0.10/0.10 0.50/0.50/0.50 0.00/1.00/1.00 0.00/1.00/1.00
0.05/0.95/0.85 0.75/0.25/0.25 0.95/0.05/0.05 0.94/0.06/0.06 0.93/0.07/0.07 0.00/1.00/1.00
0.95/0.05/0.05 0.95/0.05/0.05 0.60/0.40/0.15 0.04/0.96/0.04 0.10/0.90/0.50 0.10/0.90/0.50

Table C6. Average area-weighted composite efficiency for each
water-balance subregion of the Central Valley, California, through
the simulation period.
Waterbalance
subregion
Climate Data
1960s 1970s 1980s 1990s 2000s
1 70 68 73 76 74
2 70 68 72 75 73
3 74 74 79 82 83
4 71 70 74 78 79
5 73 72 78 80 80
6 69 69 74 77 77
7 71 69 73 77 77
8 69 69 75 78 75
9 69 70 76 79 78
10 69 72 78 80 79
11 70 70 76 78 77
12 71 70 74 77 76
13 71 72 77 80 79
14 68 73 82 86 87
15 67 69 75 76 76
16 72 72 78 79 81
17 72 72 77 79 80
18 71 72 77 79 79
19 68 72 78 79 77
20 72 73 78 81 81
21 71 73 79 81 81
-
Reference Evapotranspiration (ETo)
eter-based
equations or simple, empirical equations. The main
data required for the parameter-based equations (such as the
small number of parameters (usually air temperature and solar
Model Development 151
-
-
-
where,
T
T
⎛
ETh = 0. 0023Ra⎜
⎝
max
min
T + T ⎞⎛T
−T
max min max min
⎟⎜
2× 178 . ⎠⎝
2
is the maximum daily air temperature [ ° C],
is the minimum
daily air temperature [ ° C], and
Ra is the extraterrestrial
solar radiation
2
(megaJoule/m /day).
to be one of the simplest and most accurate of the empiri-
-
the center of each 1-mi 2
⎞
⎟
⎠

152 Groundwater Availability of the Central Valley Aquifer, California
-
-
-
Precipitation
tation
are obtained at a 1.24-mi spatial resolution from the
) indicates that the
monthly precipitation rate is interpolated for the center of each
1 mi 2 -
.
precipitation occurs, a part of this precipitation becomes
-
Surface-Water Supply
-
and ). In
and
-
). In order to compile multiple
-
Groundwater Supply
” section of this chapter), because the amount of
-
-

Water-
balance
subregion
Model Development 153
Table C7. Average reference evapotranspiration (ETo) by month for the Central Valley, California, for 1961–2003 based on temperature
data using the Hargreaves–Samani equation.
January February March April May June
1 1.13 1.79 2.43 3.68 5.00 6.32
2 1.24 1.93 2.61 3.91 5.15 6.32
3 1.39 2.15 2.91 4.22 5.34 6.55
4 1.36 2.18 2.92 4.22 5.35 6.58
5 1.28 2.08 2.81 4.14 5.32 6.54
6 1.28 2.14 2.77 4.06 5.19 6.34
7 1.15 1.96 2.65 4.00 5.24 6.45
8 1.29 2.14 2.84 4.04 5.17 6.22
9 1.24 2.09 2.79 4.01 4.98 5.94
10 1.63 2.33 3.11 4.16 5.26 6.40
11 1.53 2.43 3.16 4.24 5.35 6.44
12 1.53 2.37 3.16 4.28 5.37 6.48
13 1.75 2.54 3.29 4.39 5.57 6.72
14 1.72 2.40 3.18 4.33 5.43 6.57
15 1.61 2.32 3.15 4.39 5.51 6.60
16 1.70 2.50 3.30 4.49 5.76 6.99
17 1.70 2.51 3.30 4.52 5.72 6.79
18 1.90 2.70 3.46 4.64 5.77 6.80
19 2.10 2.62 3.33 4.38 5.38 6.48
20 2.21 2.73 3.41 4.34 5.38 6.53
21 2.28 2.70 3.31 4.19 5.13 6.24
Water-
balance
subregion
July August September October November December
1 6.79 5.98 4.71 2.62 1.34 0.91
2 6.69 5.96 4.75 2.79 1.51 1.06
3 6.97 6.23 4.98 3.02 1.78 1.35
4 7.14 6.36 5.05 3.06 1.79 1.40
5 6.92 6.15 4.86 2.94 1.68 1.18
6 6.52 5.89 4.80 2.96 1.74 1.14
7 6.74 6.00 4.76 2.82 1.60 0.98
8 6.53 5.82 4.69 2.94 1.80 1.25
9 6.09 5.45 4.54 2.88 1.75 1.10
10 6.65 5.87 4.89 3.15 1.96 1.41
11 6.93 6.16 4.99 3.20 2.10 1.72
12 6.77 6.02 4.92 3.18 2.01 1.48
13 7.16 6.40 5.30 3.46 2.20 1.73
14 6.67 5.91 4.86 3.26 2.03 1.52
15 6.74 6.04 4.93 3.34 2.05 1.42
16 7.36 6.65 5.32 3.47 2.23 1.73
17 7.20 6.61 5.23 3.51 2.26 1.76
18 7.11 6.52 5.30 3.60 2.38 1.93
19 6.58 5.99 4.98 3.40 2.24 1.83
20 6.63 6.02 5.02 3.38 2.29 1.95
21 6.33 5.76 4.88 3.32 2.28 1.96
-
-
used to satisfy the residual demand.

154 Groundwater Availability of the Central Valley Aquifer, California
Net Recharge
slope (
-
Hydraulic Properties
K) and thickness
-
member.
where
x
p
M ( x)=
n
⎛ 1
⎜
⎝
1
n p
p ⎞
∑ xk
⎟
k = 1
is the value being averaged (such as hydraulic
conductivity),
p is the averaging power-mean
exponent,
n is the number of elements being averaged, and
th
x is the k element in the list.
k
-
K ) and
K
where
F
ci ,
K
h,i
= + ⎡
⎣KF
K F
c c, i f f , i
is the fraction of coarse-grained
sediment
⎠
⎤
⎦
in a cell, estimated from sediment texture
data as described earlier in Chapter A, and
F isthe fraction
of fine-grained sediment in a
f , i
cell (1 Fci , ).
K is much smaller that K , the arithmetic mean
K and fraction of the coarse-
K 1/2 )
p th -
-
where
k
K vk
, + 1 2
F f k
, + 1 2
p
K = ⎡F
K F K
vk , + 1 ck , + 1 c +
f , k+
1
2 ⎣⎢ 2
2
represents the layer,
p
f
⎤
⎦⎥
1 p
isthe fraction of coarse-grained sediment
between layer midpoints, and
is the fraction of fine-grained
sediment
between layer midpoints.
,

p
-
-
-
p
p.
mean. K
RANGE IN HYDRAULIC CONDUCTIVITY, IN FEET PER DAY
1,000
100
10
1
0.1
0.01
0 20 40
PERCENTAGE COARSE-GRAINED DEPOSITS
EXPLANATION
Exponent of power mean—
-1.0
-0.8
-0.5
-0.3
0
0.5
1.0
Model Development 155
-
-3 ft/d
for silty clay to 13 ft/d for sand. Williamson and others (1989)
-
K ) to be
K ) to
be 4.010 -
(Harmonic mean)
(Geometric mean)
(Arithimetic mean)
60 80 100
Figure C14. Relation between hydraulic conductivity and percentage coarse-grained deposits based on hydraulic conductivity end
members and exponent of the power mean.

156 Groundwater Availability of the Central Valley Aquifer, California
K
10 ft/d (). The
mean (p
p
p).
about 6.610
10 10
5
-
-
10 to 1.510 -
-
10
10 -
is 5.210
10
6.210
Hydraulic Conductivity
in this study are K , K , and K
“” section of this chapter.
that affect the end-member K
K is 7.510 -2
K is 6.710 +2
K is 2.410 K is 3.310 +3 -
-
decrease the K
(see “
-
K ) is based on the coarse- and
-
aquifer system as opposed to the clayey lenses or interbeds
-
clays and the enhanced impedance caused by compaction
deposits about 4.810 ft/d (0.002 * 2.410 ft/d), close to the

Table C8. Measured and simulated hydraulic properties.
Model Development 157
[K K K
Hydraulic
property
Field and laboratory values Previously simulated values Values simulated in this study
c +21 31 to 104 ft/d2,3,4 +2
5 +3 f 5 to ft/d4 ft/d6 -2
5 -1 corc ft/d7 ft/d4 ft/d2 ft/d6 ft/d9
-2
-3 ous
simulations include borehole
p 4
0.25 to 0.65 5
0.0 to 0.35 5 4
0.02 to 0.20 9
-6 per ft per ft9 -6 per ft per ft9 -6 per ft
per ft5 per ft16 -6 per ft
per ft 15 per ft 9 per ft
1
2
3
4
5
6
7
8 Johnson and others (1968).
9 Williamson and others (1989).
10
11
12
13
14
15
16 Ireland and others (1984).

