Simulated Effects of Ground-Water

Management Scenarios on the Santa Fe

Group Aquifer System, Middle Rio Grande

Basin, New Mexico, 2001-40

Prepared in cooperation with the

CITY OF ALBUQUERQUE PUBLIC WORKS DEPARTMENT

U.S. DEPARTMENT OF THE INTERIOR

U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 03-4040
U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 03-4040

Simulated Effects of Ground-Water

Management Scenarios on the Santa Fe

Group Aquifer System, Middle Rio Grande

Basin, New Mexico, 2001-40

Prepared in cooperation with the

CITY OF ALBUQUERQUE PUBLIC WORKS DEPARTMENT

By Laura M. Bexfield and Douglas P. McAda

Albuquerque, New Mexico

2003
U.S. DEPARTMENT OF THE INTERIOR

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

The use of firm, trade, and brand names in this report is for identification purposes only and does

not constitute endorsement by the U.S. Geological Survey.

For additional information write to: Copies of this report can be purchased

U.S. Geological Survey

Information Services

Box 25286

Denver, CO 80225-0286

District Chief

U.S. Geological Survey

Water Resources Division

5338 Montgomery Blvd. NE, Suite 400

Albuquerque, NM 87109-1311

from:

Information regarding research and data-collection programs of the U.S. Geological Survey is available

on the Internet via the World Wide Web. You may connect to the home page for the New Mexico District

Office using the URL http://nm.water.usgs.gov.
iii

CONTENTS

Page

Abstract.................................................................................................................................................................................. 1

Introduction ........................................................................................................................................................................... 1

Purpose and scope ....................................................................................................................................................... 2

Previous investigations ................................................................................................................................................ 2

Description of study area............................................................................................................................................. 2

Acknowledgments ....................................................................................................................................................... 4

Design of model simulations ................................................................................................................................................. 4

McAda and Barroll model ........................................................................................................................................... 4

Modifications and additions to the McAda and Barroll model ................................................................................... 8

Simulated effects of ground-water management scenarios ................................................................................................... 11

Simulation I—Continued pumping at year-2000 rates................................................................................................ 11

Simulation II—Increased pumping to meet all demand.............................................................................................. 11

Simulation III—Reduced pumping to supplement surface-water supply.................................................................... 19

Selected comparisons among simulations ............................................................................................................................. 30

Summary................................................................................................................................................................................ 38

References ............................................................................................................................................................................. 38

FIGURES

1. Map showing location of the Middle Rio Grande Basin, central New Mexico ....................................................... 3

2. Map showing City of Albuquerque municipal-supply wells ................................................................................... 5

3. Diagram showing configuration of layers in the model ........................................................................................... 6

4. Map showing model grid and active model cells in layer 1..................................................................................... 7

5. Graph showing annual City of Albuquerque pumping assigned for each model simulation, 1980 to 2040............ 10

6-8. Maps showing:

6. Simulated water-table change in the Middle Rio Grande Basin between 2000 and 2040 for simulation I...... 12

7. Simulated water-level change in the production zone (layer 5) between 2000 and 2040 for simulation I....... 13

8. Simulated water-table change in the Middle Rio Grande Basin between steady state and 2040 for

simulation I .................................................................................................................................................. 14

9-11. Graphs showing:

9. Simulated water budgets for the ground-water system through 2040 in simulation I ...................................... 15

10. Simulated net inflow to the ground-water system in simulation I from (a) river leakage and (b) storage ....... 16

11. Simulated outflow from the ground-water system in simulation I from (a) evapotranspiration and

(b) drains...................................................................................................................................................... 17

12. Map showing simulated water-table change in the Middle Rio Grande Basin between 2000 and 2040 for

simulation II ....................................................................................................................................................... 18

13. Map showing simulated water-table change in the Middle Rio Grande Basin between steady state and 2040

for simulation II.................................................................................................................................................. 20

14-16. Graphs showing:

14. Simulated water budgets for the ground-water system through 2040 in simulation II..................................... 21

15. Simulated net inflow to the ground-water system in simulation II from (a) river leakage and (b) storage ...... 22

16. Simulated outflow from the ground-water system in simulation II from (a) evapotranspiration and

(b) drains...................................................................................................................................................... 23

17-20. Maps showing:

17. Simulated water-table change in the Middle Rio Grande Basin between 2000 and 2040 for simulation III ... 24

18. Simulated water-table change in the Albuquerque area between 2000 and 2040 for simulation III................ 25

19. Simulated water-level change in the production zone (layer 5) between 2000 and 2040 for simulation III.... 26

20. Simulated water-table change in the Middle Rio Grande Basin between steady state and 2040 for

simulation III ............................................................................................................................................... 27
iv

Page

21. Graphs showing simulated water budgets for the ground-water system in selected years in simulation III........... 28

22. Graphs showing simulated net inflow to the ground-water system in simulation III from (a) river leakage

and (b) storage.................................................................................................................................................... 29

23. Map showing difference between 2040 water levels for simulation III (reduced pumping) and simulation I

(continued pumping at year-2000 rates) ............................................................................................................ 31

24. Map showing difference between 2040 water levels for simulation III (reduced pumping) and

simulation II (increased pumping to meet all city demand) .............................................................................. 32

