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projects > effect of sheet flow on transport of suspended particles and particle-associated nutrients in the everglades ridge and slough landscape > project summary

Project Summary Sheet

U.S. Geological Survey, Greater Everglades Priority Ecosystems Science (GE PES) Initiative

Fiscal Year 2006 Study Summary Report

Study Title: Effect of Sheet Flow on Transport of Suspended Particles and Particle-Associated Nutrients in the Everglades Ridge and Slough Landscape
Study Start Date: October 2003 Study End Date: TBD, September 2007 to September 2010
Web Sites:;;;;;
Location (Subregions, Counties, Park or Refuge): Northern, Central, and Southern Everglades (Palm Beach, Broward, Miami-Dade)
Funding Source: GE PES
Other Complementary Funding Source(s): None
Principal Investigator(s): Jud Harvey (USGS, Reston), Greg Noe (USGS, Reston), and Ray Schaffranek (USGS, Reston)
Study Personnel: Ami Riscassi, (USGS), Jennifer O'Reilly (ECO), Joel Detty (ECO), Dan Nowacki (ECO), Leanna Westfall (ECO), and Laurel Larsen (Ph.D. student)
Supporting Organizations: USGS, SFWMD, NPS/Everglades National Park
Associated / Linked Studies:
Tides and Inflows at the Mangrove Ecotone (TIME):;
Integrated Geochemical Studies in the Everglades:,;
Freshwater Flows into Florida Bay:;
Florida Coastal Everglades Long-Term Ecological Research:

Overview & Objective(s): A primary directive in the Comprehensive Everglades Restoration Plan (CERP) is to restore Everglades hydrology toward pre-drainage conditions in a manner that will successfully restore landscape structure and function while protecting water quality. Central to CERP is the Water Conservation Area 3 Decompartmentalization & Sheet Flow Enhancement project (DECOMP) which has the objective to restore sheet flow and hydrologic connectivity in much of the Everglades. DECOMP is intended to reverse the management policies that in the past led to loss of diversity in Everglades landscape patterns (i.e., losses of ridge and slough and tree island topographic features and associated losses of diversity in flora and fauna). Increasing numbers of scientists and stakeholders believe that sheet flow and sediment transport processes are a key aspect of Everglades landscape function and a key uncertainty in the restoration (Harvey and Sklar, 2006). The National Park Service (Crisfield and McVoy, 2004), National Research Council (National Research Council, 2003), and the Department of Interior (DOI, 2005) have all recommended research to determine how changing the amount and distribution sheet flow in a “restored” Everglades will influence landscape characteristics. A growing concern is that augmenting sheet flow to benefit the hydrology of certain downstream areas could have unintended consequences to other areas, such as transporting surface-water contaminants farther into the central and southern parts of the Everglades ecosystem than ever before. Our study is necessary to identify the critical hydrologic, chemical, and biologic linkages that have shaped both the pre-drainage Everglades and the current landscape. As part of that research we will quantify the fundamental processes that determine how much farther downstream suspended sediments and associated nutrients will be transported as a result of increased sheet flow velocities. This information is necessary for understanding the critical factors that sustain the ridge and slough landscape structure and ecosystem function, and is also necessary for predicting some of the unintended side-effects of restoration activities that may accompany increases in flow and hydrologic connectivity. Our ultimate goal is to meet the Science Coordination team's challenge (SCT, 2003) of ensuring the level of scientific readiness needed to protect both Everglades landscape conditions and water quality though adaptive management of “restored” flows. Important scientific questions being addressed are:

  • How do the characteristic ridge and slough topographic variation and its associated vegetation patterns influence the sources, transport rates, and rates of interception of suspended particulates and nutrients?
  • What are relative roles of transport of fine suspended particulate matter and coarser flocculent benthic organic matter (floc) in suspended sediment and phosphorus budgets in Everglades wetlands?
  • To what extent will sources, concentrations, and transport distances of suspended sediments and nutrients in Everglades wetlands be altered by DECOMP? Will it be the increased sheet flow velocities or the extent that canals are backfilled after levee removal that will be the more important driver of changes in transport?

Status: Active

Recent Products: Noe, G.B., Harvey, J.W., and Saiers, J.E. In press. Characterization of suspended particles in Everglades wetlands. Limnology & Oceanography; Harvey, J.W., Saiers, J.E., and Newlin, J.T., 2005, Solute Transport and Storage Mechanisms in Wetlands of the Everglades, South Florida. Water Resources Research, 41(5),W05009,doi10.1029/2004WR003507; Harvey, J.W. and others, 2005, Surface-Water and Ground-Water Interactions in Water Conservation Area 2A, Central Everglades, USGS Scientific Investigations Report 2004-5069; Schaffranek, R.W. 2004. Sheet-flow velocities and factors affecting sheet-flow behavior of importance to restoration of the Florida Everglades, U.S. Geological Survey Fact Sheet 2004-3123, 4 p.; Saiers, J.E., Harvey, J.W., and Mylon, S.E., 2003, Surface-water transport of suspended matter through wetland vegetation of the Florida Everglades. Geophysical Research Letters 30(19), 1987, doi:10.1029/2003GL018132; Noe, G.B., Scinto, L.J., Taylor, J., Childers, D.L., and Jones, R.D., 2003, Phosphorus cycling and partitioning in an oligotrophic Everglades wetland ecosystem: a radioisotope tracing study. Freshwater Biology 48:1993-2008;

Planned Products: Journal articles, white paper (about Arthur R. Marshall Loxahatchee NWR) fact sheets, data reports.