158 Groundwater Availability of the Central Valley Aquifer, California
).
-
situations, such data are scarce, depth decay is obscured by
is substantial. Taylor and others (2001) and Whittemore and
-
-
-
Storage Properties
-
-
-
and inelastic compressibilities of the aquifer-system material.
-
-
-
-
in and .
layer (
-

-
and others, 1991).
-
).
thicknesses are summed and multiplied by the compressibility
10 -6
-
-
Model Development 159
-
-
future use.
lated
as the product of the estimated elastic- and inelastic-spe-
-
-
-
10 to
210
8.610 -
fers
of 1.010
10
10 per foot.
-
10
4
10
-

160 Groundwater Availability of the Central Valley Aquifer, California
-
-
consolidation
stress represents the threshold stress that deter-
-
-
-
estimated by Williamson and others (1989). These heads are
-
Hydrogeologic Units
-
, the
-
-
(
Hydrogeologic Structures
ley
(
structures (
-
the model domain ().
Initial Conditions
-
and ).
of these and possibly other conditions, steady-state simulations
-
-
-
-

-
transient effects caused by imposition of the poorly estimated
-
to dissipate transient effects caused by inaccurate initial heads
-
Model Calibration and Sensitivity
-
-
-
Model Calibration and Sensitivity 161
-
in
-
-
Observations Used in Model Calibration
model calibration, often uses hydraulic head data as the sole or
data lead to a more accurate, rapid, and unique calibration.
-
-

162 Groundwater Availability of the Central Valley Aquifer, California
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
EXPLANATION
Model calibration—
Location of stream segments used
for model calibration
Location of wells used for model
calibration
Location of subsidence measurements
used for model calibration
Central Valley model boundary
Water-balance subregion
Figure C15. Distribution of calibration data (groundwater levels, gains and losses of streamflow, and subsidence observations).

Water-Level Altitudes, Water-Level Altitude
Changes, and Water-Level Altitude Maps
http://waterdata.usgs.
gov and
).
simulation period.
-
on the basis of perforation depths, completeness of record,
-
(
parameter estimation.
tudes
at a particular time, it is necessary to accurately simu-
Model Calibration and Sensitivity 163
in the northern part of the study area, increased dramatically in
-
-
10 7 10 ft 2 for the 42.5-year simulation period
-
possibly represent errors in the databases, measurements that
). In

164 Groundwater Availability of the Central Valley Aquifer, California
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
EXPLANATION
Active model grid boundary
Model streams and canals
Model water-balance subregion
Potential horizontal flow
barrier
Wells selected for spatial
and climate coverage
Wells selected for spatial
coverage
Wells selected for wet and dry period
coverage
Remaining wells with water-level
measurements between 1961 and 2003
Figure C16. Distribution of wells with water-level-altitude data for the simulation period 1961–2003, and location of wells selected for
model calibration. Only selected wells were used for calibration; other wells are shown to display the density of wells with water-level
measurements in simulation period.

SIMULATED HYDRAULIC HEAD, IN FEET
A
500
300
100
0
-100
-300
FREQUENCY
4,000
3,000
2,000
1,000
0
-150-75-60-45-30-15 0 15 30 45 60 75 150 More
RESIDUALS, IN FEET
1 to 1 correlation line
(-
represent quasi-static conditions.
). In
Model Calibration and Sensitivity 165
-500
-500 -300 -100 0 100
300 500
A
MEASURED WATER LEVELS, IN FEET
EXPLANATION
California Department of Water Resources water-balance subregions (See figure C1 for location)
CENTRAL VALLEY
Sacramento Delta and Eastside San Joaquin
Tulare
1
2
3
4
5
6
7
8
9
Figure C17. Plots of simulated water-level altitude values compared with the measured water-level altitudes for the A, Entire modeled
area (and with inset with histogram of residuals). B, Sacramento Valley. C, Delta and Eastside. D, San Joaquin Basin. E, Tulare Basin.
10
11
12
13
14
15
16
18
19
-
-
-
20
21

166 Groundwater Availability of the Central Valley Aquifer, California
SIMULATED HYDRAULIC HEAD, IN FEET
B
500
300
100
0
-100
-100
300
100
0
-100
D
-300
-100
Figure C17. Continued.
1 to 1 correlation line
0 100
300
1 to 1 correlation line
0 100
300
-100
500
-300
-300
southeastern part of the study area (
().
300
100
-100
-300
0
500
300
100
0
-100
0 100
300
-500
-300 -100
0 100
300 500
MEASURED WATER LEVELS, IN FEET
EXPLANATION
1 to 1 correlation line
California Department of Water Resources water-balance subregions (See figure C1 for location)
B Sacramento C Delta and Eastside D San Joaquin E Tulare
1
2
3
4
5
6
7
8
9
C
E
10
11
12
13
14
15
16
18
-
-
-
19
20
21

-
Water-Table and Potentiometric-Surface Maps
Water-table and potentiometric-surface maps for the
) (Williamson and others,
altitudes for the simulation.
( and
-
, 03b06329 and
-
Sacramento Valley
-
).
Model Calibration and Sensitivity 167
-
some of the climatic effects accurately (
potentiometric surface maps (
-
and mid-to-late 1990s (
-
-
of the system (-
Delta
dent
in the simulated potentiometric-surface maps ().
(
not in this area.

168 Groundwater Availability of the Central Valley Aquifer, California
A
Water-level difference, in feet,
simulated minus estimated (Williamson
and others, 1989)—
Equal to or less than -50.0
-49.9 to -25.0
-24.9 to 0.0
0.1 to 24.9
25.0 to 49.9
Equal to or greater than 50.0
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
Simulated water-level altitude,
in feet. Spring, 1976—
Model streams
and canals
EXPLANATION
Active model grid
boundary
Model water-balance
subregion
Figure C18. The simulated A, Water-table altitude in spring 1976. B, Potentiometric-surface altitude in spring 1976, for the calibrated
transient groundwater-flow model of the Central Valley. Residuals at observation points and areal differences between hand-drawn
altitude maps also are shown. Maps showing the simulated water-table altitude and potentiometric-surface altitude in spring of 2000
are shown in and .
-160
-120
-80
-40
0
40
80
120
160
200
240
280
320
360
400
440
480
Residual (Observed minus
Simulated), in feet—
-57.3 to -55
-54.9 to -50
-49.9 to -45
-44.9 to -40
-39.9 to -35
-34.9 to -30
-29.9 to -25
-24.9 to -20
-19.9 to -15
-14.9 to -10
-9.9 to -5
-4.9 to 5
5.1 to 10
10.1 to 15
15.1 to 20
20.1 to 25
25.1 to 30
30.1 to 35
35.1 to 40
40.1 to 45
45.1 to 50
50.1 to 55
55.1 to 60

B
Potentiometric-surface difference, in feet,
simulated minus estimated (Williamson
and others, 1989)—
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
Figure C18. Continued.
Equal to or less than -50.0
-49.9 to -25.0
-24.9 to 0.0
0.1 to 24.9
25.0 to 49.9
Equal to or greater than 50.0
Model Calibration and Sensitivity 169
Model streams
and canals
EXPLANATION
Simulated potentiometric-surface
altitude, in feet. Spring, 1976—
-160
-120
-80
-40
0
40
80
120
160
200
240
280
320
360
400
440
480
Active model grid
boundary
Model water-balance
subregion
Residual (Observed minus
Simulated), in feet—
-57.3 to -55
-54.9 to -50
-49.9 to -45
-44.9 to -40
-39.9 to -35
-34.9 to -30
-29.9 to -25
-24.9 to -20
-19.9 to -15
-14.9 to -10
-9.9 to -5
-4.9 to 5
5.1 to 10
10.1 to 15
15.1 to 20
20.1 to 25
25.1 to 30
30.1 to 35
35.1 to 40
40.1 to 45
45.1 to 50
50.1 to 55
55.1 to 60

170 Groundwater Availability of the Central Valley Aquifer, California
San Joaquin Valley
ships
().
().
-
-
aquifer system ( and
and ).
-
and ).
-
Tulare Basin
-
) indicate a
simulation period. On the southeastern side of the basin,
Streamflow Observations
-
-
-
in this area.

A
Stony Creek
Cache Creek
Putah Creek
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
Stanislaus
Tuolumne
Merced
San Joaquin
STREAMFLOW
Fresno
San Joaquin
Fresno Slough
Model Calibration and Sensitivity 171
EXPLANATION
Groundwater/surface-water interaction,
in acre-feet per year—
GAIN
LOSS
Kings River
-54.97 to -44.42
-44.39 to -14.81
-14.78 to -1.48
-1.45 to 0
0.03 to 1.48
1.51 to 14.81
14.84 to 44.42
44.45 to 113.07
Active model grid boundary
Model stream cells
Model water-balance subregions
Kaweah River
Kern River
Out of groundwater
system
Into groundwater
system
Figure C19. Distribution of stream gain/loss segments used for model calibration. A, Measured gaining and losing reaches for selected
stream reaches for 1961–1977. B, simulated gaining and losing reaches for selected stream reaches for 1961–1977 for the Central Valley,
California.