25-29. Graphs showing:

25. Comparison of annualized storage rates for scenarios of reduced city pumping to (a) continued pumping

at year-2000 rates and (b) increased pumping to meet all demand............................................................. 33

26. Simulated distribution among budget components of the difference in pumping volumes between

(a) simulations I and III and (b) simulations II and III ............................................................................... 34

27. Cumulative volume of water retained in or added to storage by reduced city pumping compared to

(a) continued pumping at year-2000 rates and (b) increased pumping to meet all demand ....................... 35

28. Comparison of annualized rates of net river leakage for scenarios of reduced city pumping to

(a) continued pumping at year-2000 rates and (b) increased pumping to meet all demand ....................... 36

29. Cumulative volume of water retained in the river by reduced city pumping compared to (a) continued

pumping at year-2000 rates and (b) increased pumping to meet all demand.............................................. 37

TABLE

1. Summary of major results for each model simulation............................................................................................. 30

CONVERSION FACTORS, ABBREVIATIONS, AND DATUM

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 (NAVD

88).

Altitude, as used in this report, refers to distance above or below sea level.

Multiply By To obtain

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

square mile (mi2

) 259.0 hectare (ha)

square mile (mi2

) 2.590 square kilometer (km2)

acre-foot (acre-ft) 1,233 cubic meter (m3

)

acre-foot (acre-ft) 0.001233 cubic hectometer (hm3

)

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3

/s)

acre-foot per year (acre-ft/yr) 1,233 cubic meter per year (m3/y)

foot per day (ft/d) 0.3048 meter per day (m/d)
1

ABSTRACT

Future conditions in the Santa Fe Group aquifer

system through 2040 were simulated using the most

recent revision of the U.S. Geological Survey groundwater-flow model for the Middle Rio Grande Basin.

Three simulations were performed to investigate the

likely effects of different scenarios of future groundwater pumping by the City of Albuquerque on the

ground-water system. For simulation I, pumping was

held constant at known year-2000 rates. For simulation

II, pumping was increased to simulate the use of

pumping to meet all projected city water demand

through 2040. For simulation III, pumping was reduced

in accordance with a plan by the City of Albuquerque

to use surface water to meet most of the projected water

demand. The simulations indicate that for each of the

three pumping scenarios, substantial additional watertable declines would occur in some areas of the basin

through 2040. However, the reduced pumping scenario

of simulation III also results in water-table rise over a

broad area of the city. All three scenarios indicate that

the contributions of aquifer storage and river leakage to

the ground-water system would change between 2000

and 2040.

Comparisons among the results for simulations

I, II, and III indicate that the various pumping scenarios

have substantially different effects on water-level

declines in the Albuquerque area and on the

contribution of each water-budget component to the

total budget for the ground-water system. Between

2000 and 2040, water-level declines for continued

pumping at year-2000 rates are as much as 120 feet

greater than for reduced pumping; water-level declines

for increased pumping to meet all projected city

demand are as much as 160 feet greater. Over the same

time period, reduced pumping results in retention in

aquifer storage of about 1,536,000 acre-feet of ground

water as compared with continued pumping at year2000 rates and of about 2,257,000 acre-feet as

compared with increased pumping. The quantity of

water retained in the Rio Grande as a result of reduced

pumping and the associated decrease in induced

recharge from the river is about 731,000 acre-feet as

compared with continued pumping at year-2000 rates

and about 872,000 acre-feet as compared with

increased pumping. Reduced pumping results in slight

increases in the quantity of water lost from the groundwater system to evapotranspiration and agriculturaldrain flow compared with the other pumping scenarios.

INTRODUCTION

The City of Albuquerque, located in the Middle

Rio Grande Basin (otherwise known as the

Albuquerque Basin) of central New Mexico,

historically has obtained all its municipal-supply water

from wells completed in the sediments of the Santa Fe

Group aquifer system. Ground-water pumping by the

City of Albuquerque for municipal supply has totaled

more than 100,000 acre-feet, and as much as 126,600

acre-feet, every year since 1986 (files of the City of

Albuquerque). As a result of pumping by the City of

Albuquerque and other water users in the region, water

levels in parts of the aquifer system have declined by

more than 120 feet (Bexfield and Anderholm, 2002).

Because of the limited availability of ground water for

future municipal supply, the City of Albuquerque

currently (2002) is in the process of implementing a

plan to reduce well pumping by diverting much of its

municipal-supply water from the Rio Grande. Most of

the water taken from the river will be associated with

the San Juan-Chama Diversion Project. The city owns

rights to 48,200 acre-feet of water per year from the

project, by which water is imported from the Colorado

River Basin into the Rio Grande Basin and stored in

reservoirs upstream from the city. Although the

planned surface-water diversions will meet much of the

city’s present demand for water, ground-water

pumping will be required to supplement water supplies

during periods of large demand or drought.