Specific Relevance to Information Needs Identified in DOI's Science Plan in Support of Ecosystem Restoration, Preservation, and Protection in South Florida (DOI's Everglades Science Plan)
[See Plan on SOFIA's Web site:]:

Our proposed experiments and modeling are fundamental to building a reliable predictive capability of how the Everglades will respond to the restoration's higher flows. The research follows the DOI Science plan's main recommendation by directly addressing the following CERP Interim Goals (3.2-Sheet Flow in Natural Areas, 3.3-Hydropattern, 3.5-Everglades Wetlands Total Phosphorus, and 3.7-Ridge and Slough Pattern). The proposed combination of empirical and modeling research supports several of the critical information needs identified by the National Academy of Science and DOI's Science Plan. For example, the National Academy of Sciences has emphasized the importance of sediment transport to understanding and restoring the Everglades (NRC, 2003), while the DOI Science Plan highlights the need to understand the influence of hydrology on nutrient and contaminant transport and cycling (U.S. Department of the Interior, 2005). While our proposed work addresses fundamental questions that are relevant to management questions throughout the Everglades, at the same time it also addresses key site-specific CERP projects mentioned in the DOI Science plan. These critical CERP projects include the WCA-3A Decompartmentalization Project, and Tamiami Trail Bridge Expansion projects, in addition to broader projects related to preservation of landscape structure (e.g. Landscape-Scale Modeling Study and Ridge and Slough Performance Standards), and changing water quality and the need for more modern water-quality performance standards in the Everglades (e.g. Comprehensive Integrated Water Quality Feasibility Study). Finally, the information gained on suspended sediment and nutrient transport will aid critical modeling efforts that support the Loxahatchee Internal Canal Structures Project. In conclusion, our proposed work supports no less than six of the key projects identified by DOI as critical to the success of the Everglades restoration.

Selected Findings to Date:

- Sheet flow velocities ranged between 0.08 and 0.55 cm/s at site WCA-3A-5, which is lower than velocities measured in (1999 - 2003) in Shark Slough (0.46 to 2.29 cm/s). - Mean flow velocity in the slough was typically 34% faster, water depth was typically 20 cm greater, and average time period of surface-water inundation was approximately 20% longer compared with the ridge. - In both ridge and slough the average suspended particulate concentrations were relatively low (0.5 - 3 mg/L), and average particle size was approximately 10 um. - Particulate phosphorus tended to be associated with relatively small particles (1 um), while particulate nitrogen tended to be associated with particles of intermediate size (6 um). - The mass transport of water and suspended particulates was, on an average annual basis, approximately twice as high in the slough as it was on the ridge. - Particle capture by vegetation was more effective in the ridge than in the slough (greater than 80% of tracer particles were removed over a 30-m flow path on the ridge). - Maximum flow velocities were an order of magnitude greater during Hurricane Wilma, and velocities quickly returned to typical sheet flow conditions after hurricane passage.


Crisfield, E., and McVoy, C. 2004. Role of flow-related processes in maintaining the ridge and slough landscape, Joint Conference on the Science and Restoration of the Greater Everglades and Florida Bay Ecosystem, Palm Harbor, FL.

Harvey, J.W. and Sklar, F. 2006. WORKSHOP: Development of a Conceptual Model for Ridge and Slough Landscape Dynamics. Greater Everglades Ecosystem Restoration Conference, June 5-9, 2006, Lake Buena Vista, FL, p. 91.

U.S. Department of the Interior, 2005. Science Plan in Support of Ecosystem Restoration, Preservation, and Protection in South Florida.

National Research Council. 2003. Does water flow influence Everglades landscape patterns, Washington, D.C., The National Academies Press, 41 p.

Science Coordination Team. 2003. The role of flow in the Everglades ridge and slough landscape, South Florida Ecosystem Restoration Working Group, 62 p.

Our study will identify the critical hydrologic, chemical, and biologic linkages that have shaped both the pre-drainage Everglades and the current landscape. This information is necessary for understanding the critical factors that sustain the ridge and slough landscape and ecosystem function, and is also necessary for predicting some of the unintended side-effects of restoration activities that may accompany increases in flow and hydrologic connectivity.

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