172 Groundwater Availability of the Central Valley Aquifer, California
B
Stony Creek
Cache Creek
Putah Cr ek
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
Figure C19. Continued.
Stanislaus
Tuolumne
Merced
San Joaquin
STREAMFLOW
GAIN
LOSS
Fresno
San Joaquin
Fresno Slough
EXPLANATION
Groundwater/surface-water interaction,
in acre-feet per year
Kings River
Less than -500
-500 to -100
-99.9 to -25
Active model grid boundary
Model water-balance subregions
Kaweah River
-24.9 to 0
0.1 to 25
25.1 to 100
100.1 to 500
Greater than 500
Kern River
Out of groundwater
system
Into groundwater
system

-
-
-
-
(-
Boundary Flow Observations
-
Model Calibration and Sensitivity 173
-
Subsidence Observations
-
-
and ).
-
-
).
-
-
). Uplift also
).
pared
to estimated-subsidence maps. The simulated subsidence
( and -
). In part, this subsidence likely is caused by the
the measured declines, in these areas.

174 Groundwater Availability of the Central Valley Aquifer, California
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
1
1
2
-1
3
5 7
4
7
4
3
1
5
4
8
6
3
EXPLANATION
Subsidence, in feet, from 1961 to 1975,
(Williamson and others, 1989). Negative
values indicate uplift—
1
2 2
1
Model streams and canals
3
-1 to 0
1
2 to 5
6 to 10
Active model grid boundary
Model water-balance subregion
Figure C20. Distribution of historical subsidence, estimated from 1961 to 1977 extensometer data, Central Valley, California (modified
from Williamson and others, 1989).
4
4
1
2
3

A
11N/1E-24Q8
1
1
1
1
12S/12E-16H2,3
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
1
1
14S/12E-12H1
1
10
14S/13E-11D6
15S/13E-11D2
16S/15E-34N1
17S/15E-14Q1
18S/16E-33A1
1
20S/18E-6D1
5
5
10
5
5
18S/16E-33A1
26S/23E-16H2, 3
5
5
10 10
20S/18E-6D1
5
Model Calibration and Sensitivity 175
EXPLANATION
Active model grid boundary
Model streams and canals
Model water-balance subregion
Simulated subsidence 1962-2003, in feet
1
5
10
Subsidence observation locations
13S/15E-31J3
13S/15E-35D5
15S/16E-31N3
5
10
5
10
5
10
1
18S/19E-20P2
5
23S/25E-16N1,3,4
22S/27E-30D2
24S/26E-34F1
24S/26E-36A2
25S/26E-1A2
32S/28E-20Q1
Figure C21. A, Distribution of total simulated subsidence for water years 1962 through 2003, and locations of subsidence measurements.
B, Aggregate compaction measured at, and simulated subsidence for, selected extensometer locations, Central Valley, California.

176 Groundwater Availability of the Central Valley Aquifer, California
B
SIMULATED SUBSIDENCE, IN FEET
7
0
10
20
11N/1E-24Q8
26
1960 1970 1980 1990 2000 2010
7
0
10
20
12S/12E-16H2
12S/12E-16H3
13S/15E-31J3
EXPLANATION
Simulated subsidence Measured subsidence
26
1960 1970 1980 1990 2000 2010
26
26
1960 1970 1980 1990 2000 2010 1960 1970 1980 1990 2000 2010
7
0
10
20
26
26
1960 1970 1980 1990 2000 2010 1960 1970 1980 1990 2000 2010
7
0
10
20
WATER YEAR WATER YEAR
7
0
10
20
7
0
10
20
7
0
10
20
13S/15E-35D5
14S/12E-12H1
14S/13E-11D6
15S/13E-11D2
26
26
1960 1970 1980 1990 2000 2010 1960 1970 1980 1990 2000 2010
Figure C21. Continued.
7
0
10
20

B (Cont.)
SIMULATED SUBSIDENCE, IN FEET
7
0
10
20
26
1960 1970 1980 1990 2000 2010
7
0
10
20
Figure C21. Continued.
EXPLANATION
Simulated subsidence Measured subsidence
Model Calibration and Sensitivity 177
18S/19E-20P2
26
1960 1970 1980 1990 2000 2010
20S/18E-6D1
26
26
1960 1970 1980 1990 2000 2010 1960 1970 1980 1990 2000 2010
7
0
10
20
22S/27E-30D2
26
26
1960 1970 1980 1990 2000 2010 1960 1970 1980 1990 2000 2010
7
0
10
20
15S/16E-31N3
16S/15E-34N1
17S/15E-14Q1
18S/16E-33A1
WATER YEAR WATER YEAR
7
0
10
20
7
0
10
20
7
0
10
20
23S/25E-16N1
26
26
1960 1970 1980 1990 2000 2010 1960 1970 1980 1990 2000 2010
7
0
10
20

178 Groundwater Availability of the Central Valley Aquifer, California
B (Cont.)
SIMULATED SUBSIDENCE, IN FEET
26
1960 1970 1980 1990 2000 2010
Figure C21. Continued.
7
0
10
20
7
0
10
20
23S/25E-16N4
24S/26E-34F1
EXPLANATION
Simulated subsidence Measured subsidence
25S/26E-1A2
26
1960 1970 1980 1990 2000 2010
26
26
1960 1970 1980 1990 2000 2010 1960 1970 1980 1990 2000 2010
7
0
10
20
26S/23E-16H3
26
26
1960 1970 1980 1990 2000 2010 1960 1970 1980 1990 2000 2010
7
0
10
20
24S/26E-36A2
23S/25E-16N3
WATER YEAR WATER YEAR
7
0
10
20
7
0
10
20
7
0
10
20
32S/28E-20Q1
26
26
1960 1970 1980 1990 2000 2010 1960 1970 1980 1990 2000 2010
7
0
10
20
26S/23E-16H2

-
-
), they likely
-
-
-
Pumpage Observations
-
-
-
Model Calibration and Sensitivity 179
). In particular, the
trends are matched. The simulation matches closely in drier
the proportions and total 21 million acre-ft of annual farm
(1989).
-
-
). This most likely is a
contradict this.
Water-Use Observations
most of the factors used in its calculation are indirect measure-
-
-
some cases, is less than those estimated by Williamson (1982).
), the amount of

180 Groundwater Availability of the Central Valley Aquifer, California
PUMPAGE, IN MILLIONS OF ACRE-FEET PER YEAR
16
12
8
4
Table C9. Estimated and Central Valley Hydrologic Model-simulated average and unit evapotranspiration of applied water (ETaw) for
the Central Valley, California.
Basin
"Variable"
to
Dry
"Variable"
to
Wet
Area
(square
miles)
Dry
Wet Dry
Wet
Estimated unit (average)
ETaw 1957–1961 ETaw 1966-–1973 ETaw 1968–1978
"Variable"
to
Dry
0
1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002
Simulated ETaw
average
(1962–2003)
5,981 2.4 (2.49) 2.3 (2.84) 1.9 (3.04) 1.8 (2.20)
2,388 2.2 (1.86) 2.1 (1.96) 1.8 (1.91) 1.9 (1.00)
3,782 2.5 (2.76) 2.0 (2.48) 2.3 (3.16) 2.3 (2.90)
7,780 2.1 (4.46) 2.2 (6.390) 2.2 (7.13) 2.3 (8.20)
19,389 2.3 (11.57) 2.1 (13.67) 2.1 (15.24) 2.1( 14.30)
YEAR
EXPLANATION
Simulated agricultural
Estimated from
power usage
Figure C22. Agricultural pumpage from 1961–77 estimated from power records (Diamond and Williamson, 1983) compared to Central
Valley Hydrologic Model simulated agricultural pumpage for the Central Valley, California.

Water-Delivery Observations
).
Model Parameters
-
-
Model Calibration and Sensitivity 181
less than ten estimated at any one time. These parameters
included hydraulic properties of the aquifer system, streambed
(
mated
parameters.
-
-
” section
of this report, K h and K v
K and K
K h
K v
initial calibration efforts, the same end-member hydraulic con-
K and K
mean (
system there (). The estimated end-member hydraulic
().

182 Groundwater Availability of the Central Valley Aquifer, California
A
B
SURFACE-WATER DELIVERIES, IN MILLIONS OF ACRE-FEET PER YEAR
SURFACE-WATER DELIVERIES, IN THOUSANDS OF ACRE-FEET PER YEAR
1.6
1.2
0.8
0.4
"Variable"
to
Dry
"Variable"
to
Wet
Dry
Wet Dry
Wet
"Variable"
to
Dry
0
1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002
300
250
200
150
100
50
0
YEAR
1977 1978 1979 1980 1981 1982 1983 1984
WATER YEAR
EXPLANATION
Deliveries taken (modeled) Deliveries available
Figure C23. A, Annual water deliveries. B, monthly water deliveries from the mid 1970s to mid 1980s for water-balance subregion 14.