The shift in the primary source of municipal

supply for the City of Albuquerque from ground water

to surface water will have significant consequences for

SIMULATED EFFECTS OF GROUND-WATER MANAGEMENT

SCENARIOS ON THE SANTA FE GROUP AQUIFER SYSTEM,

MIDDLE RIO GRANDE BASIN, NEW MEXICO, 2001-40

By Laura M. Bexfield and Douglas P. McAda
2

the river-aquifer system. Estimates of these

consequences are needed to aid in the city’s

implementation of long-term water-management

strategies that will benefit regional water users and the

hydrologic system as a whole. The ground-water-flow

model developed by McAda and Barroll (2002) for the

Middle Rio Grande Basin, hereafter referred to as the

McAda and Barroll model, was used in this study to

evaluate the consequences of potential watermanagement strategies on components of the

hydrologic system such as aquifer storage and river

leakage. This study was performed in cooperation with

the City of Albuquerque.

Purpose and Scope

This report presents results of ground-water

flow-model simulations designed to compare and

contrast the effects of potential water-management

strategies by the City of Albuquerque on components

of the river-aquifer system of the Middle Rio Grande

Basin. Three scenarios of large, medium, and small

rates of ground-water pumping by the City of

Albuquerque from 2001 through 2040 were simulated

using the McAda and Barroll model for the basin. This

report evaluates and compares the resulting water

levels and water budgets for the entire Middle Rio

Grande Basin, with emphasis on the Albuquerque area.

Previous Investigations

The Middle Rio Grande Basin between Cochiti

Lake and San Acacia has been the subject of numerous

hydrogeologic investigations and ground-water-flow

models. The current study uses the most recent groundwater-flow model for the basin, which was developed

by McAda and Barroll (2002). Previous models

developed for the basin include those by Kernodle and

others (1995), Kernodle (1998), Tiedeman and others

(1998), and Barroll (2001). These previous models

were based principally on a conceptual model of the

basin as defined by Thorn and others (1993), which

incorporated geologic information from Kelley (1977),

Lozinsky (1988), and Russell and Snelson (1990);

hydrogeologic information from Hawley and Haase

(1992); and hydrologic information from Bjorklund

and Maxwell (1961). The McAda and Barroll model

incorporates additional knowledge gained primarily

through a series of investigations started in 1995 as part

of a focused effort by the U.S. Geological Survey

(USGS) and other Federal, State, and local agencies to

improve knowledge of the hydrogeology of the Middle

Rio Grande Basin. Recent geologic, hydrologic, and

hydrochemical investigations that contributed

substantially to the latest revision of the ground-waterflow model are described in McAda and Barroll (2002).

All investigations included in the recent focused effort

on the basin are detailed in Bartolino and Cole (2002)

and in collections of extended abstracts edited by

Bartolino (1997), Slate (1998), Bartolino (1999), and

Cole (2001).

Description of the Study Area

Bartolino and Cole (2002) and Thorn and others

(1993), among others, provided thorough descriptions

of the Middle Rio Grande Basin. Therefore, only a

brief description of the study area is provided here, and

the reader is referred to those publications for

additional detail. The Middle Rio Grande Basin of

central New Mexico (fig. 1) is one of a series of

physiographic basins located in the Rio Grande Rift.

The basin covers about 3,060 square miles and is

bounded by mountains reaching altitudes as high as

about 11,000 feet along most of the northern, eastern,

and southern margins and by more subdued uplifts

along the western margin.

The primary aquifer within the Middle Rio

Grande Basin is the Santa Fe Group aquifer system,

which exceeds 10,000 feet in thickness in places and

includes Santa Fe Group deposits of late Oligocene to

middle Pleistocene age and the hydrologically

connected post-Santa Fe Group alluvium of

Pleistocene to Holocene age. Sediments of the Santa Fe

Group are divided into lower, middle, and upper

sections, of which the upper section is the most

permeable.

The climate of the Middle Rio Grande Basin is

semiarid, with large evapotranspiration relative to

precipitation, so most recharge to the aquifer system

occurs either along basin margins as mountain-front

recharge and ground-water inflow or within the basin

as infiltration through streams (Thorn and others, 1993;

Kernodle and others, 1995). The Rio Grande is the

main surface drainage for the basin. The Rio Grande is

bordered by an inner valley, or flood plain, that is as

much as 6 miles wide and includes a system of

irrigation canals and drains that support agriculture.

The Rio Puerco and other ephemeral streams in the
3
4

basin also contribute recharge to the aquifer. Some

ground water flows from the Middle Rio Grande Basin

south to the Socorro Basin, but most discharge occurs

through pumping, evapotranspiration in the inner

valley, or flow into drains and gaining sections of the

Rio Grande (Thorn and others, 1993; Kernodle and

others, 1995). The City of Albuquerque is the largest

user of ground water in the basin. The city supplied

more than 475,000 people in 2001, using 92 of its

municipal-supply wells (fig. 2) (City of Albuquerque,

2002), which are described in detail in Bexfield and

others (1999).

Acknowledgments

The authors thank Greg Gates with CH2M Hill

for providing the projections of total water demand and

surface-water availability for the City of Albuquerque

that were used in this investigation. The authors also

thank Wesley Danskin with the USGS and John Stomp

with the City of Albuquerque for consulting on the

design of model simulations.

DESIGN OF MODEL SIMULATIONS

For this investigation, the McAda and Barroll

ground-water-flow model was used with only minor

modification to simulate conditions through 2000. For

2000 through 2040, many of the most recent input

parameters from the McAda and Barroll model were

duplicated without modification for each year,

although input for the Rio Grande was varied among

years in a manner described in a following section.

