Part 2: Springs Hydrogeology – Floridan Aquifer, Groundwater

Springs Academy Tuesdays
Part 2: Springs Hydrogeology – Floridan
Aquifer, Groundwater Recharge, Spring Flows
Robert L. Knight, Ph.D.
Howard T. Odum
Florida Springs Institute
Photo by John Moran
Class Schedule
Springs Academy Tuesdays
Your Instructor:
Robert L. Knight, Ph.D.
Director - Howard T. Odum Florida
Springs Institute
•B.A. Zoology (1970) – Univ. of
North Carolina
•M.S.P.H. Environmental Chemistry
and Biology (1973) – Univ. of North
Carolina
•Ph.D. Systems Ecology(1980) –
Univ. of Florida
Florida’s Spring Ecosystems
Howard T. Odum –
Father of Springs Ecology
•H.T. Odum of the University
of Florida published “Trophic
Structure and Productivity of
Silver Springs, Florida” in
Ecological Monographs
(1957)
•“Primary Production
Measurements in Eleven
Florida Springs…” Limnology
and Oceanography (1957)
Florida Springs Academy
Purpose
• Introduction to water resource issues
in Florida
• Springs are a “case history” useful
for understanding the complexity of
these issues
• Florida has an urgent need for
knowledgeable and talented citizens
capable of advocating for
implementation of urgent water
resource management decisions
Florida is Karstic
Cave Divers in the Floridan
Aquifer
Floridan Aquifer Cross Section
http://fl.water.usgs.gov/FASWAM/
Where is the Floridan Aquifer?
The Floridan
aquifer
underlies an
area that
includes all of
Florida and
parts of
neighboring
states, about
100,000 sq. mi.
http://fl.water.usgs.gov/FASWAM/
Florida’s Springs
What is a spring?
Where
groundwater
comes to the
land surface.
John Mora
North
Florida –
“Land of a
Thousand
Springs”
Data from Florida
Department of
Environmental
Protection
WMD
Springs
NWFWMD 318
SRWMD
314
SWFWMD
238
SJRWMD
151
County
Springs
Washington
95
Citrus
90
Marion
78
Jackson
71
Suwanee
64
Wakulla
64
Gilchrist
46
Lake
37
Taylor
36
Columbia
33
All Fresh Groundwater
Comes From Rain
Cave Divers in
the Floridan
Aquifer
How much groundwater is
there?
1. Average recharge to the Floridan Aquifer is
about 12 billion gallons per day
2. Trillions of gallons of freshwater are stored
in the Floridan aquifer
John Moran p
Hydrologic Cycle
(from Fernald and Patton 1984)
Florida’s
Annual
Average
Rainfall
(from Fernald
and Patton
1984)
44 to 64 inches/year
Annual Rainfall Totals in the Santa Fe River Basin
Florida’s
Annual
Water
Balance
Florida’s Water Budget
Rain 150 BGD
From GA and
AL 25 BGD
ET 107 BGD
(from Fernald and
Patton 1984)
Outflow 68 BGD
Annual
Average
and
Monthly
Rainfall
(from WRA
2005)
Florida Annual Rainfall Variability
(from Fernald and Patton 1984)
Maximum
60 to 120 inches
Minimum
27 to 35 inches
Florida’s Geology
(from Fernald and Patton 1984)
Florida’s
Groundwater
Sources
(from Fernald and
Patton 1984)
Floridan Aquifer Thickness
(from Fernald and Patton 1998)
Aquifer Confinement and Springs
• Aquifer is confined
beneath thick
sequence of sand,
silt, and clay over
much of its extent
• This limits the
amount of direct
recharge into the
system
Bush and Johnston, 1988
Average
Recharge to
the Floridan
Aquifer
(USGS data)
Florida’s Hydrologic Cycle
Recharge = 6% of Rainfall
Precipitation
Evaporation
Groundwater
Recharge
Springshed for Rainbow Springs
- extends 45 miles NE of the
spring and encompasses 737
square miles
Silver
Springs
“Potentiometric
Surface”
• The regional
water surface
of an aquifer
as expressed
in wells.