CROP COEFFICIENT, UNITLESS
1.20
1.00
0.80
0.60
0.40
0.20
0.00
JAN FEB MAR APR MAY JUN
MONTH
EXPLANATION
K
model layers and 0.5, 0.37, 0.24, 0.15, and 0.08 for layers
).
and
-
-
Single cropped
Double cropped
Figure C24. Single and double cropped crop coefficient values for truck crops.
Model Calibration and Sensitivity 183
JUL AUG SEP OCT NOV DEC
-
). Trends in subsidence
that are inaccurately simulated indicate some error in the
eter
to estimate accurately.
-

184 Groundwater Availability of the Central Valley Aquifer, California
A
B
EVAPOTRANSPIRATION, IN INCHES
EVAPOTRANSPIRATION, IN INCHES
12
10
8
6
4
2
0
12
10
8
6
4
2
0
TRUCK CROPS
JAN FEB MAR APR MAY JUN
COTTON CROPS
JAN FEB MAR APR MAY JUN
MONTH
MONTH
EXPLANATION
Crop evapotranspiration
JUL AUG SEP OCT NOV DEC
JUL AUG SEP OCT NOV DEC
Adjusted evapotranspiration
Figure C25. Original and adjusted crop coefficient values for truck and cotton crops.

Table C10. Parameter values estimated for the Central Valley Hydrologic Model.
Table C10. Parameter values estimated for the Central Valley Hydrologic Model.—Continued
Parameter
name
Parameter
description
Value Units
Model Calibration and Sensitivity 185
Estimated
using
automated
methods
Composite
scaled
sensitivity
Parameter
group
Land-use Properties
10.55 feet yes 1.37
for urban land-use class
class
for idle land-use class
class
deciduous land-use class
rice land-use class
citrus land-use class
pasture land-use class
class
truck crop land-use class
deciduous land-use class
rice land-use class
cotton land-use class
other land-use class
properties
0.98 multiplier yes 1.1810 2
properties
1.18 multiplier yes 2.2010 1
properties
Runoff
5.00 yes 1.671010
properties
1.50 yes 1.23
properties
20.71 yes 3.76
properties
10.25 yes 1.41
properties
6.04 yes 1.38
properties
1.30 yes 3.64
properties
32.29 yes 6.67109
properties
10.67 yes 1.34
properties
10.62 yes 3.52
properties
1.00 yes 1.23
properties
1.72 yes 2.671011
properties
6.08 yes 1.01
properties
4.46 yes 1.23
properties
10.00 yes 1.40
properties
7.72 yes 1.24
properties
1.20 yes 1.40
properties
4.82 yes 3.66
properties
3.00 yes 1.001010
properties
10.16 yes 2.001010
properties
7.76 yes 1.28
properties

186 Groundwater Availability of the Central Valley Aquifer, California
Table C10. Parameter values estimated for the Central Valley Hydrologic Model.—Continued
Parameter
name
Parameter
description
Value Units
Estimated
using
automated
methods
Composite
scaled
sensitivity
Parameter
group
Soil Properties
9.08 feet yes 3.51
silty-clay
properties
7.10 feet yes 1.12
properties
9.32 feet yes 3.81
sandy-loam
properties
Irrigation efficiency
0.971 multiplier yes 2.4710
1964
1
properties
0.991 multiplier yes 1.5310
1977
10
properties
1.030 multiplier no 6.7510
1
properties
1.040 multiplier no 2.46
properties
1.050 multiplier no 2.42
properties
1.060 multiplier no 1.86
properties
1.065 multiplier no 3.06
properties
1.070 multiplier no 6.66
properties
1.074 multiplier yes 1.3210
2003
1
properties
60.30 yes 4.51
properties
80.00 yes 1.21
properties
Hydraulic Conductivity
672.93 feet/day yes 4.091011
0.24 feet/day yes 1.26101
4921.50 feet/day yes 2.71
0.08 feet/day yes 4.42
1.57 feet/day yes 4.17107
0.17 feet/day yes 1.33
multipliers
the dissected uplands
0.68 feet/day yes 1.40101
1.57 feet/day yes 1.26
bedrock
multipliers

Table C10. Parameter values estimated for the Central Valley Hydrologic Model.—Continued
Parameter
name
Parameter
description
Value Units
Model Calibration and Sensitivity 187
Estimated
using
automated
methods
Composite
scaled
sensitivity
Parameter
group
0.17 feet/day yes 2.64
multipliers
0.68 feet/day yes 1.93
the dissected uplands
multipliers
Multiplier on hydraulic properties of Corcoran Clay
0.010 multiplier yes 1.35
multipliers
0.002 multiplier yes 7.45
multipliers
Horizontal Conductivity Depth Decay
1.000 multiplier no 2.35
multipliers
1.000 multiplier no 1.8310
11
multipliers
0.181 multiplier yes 2.0810
14)
10
multipliers
0.914 multiplier yes 1.46
multipliers
0.614 multiplier yes 3.8410
11
multipliers
0.100 multiplier no 9.59
multipliers
0.370 multiplier no 4.1910
1
multipliers
0.240 multiplier no 1.0010
11
multipliers
0.075 multiplier no 8.59
multipliers
0.240 multiplier no 4.1710
1
multipliers
0.180 multiplier no 4.1710
10
multipliers
- 0.060 multiplier no 4.36
multipliers
0.150 multiplier no 1.52
multipliers
0.040 multiplier no 1.84
multipliers
0.040 multiplier no 3.14
multipliers
0.080 multiplier no 1.0010
11
multipliers
0.020 multiplier no 1.73
multipliers
0.020 multiplier no 1.4210
11
multipliers

188 Groundwater Availability of the Central Valley Aquifer, California
Table C10. Parameter values estimated for the Central Valley Hydrologic Model.—Continued
Parameter
name
Parameter
description
Value Units
Estimated
using
automated
methods
Composite
scaled
sensitivity
Parameter
group
Vertical Conductivity Depth Decay
1.000 multiplier no 1.61
multipliers
1.000 multiplier no 5.94
multipliers
0.180 multiplier no 2.18
14)
multipliers
0.663 multiplier yes 1.67
multipliers
0.463 multiplier yes 5.34
multipliers
0.150 multiplier no 1.61
multipliers
0.370 multiplier no 1.40
multipliers
0.200 multiplier no 2.14
multipliers
0.100 multiplier no 1.53
multipliers
0.240 multiplier no 1.62
multipliers
0.150 multiplier no 1.78
multipliers
0.060 multiplier no 1.66
multipliers
0.150 multiplier no 1.94
multipliers
0.040 multiplier no 4.1710
10
multipliers
0.040 multiplier no 1.51
multipliers
0.080 multiplier no 4.0010
11
multipliers
0.020 multiplier no 2.52
multipliers
0.020 multiplier no 1.2510
10
multipliers

Table C10. Parameter values estimated for the Central Valley Hydrologic Model.—Continued
Parameter
name
Parameter
description
Value Units
Model Calibration and Sensitivity 189
Estimated
using
automated
methods
Composite
scaled
sensitivity
Conductance
3281.00 feet/day no 1.36
Stream Bed Hydraulic Conductivity
Parameter
group
0.04 feet/day yes 1.70
0.16 feet/day yes 1.101011
0.48 feet/day yes 4.58
2.71 feet/day yes 1.49
0.33 feet/day yes 1.21
5.64 feet/day yes 2.3710 11
3.31 feet/day yes 1.3310 10
0.19 feet/day yes 1.40
Storage Properties
1.33 multiplier yes 5.93
deposits
25.00 no 1.26
deposits
50.00 no 2.371011
dissected uplands
1.00 multiplier yes 3.33109
1.00 multiplier yes 5.73
1.37E-04 per foot yes 6.67109

190 Groundwater Availability of the Central Valley Aquifer, California
0 50 100 Miles
0 50 100 Kilometers
Shaded relief derived from U.S. Geological Survey
National Elevation Dataset, 2006. Albers Equal Area Conic Projection
EXPLANATION
Stream cell hydraulic conductivity,
in feet per day—
0.0413406
0.0564332
0.16405
0.193579
0.326131
0.3281
0.479026
0.588939
1.29271
2.71358
3.31381
5.63676
32.81
328.133
(K_SACRIVN)
(K_TRIB_NWB)
(K_SACRIV)
(K_TRIB_SW)
(K_TRIB_NE)
(K_OTHER1)
(K_SJRIV)
(K_TRIB_SEB)
(K_TRIB_NEB)
(K_SO_RIV)
(K_TRIB_SE)
(K_TRIB_NW)
(K_OTHER2)
(K_TRIB_SEC)
Active model grid boundary
Model water-balance subregions
Inflow locations
Figure C26. Distribution of cells used for streams, colored by streambed hydraulic conductivity values for cells estimated during
calibration.