Projections of total water demand and ground-water

compared to surface-water supply for the simulated

years 2000 through 2040 also are detailed in a

subsequent section.

McAda and Barroll Model

The McAda and Barroll model of the Middle Rio

Grande Basin simulates ground-water flow in the Santa

Fe Group aquifer system over an area of about 2,350

square miles. This model uses the three-dimensional,

finite-difference, ground-water-flow model code

MODFLOW-2000 (Harbaugh and others, 2000), with a

slight modification in the Layer Property Flow package

to the calculation of vertical leakage under certain

conditions, as described by McAda and Barroll (2002).

The McAda and Barroll model was developed to (1)

integrate the components of the ground-water-flow

system, including hydrologic interaction between the

ground- and surface-water systems in the basin, to

better understand the geohydrology of the basin and (2)

provide a tool for water managers to plan and

administer the use of basin water resources. The model

is described only briefly here, and the reader is referred

to McAda and Barroll (2002) for more detail.

The aquifer system is represented in the model

by nine layers (fig. 3) extending from the water table to

the pre-Santa Fe Group basement rocks, as much as

9,000 feet below sea level. The horizontal grid contains

156 rows and 80 columns, each equally spaced 3,281

feet (1 kilometer) apart (fig. 4). The grid is oriented

north-south to align with the principal directions of

anisotropy. Layers 1-5 are variable in thickness over

the model area, depending on the altitude of the steadystate simulated water table relative to the altitude of the

Rio Grande (fig. 3). The steady-state thicknesses of

layers 1, 2, 3, 4, and 5 are 30, 50, 100, 220, and 400

feet, respectively, directly below the Rio Grande and

vary in proportionate dimensions (either larger or

smaller) elsewhere. Layer 1 is relatively thin to

simulate ground-water/surface-water interaction in the

inner valley. Layer 6 is a constant 600 feet thick and

layer 7 is a constant 1,000 feet thick. Cells in layers

1-7 are active where the center of the cell is higher in

altitude than the base of the Santa Fe Group. The

thicknesses of layers 8 and 9 are one-third and twothirds, respectively, of the Santa Fe Group thickness

below layer 7. Cells in model layers 8 and 9 are active

only where their combined thickness is at least 1,200

feet.

Model layers 1-4 are represented as convertible

from confined to unconfined conditions (Harbaugh and

others, 2000)—that is, active cells in which the

simulated hydraulic head is above the designated layer

top are simulated under confined conditions, and cells

in which the simulated hydraulic head is below the

layer top are simulated under water-table conditions.

This convertible condition allows the simulated water

table to transfer to the next lower cell as simulated

water levels decline below the bottom of a cell. Model

layers 5-9 are represented as always confined.

The McAda and Barroll model simulates

predevelopment steady-state conditions and historical

transient conditions from 1900 to March 2000 in 1

steady-state and 52 historical stress periods. Average

annual conditions are simulated prior to 1990, and

seasonal (winter and irrigation season) conditions are

simulated from 1990 to March 2000.
5

40

25

25

40
6
7
8

Hydrologic properties representing the Santa Fe

Group aquifer system in the McAda and Barroll model

are horizontal hydraulic conductivity, vertical

hydraulic conductivity, specific storage, and specific

yield. The aquifer system is simulated to be

horizontally and vertically anisotropic—that is,

hydraulic conductivities along the three axes of the

model are not necessarily equal. The horizontal

hydraulic conductivity in the east-west direction (along

model rows; Kx) of the model ranges from 0.05 to 45

ft/d. The hydraulic conductivity in the north-south

direction (along model columns; Ky) of the model

ranges from 0.05 to 60 ft/d. The horizontal anisotropy

ratio (Ky /Kx) varies over the model domain from 1:1

to 5:1. Selected faults are simulated as horizontal flow

barriers, which simulate reduced hydraulic

conductivity between model cells. The vertical

hydraulic conductivity in the model is simulated by

applying a vertical anisotropy ratio (Kx /Kz) of 150:1

over the model domain. This results in simulated

vertical hydraulic-conductivity values ranging from

3 x 10-4 to 3 x 10-1 ft/d. Specific storage is simulated to

be 2 x 10-6 ft-1 and specific yield is simulated to be 0.2

(dimensionless).

Mountain-front, tributary, and subsurface

recharge; canal, crop-irrigation, and septic-field

seepage; and ground-water withdrawal are simulated as

specified-flux boundaries in the McAda and Barroll

model. At a specified-flux boundary, water is recharged

to or discharged from the simulated aquifer system

independent of simulated head in the aquifer. The

specified fluxes in the model are simulated to pass to

the next lower cell if the cell in which a flux is assigned

goes dry (see McAda and Barroll, 2002, for

modifications made to the well package of the

MODFLOW-2000 code). Mountain-front, tributary,

and subsurface recharge from adjacent ground-water

basins are specified to be constant throughout the

simulation period, whereas canal, crop-irrigation, and

septic-field seepage and ground-water withdrawal vary

through the simulation period on the basis of historical

data. Ground-water withdrawal from major production

wells with screened intervals spanning several model

layers, such as those operated by the City of

Albuquerque, is divided among layers depending on

the proportion of screen length in each layer. These

major production wells typically withdraw water from

some combination of layers 4 through 6, with most

withdrawal from layer 5.

