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

Figure 4-9. RALPH plot of the number of days during the southern river pattern
water year (SRPWY) that 200 cfs is exceeded at the USGS Lithia gage
(orange line) compared with the number of days that inundation would have
occurred if there had been a 15% reduction in river flows (blue line).........4-17
Figure 4-10. Approximate representations of flow blocks (Blocks 1, 2 and 3)
projected onto a plot of median daily flows (Julian day) recorded between
1970 and 1999 at the USGS Lithia Gage at the Alafia River. ....................4-19
Figure 4-11. Discharge at HEC-RAS transect number 84.5 (Shoal 9). Wetted
perimeter values for the entire range of modeled flows are shown in the upper
plot; values for modeled flows up to 200 cfs are shown in the lower plot...4-21
Figure 4-12. Stage flow relationships between HEC-RAS cross-section 91.5 and
flow at RS 60 cross-section (USGS Lithia gage) derived from the HEC-RAS
model of the Alafia River corridor. The upper-right plot shows the relationship
derived for the entire range of flows evaluated. The other three show
relationships used to develop regression equations for selected portions of
the flow range. ...........................................................................................4-23
Figure 4-13. Photo of Lithia Spring Major pool being utilized for recreation......4-28
Figure 5-1. Plot of local flow required to inundate the deepest part of the channel
at each HEC-RAS cross-section to a depth of 0.6 ft. A local flow of 41.75 cfs
at the limiting site (cross-section 60) is the equivalent of 59 cfs at the Lithia
gage.............................................................................................................5-2
Figure 5-2. Plot of local flow required to inundate the lowest wetted perimeter
inflection point at each HEC-RAS cross-section. .........................................5-3
Figure 5-3. Plot of predicted habitat gain/loss for largemouth bass fry based on
the flow record from 1940 to 1969 and flow reductions of 10, 20, 30, and 40
percent.........................................................................................................5-4
Figure 5-4. Elevation profile for floodplain vegetation cross-section (transect) 49.
Distances (cumulative length) are shown centered on the middle of the river
channel. .......................................................................................................5-6
Figure 5-5. Mean elevations of six vegetation classes at eight Alafia River
floodplain cross-sections (transects)............................................................5-7
Figure 5-6. Floodplain wetted perimeter versus elevation at floodplain vegetation
cross-section 51 (transect 51). Arrows indicate mean elevations for
floodplain vegetation classes at the site. .....................................................5-9
Figure 5-7. Elevations of hydric and nonhydric (upland and non-hydric soils with
flooding indicators) soils at the eight floodplain vegetation cross-sections.5-10
Figure 5-8. Percent-of-flow reductions that result in a 15% reduction in the
number of days flows at the USGS Lithia gage are achieved....................5-11
Figure 5-9. Predicted habitat gain/loss for adult large mouthbass based on the
flow record from 1970 to 1999 and flow reductions of 10, 20, 30, and 40
percent.......................................................................................................5-13
Figure 5-10. Percent dominance of instream habitats based on linear extent of
habitats along eight cross-sections in the Alafia River corridor..................5-14
Figure 5-11. Mean elevations of instream habitat at eight cross-section sites on
the Alafia River. .........................................................................................5-14
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