Sensitivity Analysis
-
limited the use of systematic parameter-estimation techniques
-
estimation techniques based on perturbation approaches for
used to identify the parameters to include in the parameter
-
-
(
K -
-
-
-
Simulation Results and Budget 191
Simulation Results and Budget
-
42-year simulation. This chapter focuses on the simulation of
are the focus of .
aquifer-system compaction and land subsidence.
( and

192 Groundwater Availability of the Central Valley Aquifer, California
COMPOSITE SCALED SENSITIVITY, UNITLESS
10 12
10 10
10 8
10 6
10 4
10 2
10 0
KC
VK_LN10_VF
HK_LS6_VF
PAS_IRO
K_TRIB_NW
PHI_F
Recharge and Discharge
-
HK_US_VF
HK_WS10_VF
K_SACRIVN
HK_LN10_VF
HK_LS7_VF
HK_LS8_VF
Parameter groups—
VK_LS9_VF
Hydraulic conductivity
HK_UWS_VF
COT_IRO
H2O_PRO
EFF_MLT2
PARAMETER IDENTIFIER
Hydraulic conductivity multipliers
Farm process properties
EXPLANATION
K_TRIB_SE
RIC_IRO
SEM_PRO
Storage properties
SUB_I
Streambed conductance
Figure C27. Relative composite sensitivity of computed water-level altitudes, flows, and subsidence information at calibration points to
changes in parameters. Composite scaled sensitivity values are used here to show relative sensitivity; the definition and derivation are
described in Hill and others (2000). The top 30 composite scaled sensitivities are plotted.
VK_WS10_VF
SS_QPC_MULT
HK_BEDRX
-
-
and and
mechanisms.
KC_S
HK_LN7_VF
HK_LN8_VF
EFF_MLT1
KC_W
HK_QPC

23%
FLOW RANGE, IN MILLIONS OF ACRE-FEET PER YEAR
17%
p
nrd
srdin
wells
egwin
tgwin
7%
20
15
10
5
0
-5
-10
-15
3%
INFLOWS
Precipitation
p
nrd
10%
Non-routed deliveries
into farm
Semi-routed deliveries
into farm
Groundwater well pumping
deliveries into farm
Evaporation from groundwater
into the farm
Transpiration from groundwater
into the farm
srd in
wells
40%
egwin tgwin
ei
egwout
ep
egw out
ti
3%
30%
3%
tp
8%
Evaporation from irrigation
out of the farm
Evaporation from precipitation
out of the farm
Evaporation from groundwater
out of the farm
Transpiration from irrigation
out of the farm
Transpiration from precipitation
out of the farm
tgw out run
Figure C28. Average annual components of farm budget for water years 1962–2003.
ei
ep
ti
tp
dp
Simulation Results and Budget 193
8%
OUTFLOWS
tgwout
run
dp
29%
12%
7%
Transpiration from groundwater
out of the farm
Overland runoff out
of the farm
Deep percolation out
of the farm

194 Groundwater Availability of the Central Valley Aquifer, California
WATER FLOW, IN MILLIONS OF ACRE-FEET PER YEAR
60
40
20
0
-20
-40
-60
1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002
Evapotranspiration
Runoff
Deep percolation
-
( and and , , and
1962 and 2003,
-
-
YEAR
EXPLANATION
Figure C29. Farm budget changes through time for the Central Valley, California.
Evapotranspiration from groundwater
Groundwater pumpage
Surface-water deliveries
Precipitation
Flow into landscape
system
Flow out of landscape
system
-
son
and others (1989) (
).

A
ESTIMATED WATER USAGE,
IN MILLIONS OF ACRE-FEET PER YEAR
B
ESTIMATED WATER USAGE,
IN MILLIONS OF ACRE-FEET PER YEAR
6
5
4
3
2
1
0
6
5
4
3
2
1
0
Simulation Results and Budget 195
"Variable"
to
Dry Wet
Dry Wet
1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982
WATER YEAR
1977 1978 1979 1980 1981 1982 1983 1984 1985
WATER YEAR
Total farm delivery requirements
Routed surface-water deliveries
EXPLANATION
Non-routed surface-water deliveries
Groundwater pumpage
Figure C30. Farm budget changes through time for water-balance subregion 13, western San Joaquin Valley, Central Valley, California.
A, Water years 1962–2003. B, Water years 1977–1985.

196 Groundwater Availability of the Central Valley Aquifer, California
A (continued)
Wet Dry
Wet
to year and month to month (
opposite effects.
Water pumped from the aquifer system may or may not
areas, replenishment only occurs in years of abundant precipi-
"Variable"
to
Dry
1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003
WATER YEAR
Figure C30. Continued.
ESTIMATED WATER USAGE,
IN MILLIONS OF ACRE-FEET PER YEAR
-
this report.
6
5
4
3
2
1
0

WATER FLOW, IN MILLIONS OF ACRE-FEET PER YEAR
A
40
30
20
10
0
-10
-20
-30
Aquifer-System Storage
( and
-
Simulation Results and Budget 197
-40
1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002
Landscape recharge
General-head boundary
Farm wells
Pumpage
Stream leakage
Subsidence
Storage
YEAR
EXPLANATION
Groundwater Surface water
Landscape recharge
General-head boundary
Pumpage
Figure C31. Groundwater budget changes through time for the Central Valley. A, All values. B, Net values.
Stream leakage
Subsidence
Storage
Flow into groundwater
system
Flow from groundwater
system
and
-

198 Groundwater Availability of the Central Valley Aquifer, California
WATER FLOW, IN MILLIONS OF ACRE-FEET PER YEAR
B
20
15
10
5
0
-5
-10
-15
-20
1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002
Figure C31. Continued.
Specific yield and
compressibility of water
General-head boundary
YEAR
EXPLANATION
Elastic and inelastic storage
Stream leakage
Landscape recharge
Pumpage
Flow into groundwater
system
Flow out of groundwater
system

Table C11. Simulated farm budget for the Central Valley, California, in acre-feet per year.
bold italicbolditalic.
Year Precipitation
Surface-water
deliveries
Groundwater
pumpage
Evapotrans- piration
Runoff
Simulation Results and Budget 199
Evapotrans-
piration from
groundwater
Deep percolation
1962 14,281,000 10,808,000 11,271,000 25,505,000 1,310,000 3,522,000 12,967,000
1963 17,119,000 9,625,000 9,096,000 26,300,000 1,097,000 3,056,000 11,391,000
1964 9,877,000 9,079,000 12,156,000 24,584,000 795,000 3,484,000 9,108,000
1965 15,590,000 9,915,000 9,355,000 25,448,000 1,221,000 3,337,000 11,425,000
1966 10,876,000 9,619,000 12,918,000 24,920,000 1,071,000 3,663,000 10,976,000
1967 19,718,000 10,583,000 8,743,000 25,748,000 1,652,000 3,514,000 15,012,000
1968 11,127,000 9,322,000 12,734,000 26,118,000 820,000 3,639,000 9,798,000
1969 23,300,000 11,002,000 8,231,000 25,937,000 2,015,000 4,039,000 18,433,000
1970 18,345,000 10,261,000 10,738,000 26,122,000 1,675,000 4,342,000 15,723,000
1971 14,102,000 9,701,000 10,569,000 25,198,000 1,159,000 4,114,000 11,973,000
1972 8,042,000 10,200,000 12,875,000 25,015,000 716,000 4,139,000 9,394,000
1973 21,343,000 11,136,000 8,253,000 25,934,000 1,772,000 4,043,000 16,914,000
1974 17,548,000 11,581,000 7,854,000 26,366,000 1,311,000 3,966,000 13,154,000
1975 14,527,000 11,279,000 7,925,000 25,525,000 1,024,000 3,927,000 10,995,000
1976 9,301,000 9,560,000 10,558,000 25,581,000 453,000 3,894,000 7,177,000
1977 7,152,000 7,034,000 15,551,000 25,389,000 436,000 3,445,000 7,279,000
1978 24,651,000 10,546,000 6,768,000 27,474,000 1,755,000 3,521,000 16,088,000
1979 14,134,000 12,364,000 7,661,000 26,325,000 941,000 3,857,000 10,657,000
1980 18,453,000 11,735,000 6,230,000 26,189,000 1,257,000 3,616,000 12,472,000
1981 12,350,000 11,440,000 9,108,000 26,510,000 810,000 3,965,000 9,435,000
1982 22,260,000 11,133,000 4,956,000 26,990,000 1,386,000 3,360,000 13,176,000
1983 28,589,000 10,166,000 4,341,000 26,664,000 2,050,000 3,532,000 17,703,000
1984 13,603,000 12,098,000 7,258,000 25,091,000 1,148,000 4,640,000 11,233,000
1985 11,972,000 10,760,000 7,647,000 25,435,000 700,000 4,055,000 8,204,000
1986 19,712,000 11,273,000 5,836,000 26,435,000 1,324,000 3,809,000 12,738,000
1987 10,048,000 10,509,000 8,843,000 25,282,000 581,000 4,171,000 7,620,000
1988 12,796,000 9,390,000 9,815,000 26,129,000 792,000 3,880,000 8,850,000
1989 12,632,000 9,663,000 9,830,000 26,131,000 741,000 3,549,000 8,662,000
1990 10,121,000 8,356,000 11,690,000 25,993,000 487,000 3,331,000 6,919,000
1991 11,763,000 8,009,000 12,549,000 25,424,000 793,000 3,436,000 9,395,000
1992 13,684,000 7,889,000 12,229,000 26,666,000 821,000 3,334,000 9,546,000
1993 22,192,000 10,538,000 6,958,000 26,430,000 1,645,000 3,262,000 14,726,000
1994 11,690,000 9,676,000 9,522,000 26,196,000 617,000 3,332,000 7,295,000
1995 24,818,000 10,345,000 5,737,000 25,428,000 1,913,000 3,366,000 16,739,000
1996 17,151,000 11,843,000 6,485,000 25,973,000 1,240,000 3,814,000 11,969,000
1997 16,299,000 11,567,000 6,644,000 24,859,000 1,294,000 4,120,000 12,347,000
8,946,000 4,535,000 25,846,000 2,139,000 3,190,000 18,646,000
1999 12,511,000 10,006,000 4,831,000 22,538,000 757,000 3,969,000 7,885,000
2000 15,602,000 10,116,000 4,887,000 23,765,000 1,019,000 4,157,000 9,822,000
2001 13,197,000 9,099,000 6,127,000 24,232,000 673,000 3,925,000 7,316,000
2002 12,868,000 9,425,000 7,137,000 23,175,000 943,000 4,050,000 9,238,000
2003 16,050,000 9,571,000 5,643,000 24,252,000 1,009,000 3,695,000 9,554,000
15,752,000 10,171,000 8,621,000 25,598,000 1,128,000 3,740,000 11,427,000