Impacts on Groundwater Quantity
1. Reduced rainfall and recharge
due to climatic variation
2. Reduced recharge due to land
use changes
3. Net consumption due to
human activities
4. Reduced regional
groundwater levels due to
consumption in neighboring
areas
Increasing Groundwater Uses
Agriculture
Residential
Golf Course
Florida Groundwater Use - 2005
• Total estimated
groundwater use
in Florida in 2005
was 4.2 billion
gallons per day
• Public water
supply accounted
for 2.2 BGD
• Agriculture
accounted for 1.3
BGD (USGS 2009)
The Floridan Aquifer is Over-Permitted
Existing Groundwater
Consumptive Use
Permits:
– Total permits –
28,630
– Estimated 2010
pumping – 2,622
MGD = 26% of
recharge
– Total allocated
groundwater use –
4,630 MGD = 46%
of entire aquifer
recharge!
Water Management District data
North Florida Groundwater Pumping (2010)
Pumping is
concentrated in
urban and industrial
population centers:
•Polk – 251 MGD
2,622
MGD
•Orange – 249 MGD
•Duval – 155 MGD
•Hillsborough – 151
MGD
•Pasco, Lake, Volusia,
Osceola > 90 MGD each
•Marion – 69 MGD
USGS Data
Florida’s Hydrologic Cycle
Pumping = 30% of Recharge
Precipitation
Evaporation
Groundwater
Recharge
Fernald and Patton 1984
Groundwater
Pumping
Net Consumptive Uses
• Total water use is the total quantity pumped from a
source (groundwater or surface water)
• Net consumptive use is the amount of water that is
not returned to it source of origin
• Net consumptive use includes evapotranspiration
and export in a product or to a different discharge
point
• Water conservation increases % net consumptive
use
Natural Recharge (P-ET-RO)
Human Net Use (Pump –
Return)
Springshed
Spring
Flow
Cones of Depression
Unconfined Aquifer
Confined Aquifer
Source SRWMD 2011
Increased Groundwater Pumping Lowers
Aquifer Pressure (levels)
Average
decline
about 0.15
feet per year
≈350 MGD
Groundwater Levels at Lake Butler, FL
(USGS 2007)
Floridan Aquifer Level Decline (2000)
Decline in the
potentiometric
levels of the
Floridan Aquifer:
•Northeast FL: 20
to 60 ft
•Marion County: 4
to 20 ft
Silver Springs
Groundwater
Basin
Rainbow Springs
Groundwater Basin
•Orlando area: 10
to 34 ft
•Southwest FL: 20
to >60 ft
Florida Geological Survey
Surface of the
Floridan
Aquifer PreDevelopment
Conditions
(from Grubbs and
Crandall 2007)
Surface of
the Floridan
Aquifer and
Groundwater
Flow
(May 1980)
(from Grubbs and
Crandall 2007)
Estimated lost flow = 80 MGD
Excessive Pumping Has Reduced Spring Flow to
Suwannee River Springs
Jacksonville
• Groundwater
contributing
area to
Suwannee
Basin was
reduced by
about 1,900
mi2 from 1936
to 2005, about
120 MGD
White Springs
Groundwater
Flow Direction
(from D. Still/SRWMD and J. Grubbs/USGS)
The Floridan Aquifer is a Groundwater Conduit
The “Limestone Pipeline”
Floridan Aquifer Regional Transfers
Regional groundwater
pumping centers are
lowering Floridan
Aquifer levels,
resulting in
groundwater transfers
throughout North and
Central Florida and
reducing spring and
river flows
Silver Springs
Groundwater Basin
The Upper Suwannee River Nearly
Stopped Flowing in June 2011
John Moran
photo
Florida Groundwater Budget
Floridan Aquifer Water Balance
Rain (P)
Return
ET Pump (C) (R)
Groundwater (GW)
ΔGW = P + R –ET – C - Q
Q = P + R –ET – C - ΔGW
Spring
Discharge
(Q)
Floridan Aquifer Water Balance
Summary of Predevelopment
Conditions:
– Total regional spring
flow = 12 BGD
– Florida spring flow =
11 BGD
Bush and Johnston 1988
Average Florida Spring Discharge
Rosenau et al. (1977) and Means (2008)
• Florida’s 27 First Magnitude Springs
– 9,600 cfs (6.2 billion gallons per day)
• Florida’s 300 known springs with
discharge measurements
– 12,600 cfs (8 billion gallons per day)
• Estimate for 700+ springs counting the
above
– 13,900 cfs (9 billion gallons per day)
Estimated Spring Flow Changes
in Florida (1930-2000)
Time Period
Predevelopment
1930-1940
1940-1950
1950-1960
1960-1970
1970-1980
1980-1990
1990-2000
1
Estimated Total Average
Discharge 1
Initial Decade Final Decade
(mgd)
(mgd)
11,234
10,489
10,869
10,869
10,744
10,744
12,144
12,144
12,396
12,396
10,394
10,394
8,199
8,199
7,153
Includes FDEP springs database and assigns 0.5 cfs to remaining
628 documented springs
Percent
Change
--4
-1
13
2
-16
-21
-13
Percent
Cumulative
Change
--3.6
2.4
15.8
18.2
-0.9
-21.8
-31.8
N
--22
31
33
50
44
43
102
Estimated Spring Flow Changes
by WMD (1930-2000)
WMD
NWF
SJR
SR
SWF
Total
#
Springs
318
151
314
238
1,021
Est.
