Hook gauges being used to measure water-surface elevation in sawgrass during a flow experiment in the tilting flume at Stennis Space Center, Mississippi.

Abstract

The U.S. Geological Survey is studying the wind sheltering effects of vegetation in the Florida Everglades. In order to test both the flow resistance and wind sheltering effects of sawgrass, uniform dense stands of sawgrass were grown in a tilting flume at Stennis Space Center, Mississippi. In June, 1997, one end of the flume was covered with a wind cowling with a removable top, and a series of experiments were conducted between June, 1997 and July, 1998. During each set of experiments, the sawgrass was sampled for vegetative characteristics, biomass, and leaf area index. The results of the analyses of the vegetation samples are summarized in a series of appendixes.

Introduction

The U.S. Geological Survey (USGS) is studying vegetative resistance to flow and the wind sheltering effects of vegetation in the South Florida Everglades as part of the USGS South Florida Ecosystem study. Living and dead vegetation in the water column can be expected to retard the flow of water, depending upon its density. In order to test the flow resistance of sawgrass under controlled conditions, uniform dense stands of sawgrass were grown in pans that were fit tightly into the USGS tilting flume at Stennis Space Center, Mississippi, to form a 61-m long, 1.8-m wide artificial sawgrass ecosystem (Lee and Carter, 1996). The depth of water in the flume was controlled by adding or removing metal plates (stop logs) at the downstream end. An initial series of experiments were conducted at various flow depths, and vegetative resistance was calculated from velocity, flow depth, and surface-water slope. This report describes the flume experiments and presents results of analyses of the vegetation samples.

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Related information:

SOFIA Project: Vegetative Resistance to Flow in the Everglades