200 Groundwater Availability of the Central Valley Aquifer, California
Table C12. Simulated groundwater budget for the Central Valley, California, in acre-feet per year.
Table C12. Simulated groundwater budget for the Central Valley, California, in acre-feet per year—Continued.
[bold italic
bold bolditalic
italic
bolditalic
OUT]
OUT]
Year
Specific yield and
compressibility
of water IN
GHB IN
Elastic and inelastic
storage IN
Stream
leakage IN
Farm
recharge IN
Pumpage
IN 1
1962 8,613,000 57,000 3,150,000 3,791,000 12,166,000 439,000
1963 6,688,000 32,000 2,582,000 2,619,000 10,597,000 448,000
1964 8,424,000 58,000 3,320,000 1,957,000 8,299,000 451,000
1965 6,990,000 49,000 2,559,000 2,715,000 10,638,000 452,000
1966 8,331,000 63,000 3,369,000 2,171,000 10,197,000 465,000
1967 6,527,000 37,000 2,389,000 3,284,000 14,196,000 463,000
1968 8,849,000 59,000 3,206,000 1,684,000 8,957,000 464,000
1969 8,351,000 35,000 1,950,000 5,879,000 17,582,000 479,000
1970 9,620,000 23,000 2,515,000 2,425,000 14,898,000 565,000
1971 8,774,000 25,000 2,326,000 1,891,000 11,129,000 558,000
1972 9,570,000 56,000 2,859,000 1,445,000 8,511,000 557,000
1973 7,424,000 26,000 1,839,000 2,919,000 16,122,000 490,000
1974 7,262,000 20,000 1,643,000 2,398,000 12,247,000 463,000
1975 7,667,000 29,000 1,664,000 1,901,000 10,189,000 436,000
1976 9,005,000 60,000 2,099,000 1,224,000 6,313,000 430,000
1977 10,460,000 102,000 3,827,000 1,347,000 6,436,000 477,000
1978 7,231,000 46,000 1,409,000 4,261,000 15,387,000 478,000
1979 7,636,000 42,000 1,429,000 1,719,000 9,930,000 395,000
1980 6,741,000 29,000 1,195,000 2,600,000 11,765,000 374,000
1981 8,560,000 47,000 1,693,000 1,405,000 8,731,000 367,000
1982 5,916,000 21,000 995,000 2,781,000 12,536,000 343,000
1983 5,928,000 8,000 827,000 4,266,000 17,069,000 301,000
1984 9,222,000 12,000 1,340,000 1,825,000 10,613,000 313,000
1985 8,734,000 22,000 1,457,000 1,387,000 7,597,000 356,000
1986 7,199,000 17,000 1,177,000 2,712,000 12,106,000 340,000
1987 9,340,000 25,000 1,782,000 1,062,000 7,085,000 338,000
1988 9,462,000 34,000 2,136,000 1,211,000 8,202,000 344,000
1989 8,803,000 42,000 2,198,000 1,300,000 8,065,000 362,000
1990 9,428,000 62,000 2,991,000 1,113,000 6,292,000 394,000
1991 10,969,000 67,000 3,188,000 3,908,000 8,830,000 470,000
1992 9,813,000 67,000 3,153,000 1,324,000 8,941,000 497,000
1993 7,367,000 40,000 1,589,000 2,339,000 14,114,000 425,000
1994 8,959,000 55,000 2,310,000 1,417,000 6,773,000 381,000
1995 10,261,000 26,000 1,337,000 8,331,000 16,185,000 414,000
1996 8,420,000 20,000 1,237,000 2,296,000 11,452,000 312,000
1997 9,249,000 22,000 1,277,000 3,735,000 11,851,000 299,000
1999 8,626,000 17,000 1,133,000 1,715,000 7,381,000 248,000
2000 8,730,000 20,000 1,245,000 1,862,000 9,176,000 264,000
2001 9,324,000 25,000 1,622,000 1,680,000 6,716,000 283,000
2002 9,699,000 26,000 1,877,000 2,011,000 8,686,000 316,000
2003 8,533,000 24,000 1,560,000 2,197,000 8,950,000 305,000
8,465,000 37,000 2,011,000 2,561,000 10,739,000 401,000

Table C12. Simulated groundwater budget for the Central Valley, California, in acre-feet per year—Continued.
Simulation Results and Budget 201
bold italic
bolditalic
OUT]
Year
Specific yield and
compressibility of
water OUT
GHB OUT
Elastic and inelastic
storage OUT
Stream
leakage OUT
Farm recharge
OUT 2
Pumpage
OUT 3
Farm wells
OUT
1962 10,634,000 105,000 1,153,000 1,850,000 2,648,000 1,628,000 10,185,000
1963 8,192,000 120,000 1,007,000 1,738,000 2,209,000 1,513,000 8,170,000
1964 4,694,000 53,000 809,000 1,689,000 2,618,000 1,720,000 10,911,000
1965 8,013,000 98,000 1,058,000 1,729,000 2,493,000 1,548,000 8,449,000
1966 5,811,000 65,000 864,000 1,667,000 2,807,000 1,815,000 11,548,000
1967 11,462,000 132,000 1,259,000 1,983,000 2,630,000 1,468,000 7,948,000
1968 4,601,000 56,000 793,000 1,814,000 2,729,000 1,986,000 11,220,000
1969 17,398,000 263,000 1,537,000 2,905,000 3,122,000 1,738,000 7,290,000
1970 11,241,000 182,000 1,164,000 2,558,000 3,439,000 2,151,000 9,297,000
1971 6,685,000 126,000 1,030,000 2,361,000 3,197,000 2,158,000 9,129,000
1972 3,466,000 46,000 875,000 1,976,000 3,168,000 2,328,000 11,119,000
1973 12,662,000 165,000 1,406,000 2,333,000 3,169,000 1,962,000 7,109,000
1974 8,543,000 154,000 1,201,000 2,457,000 2,999,000 1,953,000 6,708,000
1975 6,496,000 115,000 1,125,000 2,361,000 3,060,000 1,963,000 6,752,000
1976 2,127,000 39,000 892,000 1,922,000 2,945,000 2,154,000 9,037,000
1977 1,918,000 10,000 531,000 1,552,000 2,527,000 2,502,000 13,593,000
1978 14,447,000 164,000 1,564,000 2,131,000 2,736,000 1,862,000 5,889,000
1979 6,590,000 86,000 935,000 1,982,000 3,040,000 1,984,000 6,516,000
1980 9,350,000 142,000 1,081,000 2,146,000 2,845,000 1,885,000 5,242,000
1981 4,987,000 61,000 787,000 1,963,000 3,168,000 2,173,000 7,641,000
1982 10,469,000 182,000 1,122,000 2,225,000 2,660,000 1,799,000 4,123,000
1983 15,728,000 331,000 1,134,000 3,009,000 2,858,000 1,737,000 3,583,000
1984 7,235,000 232,000 666,000 3,051,000 3,966,000 2,169,000 5,988,000
1985 4,195,000 118,000 772,000 2,504,000 3,400,000 2,247,000 6,298,000
1986 9,712,000 186,000 1,006,000 2,597,000 3,133,000 2,070,000 4,825,000
1987 3,336,000 94,000 673,000 2,203,000 3,586,000 2,398,000 7,321,000
1988 4,666,000 68,000 778,000 1,957,000 3,182,000 2,481,000 8,238,000
1989 4,546,000 55,000 756,000 1,775,000 2,894,000 2,505,000 8,221,000
1990 2,779,000 33,000 582,000 1,641,000 2,635,000 2,724,000 9,871,000
1991 8,216,000 99,000 728,000 2,041,000 2,785,000 2,847,000 10,702,000
1992 5,346,000 49,000 856,000 1,547,000 2,644,000 2,820,000 10,513,000
1993 11,676,000 116,000 1,325,000 1,881,000 2,584,000 2,290,000 5,992,000
1994 3,835,000 52,000 818,000 1,686,000 2,728,000 2,627,000 8,133,000
1995 20,424,000 384,000 1,475,000 4,125,000 2,756,000 2,398,000 4,970,000
1996 8,814,000 231,000 933,000 2,510,000 3,245,000 2,475,000 5,509,000
1997 10,716,000 249,000 1,012,000 2,610,000 3,568,000 2,645,000 5,614,000
1999 4,894,000 240,000 688,000 2,793,000 3,422,000 3,130,000 3,938,000
2000 7,112,000 195,000 732,000 2,411,000 3,468,000 3,306,000 4,052,000
2001 4,471,000 137,000 636,000 2,166,000 3,284,000 3,869,000 5,068,000
2002 6,189,000 130,000 710,000 2,086,000 3,448,000 4,053,000 5,979,000
2003 6,966,000 137,000 879,000 2,041,000 3,046,000 3,768,000 4,712,000
8,131,000 142,000 972,000 2,240,000 2,988,000 2,314,000 7,410,000

