WATER QUANTITY: DEPLETION OR
DROUGHT?
(Some Groundwater Principles & Issues)
Leonard F. Konikow
Emeritus Scientist, U.S. Geological Survey
Reston, VA
email: lkonikow@usgs.gov
University of Florida
November 12, 2015
About 900 million people lack access to safe
drinking water.
--UNESCO (2009)
2 billion people worldwide depend on
groundwater supplies.
--UNESCO (2012)
Download from:
http://pubs.usgs.gov/circ/circ1139/
From: Alley et al., USGS Circ. 1186 (1999)
GROUNDWATER: THE HIDDEN RESOURCE
GROUNDWATER FLOW: HIDDEN, BUT NOT MYSTERIOUS
From: Winter and others, USGS Circ. 1139 (1999)
DARCY’S LAW
Δh
Q=KA
ΔL
GROUNDWATER FLOW EQUATION
∂ ⎛
∂h ⎞
∂h
⎜⎜ Kij
⎟⎟ + W = S s
∂xi ⎝
∂xi ⎠
∂t
GEOLOGIC MATERIALS ARE HETEROGENEOUS
R.R. Parizek
Carbonate rocks in
central Pennsylvania
Account for water with a “budget” Water budgets: a unifying theme for assessment of groundwater availability Understanding water budget components can be used to aid management of resource Healy and others (2007)
Precipitation + Inflow = ET + Storage Change + Outflow
THE WORLD IS CHANGING
•  CLIMATE
•  HYDROLOGY
Glen Canyon Dam and Lake Powell
Photograph by Michael Collier (from USGS Circular 1223)
Daily Discharge. Colorado River at Lees Ferry, AZ
1946
2014
From: Bob Hirsch
GROUNDWATER: WATER SUPPLY FROM WELLS
From: USGS Circular 1279 (2005)
WATER SUPPLY
FROM WELLS
Drilling a
Water-supply
Well
Los Angeles County
production well
Flowing artesian well near Artesia,
Eddy County, New Mexico. (1904)
Pumping irrigation well, near
La Junta, Colorado.
“SOURCE OF WATER DERIVED FROM WELLS”
PUMPAGE
PUMPAGE
INCREASE
IN
RECHARGE
REMOVAL OF WATER
STORED IN SYSTEM
DECREASE
IN
DISCHARGE
DEPLETION
WHAT IS THE LONG-TERM CHANGE IN VOLUME OF
GROUNDWATER CONTAINED IN THE SUBSURFACE?
“SOURCE OF WATER DERIVED FROM WELLS”
PUMPAGE
PUMPAGE
INCREASE
IN
RECHARGE
REMOVAL OF WATER
STORED IN SYSTEM
CAPTURE
DECREASE
IN
DISCHARGE
Streamflow Depletion by Wells
n  An extremely important issue affecting water
and environmental management
n  Streamflow depletion results from:
•  Induced infiltration
•  Reduced groundwater discharge (base flow)
n  Similar effects on springs, lakes, ponds,
wetlands, and coastal estuaries.