The Rio Grande, riverside drains, interior drains,

Jemez River, Jemez Canyon Reservoir, Cochiti Lake,

and riparian evapotranspiration are simulated in the

model as head-dependent flux boundaries. At a headdependent flux boundary, water is recharged or

discharged as a function of simulated hydraulic head in

the aquifer system and specified information for the

boundary, such as a specified river stage or a specified

evapotranspiration surface. Specified boundary

information varies through the simulation period on the

basis of historical data. The head-dependent flux

boundaries in the model can be used to estimate the

effects of changes in aquifer-system stresses on the

fluxes at these boundaries.

Modifications and Additions to the McAda

and Barroll Model

To simulate future conditions in the Middle Rio

Grande Basin under various scenarios of ground-water

pumping by the City of Albuquerque, operation of the

McAda and Barroll model through 2000 was modified

slightly. Two City of Albuquerque municipal-supply

wells, Gonzales 3 and Zamora 2 (fig. 2), which were

brought online in 1999 and 1998, respectively, were not

included in the original model. Because these wells

were projected to pump substantial quantities of water

during the time period of interest, they were added into

the model beginning with the years during which they

first produced water that was delivered to city

customers. Also, layer 5 of the model was assigned to

be convertible from confined to unconfined conditions.

For 2000 through 2040, many of the most recent

parameters input to the McAda and Barroll model were

duplicated without modification. These parameters

included those for mountain-front recharge, tributary

recharge, underflow, recharge from irrigation

(generally 1992 data), recharge from septic-tank

effluent (based on 1990 population data), drain

conditions, and evapotranspiration conditions. With the

exception of City of Albuquerque data, the most recent

data available in the McAda and Barroll model for

ground-water pumping also were included in all model

simulations for each year from 2000 through 2040. For

major municipal and commercial pumping, the

pumping data used generally were from 2000, except

where 1999 data were the most recent available. Data

for these years did not appear anomalously high or low

compared with data for previous years. The use of
9

domestic-well pumping based on 1990 population data

also was continued. No attempt was made to simulate

future changes in pumping from wells other than those

operated by the City of Albuquerque because future

pumping by such wells is not the focus of this study, is

subject to multiple uncertainties, and is small by

comparison.

City of Albuquerque ground-water pumping

between 2000 and 2040 differed among three different

model simulations intended to represent scenarios of

small, medium, and large ground-water use. For

simulation I, ground-water pumping in all city

municipal-supply wells was maintained at known year2000 rates for each year through 2040 (fig. 5),

representing medium ground-water use. Year-2000

pumping data were used rather than an average of

recent years because some older wells were retired and

newer wells were brought online in the late 1990’s;

year-2000 data were not anomalously large or small

compared with data for other recent years.

For simulation II (representing large groundwater use), city pumping was adjusted to simulate the

use of ground-water pumping to meet all projected

water demand, which is expected to rise substantially

through 2040. Annual projections of future water

demand were obtained from Greg Gates (CH2M Hill,

written commun., 2001), consultant to the City of

Albuquerque. The projections of future demand were

input to the model by applying individual multipliers

for each future year and season to the known year-2000

pumping data. In essence, these multipliers represent

the ratio of total projected demand during each future

year to total pumping during the year 2000. However,

because the winter season used in the model is defined

to extend across 2 years (from November of one year to

mid-March of the following year), the winter

multipliers had to be adjusted to take into account the

annual projections of both years. Therefore, multipliers

were calculated as follows:

For simulation III (representing small groundwater use), city pumping was adjusted to match

projections by Greg Gates (written commun., 2001) of

future ground-water use that assume surface water is

available to meet much of the total water demand,

resulting in decreased pumping (fig. 5). These

projections take weather cycles into account to

determine the likely availability of surface water in any

given year. As for simulation II, the ground-water

pumping projections were translated into the model by

calculating multipliers that were applied to year-2000

pumping for each year and season. Equations 1 and 2

were again used, except that “total projected groundwater pumping” was substituted for “total projected

demand” for each future year, y or (y+1).

For all model simulations, conditions in the Rio

Grande were varied for each year between 2006 (the

year that surface water is anticipated to be available for

delivery to City of Albuquerque customers) and 2040

to match the weather cycles that Greg Gates (written

commun., 2001) assumed in determination of groundwater pumping projections. Greg Gates used historical

streamflow data for selected average, wet, and dry

years to calculate the potential availability of surface

water in each year from 2006 to 2040, depending on the

weather conditions assumed for that year. For this

investigation, the 25th and 75th percentiles of

streamflow were calculated from the same streamflow

data used by Greg Gates (written commun., 2001). For

each of the three divisions of streamflow data (data up

to the 25th percentile, data between the 25th and 75th

percentiles, and data above the 75th percentile),

“average” river conditions within that division were

determined. These conditions were then used to

establish “typical” wet, dry, and normal configurations

of the Rio Grande for use in the model. The

configuration used in the model for any given year was

chosen to match the approximate weather conditions

and associated surface-water availability assumed by

Greg Gates (written commun., 2001) for that year.

