Circulation and Transport Within a System of Shallow, Interconnected Barrier Island Lagoons

CIRCULATION AND TRANSPORT WITHIN A SYSTEM OF SHALLOW, INTERCONNECTED BARRIER ISLAND LAGOONS

STEVEN J. PEENE

A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY

UNIVERSITY OF FLORIDA

1995 ACKNOWLEDGEMENTS

I would like to express my gratitude to my advisor and supervisory committee chairman, Dr. Y. Peter Sheng, for his guidance and support throughout my doctoral program. The freedom he allowed me in the development of the field measurement program provided an education I could not have gotten anywhere else. I would also like to thank the members of my committee, Dr. Robert G. Dean, Dr. Max Sheppard,

Dr. Daniel Hanes and Dr. Clay Montague, for their advice and support.

I must thank everyone out at the Coastal Laboratory where I spent the best parts of my years in the program. Special thanks to Vernon Sparkman and Jim Joiner who not only provided most of the brain power for the field work but also friendship, patience, guidance and fun. Special thanks also to Sidney Schoefield, Danny Brown,

Don Mueller, Mark Southerland, Chuck Broward, Vik Adams and George Chappel.

I will never forget volleyball the Cypress Lodge, redneck preppies, tower ramming, gator skiing, mutiny on the Munson, the sinking of the Anna Capri and all my friends at the lab.

As my time in the program was rather lengthy, I was fortunate to make many good friends. I owe them a lot because they helped make my time at the University fun. Thanks to Tom B., Rick, Victor, Yuming, Sam, Jeff, Barry, Gusty, Mike and

Sheila, Phil and Lynn, Becky and Terry, Sandra, Lucy, Laura, Paul, Jei Kok, Dave,

H.K. Lee, Phil H., Mark P., and Eduardo. A special thanks to all the members of

L.A.S. whom I will always count as my good friends.

Thanks to my parents for always believing in me and supporting me in whatever endeavor I undertook. Also to my sister C.J. for her love and support through this

11 whole craziness.

Finally, my wife Christina, whom I met at the start of this program, fell in love with and married as a doctoral candidate. She always stood by me and supported

