publications > open file report > OFR-99-218
U.S. Department of the Interior
Vegetative Resistance to Flow in South Florida: Summary of Vegetation Sampling at Sites NESRS3 and P33, Shark River Slough, November, 1996
By: Virginia Carter, Justin T. Reel, Nancy B. Rybicki, Henry A. Ruhl, Patricia T. Gammon, and Jonathan K. Lee
The U.S. Geological Survey is one of many agencies participating in the effort to restore the South Florida Everglades. We are sampling and characterizing the vegetation at selected sites in the Everglades as part of a study to quantify vegetative flow resistance. The objectives of the vegetation sampling are (1) to provide detailed information on species composition, vegetation characteristics, vegetation structure, and biomass for quantification of vegetative resistance to flow, and (2) to use this information to classify the vegetation and to improve existing vegetation maps for use with numerical models of surface-water flow. Vegetation was sampled at two sites in the Shark River Slough in November, 1996. The data collected and presented here include those for live and dead standing sawgrass, other dead material, periphyton biomass, vegetation characteristics and structure, and leaf area index.
The Florida Everglades is a vast, diverse wetland ecosystem characterized by small ground-surface slopes, slowly moving surface waters, and dense aquatic vegetation. The South Florida ecosystem has been greatly altered during the last 100 years. A complex water-management system that includes levees, canals, pumps, and water-control structures now regulates flooding and provides a steady supply of fresh water to urban areas and agriculture. Drainage projects have diverted much of the water that originally flowed slowly southward from Lake Okeechobee through the Everglades. Restoration and management of the Everglades ecosystem requires understanding and manipulation of the amount and timing of water flows throughout the ecosystem.
The spatial and temporal distribution of water and water-borne contaminants in the Everglades must be understood if degradation of the ecosystem is to be halted and reversed. To understand how water moves through the Everglades ecosystem, it is necessary to quantify the forces affecting the flow. The vegetative resistance exerted on the water flow is one of the most important but least understood forces affecting Everglades surface-water flows. The aquatic vegetation affects both the depth of water and the rate at which it moves. The presence of living and dead plant material in the water column creates drag forces on the moving water. Water flows most slowly and the surface-water slope is largest in areas where the vegetation is the most dense.
We are sampling and characterizing the vegetation at selected sites in the Everglades as part of a study to quantify vegetative flow resistance. This information will be used to improve numerical models of surface water flow. The objectives of the vegetative sampling are: (1). To provide detailed information on species composition, vegetative characteristics, vegetative structure, and biomass for quantification of vegetative resistance to flow, and (2) To use this information to classify the vegetation and to improve existing vegetation maps for use with models of surface-water flow.
This is the second in a planned series of data reports summarizing the vegetation information collected in the South Florida Everglades. The first report in the series was published as U. S. Geological Survey Open-File Report 99-187 (Carter and others, 1999).
U.S. Department of the Interior, U.S. Geological Survey
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