The Impact of
Unsustainable Ground
Water
Frederick Bloetscher, Ph.D., P.E.
Florida Atlantic University
Familiar Hydrologic
y
g Cycle
y
to Thunderheads
Evapotranspiration
Rainfall
Runoff
Surface Waters
Surface Level
Groundwater
Flow to Ocean
In Action…
In Action…
Sustainable Withdrawals <
Consumption + Returns (to
hydrologic cycle)
Groundwater must be extracted overpumping may become a bigger
problem where recharge is reduced or
sustainable
t i bl yield
i ld iis exceeded
d d
USGS 1323 (Reilly et al, 2009)
USGS 1323 (Reilly et al 2009)
• “In contrast to rivers and lakes, ground‐water systems are hidden from direct observation and
systems are hidden from direct observation and measurement,
• The sources of water to ground‐water systems and The sources of water to ground water systems and
the time required for the effects of withdrawals to p p g
propagate through the system and be observed are g
y
different for each system,” and often unclear
• “The amount of detail (spatial scale) needed to describe the resource depends on the objectives and purpose of the desired information USGS 1323 (Reilly et al, 2009)
USGS 1323 (Reilly et al 2009)
• The amount of change in ground‐water levels that is i
important is different for different ground‐water i diff
f diff
d
systems
• Not all water pumped is consumed and much of the N t ll t
di
d d
h f th
water pumped is redistributed and changes the ground‐water
ground
water flow system, and
flow system and
• The chemical quality of the water is important in determining its suitability (and thus its availability)
determining its suitability (and thus its availability) for various uses.”
• Groundwater withdrawals can and usually do affect y
the amount (and quality) of surface water.”
Groundwater intercepts – if surface
water is lower, groundwater will be
reduced…..
Land Surface
Surface Water
Groundwater Level
Groundwater/Surface Water Interface
Less Recharge means lower aquifer levels and less aquifers draining to
levels, and less aquifers draining to surface waters
Groundwater is NOT protected
Average Rainfall
Water available for recharge throughout the United States – note most areas are very low United States note most areas are very low
(source: Reilly et al 2009)
Groundwater Pumping
Groundwater Pumping
• USGS
USGS estimates that the pumpage of fresh estimates that the pumpage of fresh
ground water in the US is approximately 83 Unless
it is in8 percent
the wrong
places!!1
BGD or about
BGD or about 8 percent of the estimated 1 of the estimated
trillion gallons per day of natural recharge to the Nation’ss ground
the Nation
ground‐water
water systems, (Hutson systems (Hutson
and others, 2004)
• Doesn
Doesn’tt sound so bad right?
sound so bad right?
Water Deficit Areas (source: Reilly et al 2009)
Changes
g in GW 1942-1989
Note all are areas where subsidence is indicated
Where is the Recharge?
g
0
Surficial
A if
Aquifer
200
400
Fresh Water
Water Table Aquifer
Highly Productive
Hawthorn
Group
600
800
Silts and Clays
Confining Unit
1000
1200
Semi-Confined Aquifer
Brackish Water Productive
1400
1600
Floridan
Aquifer
System
Water‐level declines
Red regions indicate areas in excess of 500 square miles that have water‐level decline in excess of g
q
40 feet in at least one confined aquifer since predevelopment, or in excess of 25 feet of decline in unconfined aquifers since predevelopment. Blue dots are wells in the USGS National Water Information System database where the measured water‐level difference over time is equal to or greater than 40 feet. What Happens when
Groundwater Levels Fall
Land subsidence
Sustainable (?) Groundwater Water Sustainable
(?) Groundwater Water
Examples
Water Budget
ET
HYDROPOWER
OUTFLOW
URBAN USAGE
RUNOFF
AG USAGE
P ET + Runoff – Outflow – GW = ΔS
P-
Upper Klamath Dam
pp
Klamath River at Pacific Ocean
Klamath River at Pacific Ocean
24
Water Supply Variables pp y
Qoutt
Klamath Tribe
g
Agriculture/Stock
•rainfall
g
•groundwater
•surface water
Klamath
h
Qin
Agriculture/Crops
Public Supply
Tourism/Wildlife Refuge
Industrial/Fishermen
Must balance:
Qin = Qout
Department of Civil Engineering • Bloetscher • EES 6025 • Fall 2005
Department of Civil Engineering • Bloetscher • EES 6025 • Fall 2005
25
Priority to Maximize Economic
V l off the
Value
th Klamath
Kl
th B
Basin
i
Industry
Agriculture
Tourism
Current
2000
Potential Priority Economi
value
Value
Water c Valued
($M/yr)
($M/yr)
Rights Priority
$
200 $
200
1
4
$
700 $ 1,500
2
Commercial
Fishery
Timber
Tribes
$
$
n/a
70 $ 4,500
250 $
250
n/a
n/a
n/a
2
1
3
1a
Competition in Basin
Competition in Basin
•
•
•
•
Agricultural Production Timber production
Salmon harvest
Salmon harvest
Urban Development
Priority?
