The relation between the height, density, and composition of vegetation and flow-velocity profiles in a sawgrass marsh was determined as part of a study of the movement of water in the Everglades National Park. Measurements were made at two sites, first in April and then again in November 1996. Vegetation at one site consisted primarily of dense sawgrass that was 1.5 to 3 m in height. Vegetation at the other site consisted of sparse sawgrass that was 1 to 1.5 meters in height, rushes, bladderwort, and periphyton. An Acoustic Doppler Velocity meter was used to measure horizontal flow velocities in 5-cm vertical increments through the entire water column, from the water surface to the bed at 10 to 15 sample locations at each site, where the depth of the water column varied between .2 and .5 m. In addition, 0.5-m square plots of vegetation were harvested in 10-cm vertical layers through the water column at each sample location. The vertical layers of each plot were harvested to determine the density and composition of the vegetation contained in each layer. Measurement results indicate that flow velocities at sample locations at both sites generally were larger in the middle part of the water column compared with those near the bed or the surface. Small flow velocities near the surface reflect the affects of vegetative drag caused by dense vegetation, such as sawgrass leaves, and bladderwort, and periphyton near the surface. Small velocities near the bed reflect drag caused by the high density of decaying plant litter near the bed. Few sawgrass culms rise through the middle part of the water column and create little vegetative drag; this, consequently, permits the larger flow velocities that occur in the middle of the water column.

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