Multiplier for summer = Total projected demand in year y (1)

pumping in year y Total pumping in 2000

Multiplier for Number of winter Total projected Number of winter Total projected

winter pumping = days in year y x demand in year y + days in year (y+1) x demand in year (y+1) (2)

year y to (y+1) Total number of Total pumping Total number of Total pumping

 winter days in 2000 winter days in 2000

The resulting increases in pumping for simulation II

are shown in figure 5.
10

1980 1990 2000 2010 2020 2030 2040

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

160,000

180,000

Figure 5. Annual City of Albuquerque pumping assigned for each model simulation, 1980 to 2040. Total pumping, in acre-feet

Simulation l

Simulation ll

Simulation lll
11

SIMULATED EFFECTS OF GROUNDWATER MANAGEMENT SCENARIOS

Results of model simulations I, II, and III for

scenarios of future ground-water pumping by the City

of Albuquerque were examined for changes in

simulated water levels and contributions of the various

components of the simulated water budget for the

aquifer over time. Although results were examined

basinwide, emphasis was placed on results in the

Albuquerque area, where the most significant changes

are expected.

Simulation I—Continued Pumping at Year2000 Rates

The model indicates that continued pumping at

known year-2000 rates through 2040 would add

substantially to water-level decline already present in

the aquifer in 2000 relative to predevelopment

conditions. Additional water-level decline

(supplementary to the decline present in 2000) through

2040 is substantial both at the water table and in the

production zone of the aquifer. The area of additional

water-table decline of at least 5 feet extends from about

the Zia and Sandia Indian Reservations on the north to

the Isleta Indian Reservation on the south and from

almost the western boundary to the eastern boundary of

the model, with the exception of areas close to the Rio

Grande (fig. 6). The greatest additional water-table

decline occurs near the eastern edge of Albuquerque

and near the northwestern corner of the city; additional

water-table decline of 60 to 100 feet is common in both

areas. In the production zone of the aquifer (defined in

a previous section as best represented by layer 5 of the

model), additional water-level decline extends over a

somewhat larger area, but generally is of slightly

smaller magnitude (fig. 7). Near the northwestern

corner of the city, additional water-level decline in the

production zone generally is less than about 60 feet,

whereas in the eastern part of the city it generally is less

than about 80 feet. This simulation indicates that

pumping at year-2000 rates through 2040 results in

total water-table decline relative to predevelopment

conditions that commonly exceeds 120 feet near the

northwestern corner of the city and 200 feet in the

eastern part of the city, with maximum decline

exceeding 225 feet (fig. 8). Water-level decline in the

production zone is of similar magnitude for the same

time period. Despite sustained pumping and substantial

water-level decline over this extended time period, no

model cells at the Rio Grande went dry, indicating that

saturated hydraulic connection was never lost between

the river and the ground-water system.

Simulation I indicates substantial changes in the

water budget of the aquifer between 2000 and 2040 as

pumping continues at year-2000 rates. During this

period, net river leakage (inflow to the ground-water

system from the river minus outflow from the groundwater system to the river) represents an increasing

percentage of total inflow to the ground-water system

over time as a result of the larger hydraulic gradients

created as water levels continue to decline in the

aquifer. Net river leakage increases from about 33 to 37

percent of total inflow during the summer and 36 to 44

percent of total inflow during the winter (fig. 9). The

actual contribution rate of river leakage to the system

during 2000 to 2040 increases by about 12 percent

during the summer and 16 percent during the winter

(fig. 10a). The percentage contribution of water to the

system from net storage (inflow to the ground-water

system from storage minus outflow from the groundwater system into storage) during this time period

decreases as greater river recharge is induced and the

quantity of water available from storage declines.

Between 2000 and 2040, the contribution from net

storage drops from about 10 to 7 percent of total inflow

during the summer and 40 to 30 percent of total inflow

during the winter (fig. 9). The actual rate of inflow from

storage decreases by about 27 percent during the

summer and 28 percent during the winter (fig. 10b).

The outflow budget for the 2000-40 period shows that

both percentage losses and actual rates of loss through

evapotranspiration and drain flow are nearly constant

for summer and winter (figs. 9 and 11).

Simulation II—Increased Pumping to Meet

All Demand

Simulation II represents the scenario of large

pumping by the City of Albuquerque to meet all water

demand through 2040. Simulation II results in the same

general areal pattern and extent of additional waterlevel decline (over decline present in 2000) as observed

in simulation I; however, the magnitude of additional

decline is substantially greater. Between 2000 and

2040, additional decline commonly exceeds 90 feet in

the northwestern part of Albuquerque and 120 feet in

the eastern part (fig. 12). This simulation indicates that

increased pumping through 2040 would result in total

water-table decline since predevelopment that

commonly exceeds 150 feet near the northwestern

corner of the city and 250 feet in the eastern part of the
12
13
14
15
16
17
18
19

city, with maximum water-table decline exceeding 280

feet (fig. 13). For both time ranges (2000-40 and

predevelopment-2040), water-level decline in the

production zone is of similar magnitude as water-table

decline. As with simulation I, no model cells at the Rio

Grande went dry during this simulation.

