Chapter 1 Minimum Flows and Levels - Southwest Florida Water ...

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Table 5-2. Elevations and lengths of floodplain vegetation/soils cross-sections (transects) along the Braden River. N is the number of elevation measurements made along each transect. Median relative elevations are the vertical distance between the channel bottom and median elevations. Downstream Upstream Transect Transect Length (feet) Maximum Elevation (NGVD) Channel Elevation (NGVD) Median Elevation (NGVD) Median Relative Elevation (feet) 1 653 28.9 17.5 25.9 8.4 41 2 500 28.1 17.6 24.8 7.2 45 3 850 35.6 16.9 25.6 8.7 51 4 650 27.1 15.0 23.2 8.2 34 5 400 26.4 14.3 24.1 9.8 40 6 450 26.5 13.6 21.6 8.0 40 7 250 23.9 9.7 19.3 9.6 20 8 300 21.3 6.6 15.8 9.2 24 9 350 20.4 3.2 14.8 11.6 25 10 400 20.6 -0.2 12.9 13.1 20 11 380 19.0 2.8 12.9 10.1 31 12 385 16.3 -3.4 8.6 12.0 33 13 550 16.7 -1.2 5.7 6.9 44 14 650 15.3 -2.2 3.8 6.0 62 15 380 16.2 -4.0 3.8 7.8 33 N Local (cross-section site) flows needed to overflow at least one of the river's banks were higher than the 1% exceedance level at 6 of the 15 sampled crosssections. Local flows required to top the bank on at least one side of the river at the other 9 cross-sections ranged from 372 to 625 cfs (see Appendix RH for channel bank and other floodplain feature elevations and associated flows for all cross-sections). The mean of corresponding flows at the Braden River near Lorraine gage needed to top one side of the river bank at the nine cross-sections was 507 cfs (see Table 5-3). Flows required to permit discharge over banks on both sides of the river exceed the 1% exceedance level at all but one crosssection site (Table 5-3), indicating that the riparian corridor in this portion of the watershed is infrequently inundated by out-of-bank flows. Floodplain wetted perimeter plots (patterned after the wetted perimeter plots used for identification of the lowest wetted perimeter inflection point) were developed for each floodplain vegetation cross section (see Appendix RH). The plots were developed to show the linear extent of inundated floodplain (wetted perimeter) associated with measured floodplain elevations, including the median elevations of the floodplain vegetation classes. For example, Figure 5-6 shows a floodplain perimeter plot for floodplain vegetation transect 15. Based on the plot, 125 linear feet of floodplain would be inundated when the river is staged at the 5-8
mean elevation of the Oak/popash vegetation class. Local flows necessary to inundate the first major slope change in wetted perimeter beyond the top of bank at each transect were evaluated using the HEC-RAS model (see Appendix RH). Analysis of flows at the Braden River near Lorraine gage corresponding to the local flows indicated that a mean flow of 112 cfs would be necessary at the gage to inundate the lowest major inflection point associated with maximizing floodplain inundation levels for the minimum amount of river flow (Table 5-3). If higher flows were to occur and inundate the floodplain, the next major breakpoint in the wetted perimeter would require a mean of 289 cfs at the Braden River near Lorraine gage site. 400 Wetted Perimeter (feet) 350 300 250 200 150 100 50 Oak/popash Hickory/oak 0 -7 -2 3 8 13 18 Elevation (feet above NGVD) Figure 5-6. Floodplain wetted perimeter versus elevation at floodplain vegetation/soils cross-section (Transect) 15. Vertical bars indicate mean elevations of two floodplain vegetation classes observed at the site. 5.4.2 Inundation of Floodplain Vegetation Classes and Soils Six distinct vegetation classes were identified along the Braden River study corridor based on woody species composition and importance values (PBS&J 2006). Wetland classes were characterized by obligate and facultative wetland species such as popash (Fraxinus caroliniana), willow (Salix caroliniana), and dahoon holly (Ilex cassine). Upland vegetation classes were dominated by laurel oak (Quercus laurifolia), pignut hickory (Carya glabra), and slash pine (Pinus elliottii). Cabbage palm (Sabal palmetto) occurred in all but one vegetation class. 5-9
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Proposed Minimum Flows and Levels f
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Table of Contents TABLE OF CONTENTS
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5.5 PRESCRIBED FLOW REDUCTION FOR B
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Figure 2-19. Potassium concentratio
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Figure 5-13. Median daily flow at t
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mean feature elevations are listed
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For the high flow season of the yea
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Acknowledgements The authors would
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fluctuations in water flows or leve
