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

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Chapter 4 Technical Approach for Establishing Minimum Flows and Levels for the Upper Braden River 4.1 Overview A number of methods were used to determine the minimum flow requirements for the upper, fresh water segment of the Braden River. The approach outlined for the river involves identification of a low flow threshold and development of prescribed flow reductions for periods of low, medium and high flows (Blocks 1, 2 and 3). The low flow threshold is used to identify a minimum flow condition and is expected to be applicable to river flows throughout the year. The prescribed flow reductions are based on limiting potential changes in aquatic and wetland habitat availability that may be associated with changes in river flow during Blocks 1, 2 and 3. 4.2 Transect Locations and Field Sampling of Instream and Floodplain Habitats The Braden River is the largest tributary to the Manatee River (Trommer et al. 1999) and is a source of freshwater supply for the City of Bradenton, Florida. The river flows for approximately 22 miles in south-central Manatee County and northern Sarasota County to the Manatee River and includes an 83 square mile watershed. The river segment delineated for MFLs determination was confined to areas upstream of the USGS Braden River at Linger Lodge near Bradenton gage site, which is located approximately 0.5 miles east of Interstate 75. This river segment includes 8.6 miles of relatively straight, naturally incised channel that drains 26 square miles of headwaters that are unaffected by backwater effects from Bill Evers Reservoir (Figure 4-1). Bill Evers Reservoir was created in 1985 through excavation of Ward Lake to increase storage capacity in the basin to 1.4 billion gallons of water. Permanent backwater conditions extend upstream from the reservoir dam for approximately six miles and the lower reaches of its tributaries are also affected. Field sampling in support of MFLs development for the upper Braden River involved characterization of cross-sectional physical, hydrologic and habitat features. Four types of cross-sectional information were collected, including data used for HEC-RAS modeling, Physical Habitat Simulation (PHABSIM) modeling, instream habitat assessment, and floodplain vegetation/soils assessments. HEC-RAS cross-sections were established to develop flow and inundation statistics for the other cross-section sites based on existing flow records for the 4-1
USGS Braden River near Lorraine gage site which is located near Lorraine Road. Figure 4-1. Braden River watershed and location of USGS streamflow gaging stations. The USGS Braden River at Linger Lodge near Bradenton FL gage represented the most downstream extent of the MFLs study area. 4.2.1 HEC-RAS Cross-Sections Cross-section channel geometry data used to generate a HEC-RAS model for the upper Braden River were developed from 15 transects that included the river channel and floodplain (Figures 4-2 and 4-3). Transect elevation data relative to the National Geodetic Vertical Datum of 1929 were obtained by District surveyors, and were subsequently converted to elevations relative to the North American Vertical Datum of 1988 based on conversion factors obtained from USGS. Further refinement of the HEC-RAS model included the use of additional channel elevation data (relative to the North American Vertical Datum of 1988) derived from airborne LiDAR mapping data of the watershed (see discussion in Modeling Approaches below). All or some of the 15 HEC-RAS transect sites were also used as locations for data collection in support of PHABSIM analyses, instream habitat evaluations, and for floodplain vegetation/soils characterization. 4-2
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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
Page 15 and 16: Acknowledgements The authors would
Page 17 and 18: fluctuations in water flows or leve
Page 19 and 20: Common to this list and the flow re
Page 21 and 22: Fundamental to the approach used fo
Page 23 and 24: 300 250 Block 1 Block 3 Block 2 Flo
Page 25 and 26: are outlined in Chapter 4. In Chapt
Page 27 and 28: as the freshwater segment upstream
Page 29 and 30: attributed to analytic precision di
Page 31 and 32: Figure 2-4. 1999 land use/cover map
Page 33 and 34: Table 2-2. Land use/cover and land
Page 35 and 36: Figure 2-8. 1999 Land use/cover map
Page 37 and 38: Figure 2-10. 1972 Land use/cover ma
Page 39 and 40: Smith and Stopp (1978) note that "i
Page 41 and 42: 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: Figure 3-1. Example of low flow in
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 and 94: Floodplain profiles and vegetation
Page 95 and 96: mean elevation of the Oak/popash ve
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
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Hupalo, R., C. Neubauer, L. Keenan,
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communities in the corridors of the
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Wharton, C.H., W.M. Kitchens, E.C.
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Confined Aquifer - A term used to d
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Instream Habitats - A specific type
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Riffle - A relatively shallow reach
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Chapter 8 Appendix A A Review of
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steps to reduce the uncertainty and
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2007). In addition, the approach us
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with limited biological knowledge o
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the other factors listed above or w
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have now been developed and adopted
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An example of the primary output fr
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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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