Prepared in cooperation with Pinellas County, Southwest Florida Water Management

District, and Tampa Bay Water

U.S. Department of the InteriorU.S. Geological Survey

Professional Paper 1758

Comparative Hydrology, Water Quality, and Ecology

of Selected Natural and Augmented Freshwater

Wetlands in West-Central Florida

U.S. Department

of the Interior

U.S. Geological S

urvey

Scientific Investiga

tions Report 2005-

5109

Bathymetry and V

egetation in Isol

ated Marsh and

Cypress

Wetlands in the

Northern Tampa B

ay Area, 2000-20

04Prepare

d in cooperation w

ith Pinellas Coun

ty, Southwest Flo

rida

Water Managem

ent District, and T

ampa Bay Water

U.S. Department of the InteriorU.S. Geological Survey

Fact Sheet 2006–3118October 2006

Prepared in cooperation withPinellas County, Southwest Florida Water Management

District, and Tampa Bay WaterStrength in Numbers: Describing the Flooded Area of

Isolated Wetlands

Printed on recycled paper

IntroductionThousands of isolated, freshwater wetlands are scattered

across the karst1 landscape of central Florida. Most are small

(less than 15 acres), shallow, marsh and cypress wetlands that

flood and dry seasonally. Wetland health is threatened when

wetland flooding patterns are altered either by human activi-

ties, such as land-use change and ground-water pumping, or

by changes in climate. Yet the small sizes and vast numbers of

isolated wetlands in Florida challenge our efforts to charac-

terize them collectively as a statewide water resource. In the

northern Tampa Bay area of west-central Florida alone, water

levels are measured monthly in more than 400 wetlands by

Tampa Bay Water and the Southwest Florida Water Manage-

ment Distirct (SWFWMD). Many wetlands have over a decade

of measurements.The usefulness of long-term monitoring of wetland water

levels would greatly increase if it described not just the depth of

water at a point in the wetland, but also the amount of the total

wetland area that was flooded. Water levels can be used to esti-

mate the flooded area of a wetland if the elevation contours of

the wetland bottom are determined by bathymetric mapping.

Despite the recognized importance of the flooded area

to wetland vegetation, bathymetric maps are not available to

describe the flooded areas of even a representative number of

Florida’s isolated wetlands. Information on the bathymetry of

isolated wetlands is rare because it is labor intensive to collect

the land-surface elevation data needed to create the maps.

Five marshes and five cypress wetlands were studied by

the U.S. Geological Survey (USGS) during 2000 to 2004 as

part of a large interdisciplinary study of isolated wetlands in

central Florida. The wetlands are located either in municipal

well fields or on publicly owned lands (fig. 1). The 10 wetlands

share similar geology and climate, but differ in their ground-

water settings. All have historical water-level data and multiple

vegetation surveys.A comprehensive report by Haag and others (2005)

documents bathymetric mapping approaches, the frequency

of flooding in different areas of the wetlands, and the relation

between flooding and vegetation in these wetlands. This fact

sheet describes bathymetric mapping approaches and partial

results from two natural marshes (Hillsborough River State

Park Marsh, and Green Swamp Marsh) and one impaired marsh

(W-29 Marsh) that is located on a municipal well field and is

affected by ground-water withdrawals. (fig. 1).Wetland PerimetersDefining wetland perimeters is fundamental to creating the

bathymetric maps. At 9 of the 10 wetland sites in this study, a

saw palmetto fringe delineated the perimeter of the wetland

and defined the elevation corresponding to 100 percent flooded

1Terms defined in the glossary are in bold print where first used in

this fact sheet.

To identify changes in flooded area that signal changes in the

acreage of wetland vegetationTo summarize wetland water levels into a regional view of

wetland statusTo help identify wetland/ground-water interactions

To provide information that can be used to increase the

similarity of mitigation wetlands and natural wetlands

•

•

•

•

Why describe the flooded area ofisolated wetlands?

Prepared in

cooperatio

n with the

St. Johns R

iver Water M

anagement

District,

the Southwe

st Florida W

ater Manage

ment Distri

ct,

and Tampa

Bay Water

U.S. Geolog

ical Survey

Circular 13

42

U.S. Depart

ment of the

Interior

U.S. Department of the InteriorU.S. Geological Survey

Fact Sheet 2011–3094August 2011

Florida Water Science Center

USGS Research on Florida’s Isolated Freshwater Wetlands

Printed on recycled paper

IntroductionThe U.S. Geological Survey (USGS) has

studied wetland hydrology and its effects on wetland health and ecology in Florida since the 1990s. USGS wetland studies in Florida and other parts of the Nation provide resource man-agers with tools to assess current conditions and regional trends in wetland resources.