Compared with simulation I, simulation II shows

a similar increase in the percentage of inflow to the

ground-water system through net river leakage

between 2000 and 2040 (fig. 14, compared with fig. 9).

However, as a result of greater water-level decline and

associated hydraulic gradients, the actual rate of inflow

through net river leakage shows a larger increase for

simulation II, equaling about 20 percent during the

summer and 30 percent during the winter (fig. 15).

Unlike simulation I, the net percentage and rate of

contribution of water to the ground-water system from

storage in simulation II increase between 2000 and

2040 for the summer months (figs. 14 and 15),

probably because the additional recharge induced from

the Rio Grande is not sufficient to replace all the

ground water being removed by pumping. For the

winter months, the net percentage and rate of

contribution from storage show decreases for both

simulations, but the decreases are smaller for

simulation II than for simulation I (figs. 14 and 15). The

outflow budget for simulation II indicates that losses

through both evapotranspiration and drain flow

decrease by about 5 to 8 percent between 2000 and

2040 (fig. 14), which corresponds to the increasing

outflow of water from the system through pumping and

the associated decline in the water table. Actual rates of

loss through evapotranspiration and drain flow

decrease by about 2 to 7 percent (fig. 16).

Simulation III—Reduced Pumping to

Supplement Surface-Water Supply

Simulation III represents the scenario of small

pumping by the City of Albuquerque to supplement the

use of surface water for municipal supply through

2040. Between 2000 and 2040, the reduced pumping of

simulation III results in continued water-level decline

(over decline present in 2000) in some areas and waterlevel rise in others. Additional water-table decline

occurs primarily along the western and eastern margins

of Albuquerque, including across most of Rio Rancho

to the northwest and Kirtland Air Force Base to the

southeast (fig. 17), where municipal-water suppliers

other than the City of Albuquerque were simulated as

continuing to pump at year-2000 rates. The additional

water-table decline in these areas is generally less than

60 feet in magnitude. The water table rises over much

of the area of Albuquerque that is east of the Rio

Grande as well as over a small area west of the river

(fig. 18). The magnitude of water-table rise exceeds 25

feet in places and is greatest in the area of the

Leyendecker, Charles Wells, and Thomas well fields,

which is where some of the largest water-table declines

had previously occurred. Water-level rise in the

production zone of the aquifer is of a similar magnitude

as water-table rise but is even more widespread (fig.

19). Simulated water levels indicate that water-table

rise begins before 2010 and exceeds 50 feet in areas by

2020, but ceases before 2030 as projected pumping

rates (fig. 5) continue to grow from a low around 2010

to meet increasing demand that cannot be supplied by

surface water. This simulation using projected

pumping reductions through 2040 indicates that total

water-table decline since predevelopment is generally

less than 110 feet west of the Rio Grande and less than

130 feet east of the river (fig. 20).

Between 2000 and 2040, this simulation with

reduced pumping shows only a slight increase (1

percent) in the percentage of inflow to the groundwater system through net river leakage in the summer

and essentially no change in the winter (fig. 21). The

actual rate of inflow through net river leakage during

this time period decreases by about 5 percent in the

summer and 14 percent in the winter (fig. 22) because

of the reduced hydraulic gradients associated with

rising water levels. Similar to simulation I, the net

percentage and rate of contribution of water to the

system from storage during this time period decrease

for both the summer and winter seasons (figs. 21 and

22), probably because net river inflow is sufficient to

replace ground water removed by pumping. The actual

net rate of inflow from storage decreases by about 63

percent during the summer and 18 percent during the

winter (fig. 22). The outflow budget indicates that the

loss through evapotranspiration increases by only

about 2 percent between 2000 and 2040 (fig. 21); the

actual rate of loss is nearly constant. Percentage losses

through drains also increase between 2000 and 2040

for both the winter and summer seasons (fig. 21),

whereas actual rates of loss are nearly constant. A

slight increase in outflow from the system through

evapotranspiration and drain flow is expected because

plant roots and ground-water drains would intercept the

higher water table over a larger area. The rate of

outflow through pumping (and, consequently, the

percentage of outflow through pumping) was decreased

through model input.
20
21
22
23
24
25
26
27
28
29
30

SELECTED COMPARISONS AMONG

SIMULATIONS

Results of simulations I, II, and III indicate that

the various pumping scenarios have substantially

different effects on water levels in the Albuquerque

area and on the contribution of each budget component

to the overall water budget for the ground-water

system. These different effects are summarized in

table 1. Between 2000 and 2040, water-level declines

in the Albuquerque area for continued pumping at year2000 rates (simulation I) are as much as 100 feet

greater than for reduced pumping (simulation III)

(fig. 23). Water-level declines for increased pumping to

meet all projected city demand (simulation II) are as

much as 160 feet greater than for reduced pumping

(fig. 24).

Compared with the other pumping scenarios,

reduced pumping results in the depletion of much less

ground water from aquifer storage between 2000 and

2040 (table 1). In simulation III, the net result of

reduced pumping is replenishment of water in storage

(that is, negative net storage) between about 2006 and

2020 (fig. 25), when pumping volumes are at their

lowest (fig. 5). Between 2000 and 2040, the cumulative

volume of water retained in or added to storage in the

aquifer under the scenario of reduced pumping

compared to continued pumping at year-2000 rates

totals about 1,536,000 acre-feet (fig. 25a). This volume

represents about 64 percent of the total difference in

pumping volumes between simulations I and III (fig.

