Weeki Wachee River System Recommended Minimum Flows and ...

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Additional exploratory attempts using average daily salinity and gauge height, daily ranges and transformations (cube root) of flow and gauge height and/or interactive terms (e.g. gauge height * discharge), did not improve the results with r 2 adj ranging from 0.03 to less than 0.001. The variation in gauge height due to a predictable tide signal was removed in an attempt to improve the sensitivity of salinity to spring flow. A regression model (Section 4.1) based on known tidal harmonics was fit to the Bayport data and the tide signal removed from the gauge height. Other variables that could be controlling salinity were identified and evaluated through step-wise multivariate regression. Only variables that were both significant (p< 0.05) and physically logical were retained. For example, flow variables that exhibited a positive relationship with salinity were rejected. It was theorized that discharge from the Withlacoochee River may have a major affect on Gulf salinity due to the magnitude of discharge. Daily discharge measurements from the Withlacoochee at Holder, along with several moving averages and sums (7, 15, 30, 45 and 60 days prior) were also included as candidate Independent variables. When regressed against the observed salinity at Bayport, only the daily flow and the seven day sum were negatively associated with salinity and were retained for the step-wise evaluation. Wind can also have a dramatic effect on water levels and water movement along this portion of the coast due to the shallow nature of the Gulf in this vicinity. Hourly meteorological data was obtained for the NDBC station on Cedar Key, which is located 45 miles northwest of Bayport. Wind was converted to both North and East vectors corresponding to long-shore and offshore vectors. Daily averages were developed for each vector and used as candidate Independent variables. Each was squared to account for the wind shear force on the surface water. In addition, the daily average barometric pressure was calculated from the hourly observations. Of the possible wind variables, vector north and vector east squared explained the greatest amount of variation in observed salinity (r 2 ranging from 0.04 – 0.05) and were retained as candidate independent variables for the subsequent step-wise evaluation. For purposes of continued evaluation, the year 2004 was chosen to maximize the impact of spring discharge on salinity. The spring discharge (191 cfs) during 2004 was ranked 7 th highest out of the past 35 years, and it represents the year of highest flow with concurrent 15-minute stage data. The final candidate variables selected were a) gauge height, b) spring discharge, c) barometric pressure, d) Withlacoochee flow at Holder, e) seven day sum of Holder flow, f) north vectored wind and g) east vectored wind squared. Table 4-6 illustrates the importance of each subsequent variable in predicting salinity at Bayport (n= 35,136). ____________________________________________________________________________________________ Proposed Minimum Flows and Levels for Weeki Wachee River Page 62 of 164 Tide, Salinity and Water Quality
Table 4-6. Step-Wise Salinity Regression Bayport, Fl. Step Terms r 2 adj 1 Intercept + Gage Height 0.415 2 Step 1 terms + Barometric Pressure 0.493 3 Step 2 terms + Holder Flow 0.552 4 Step 3 terms + Spring Flow 0.610 (1) (1) Spring flow positively related to salinity – reject term Thus, as in the simpler regressions, discharge from the spring does not have a major effect on salinity at Bayport that can be modeled simply. and the relatively constant nature of the spring discharge (e.g. minimal variance) is probably largely incorporated into the intercept term. 4.2.3 Isohaline Estimation Regressions predicting the location of salinity isohalines in the Weeki Wachee were developed for a suite of salinities. This discussion includes a description of the attempts to relate the location of those salinity isohalines to candidate forcing functions. The location of each sample point on the river along a standard river kilometer system was developed from reported latitude / longitude pairs, structures or from reported distances from structures. River km zero is located at 28.5338 o N / 82.6519 o W which is approximately 150 meters west of the fishing pier at the mouth of the Weeki Wachee river. Distance accumulated upstream of this point is positive and distance into the Gulf is measured in negative kilometers along a thalweg corresponding to the marked approach channel (See Figure 3-1). Observations were sorted by calendar date, and the locations of bottom isohalines were estimated by linear interpolation between salinity readings bracketing the desired isohaline. The time of observation was not considered as most of the field sampling efforts appeared to progress in a monotonic fashion along the river. Locations were determined for the following salinities: 0.5 2, 3.5** 13 , 6, 8, 10, 11.5 ** , 14, 16, 18, and 20 ppt. There are insufficient observations to estimate higher salinity isohalines. Figure 4-9 provides a summary of the interpolated locations as a function of river kilometer. The irregular lines represent the median position of each isohaline for each monitoring program. Figure 4-8 illustrates that the range of isohaline locations varies greatly with monitoring program, reflecting the differences in flow conditions with the most upstream locations associated with the 1994-96 District program and the most downstream locations associated with the 1984-85 Mote Marine program. The median flow of program sampling days is as follows: Mote Marine 1984-85 = 214 cfs, SWFWMD 1985- 13 The 3.5 and 11.5 ppt isohalines were chosen because these values represent mid-points taken from the benthic principal component analysis described in section 5.1.2 ____________________________________________________________________________________________ Proposed Minimum Flows and Levels for Weeki Wachee River Page 63 of 164 Tide, Salinity and Water Quality
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Weeki Wachee River System Recommend
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Conversion Table Metric to U.S. Cus
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5.2 FISH ..........................
