Abstract

Surface-water flow velocity in the wetlands of Taylor Slough, Everglades National Park, is controlled by factors such as water depth, landsurface gradient, wind effects, and the type and density of vegetation. In order to evaluate the effect of vegetation on this shallow surface-water flow for model development, it is necessary to extrapolate from point measurements of velocity and surface-water slope made concurrently with characterization of vegetation at locations throughout the slough to the entire model area. At these flow measuring locations, vegetation, including periphyton, was harvested in horizontal layers, either 10 cm or 20 cm thick, from the bed through the water column to the top of the plants, in 0.5-m square quadrats. Species composition, density, leaf and(or) culm number and size, biomass, and leaf area index were determined for each layer. The vegetation samples were grouped into classes by species composition and biomass. A geographic information system graphical user interface (DBView) was developed and used to assimilate and interpret the various spatial data, such as a 68-class 1993-94 Landsat vegetation map of southern Florida, a 20-class Landsat Thematic Mapper image, digital orthophoto quadrangles, land-surface elevations, and digital line graphs. Working with both sets of Landsat data, color infrared aerial photographs, and other available maps, we recombined Landsat vegetation classes to delineate the areal extent of basic vegetation types throughout the slough. These vegetation types have different effects on flow velocity and may be associated with different model roughness characteristics. After crosschecking the final vegetation classes on each Landsat map with actual field vegetation samples and specific ground-truth observations, we selected an 8-class vegetation map from Landsat Thematic Mapper images for use with surface-water models in Taylor Slough.