U.S. Department of the Interior
U.S. Geological Survey
OFR-99-187

Airboat in the Everglades.

Abstract

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 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 numerical models of surface-water flow. Vegetative sampling was conducted in the Shark River Slough in April, 1996. The data collected and presented here include live, dead, and periphyton biomass, vegetation characteristics and structure, and leaf area index.

Introduction

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 additional water-control structures 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 manipulating 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 resistance exerted on the flow by the vegetation is a dominant but little understood force 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:

• To provide detailed information on species composition, vegetative characteristics, vegetative structure, and biomass for quantification of vegetative resistance to flow, and
• To use this information to classify the vegetation and to improve existing vegetation maps for use with models of surface-water flow.

Site map showing the locations of sites P33 and NESRS3. (Figure 1 in the OFR. Click on image for larger version.)

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Related information:

SOFIA Project: Vegetative Resistance to Flow in the Everglades