n  Many legal ramifications
HYPOTHETICAL GROUNDWATER SYSTEM THAT
DISCHARGES TO A STREAM
FROM: Heath (1983)
EFFECTS OF PUMPING IN A HYPOTHETICAL
GROUNDWATER SYSTEM THAT DISCHARGES TO A STREAM
FROM: Heath (1983)
EFFECTS OF PUMPING IN A HYPOTHETICAL
GROUNDWATER SYSTEM THAT DISCHARGES TO A STREAM
FROM: Heath (1983)
MEASURES OF
GROUNDWATER DEPLETION:
WATER-LEVEL DECLINE
VS
VOLUMETRIC DECREASE
AREAS & WELLS WITH WATER-LEVEL DECLINES > 40 FT SINCE
PREDEVELOPMENT (>25 FT IN UNCONFINED AQUIFERS)
From: USGS Circ. 1323 (Reilly et al., 2008)
GROUNDWATER LEVEL, in
FEET BELOW LAND SURFACE
Water Level in Well, Las Vegas, NV
0
Well 361843115161001
50
100
150
200
1950
1970
1990
2010
SOURCE: U.S. Geological Survey
GW DEPLETION NEAR DENVER, CO
Headlines courtesy of John E. Moore
Santa Cruz River, near Tucson, AZ
1942
1989
From: USGS Circular 1308 (2007)
GROUNDWATER LEVEL (ft BLS)
Groundwater Level vs Population, Las Vegas
0
50
100
150
200
1950
1970
1990
2010
TRENDS IN U.S. POPULATION AND FRESHWATER
WITHDRAWALS BY SOURCE, 1950-2010
300
300
200
200
100
100
0
1950
1960
1970
1980
1990
2000
2010
POPULATION, IN MILLIONS
WITHDRAWALS,
IN BILLION GAL. PER DAY
400
0
From: Maupin et al. (2015); USGS Circular 1405
MEASURES OF
GROUNDWATER DEPLETION:
WATER-LEVEL DECLINE
VS
VOLUMETRIC DECREASE
CHANGES IN
GROUNDWATER LEVELS
IN HIGH PLAINS AQUIFER
(PREDEVELOPMENT-2013)
VOLUME REMOVED
FROM STORAGE
≈ 243 km3 (by 2000)
& 388 km3 (by end of
2012)
from: V.L. McGuire (2014); SIR 2014-5218
CHANGES IN
SATURATED
THICKNESS OF HIGH
PLAINS AQUIFER
(PREDEVELOPMENT-20
13)
[as %]
EXPLANATION Saturated-­‐thickness changes, in % of predevelopment saturated thickness Declines More than 50 25 to 50 10 to 25 No substanKal change 10 to -­‐10 Rises 10 to 25 More than 25 from: V.L. McGuire (2014); SIR 2014-5218
CUMULATIVE VOLUMETRIC GROUNDWATER
DEPLETION (1900-2008) in km3
GROUNDWATER DEPLETION (km3)
From: Konikow (2013) U.S. Geol. Survey SIR 2013-5079
DEPLETION INTENSITY (2000-2008)
CENTRAL VALLEY AQUIFER SYSTEM, CALIFORNIA
From: Faunt & Sneed (2015)
CUMULATIVE GLOBAL GW DEPLETION, 1900-2008
4,530 km3
in 2008
3,370 km3
in 2000
CUMULATIVE GLOBAL GW DEPLETION, 1900-2008
20TH CENTURY:
9.3 mm ≅ 5.5 %
CUMULATIVE GLOBAL GW DEPLETION, 1900-2008
RECENT SLR =
3.1 mm/yr;
GWD:
0.40 mm/yr ≅ 13%
(2014)
National Academy
of Sciences
(2013)
The future?
§  GROWING POPULATION à INCREASED
DEMANDS FOR FOOD & WATER SUPPLY
(DRIVING FORCE)
§  CLIMATE & HYDROLOGIC SYSTEMS ARE
CHANGING
§  BOTH MANAGEMENT & ADAPTATION TO
CHANGE WILL BE NECESSARY
CONCLUSIONS
•  GROUNDWATER IS AN ENORMOUSLY
VALUABLE BUT HIDDEN RESOURCE
•  QUANTITATIVE UNDERSTANDING OF
GROUNDWATER FLOW HAS ADVANCED
SUBSTANTIALLY DURING LAST SEVERAL
DECADES
CONCLUSIONS
•  GROUNDWATER DEPLETION CAN
AFFECT SUSTAINABILITY &
VIABILITY OF WATER SUPPLY
•  DEPLETION CAN CAUSE DETRIMENTAL
ENVIRONMENTAL EFFECTS
•  GW DEPLETION IS GROWING
CONCLUSIONS
•  GROUNDWATER USE AND DEPLETION
ARE STRONGLY LINKED TO CLIMATE
& CLIMATE CHANGE
•  INNOVATIVE WATER MANAGEMENT
ACTIONS CAN HELP MITIGATE
PROBLEMS