Long-Term Groundwater Depletion in the United States

Leonard F. Konikow U.S. Geological Survey

Reston, VA

GWPC Annual Forum St. Louis, Missouri September 23, 2013

WATER SUPPLY FROM WELLS

From: USGS Circular 1279 (2005)

Flowing artesian well near Artesia, Eddy Co., New Mexico, 1904. (USGS Photo Library)

Pumping irrigation well, near La Junta, Colorado. (L.F. Konikow)

Drilling a Water Supply Well (USGS Circ. 1308)

Los Angeles County production well (USGS Circ. 1247)

WATER SUPPLY FROM WELLS

REMOVAL OF WATERSTORED IN SYSTEM

PUMPAGE

DECREASE IN

DISCHARGE

INCREASE IN

RECHARGE

DEPLETION

C.V. Theis (1940)

WHAT IS THE LONG-TERM CHANGE IN VOLUME OF GROUNDWATER CONTAINED IN THE SUBSURFACE?

PUMPAGE

“SOURCE OF WATER DERIVED FROM WELLS”

REMOVAL OF WATERSTORED IN SYSTEM

PUMPAGE

DECREASE IN

DISCHARGE

INCREASE IN

RECHARGE

CAPTURE

C.V. Theis (1940)

PUMPAGE

“SOURCE OF WATER DERIVED FROM WELLS”

POSSIBLE EFFECTS OF GROUNDWATER DEPLETION:

• LOWER WATER TABLES & POTENTIOMETRIC

HEADS • GREATER PUMPING LIFTS & ENERGY COSTS • REDUCED WELL YIELDS • REDUCED BASE FLOW OF STREAMS & SPRINGS • REDUCED GW DISCHARGE TO WETLANDS, LAKES, ESTUARIES, & OCEANS • LAND SUBSIDENCE • DEGRADATION OF GROUNDWATER QUALITY • UNSUSTAINABLE SUPPLIES • FEWER WATERLOGGING PROBLEMS • SEA-LEVEL RISE

MEASURES OF GROUNDWATER DEPLETION:

WATER-LEVEL DECLINE

VS

VOLUMETRIC DECREASE

Water Level in Well, Las Vegas, NV

Well 361843115161001

SOURCE: U.S. Geological Survey

0

50

100

150

200

GR

OU

ND

WAT

ER

LE

VE

L, i

n FE

ET

BE

LO

W L

AN

D S

UR

FAC

E

1950 1970 1990 2010

From: USGS Circ. 1323 (Reilly et al., 2008)

AREAS & WELLS WITH WATER-LEVEL DECLINES > 40 FT SINCE PREDEVELOPMENT (>25 FT IN UNCONFINED AQUIFERS)

MEASURES OF GROUNDWATER DEPLETION:

WATER-LEVEL DECLINE

VS

VOLUMETRIC DECREASE

Available for downloading from: http://pubs.usgs.gov/sir/2013/5079/

CUMULATIVE VOLUMETRIC GROUNDWATER DEPLETION (1900-2008) in km3

From: Konikow (2013) U.S. Geol. Survey SIR 2013-5079

GROUNDWATER DEPLETION (km3)

NONDIMENSIONAL RELATIONS

=PUMPAGE DEPLETION +CAPTURE

DEPLETION VOLUMEDEPLETION FRACTION =CUMULATIVE PUMPAGE

CAPTURE FRACTION = 1- (DEPLETION FRACTION)

DEPLETION FRACTION IN SELECTED U.S. AQUIFERS

AREA DEPLETION FRACTION

CAPTURE FRACTION

HIGH PLAINS (OGALLALA)

AQUIFER 0.27 0.73

NEBRASKA H.P. 0.00 1.00

TEXAS H.P. 0.42 0.58

(1950-2000)

CAPTURE FRACTION

CO

UN

T

RANGE RANGE

DEPLETION FRACTION

mean = 0.39 mean = 0.61

n = 34

DEP

LETI

ON

FR

AC

TIO

N

CA

PTU

RE

FRA

CTI

ON

0

0.2

0.4

0.6

0.8

1.0

DEPLETION VS. CLIMATE

AVERAGE ANNUAL PRECIPITATION (cm)

AVERAGE GW DEPLETION RATE (20TH CENTURY)

AVERAGE GW DEPLETION RATE (2001-2008)

CHANGE IN AVERAGE GW DEPLETION RATE (FROM 1961-80 TO 2001-2008)

DEPLETION INTENSITY (in m/yr)

= ××

3

2DepletionVolume(km ) 1000mArea(km ) Time(yrs) km

DEPLETION INTENSITY (1900-2000)

DEPLETION INTENSITY (2000-2008)

CHANGE IN DEPLETION INTENSITY (1900-2000 vs 2001-2008)

LONG-TERM GROUNDWATER DEPLETION IN THE U.S.

1,000 km3 in 2008

800 km3 in 2000

DECADAL SCALE RATE OF GROUNDWATER DEPLETION IN THE UNITED STATES,

1900 TO 2008

The future? GROWING POPULATION INCREASED DEMANDS FOR FOOD & WATER SUPPLY (DRIVING FORCE) CAN WE (& SHOULD WE) DO ANYTHING TO CONTROL/LIMIT GROUNDWATER DEPLETION? (MANAGEMENT/LEGAL/POLITICAL/SOCIO-ECONOMIC ASPECTS)

• IN U.S., GW DEPLETION IS GROWING

• DEPLETION RATE IS ACCELERATING

CONCLUSIONS

ON AVERAGE: • MOST GW WITHDRAWALS BALANCED BY CAPTURE

• LESS BALANCED BY GW STORAGE DEPLETION

CONCLUSIONS

• GROUNDWATER DEPLETION CAN AFFECT SUSTAINABILITY & VIABILITY OF WATER SUPPLY

• DEPLETION CAN CAUSE DETRIMENTAL ENVIRONMENTAL EFFECTS

• INNOVATIVE WATER MANAGEMENT ACTIONS CAN HELP MITIGATE PROBLEMS

CONCLUSIONS

• DECREASE DEMAND (esp. in IRRIGATED AGRICULTURE)

• INCREASE SUPPLY, for example:

MANAGEMENT/POLICY OPTIONS

MANAGED AQUIFER RECHARGE DESALINATION ALTERNATE SOURCES OF SUPPLY