Wetlands are a valuable natural and ecological resource in Florida and represent a greater percentage of the land surface than in any other state in the conterminous United States (Dahl, 2006). Wetlands covered an estimated 50 percent of the State before land-use changes and other human activities began to cause wet-land losses in Florida (Dahl, 1990). In 1996, an estimated 11.4 million acres of wetlands remained, occupy-ing 29 percent of the State. Fresh-water wetlands make up 90 percent of the total wetland area Statewide, and coastal wetlands make up 10 percent. About 55 percent of the freshwater wetlands in Florida are forested, about 25 percent are marshes or emergent wetlands, 18 percent are shrub/scrub wetlands, and the remaining 2 percent are freshwater ponds (Dahl, 2005).

Wetland hydrologists in the USGS Florida Water Science Center (FLWSC) have completed a number of interdisciplin-ary studies assessing the hydrology, ecology, and water quality of wetlands. These studies have expanded the understand-ing of wetland hydrology, ecology, and related processes including: (1) the effects of cyclical changes in rainfall and the influence of evapotranspiration; (2) surface-water flow, infiltration, groundwater movement, and groundwater and surface-water interactions; (3) the effects of water quality and soil type; (4) the unique biogeo-chemical components of wetlands required to maintain ecosystem functions; (5) the effects of land use and other human activities; (6) the influ-ences of algae, plants, and invertebrates on envi-ronmental processes; and (7) the effects of seasonal variations in animal communities that inhabit or visit Florida wetlands and how wetland function responds to changes in the plant community.

Advances in Understanding Wetland Hydrology and Ecology

Freshwater wetlands of central Florida are relatively small, mostly

isolated, and widely distributed (Haag and Lee, 2010) but are a dominant feature

of the landscape, numbering in the thou-sands. The relatively small size and large

number of freshwater wetlands present challenges for characterizing these wetlands

collectively as a statewide water resource (Lee and Haag, 2006). Freshwater wetlands

are distributed differently in central Florida than in other parts of the State. In the pan-

handle and in northern Florida, there are fewer isolated wetlands than in the central and south-ern parts of the State, and few of those wetlands

are affected by activities such as groundwater withdrawals. In southern Florida, the vast wetlands of the Everglades and the Big Cypress Swamp blanket the landscape and form contiguous shallow

expanses of water, which often exhibit slow but continuous flow toward the southwestern coast.

Comparing altered wetlands to natural wetlands in the same region improves the ability to interpret the gradual and cumula-tive effects of human populations on freshwater wetlands. Hydrologic differences require explicit atten-tion because they affect nearly all wetland functions and are an over-riding influence on other compari-sons involving wetland water quality and ecology. Research conducted by FLWSC hydrologists resulted in several new approaches for quantifying wetland characteristics and evaluating the hydrology, water quality, and ecol-ogy of isolated freshwater marsh and cypress wetlands in the mantled karst terrain of central Florida (Lee and others, 2009). Key components of the research included the evaluation of (1) the hydrogeologic framework of

wetlands and wetland and groundwater interactions; (2) wetland water budgets, with

a focus on the role of leakage and runoff; (3) the water quality of wetland surface waters and the geochemistry of

underlying aquifers; (4) the frequency, duration, depth, and spatial extent of wetland flooding; and (5) assessments of periphyton communities, aquatic vegetation, and macroinverte-brate taxa richness and density.

Florida’s wetlands are complex ecosystems that are increasingly important to residents. In many places, wetlands are flanked by uplands, generating a mosaic of contrasting environments – unique wildlife habitat often adjacent to dense human populations. As the population of Florida increases, the number of residents living near wetlands also increases. Living in close proximity to wetlands provides many Floridians with an increased awareness of nature and an opportunity to examine the relationship between people and wetlands. Specifi-cally, these residents can observe how wetlands are affected by human activities. FLWSC hydrologists have conducted studies to address the need for a broader understanding of the interactions between wetland ecosystems, surface-water and groundwater resources, and human activities in Florida (Lee and others, 2009; Haag and Lee, 2010; Metz, 2011).

