Alafia River Minimum Flows and Levels - Southwest Florida Water ...

Figure 4-5. Upstream vegetation cross-section (transect) locations and GAP classes for
the Alafia River
To characterize forested vegetation communities along each cross-section,
changes in dominant vegetation communities, or classes were located and used
to delineate boundaries between vegetation classes. At each change in
dominant vegetation class, plant species composition, density, basal area and
diameter at breast height (for woody vegetation with a dbh > 1 inch) were
recorded. Distance to the center of the river channel was also measured for
each vegetation class.
Soils along the floodplain vegetation cross-sections were evaluated for the
presence of hydric or flooding indicators, as well as saturation and/or inundation
condition. At least three soil cores were examined to a minimum depth of 20
inches within each vegetation class at each cross-section. Soils were classified
as upland (non-hydric), hydric or non-hydric with the presence of flooding
indicators.
Ground elevation data were used to compare vegetation, soils and distance data
within and among cross-sections. For some comparisons, vegetation elevations
were normalized to the lowest channel elevations at the cross-section to account
for differences in absolute elevations among the cross-sections. Floodplain
wetted perimeter (linear extent of vegetation classes along the ground surface
plotted against elevation change) was calculated to identify vegetation classes in
which small changes in elevation (or river stage) would result in large changes in
the amount of habitat exposed or inundated. The HEC-RAS floodplain model
was used to determine local cross-section flows and corresponding flows at the
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