202 Groundwater Availability of the Central Valley Aquifer, California
Table C12. Simulated groundwater budget for the Central Valley, California, in acre-feet per year—Continued.
bold italic
bolditalic
OUT]
Year
Net specific
yield and compressibility
of water
Net GHB
Net elastic
and inelastic
storage
Net stream
leakage
Net farm
recharge
Net Pumpage 4
1962 1,997,000 1,941,000 9,519,000
1963 1,575,000 881,000 8,388,000
1964 3,730,000 4,000 2,511,000 268,000 5,681,000
1965 1,500,000 986,000 8,145,000
1966 2,521,000 2,505,000 504,000 7,389,000
1967 1,129,000 1,301,000 11,566,000
1968 4,247,000 2,000 2,413,000 6,229,000
1969 413,000 2,974,000 14,460,000
1970 1,351,000 11,459,000
1971 2,089,000 1,296,000 7,932,000
1972 6,103,000 10,000 1,984,000 5,343,000
1973 433,000 586,000 12,953,000
1974 442,000 9,247,000
1975 1,171,000 –86,000 539,000 –461,000 7,129,000 –8,279,000
1976 6,878,000 22,000 1,208,000 3,368,000
1977 8,542,000 92,000 3,296,000 3,909,000
1978 2,130,000 12,651,000
1979 1,046,000 494,000 6,890,000
1980 114,000 454,000 8,920,000
1981 3,573,000 906,000 5,562,000
1982 556,000 9,877,000
1983 1,258,000 14,211,000
1984 1,987,000 674,000 6,647,000
1985 4,539,000 685,000 4,197,000
1986 171,000 116,000 8,973,000
1987 6,004,000 1,109,000 3,499,000
1988 4,796,000 1,358,000 5,020,000
1989 4,257,000 1,442,000 5,171,000
1990 6,649,000 29,000 2,409,000 –528,000 3,657,000 –12,201,000
1991 2,753,000 2,460,000 1,868,000 6,045,000
1992 4,467,000 18,000 2,297,000 6,297,000
1993 264,000 459,000 11,531,000
1994 5,124,000 3,000 1,492,000 4,045,000
1995 4,206,000 13,428,000
1996 303,000 8,206,000
1997 266,000 1,125,000 8,283,000
1999 3,732,000 445,000 3,959,000
2000 1,619,000 513,000 5,708,000
2001 4,853,000 986,000 3,432,000
2002 3,510,000 1,168,000 5,237,000
2003 1,566,000 680,000 155,000 5,904,000
334,000 1,039,000 321,000 7,751,000
1
2
3
4

Model Uncertainty and Limitations
-
to facilitate addition of more detailed features that may be
of the study, the use of numerical models to simulate hydro-
-
and Whealan, 2005). One component of model error relates to
2 model
cells and features smaller cells that are not simulated. In reality,
the model is likely only to represent features accurately
2
-
able
model solutions to mass-balance residuals of less than
-
Model Uncertainty and Limitations 203
-
near the land surface to 256,000 acre-ft at depth. Within each
of these cells, the hydraulic properties are interpolated or
-
results and analyses that depend on the early part of the simu-
-
tain
include hydraulic properties, the location and properties
-
-
-
-
-

204 Groundwater Availability of the Central Valley Aquifer, California
to constrain these features.
-
-
of the skin factor is uncertain. This skin factor promotes or
-
these areas.
K
-
addition to K
-
source of model error and may affect the local accuracy of the
-

(
the quality and spatial distribution of input data and of
-
-
Future Work 205
tional
features.
land-use and crop distributions are used to estimate pump-
-
Future Work
The performance, utility, detail, and accuracy of the
-
-
-
enhancements may create more accurate or realistic simulations.
In order for these simulations to be as accurate and real-
limitations of the current state of the model. The simulation
simulation of aquifer-system compaction. Thick interbeds
-

206 Groundwater Availability of the Central Valley Aquifer, California
-
-
-
-
-
-
-
-
-
commun., 2008).
-
-
-
-
-
-
2006a).
-
distributions could be based on land-use distributions that
-

-
-
-
nia
and other stakeholders an ability to forecast the potential
-
-
-
References Cited
References Cited 207
2009, at
html
http://
html
-
-
-
map.
44 p.
-

208 Groundwater Availability of the Central Valley Aquifer, California
91 p.
-
-
-
-
-
16, 2009, at
2009, at
html
-
http://water.usgs.gov/pubs/
-
-
-
letin
190, 508 p.

References Cited 209
-
5211, 36 p.
-
-
-
-
-
-
-
-
-
nia, doctoral dissertation, 175 p.
-
-
-
-
-
-
-

210 Groundwater Availability of the Central Valley Aquifer, California
-
-
tion
no. 207, 83 p.
-
-
-
-
-
-
-
76-41, 46 p.
-
54 p.
-
http://pubs.usgs.

References Cited 211
-
-
-
-
-
-
-
-
2009, at
-
-
-
-

212 Groundwater Availability of the Central Valley Aquifer, California
-
-
-
93-1, 170 p.
-

Appendix 1. Supplemental Information—Modifications to
Modflow-2000 Packages and Processes
By Wolfgang Schmid and R.T. Hanson
Introduction
-
-
-
http://water.usgs.gov/nrp/
).
Layer-Property Flow Package (LPF)
-
-
-
-
Multiplier Package (MULT)
tion
as an additional binary operator that could be performed
-
a cell-by-cell basis (
-
-
uses the “^” as a binary operator similar to the other binary
-
-
tion
needs to occur prior to other mathematical operations,
the user should make this binary operation a separate input
command prior to other mathematical operations.
Time-Series Package (HYDMOD)
-
-

214 Groundwater Availability of the Central Valley Aquifer, California
Streamflow Routing Package (SFR1)
ers,
2004) includes an additional option to compute streambed
-
The Farm Process (FMP1)
-
-
and by crop for the entire simulation or each stress period. The
-
-
-
-
-
Concepts and Input Instructions for
New FMP1 Features
-
-

Data for each Simulation
Item No. Input instruction for each item
0
The Farm Process (FMP1) 215
1
2 ICUFL
ISRDFLISRRFL
IFBPFL {Option} read
3
4 [xyz] read*
5
6
or [Farm-ID OFE(FID,CID ), OFE(FID,CID ), … , OFE(FID,CID )]
7
1 2
8
9
10
11
12
13
14 PSI(1) PSI(2) PSI(3) PSI(4)
15 0 1 2 3 {NONIRR}
16
17
18
19
20 Reach
[Farm-ID Row Column Segment Reach]

216 Groundwater Availability of the Central Valley Aquifer, California
Data for each Stress Period
Item No. Input instruction for each item
21
22
23
24
)]
1 2
25
26
27
28
29
30
31
32
33
1 2
t .
34
35
36