USGS Wetland Research Capabilities

Wetland hydrologists in Florida design studies to:

Compare the hydrology, water quality, and ecology of isolated wetlands that have different vegetation types and hydrologic settings.

Use sediment coring, drilling, and geophysical surveying tools to describe the geologic framework of wetlands.

Describe the hydrogeologic setting of freshwater wetlands and quantify their groundwater interactions.

Ground penetrating radar profile

Ground penetrating radar profile

40

30

20

10

-10

Cypress wetlands, Starkey well field

38.1

5

0

33.1936.88

35.21

38.2

7

41.75

38.95

32.50

50

38.8

6

Elev

atio

n, in

feet

abo

ve a

nd b

elow

N

atio

nal G

eode

tic V

ertic

al D

atum

of 1

929

35.93

Upper Floridan aquifer 32.50 Depth 130 feet Casing 80 feet

Study the effect of climate and groundwater withdrawals from well fields on wetland hydrology.

Map the bottom elevations of wetlands to relate wetland water levels to flooded area and plant zonation.

0 1 2 MILES

0 1 2 KILOMETERS

W-56 Cypress

W-12Cypress

W-33 Cypress

W-16 Marsh

6260 64 665858606668 68

5658 60

5452

50

48

46

64 62

70

EXPLANATIONWell-field boundary

Potentiometric contour

Observation well

Study wetland name and location

– Shows altitude at which water wouldhave stood in tightly cased wells. Hachures indicatedepressions. Contour interval 2 feet. Datum is NationalGeodetic Vertical Datum of 1929.

W-33 Cypress

60

28°18’

28°16’

82°20’82°22’82°24’82°26’82°28’

Source: U.S. Fish and Wildlife Service,National Wetlands Inventory polygon data, March, 2004;Universal Transverse Mercator projection, zone 17

Define the relationship between standing water levels, flooded area, and flooded volumes in wetlands.

Compare flooding patterns in wetlands that are natural, impacted, and augmented with additional water to help evaluate the success of mitigation efforts.

Monitor vegetation at different elevations in wetlands to relate flooding frequency and plant zonation.

Area

Volume

0

1

2

3

4

5

6

7

67 68 69 70

Wetland stage, in feet above sea level

Area

, in

acre

s

W-2910

89

Volu

me,

in a

cre-

feet

76543210

Percent of total area inundated

0 to

20

21 to

40

41 to

60

61 to

80

81 to

100

0 to

20

21 to

40

41 to

60

61 to

80

81 to

100

Num

ber o

f mon

ths

Natural/Control, Hillsborough River State Park marsh

Augmented, Duck Pond marsh

Impacted/Wellfield, W-29 marsh

Average YearAugust 2001 – July 2002

Wet Year

10

0

10

0

10

0

August 2002 – July 2003

5

5

5

50 METERS

150 FEET

0

0

N

Perc

enta

ge o

f tim

e Recent period, 12/12/2000 to 9/30/2002

Later period, 12/10/2002 to 6/28/2004

100

80

60

40

20

0

41 to

60

61 to

80

81 to

100

0 to

20

21 to

40

EXPLANATION

Wetland perimeter – At 100 percent inundation Vegetation plots Deepest point Staff location – Recent Staff location – Historic

Flooded area–In percent of total wetland area

0 to 20

21 to 40

41 to 60

61 to 80

81 to 100

Percentage of total wetland area inundated

100

80

60

40

20

0

41 to

60

61 to

80

81 to

100

0 to

20

21 to

40

Conduct water-budget studies to quantify surface-water and groundwater fluxes in wetlands.

Wetland Research Needs in Florida Include

• Assessing the response of natural and altered wetland systems to climate change;

• Determining the effects of climate change on groundwater and surface-water interactions in freshwater and coastal wetlands;

• Characterizing wetland ecosystem structure, function, and critical processes affecting ecosystem sustainability and health;

• Characterizing and quantifying interactions between the physical, chemical, and biological components of wetland ecosystems;

• Determining how wetland ecosystems change in response to human activities; and

• Assessing recovery of wetland water levels as groundwater withdrawals from well fields are reduced.

Water-Budget TermsRainfall (P)Evaporation (E)

Runoff (RO)

Groundwater inflow (GI)

Leakage (GO)

Change in volume (∆V)

References for Additional InformationGerman, E.R., 1996, A method for evaluating water-level response to

hydrologic stresses in karstic wetlands in central Florida, using a simple water-balance model: U.S. Geological Survey Water-Resources Investi-gations Report 96–4216, 51 p.