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Figure 3-2 Location of Bathymetric
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LIST OF TABLES Table 1-1 Rule-of-Th
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Table 8-1 Summary of Weeki Wachee M
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Executive Summary Minimum Flows and
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CHAPTER 1 - PURPOSE & BACKGROUND OF
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1) flood flows that determine the b
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the area." What constitutes "signif
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Table 1-1 Rule-of-Thumb Estimates f
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this report identifies specific res
Page 26 and 27: 1.6 Content of Remaining Chapters I
Page 28 and 29: CHAPTER 2 - WATERSHED CHARACTERISTI
Page 30 and 31: # # # circular vent 1.8 meters in d
Page 32 and 33: Figure 2-5 1970s Aerial with 1999 U
Page 34 and 35: is a variation of the Seminole word
Page 36 and 37: Figure 2-6 Hurricane Tracks near Ba
Page 38 and 39: varied by period. The variation was
Page 40 and 41: 2.3.2 Baseline Period Figure 2-10 i
Page 42 and 43: found (ktau p=0.06) between total g
Page 44 and 45: similarly across the springsheds ex
Page 46 and 47: Figure 2-15 Wavelet Filtered Discha
Page 48 and 49: Figure 2-16 INTB Groundwater Model
Page 50 and 51: 2.6 Seasonal Blocks As described in
Page 52 and 53: Table 2-6 Median (cfs) Flow by Bloc
Page 54 and 55: # # # Surface waters in this stretc
Page 56 and 57: 3.1.3 Segmentation Segmentation was
Page 58 and 59: Figure 3-5 Dominant SAV and Median
Page 60 and 61: Figure 3-6 Sediment Characteristics
Page 62 and 63: Figure 3-7 Shoreline / Buffer Veget
Page 64 and 65: CHAPTER 4 - TIDE, SALINITY & WATER
Page 66 and 67: Two additional harmonic pairs were
Page 68 and 69: Figure 4-5. Median Bottom Salinity
Page 70 and 71: Figure 4-7 Salinity Range (1984-200
Page 72 and 73: uncovering in response to strong wi
Page 74 and 75: E) Salinity = β o + β 1 *Flow 2 +
Page 78 and 79: 86 = 186 cfs, SWFWMD 1994-96 = 167
Page 80 and 81: A regression of the form below was
Page 82 and 83: Table 4-8 Median Water Quality of W
Page 84 and 85: Figure 4-10 Nitrate Concentration a
Page 86 and 87: CHAPTER 5 - BIOLOGICAL CHARACTERIST
Page 88 and 89: Figure 5-1 Principal Component Anal
Page 90 and 91: measured volume sampled which was t
Page 92 and 93: 5.2.2 Relation to inflow Response t
Page 94 and 95: Table 5-7 Location Response (km u )
Page 96 and 97: Table 5-9 Abundance Response to Inf
Page 98 and 99: animals can survive chronic exposur
Page 100 and 101: Figure 5-3 Number of Aerial Manatee
Page 102 and 103: Figure 5-5(a) Molluscan Presence /
Page 104 and 105: Table 5-11 Rank Order of Mollusc Ab
Page 106 and 107: Figure 5-5 Polymesoda caroliniana A
Page 108 and 109: Figure 6-1 Plankton Tow Flows Compa
Page 110 and 111: In application, a baseline area and
Page 112 and 113: 6.1.4 Benthos Protection for benthi
Page 114 and 115: Figure 6-3. Location of the Three P
Page 116 and 117: 7.2 Manatee Approach Establishing a
Page 118 and 119: Figure 7-2 Joint Probability of Occ
Page 120 and 121: Figure 7-3 Maximum Day Manatee Usag
Page 122 and 123: Figure 7- 6 Example Calculations fo
Page 124 and 125: Figure 7- 7 Estimation of Flow Redu
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Figure 7-8. Summary Results for the
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The reductions in flow that meet th
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probably accounts in part for the d
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Postel, S. and B.Richter. 2003. Riv
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Stanford, J.A., J.V.Ward, W.J. Liss
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Culter, J.K. 1986. Water Chemistry.
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CHAPTER 10 - APPENDICES 10.1 Append
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The wavelet used is the symmlets wa
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explains, the energy plot shows the
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0 if no significant withdrawal Z =
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One advantage of using this regress
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Technical Memorandum January 22, 20
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Lecanto 1 & 2 #S Well Site Descript
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Figure 4. HSPF subbasins in the INT
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Most of the limestone mines located
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3.1.3 Septic Tank Recharge in the S
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Figure 10. Groundwater grid in the
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Basso, R.J., 2004, Hydrogeologic Se
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10.2 Appendices - Chapter 3 Appendi
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10.3 Appendices - Chapter 4 Appendi
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Appendix 4-2 Data Sources Water qua
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Appendix 4-3 Water Quality Trend Gr
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Water Quality Trend Graphics, conti
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United States Department of the Int
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October 8,2008 Florida Fish and Wil
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Martin Kelly, Ph.D. Page 3 October
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Scientific Peer Review of the Propo
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Determining a low flow need during
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Current state water policy, as expr
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Spring, Twin Dees Spring and possib
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under varying flow regimes. The fir
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Weeki Wachee Rainfall, Springflow a
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6.0 Discharge:Precipitation (cfs/in
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Nevertheless, a major concern with
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system grid is not totally orthogon
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In a hydrodynamic model study, one
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analysis was rather cursory. The Di
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(taxa) richness in the WWRS. If the
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Freshwater Habitats Approximately 1
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ERRATA and EDITORIAL COMMENTS Page
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Page Paragraph Line Comment 14 Some
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Page Paragraph Line Comment 21 The
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Page Paragraph Line Comment 26 The
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REFERENCES Alber, M. 2002. A Concep
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Richter, B. D., J. V. Baumgartner,
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the regression equation used to pre
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and the three independent approache
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The Southwest Florida Water Managem
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the model in terms of tides, salini
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Attachment 1 - Comparison of salini
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Figure 1. Predicted drawdown (feet)
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