Factors that influence the hydrologic recovery of wetlands in the Northern Tampa Bay area, Florida

Abstract

For more information on the USGS-the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment, visit http://www.usgs.gov or call 1-888-ASK-USGS. For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprodTo order this and other USGS information products, visit http://store.usgs.gov Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted materials contained within this report. AcknowledgmentsThe author acknowledges Southwest Florida Water Management District (SWFWMD) employees Michael Hancock for his help with the study wetland selection and for his constructive technical discussions and review comments, Robert Peterson for his help in compiling groundwater withdrawal data for the Northern Tampa Bay well fields, and Vince Pelham and Robert Parker for performing geophysical logging tests for several study wells. Special recognition is given to former SWFWMD employee Ted Rochow for his long-term effort in documenting the history of wetlands in the Northern Tampa Bay area.The author also acknowledges Tampa Bay Water employees Warren Hogg and Jeff Geurink for their constructive technical review comments, and Patricia Fesmire and Chris Shea for their help with the study wetland selection. The author would like to thank Reynolds, Smith, and Hills employee Cynthia Wheeler for her assistance with initial logistics in the monitoring of the study area wetlands.Special recognition is given to U.S. Geological Survey (USGS) employees Terrie M. Lee and Amy Swancar for their valuable technical insight during this project, and Leel Knowles, James LaBaugh, and Arturo Torres for their constructive technical review comments. The author acknowledges the assistance of Nancy DeWitt and Billy J. Reynolds of the USGS St Petersburg Coastal and Marine Science Center for the collection of vibracores at six of the study wetlands. The author also expresses gratitude for field support and data analysis provided by the USGS interns from the University of South Florida; Geoffrey Fouad, Robert Schroeder, William Pfeiffer, Scott Orr, Suzana Hernandez, and Gene Morell. Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).Elevation, as used in this report, refers to distance above the vertical datum. Acronyms and Additional AbbreviationsGIS geographic information system GPR ground-penetrating radar LIDAR Light Detection and Ranging NOAA National Oceanic and Atmospheric Administration NWI National Wetland Inventory SWFWMD Southwest Florida Water Management District USGS U.S. Geological Survey WAP Wetland Assessment Procedure < less than > greater thanThe increase in the potentiometric surface of the Upper Floridan aquifer below the wetland was the primary factor influencing the h...

Flooded area and plant zonation in isolated wetlands in well fields in the Northern Tampa Bay Region, Florida, following reductions in groundwater-withdrawal rates

“…data, 2009). The small size of this wetland makes it particularly responsive to the effects of below-average rainfall because the smaller storage capacity allows it to dry out more quickly (Metz, 2011). Few alterations have occurred at this wetland since monitoring began other than controlled burns of adjacent saw palmetto (Michael Hancock, Southwest Florida Water Management District, unpub.…”

“…3) by about 3 ft during the post-reduction period, which likely decreased induced leakage from the overlying surficial aquifer and from the wetland. Metz (2011) reported that an increase in the potentiometric surface of the Upper Florida aquifer below wetlands was the primary factor affecting hydrologic recovery of wetlands in well fields.…”

“…In a study of factors known to influence the hydrologic condition of wetlands, Metz (2011) reported that karst features below or near wetlands, subsidence, and high permeability sediments underlying wetlands impeded the ability of these wetlands to recover when groundwater-withdrawal rates were reduced. Metz (2011) also reported that wetlands isolated from surfacewater connections to near-by water sources, such as other wetlands, streams, and ponds, were less likely to recover after groundwater-withdrawal rates were reduced.…”

“…The median elevation of the potentiometric surface of the Upper Floridan aquifer increased beneath Q-1 by about 2 ft after reductions in groundwater-withdrawal rates, but remained 6 ft below the wetland bottom. Other factors, including karst features below or near the wetland bottom, high permeability sediments underlying the wetland, and topographic isolation from other surface waters could contribute to the lack of recovery of water levels in these wetlands (Metz, 2011).…”

“…Groundwater withdrawals in the region have increased since the 1930s, and by the early 2000s, withdrawals for municipal water supply from the Upper Floridan aquifer reached a maximum rate of 165 million gallons per day (Mgal/d;Tampa Bay Water, 2004). The increased groundwater-withdrawal rates have lowered the potentiometric surface of the Upper Floridan aquifer and induced downward leakage from the water table in the overlying surficial aquifer (Hancock, 1999;Metz and Sacks, 2002;Haag and others, 2005;Lee and others, 2009;Metz, 2011). Downward leakage from the surficial aquifer also has induced downward leakage from wetlands in well fields, which has altered wetland hydroperiod (the seasonal pattern of the water level in a wetland).…”