Historic
Flow
(MGD)
2,397
1,277
4,745
2,070
10,489
Current
Avg.
Flow
(MGD)
2,013
1,000
2,449
1,691
7,153
Change
Flow
(MGD)
-385
-276
-2,296
-379
-3,336
%
Change
-16
-22
-48
-18
-32
Population Increase and Silver Springs Flow
Declines to 2008
FDEP concluded that there has been a 250 cfs (160 MGD)
flow decline (Harrington et al. 2010)
Spring Flows are Declining Statewide
Silver Springs
Rainbow Springs
Estimated combined flow decline is
>300 MGD and Silver Springs
decline is 230 MGD (44%)
Evidence of Regional
Groundwater Transfers
WMD
NWF
SJR
SR
SWF
Total
#
Springs
318
151
314
238
1,021
%
Change
Spring
Flow
-16
-22
-48
-18
-32
Est.
Avg.
2010
Pumping
Recharge Pumping
as %
(MGD)
(MGD) Recharge
2,299
253
11
1,530
979
64
3,067
219
7
1,893
965
51
8,790
2,416
27
Estimated Decadal and Cumulative
Florida Spring Flow Changes
Comparison Between Estimated Florida Spring
Flows and Pumping from the Floridan Aquifer
Groundwater use data from USGS
Springs Flow From the Top of the Aquifer
A drop of less than 10
feet in the aquifer level
can dry up a major
spring!
White Springs on the Suwannee River in the
1920s
72 cfs
(Scott et al.
2004)
White Springs on the Suwannee River 2011
Declining
flows
since
1960s
(John Moran
photo)
A Non-Flowing Spring is a Sinkhole
Worthington
Springs on
the Santa Fe
River stopped
flowing in the
1950s
Poe Springs on the Santa Fe River Stopped
Flowing in May 2012
Poe Springs average flow pre-1972 was 72 cfs. Since 2000
the average flow was 44 cfs. Poe Springs flow in May 2012
was less than 1 cfs.
100
90
80
Pre-1972
average
Spring Flow (cfs)
70
60
50
40
2000 – 2011
average
30
20
10
0
April 26, 2012 flow = 2.9 cfs
The Upper Santa Fe River to Below Poe Springs
Stopped Flowing in May 2012
John Moran photo
This is a BIG problem for Florida!
• More pumping = lower
aquifer levels
• Lower aquifer levels =
dry wells
• Lower aquifer levels =
more sinkholes
• Lower aquifer levels =
salt water intrusion
• Lower aquifer levels =
lower spring flows
• Lower spring flows =
dry rivers and no
wildlife or recreation
Karst Productions, Inc.
Summary
• Florida is blessed by high
rainfall and large
underground aquifers
• Human consumptive uses are
lowering aquifer levels
• Some springs have gone dry
and others have seriously
declining flows
• The aquifer has limited
capacity to maintain both
healthy springs and intensive
human water use practices
• We need to balance our
groundwater “checkbook” to
provide for a sustainable
future!
John Moran photo
Florida Springs
Protection Goal:
Restore and
Protect Springs
for Future
Generations
www.floridaspringsinstitute.org
John Moran Photo