Dahl, T.E., 1990, Wetland losses in the United States 1780s to 1980s: Washington, D.C., U.S. Fish and Wildlife Service report, 21 p.

Dahl, T.E., 2005, Florida’s wetlands: An update on status and trends 1985 to 1996: Washington D.C., U.S. Fish and Wildlife Service report, 80 p.

Dahl, T.E., 2006, Status and trends of wetlands in the conterminous United States, 1998 to 2004: Washington D.C., U.S. Fish and Wildlife Service report, 80 p.

Darst, M.R., Light, H.M., 2008, Drier forest composition associated with hydrologic change in the Apalachicola River floodplain, Florida: U.S. Geological Survey Scientific Investigations Report 2008–5062, 81 p., plus 12 apps.

Haag, K.H., and Lee, T.M., 2006, Flooding frequency alters vegetation in isolated wetlands: U.S. Geological Survey Fact Sheet 2006–3117, 4 p., accessible at http://pubs.usgs.gov/fs/2006/3117/.

Haag, K.H., and Lee, T.M., 2010, Hydrology and ecology of fresh-water wetlands in central Florida—A primer: U.S. Geological Survey Circular 1342, 138 p. (Also available at http://pubs.usgs.gov/circ/1342/.)

Haag, K.H., Lee, T.M., and Herndon, D.C., 2005, Bathymetry and vegeta-tion in isolated marsh and cypress wetlands in the northern Tampa Bay area, 2000–2004: U.S. Geological Survey Scientific Investiga-tions Report 2005–5109, 49 p. (Also available at http://pubs.usgs.gov/sir/2005/5109/.)

Knowles, L., Jr., Phelps, G.G., Kinnaman, S.L., and German, E.R., 2005, Hydrologic response in karstic-ridge wetlands to rainfall and evapo-transpiration, central Florida, 2001–2003: U.S. Geological Survey Scientific Investigations Report 2005–5178, 82 p.

Lee, T.M., and Haag, K.H., 2006, Strength in numbers: Describing the flooded area of isolated wetlands: U.S. Geological Survey Fact Sheet 2006–3118, 4 p. (Also available at http://pubs.usgs.gov/fs/2006/3118/.)

Lee, T.M., Haag, K.H., Metz, P.A., and Sacks, L.A., 2009, Comparative hydrology, water quality, and ecology of selected natural and augmented freshwater wetlands in west-central Florida: U.S. Geological Survey Professional Paper 1758, 152 p. (Also available at http://pubs.usgs.gov/pp/1758/.)

Light, H.M., Vincent, K.R., Darst, M.R., and Price, F.D., 2006, Water-level decline in the Apalachicola River, Florida, from 1954 to 2004, and effects on floodplain habitats: U.S. Geological Survey Scientific Investi-gations Report 2006–5173, 83 p., plus CD.

Merritt, M.L., 1992, Representing canals and seasonal inundated wetlands in a ground-water flow model of a surficial aquifer, in Jones, M.E., and Laenen, Antonius, eds., Interdisciplinary approaches in hydrology and hydrogeology: American Institute of Hydrology, p. 31-45.

Metz, P.A., 2011, Factors that influence the hydrologic recovery of wetlands in the Northern Tampa Bay area: U.S. Geological Survey Scientific Investigations Report 2011–5127, 58 p.

Schiffer, D.M., 1989, Effects of highway runoff on the quality of water and bed sediments of two wetlands in central Florida: U.S. Geological Survey Water-Resources Investigations Report 88–4200, 63 p.

For more information contact: Arturo E. Torres (aetorres@usgs.gov) Terrie M. Lee (tmlee@usgs.gov) Kim H. Haag (khhaag@usgs.gov) Patricia A. Metz (pmetz@usgs.gov)

U.S. Geological SurveyFlorida Water Science Center(FLWSC-Tampa)10500 Univ. Center Dr., Suite 215, Tampa, Florida 33612

00 10 20 30 40 50 60 70 80 90 100 110 120

2

4

6

8

Vol

ume,

in a

cre-

feet

Weeks

Weekly average wetland volume

Rainfall and Wetland Stage Augmentation Water

IntroductionAdvances in Understanding Wetland Hydrology and EcologyUSGS Wetland Research CapabilitiesWetland hydrologists in Florida design studies to

Wetland Research Needs in Florida IncludeReferences for additional information