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Common to this list and the flow re
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Fundamental to the approach used fo
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300 250 Block 1 Block 3 Block 2 Flo
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are outlined in Chapter 4. In Chapt
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as the freshwater segment upstream
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attributed to analytic precision di
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Figure 2-4. 1999 land use/cover map
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Table 2-2. Land use/cover and land
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Figure 2-8. 1999 Land use/cover map
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Figure 2-10. 1972 Land use/cover ma
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Smith and Stopp (1978) note that "i
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2.4.2.1 Multidecadal Periods of Hig
Page 43 and 44: 2.4.3.2 Step Trend in River Flows K
Page 45 and 46: Table 2-4. Results of Kendall's tau
Page 47 and 48: 2.4.4 Benchmark Periods Climate-bas
Page 49 and 50: Oscillation were examined. On a sea
Page 51 and 52: Water Chemistry 2.4.6 Water Quality
Page 53 and 54: Braden River near Lorraine, FL 0.6
Page 55 and 56: Peace River at Arcadia, FL 10 Potas
Page 57 and 58: Table 2-8. Summary statistics for B
Page 59 and 60: 3.2 Resources and Area of Concern T
Page 61 and 62: habitat, the greater area of stream
Page 63 and 64: levels such as fish have been shown
Page 65 and 66: Figure 3-1. Example of low flow in
Page 67 and 68: USGS Braden River near Lorraine gag
Page 69 and 70: instream cross-sections were sample
Page 71 and 72: Figure 4-2. Upstream vegetation cro
Page 73 and 74: supports water surface profile calc
Page 75 and 76: The HEC-RAS model was run using 21
Page 77 and 78: Adult Spotted Sunfish Adults - Brad
Page 79 and 80: species of interest. For example cu
Page 81 and 82: 4.4 Seasonal Flow and Development o
Page 83 and 84: Wetted Perimeter - Sta. 44.9 25 20
Page 85 and 86: factors, the most conservative of w
Page 87 and 88: Chapter 5 Results and Recommended M
Page 89 and 90: Wetted Perimeter Requirements Flow
Page 91 and 92: 40 35 30 25 20 15 10 5 0 May June M
Page 93: Floodplain profiles and vegetation
Page 97 and 98: Table 5-3. Mean (±SD) flows at the
Page 99 and 100: Elevaton (NGVD) 27.0 22.0 17.0 12.0
Page 101 and 102: Table 5-7. Median elevations, in fe
Page 103 and 104: 80 70 60 Flow reduction (%) 50 40 3
Page 105 and 106: Table 5-8. Recommended percent flow
Page 107 and 108: 100 90 80 % DOMINANCE 70 60 50 40 3
Page 109 and 110: Table 5-9. Mean elevation of instre
Page 111 and 112: The second standard was developed t
Page 113 and 114: Table 5-10. Proposed Minimum Flows
Page 115 and 116: Division Information and Technology
Page 117 and 118: Hupalo, R., C. Neubauer, L. Keenan,
Page 119 and 120: communities in the corridors of the
Page 121 and 122: Wharton, C.H., W.M. Kitchens, E.C.
Page 123 and 124: Confined Aquifer - A term used to d
Page 125 and 126: Instream Habitats - A specific type
Page 127 and 128: Riffle - A relatively shallow reach
Page 129 and 130: Chapter 8 Appendix A A Review of
Page 131 and 132: steps to reduce the uncertainty and
Page 133 and 134: 2007). In addition, the approach us
Page 135 and 136: with limited biological knowledge o
Page 137 and 138: the other factors listed above or w
Page 139 and 140: have now been developed and adopted
Page 141 and 142: An example of the primary output fr
Page 143 and 144: prevent negative effects associated
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methods, such as LiDAR, to improve
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habitat reduction criterion and the
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Summary, Special Publication SJ2002
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Errata / comments by page number in
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4-20 Section 4.7.1, 1 st paragraph,
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Chapter 9 Appendix B - Staff Respon
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2) The panel notes that the period
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4) One aspect of Chapter 2 should b
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Preventing Significant Harm - 15% C
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they aren't getting enough particul
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Habitat Criteria and Characterizati
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Compliance Standards and Proposed M
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Glossary of Terms 13) When an inter
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