Ecosystem
Urban supplies
Ag Use
Transportation
Impact of Loss of Groundwater
p
Industry
Impact of
Lost of
GW
Primary
Water
Sources
Potential
Losses
($M)
Agriculture
high
65%
Surface,
35% GW
Tourism
medium
GW
est $500
high
low
low
low
SW w/GW
back-up
SW
SW
SW
$70
present
0
0
0
Commercial
Fishery
Timber
Tribes
Power
$200
Comparison of User Values (AW)
Based on Optimal Decision
Based on Optimal Decision
Economic Issues
Economic Issues
• The
The higher water quality and increased higher water quality and increased
salmon population will cause an increase in tourism • 1:10 Ag crops would be lost
• Timber production may be reduced by 13% Timber production may be reduced by 13%
because their water usage was decreased by 13%
• Capital costs associated with implementing re‐
use facilities
What y
you want to avoid…..
Dakota Aquifers
q
Depletion of Dakota Aquifer
Depletion of Dakota Aquifer
Volume
withdrawn
ithd
(km3)
Basin
Type
Area
(km2)
Time
e
Period
Total Pore
Lost pore
volume volume as
lost
% of total
withdrawals
ithd
l
Dakota Confined 171,000 1880 19.7 14.9
Aquifer
to
System
1980
76
33 yrs left?
Dakota Concern
Dakota Concern
.
• Public
Public drinking water supplies include 251 drinking water supplies include 251
MGD from ground water serving 545,104 people or 78 percent of the total population
people, or 78 percent of the total population of the state of South Dakota • There are not sufficient, widespread surface There are not sufficient widespread surface
water to replace it
Dakota Hydro Cycle
Dakota Hydro Cycle
• Rainfall averages around 20 in/yr
• particularly limited in the summer months when temperatures climb into the high 90s.
when temperatures climb into the high 90s. • ET is high. • Historically much of the surface was parched Hi t i ll
h f th
f
h d
during summer months Dakota Industry
Dakota Industry
• Large scale agriculture was encouraged. Cropping of the Dakotas began in the late 19th century and has the Dakotas began in the late 19
century and has
accelerated with the advent of groundwater p p g y
pumping systems. • South Dakota is home to 21.9 million acres of rangeland, 16.7 million acres of cropland, over 2 g
p
million acres of pasture, and over 500,000 acres of forest.
• The combined value of these and other agricultural products in South Dakota exceeds $3.8 billion annually ll
Analysis of Alternative Water
S
Supply
l M
Methods
h d
Water Quality
Solution
Reuse
Low Pressure
RO
Medium
Pressure RO
Dams
Cost/
1000
gal
Capital
(100
MGD)
Est
Distrib.
Cost
AW 20 yrs
3.5
250
6600
$677,411,722
5
450
6600
$748,210,240
7.5
550
6600
$847,484,498
billions
But………
• 100 MGD (or any large quantity) of wastewater to reuse is NOT available in any centralized point
• No widespread surface sources except Missouri River (otherwise allocated)
• There may saltwater sources (RO), but no obvious place for disposal of concentrate
obvious place for disposal of concentrate
• Hence – there is no obvious quantity solution
Historical SE Florida
Water System
Florida Potential Climate
Change Problem
There is no soil storage – So flooding
occurs eastt off dike,
dik westt off I-95
I 95
Consequences…
• Saltwater Intrusion may be offset with GW rise
• Flooding during storms, mostly because GW Flooding during storms mostly because GW
rise = Loss of soil storage capacity
• Hurricane frequency uncertain, but 3 ft SLR is a H i
f
t i b t 3 ft SLR i
problem
Likelyy Coastal & Western Flooding
g
Solution?
• Reuse/Regional Wastewater Disposal P i i i
Participation • Brackish/Salt sources for potable use
• Reverse Osmosis
R
O
i
• Ultraviolet
• Advanced Oxidation
• HUGE CARBON
• FOOTPRINT
$$$$$$$$$$$$$$$$$
Cost…
• 600 MGD of Wastewater RO’ed = $6 B capital
• Power Cost @ 3 MW/MGD Power Cost @ 3 MW/MGD = 1.8 GW power 1.8 GW power
supply needed
• 250 MGD of saltwater sources RO’ed = $4.5 B
• Power cost @ 5 MW/MGD = 1.25 GW needed
• FPL wants 2 new 1 GW nuclear reactors
• Which means 200 MGD cooling water
Which means 200 MGD cooling water
Conclusions
• Groundwater is decreasing in many areas – it is not sustainable
is not sustainable
• Worst in the west – pumping GW artificially makes it look like water is available
k
l klk
l bl
• Water supply decisions affect not only the current and proposed water users, but may have far‐reaching economic and power effects
Conclusions
• The effects may not be immediate, but pose challenges to future generations. h ll
f
i
• Basin solutions needed:
– The potential for the prioritization of a lesser use over the other uses may create permanent effects that would reduce the GNP of that sector. – Sustainability issues from macro‐level should be evaluated when new allocations are considered, l
d h
ll
i
id d
incl power and ecosystems – Some long‐term effects have limited alternatives. S
l
t
ff t h
li it d lt
ti
What you want to avoid
avoid…..
Questions?
Threatened RM greenback cutthroat trout