Root Uptake Under Variably Saturated
Conditions (PSI specified in Item 14)
the simulation of transpiration uptake from unsaturated root
-
http://
).
Current Concept of Root Uptake from
Unsaturated Conditions
uptake from saturated conditions.
-
-
1
4 2, 3 ). The
1 2 3 4
4 3 2 1 are con-
h b
The Farm Process (FMP1) 217
ux ).
AURZ(h) = TRZ AZ WZ, hh ≥ h
GSE AZ h, h h ≥ h
0 h ≥ ux
b w0
w0 ux
with :
T
T h T , AURZ h / TRZ
c− pot
( )= ( )
gw−act −unsat c− pot
Tgw−act −unsat
= potential transpiration;
= actual transpiration
(root uptake) from groundwater .
Expanded Concept of Root Uptake from Variably
Saturated Conditions
-
uptake from both unsaturated and saturated conditions occurs.
-
1 2
(
(1)
(2)

218 Groundwater Availability of the Central Valley Aquifer, California
Ground
Surface
Groundwater
Level
Bottom of
Root Zone
Wilting
| |
4 | |
3 2
1
Depth below Surface
= 1
= 0
Anoxia &
High
Pressure
ln (| |), for < 0 Soil Water Pressure Head , for 0
| | =
| |(d)
Stress Response
= h - z
Depth below Surface
User specified stress response function,
Simplified stress response function in FMP
Pressure head distribution in unsaturated root
zone: | | = | |(d) solved by analytical solution
Hydrostatic pressure heads in saturated root
zone: = h - z = head minus elevation
Unsaturated Zone within Root Zone
Saturated Zone within Root Zone
Saturated Zone below Root Zone
Zero uptake Full uptake
0 Stress Response 1
Wilting Zone with
zero uptake (WZ)
Active Unsaturated
Root Zone with full
uptake (AURZ)
Active Saturated
Root Zone with
full uptake
(ASRZ1)
Active Saturated
Root Zone with
reduced
uptake
(ASRZ2)
Inactive
Saturated
Zone below
Root Zone
with zero uptake
Inactive Saturated
Zone with zero
uptake due to
High Pressure (> 1)
and Anoxia
Figure 1-1. Evaluation of active and inactive parts of a variably saturated root zone in FMP (Concept of stress response, , as a
function of pressure heads, , varying over depth, d).

2
displayed in
is found.
2
(full 2
1
and the pressure head at the bottom of
2 1
is not found
1
but by the pressure
1
the uptake from saturated conditions is formulated as
Tgw−act−sat ( h)= Tc−pot i( ASRZ1( h) + ASRZ 2( h) i
( h)) / TRZ (3)
( )= ( ( ) + ( )+
ASRZ 2( h) i
( h)) / TRZ
T h T i AURZ h ASRZ1 h
gw−act c− pot
and
1 2 1
2
depend on the simulated
ASRZ 2( h) i ( h)
-
k k
gw−act ( )= c− pot ( ( )+ ( )+
k
T h T i AURZ h ASRZ1 h
( ) ( ))
k k−1
ASRZ 2 h i
h / TRZ
can
be split into non-head-dependent and head-dependent terms.
, is separated into terms either dependent
or not dependent on the head of the current iteration. While
(4)
(5)
The Farm Process (FMP1) 219
made here.
possible transpiration.
transpiration components. These components are fed either by
-
,
-
possible transpiration may be supplemented by precipitation
,
-
stress response,
1 2
1 2 ) may
response,
2 is found
2
1 2

220 Groundwater Availability of the Central Valley Aquifer, California
Example 1:
= 30 inches
1
Head-dependent Combinations
of Transpiration Components
Case 1: Transpiration =
Uptake from saturated root zone
Case 2: Transpiration =
Uptake from saturated root zone plus
Capillary uptake from unsat. root zone
Case 3: Transpiration =
Uptake from saturated root zone plus
Capillary uptake from unsat. root zone
plus uptake from irrigation and
precipitation
Case 4: Transpiration =
Capillary uptake from unsat. root zone
plus Uptake from irrigation and
precipitation
Case 5: Transpiration =
Uptake from irrigation and
precipitation
T
c-pot Potential Transpiration
Tgw-sat Transpiration fed by groundwater
uptake in saturated root zone
Tgw-unsat Transpiration fed by capillary
groundwater uptake in unsaturated
root zone
Ti Transpiration fed by irrigation
Tp Transpiration fed by precipitation
Ec-pot Potential Evaporation
Egw-sat Surface Evaporation from
ponding groundwater
Egw-unsat Surface Evaporation fed by
capillary rise from groundwater
Ei Evaporation fed by irrigation
Ep Evaporation fed by precipitation
1
EXPLANATION
Positive pressure head with
maximum transpiration
2 Positive pressure head with
zero transpiration
Transpiration from fully active
portion of the saturated
rootzone (ASRZ1)
Transpiration from partially
active portion of the
saturated rootzone (ASRZ2)
Total Transpiration from the
saturated root zone
Ground
Surface
Root
zone
Capillary
Fringe
water
level
Tgw
-Extinction
1
1
water level
2
2
water level
Components of Transpiration and
Evaporation with varying Water Level
T gw-unsat
T c-pot
E
c-pot
Capillary
Fringe
E -Extinction
gw
water
level
c-pot
Tc-pot Tc-pot
Flux
Example 2:
Root zone = 30 inches
1
2
T gw-sat
= 30 inches
= 10 inches
E gw
T i T p E i
Subcomponents of Transpiration
from Saturated Conditions
Root
Zone
E p
Ground
Surface
1
1
1
1
2
2
2
2
water level
water level
Subcomponents of Transpiration
from Saturated Conditions
T
Example 1:
Root zone = 30 inches
1
2
= 20 inches
= 10 inches
Flux
Example 3:
Root zone = 30 inches
1
2
= 40 inches
= 10 inches
Flux
Subcomponents of Transpiration
from Saturated Conditions
Figure 1-2. Conceptualization to the change of transpiration uptake from a saturated root zone with varying water level (Three
examples with different 1 values; example 1 at top includes conceptualization of all transpiration and evaporation components with
varying water level).
Root
Zone
Root
Zone

Input Instructions
-
after the section titles.
pressure heads. Therefore, the user must be able to enter any
1 and
2
2
1 -
3 4
3 4 )
Matrix of On-Farm Efficiencies (OFE specified
in Items 7 or 24)
-
The Farm Process (FMP1) 221
Input Requirements
...
1 1,1 1,2 … 2 2,1 2,2 … … … … … … …
… CAUTION
Data Output
each iteration, each time step, or selected time steps either to

222 Groundwater Availability of the Central Valley Aquifer, California
Non-Irrigation Crops (NONIRR Specified in
Items 15 or 27)
-
-
percolation.
…
1
2
…
1 2 …
1 2 …
Or
-
1 1 … 1
2 2 … 2
… … … … …
…
Consumptive Use Options (ICUFL Specified in
Item 2; ETR Specified as New Item)
1.
c
c c-pot ) and
2.
3. -
-
4. -
c
c c
c c-pot
-
after item 27).
Semi-Routed Delivery (ISRDFL in Item 2; REACH
in Items 20 or 34)
ber
and reach number. Therefore, option 5 became obsolete

Semi-Routed Surface-Water Runoff-Return Flow
(ISRRFL in Item 2 and ROW COLUMN SEGMENT
REACH Specified as New Item)
-
of the farm.
and reach numbers is read for the entire
simulation.
and reach numbers is read for each stress
period.
-
a farm. If none of these are found, then, by second priority,
The Farm Process (FMP1) 223
-
-
-
-
-
Farm-Related Data List for Semi-Routed Runoff-Return
Flow Locations (New Item Added After Items 20 or 34):
are attributed
simulation.
must be equal to the sequential number of a

224 Groundwater Availability of the Central Valley Aquifer, California
full set of informa- -
mation
if more than one
the cell
0 0 if more than one
location by
coordinates
of location
by reach
numbers
Additional Auxiliary Variable (AUX NOCIRNOQ
Specified in Item 2)
Farm Budget Output Options (IFBPFL Specified
in Item 2)
-
IFBPFL = 1 -
Time step
Flow rates into a farm:
Flow rates out of farm:

-
IEBPFL=2
Time step
Flowrates into a farm:
farm
the farm
Flowrates out of a farm:
farm
the farm
the farm
farm
Transpiration from precipitation out of
the farm
the farm
-
-
-
-
References Cited
References Cited 225
-
-
-
46 p.
-
-
-

Manuscript appproved on April 16, 2009
Prepared by the USGS Publishing Network,
Publishing Service Center, Sacramento, California
For more information concerning the research in this report, contact
the
California Water Science Center Director,
U.S. Geological Survey, 6000 J Street
Sacramento, California 95819

Printed on recycled paper
Groundwater Availability of
the Central Valley Aquifer, California
Faunt — Groundwater Availability of the Central Valley Aquifer, California Professional Paper 1766