26a). For the scenario of reduced pumping compared

with increased pumping to meet all city demand, the

cumulative volume of water retained in or added to

storage is about 2,257,000 acre-feet (fig. 25b), or about

69 percent of the total difference in pumping volumes

between simulations II and III (fig. 26b). For

simulation III relative to simulation I, the cumulative

volume of water retained in or added to storage

increases most rapidly between about 2006 and 2024

(fig. 27a); for simulation III relative to simulation II,

the cumulative volume of water “saved” increases more

steadily over time (fig. 27b).

The simulation III scenario of reduced city

pumping also results in the depletion of much less

surface water from the Rio Grande compared with the

other pumping scenarios (fig. 28 and table 1). The

volume of water retained in the river per year increases

continually from about 2006 through 2020, at which

time this volume remains fairly steady from year to

year (fig. 28a). This pattern is probably related to

changing hydraulic gradients near the river as a result

of water-level rise. The cumulative volume of water

retained in the river between 2000 and 2040 as a result

of reduced compared with continued pumping totals

about 731,000 acre-feet (figs. 28a and 29a) or about 30

percent of the total difference in pumping volumes

between simulations I and III (fig. 26a). The

cumulative volume retained in the river as a result of

reduced compared with increased pumping totals about

872,000 acre-feet (figs. 28b and 29b) or about 26

percent of the total difference in pumping volumes

between simulations II and III (fig. 26b).

Because the scenario of reduced city pumping

results in higher water levels compared with the other

pumping scenarios, more water is lost from the aquifer

system to evapotranspiration and to the drain system

(table 1). The cumulative volume of water lost to

evapotranspiration under the scenario of reduced

compared with continued pumping totals about 38,000

acre-feet between 2000 and 2040; the cumulative

volume lost to the drain system is about 107,000 acrefeet. Under the scenario of reduced compared with

increased pumping, about 43,000 acre-feet is lost to

evapotranspiration and about 122,000 acre-feet is lost

to the drain system. Increased evapotranspiration and

drain flow constitute about 2 and 4 percent,

respectively, of the total difference in pumping

volumes between simulations I and III (fig. 26a) and

about 1 and 4 percent, respectively, of the total

difference in pumping volumes between simulations II

and III (fig. 26b).

Table 1. Summary of major results for each model simulation

From 2000 to 2040, cumulative annualized volume (in acre-feet) of:

Simulation

95th percentile

of water-table

decline from

steady state

(in feet)

Net inflow from

river leakage

Net inflow from

storage

Outflow to

evapotranspirationOutflow to

drain flow

I (medium pumping) 162 5,498,000 2,146,000 3,351,000 5,132,000

II (large pumping) 199 5,638,000 2,867,000 3,346,000 5,117,000

III (small pumping) 101 4,766,000 610,000 3,389,000 5,239,000
31
32
33
34
35
36
37
38

SUMMARY

The model developed by McAda and Barroll for

the Santa Fe Group aquifer system of the Middle Rio

Grande Basin was used to simulate future conditions in

the aquifer for three different scenarios of groundwater pumping by the City of Albuquerque through the

year 2040. For simulation I, city pumping was

maintained at the year-2000 rate for each subsequent

year (medium ground-water use). For simulation II,

pumping was adjusted to equal the total city water

demand that a City of Albuquerque consultant

projected for each year through 2040 (high groundwater use). For simulation III, pumping was adjusted to

equal just the portion of projected demand to be

supplied by ground water once surface water begins to

be delivered to city customers (low ground-water use).

Whereas water levels in all three simulations decline

between 2000 and 2040 in some areas around

Albuquerque, water levels in simulation III also rise

over large areas. In simulation III, water levels decline

as much as 100 feet less than in simulation I and 160

feet less than in simulation II.

In addition to smaller water-level declines, the

reduced pumping of simulation III results in

substantially smaller inflow to the ground-water system

from aquifer storage and river leakage than either

simulation I or II. Whereas the rate of inflow of river

leakage to the aquifer system between 2000 and 2040

increases by 12 percent or more for simulations I and

II, it decreases by 5 percent or more for simulation III.

The cumulative retention of water in the river as a result

of reduced pumping is 731,000 acre-feet as compared

to continued pumping at year-2000 quantities and

872,000 acre-feet as compared to increased pumping to

meet all city water demand. The cumulative retention

of ground water in storage in simulation III is

1,536,000 acre-feet as compared to simulation I and

2,257,000 acre-feet as compared to simulation II.

Although the reduced pumping of simulation III results

in a slight increase in loss of ground water to

evapotranspiration and drain flow between 2000 and

2040, this loss totals only 5 to 6 percent of the

difference in the volume of ground-water pumping

between simulation III and either of the other

simulations. These simulations indicate that reduced

ground-water pumping by the City of Albuquerque

through 2040 would have beneficial effects on the

regional ground-water system, including substantially

reduced water-level declines, increased aquifer storage,

and reduced infiltration of surface water from the Rio

Grande.

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