me. She went through all the tough times and always told me I could make it. She

never lost faith in me. TABLE OF CONTENTS

ACKNOWLEDGEMENTS ii

LIST OF FIGURES viii

LIST OF TABLES xviii

ABSTRACT xxii CHAPTERS

1 INTRODUCTION 1

1.1 Barrier Island Lagoons 1

1.2 General Circulation and Transport within Barrier Island Lagoons . . 2

1.3 Study Area Description 4

1.4 Statement of Purpose 6

1.5 Presentation Outline 8

2 LITERATURE REVIEW 10

2.1 Analyses of Field Measurements 10

2.2 Simplified Analytic Solutions and Numerical Models 16

2.3 Multidimensional Modeling 23

2.4 Studies Relative to Sarasota Bay 25

2.5 Chapter Summary 26

3 FIELD DATA COLLECTION 28

3.1 Introduction 28

3.2 University of Florida Data Collection Stations 28

3.2.1 Bay Stations 29

3.2.2 Offshore Stations 36

IV 3.3 Tide and Discharge Measurements Taken by the USGS 38

3.3.1 Tidal Data 38

3.3.2 Discharge Measurements 40

4 FIELD DATA ANALYSIS 41

4.1 Introduction 41

4.2 Decomposition of Water Surface Elevations, Currents and Wind ... 42

4.2.1 Presentation and Discussion of Raw Data 44

4.2.2 Spectral Analysis of Tides, Currents and Wind 58

4.2.3 Harmonic Analysis of Tides and Currents 69

4.2.4 Analysis of Sub-Tidal Tides and Currents 86

4.3 Discharge Measurements 98

4.4 Freshwater Inflow Measurements 105

4.5 Salinities Measured at the UFL Bay Stations 108

4.6 Chapter Summary 113

5 FORMULATION OF MODEL EQUATIONS 118

5.1 The Cartesian Equations of Motion and Transport 118

5.2 General Cartesian Boundary Conditions 121

5.2.1 Eree Surface Boundary Conditions 121

5.2.2 Bottom Boundary Conditions 122

5.2.3 Lateral Boundary Conditions 123

5.2.4 Initial Conditions 124

5.3 Vertically Integrated Equations 125

5.4 Sigma Stretching of Equations 126

5.5 Non-Dimensionalization of Equations 128

5.6 Boundary Eitted Equations 129

5.6.1 Grid Generation 130

5.6.2 Transformation of the Equations of Motion and Transport . . 131

V 6 THREE DIMENSIONAL NUMERICAL MODELING 137

6.1 Numerical Grid and Bathymetry 137

6.2 Boundary Conditions 142

6.2.1 Tidal Forcing 142

6.2.2 Wind Forcing 144

6.3 Quantifying Model Accuracy 146

6.3.1 Calculation of the RMS Errors 148

6.3.2 Comparison of the Simulated and Measured Energies 156

6.3.3 Comparison of the Measured and Simulated Harmonics .... 162

6.3.4 Comparison of the Measured and Simulated Residuals 173

6.3.5 Comparison of the Measured and Simulated Discharges .... 180

6.3.6 Comparison of the Measured and Simulated Salinities 186

6.4 Model Sensitivity 192

6.4.1 Bottom Friction 193

6.4.2 Horizontal Diffusion 197

6.4.3 Vertical Turbulence 200

6.4.4 Bathymetric Conditions 205

6.4.5 Vertical Resolution 206

6.4.6 Summary of Model Accuracy and Sensitivity 206

6.5 The Relative Influence of the Model Forcing Mechanisms 209

6.5.1 Periodic/Short Term Forcings 210

6.5.2 Residual Forcings 215

7 SUMMARY AND CONCLUSIONS 224 APPENDICES

A INSTRUMENT CALIBRATION 231

B DATA PLOTS 247

vi C NUMERICAL SOLUTION OF EQUATIONS 282

C.l Introduction 282

C.2 General Structure of Numerical Solution and Grid 282

C.3 Alternating Direction Implicit Solution for the External Mode .... 284

C.4 Internal Mode Solution 287

C.5 Calculation of Vertical Velocities 289

C.6 Finite Difference Solution of Advection- Diffusion Equations 290

C.7 The Non-Dimensional Variables and Parameters 294

C.8 The Tensor Invarient Equations of Motion 296

BIBLIOGRAPHY 298

BIOGRAPHICAL SKETCH 303

vii LIST OF FIGURES

1.1 A site map of the Sarasota Bay System and its location relative to the State of Florida and the Gulf of Mexico 5

2.1 The idealized geometry for the canal/inlet system utilized in the study by van de Kreeke, along with the variation in the net discharge as a function of inlet depth, width and length (van de Kreeke and Cotter, 1974) 18

2.2 The idealized channel geometry used in the solution of the 1-D Equations of Momentum and Continuity (Speer and Aubrey, 1985) 21

3.1 The locations of the UFL and USGS data collection stations within Anna Maria Sound and Big Sarasota Bay, 1991 deployment. ... 30

3.2 The locations of the UFL and USGS data collection stations in Little Sarasota Bay and Blackburn Bay, 1991 deployment 31

3.3 A schematic of the University of Florida instrument platforms. . 32

3.4 A schematic diagram of the offshore data collection stations ... 37

4.1 The measured water surface elevations from Julian Day 255 to 285, 1990. a) offshore; b) USGS-05 (Big Pass); c) USGS-04 (Roberts Bay); d) USGS-06 (Little Sarasota Bay) 45

4.2 The measured water surface elevations from Julian Day 200 to 230, 1991. a) UFL-01; b) USGS-05 (Big Pass); c) USGS-04 (Roberts Bay); d) USGS-06 (Little Sarasota Bay) 46

4.3 A comparison of measured water surface elevations from Julian Day 220 to 225, 1991 at USGS-05 (Big Pass) and USGS-06 (Little Sarasota Bay) 47

4.4 The bathymetric cross-section at station UFL-Bl 48

4.5 The current vector components measured from Julian Day 200 to 230, 1991 at UFL-Bl. a) Surface East-West Velocity; b) Surface North- South Velocity; c) Bottom East- West Velocity; d) Bottom North- South Velocity 49

viii 4.6 The current vector components measured from Julian Day 200 to 230, 1991 at UFL-B2. a) Surface East- West Velocity; b) Surface North-South Velocity; c) Bottom East-West Velocity; d) Bottom North-South Velocity 51

4.7 The current vector components measured from Julian Day 200 to 230, 1991 at UFL-B3. a) Surface East- West Velocity; b) Surface North-South Velocity; c) Bottom East- West Velocity; d) Bottom North-South Velocity 53

4.8 Idealized velocity profiles under laminar and turbulent boundary layers 54

4.9 The current vector components measured from Julian Day 200 to 230, 1991 at UEL-B4. a) Surface East- West Velocity; b) Surface North-South Velocity; c) Bottom East-West Velocity; d) Bottom North-South Velocity 55

4.10 The wind velocity vector components, a) East- west component measured at the Sunshine Skyway (Julian Day 280 to 310, 1990); b) north-south component measured at the Sunshine Skyway (Ju- lian Day 280 to 310, 1990); c) east-west component measured at UFL-B3 (Julian Day 200 to 230, 1991); d) north-south component measured at UEL-B3 (Julian Day 200 to 230, 1991) 57

4.11 Spectral density of water surface elevations measured from Julian

Day 255 to 315, 1990. a) USGS-05; b) USGS-04; c) USGS-06 . . 60

4.12 Spectral density of water surface elevations measured from Julian

Day 200 to 260, 1991. a) USGS-05; b) USGS-04; c) USGS-06 . . 61

4.13 The spectral density of the measured surface north-south current components measured from Julian Day 200 to 260, 1991. a) UFL- Bl; b) UFL-B2; c) UFL-B3; d) UFL-B4 66

4.14 Spectral density of the measured wind speed components from Julian Day 200 to 260, 1991 at UFL-B3. a) East-west component; b) north-south component 68

4.15 The Overtide Ratios and Form Numbers calculated from the measured water surface elevations, a) Julian Day 255 to 315; b) Julian Day 200 to 260 74

4.16 The primary harmonic ellipses at UFL-Bl for Julian Day 200 to 260, 1991. a) Surface velocities; b) bottom velocities 77

4.17 The primary harmonic ellipses at UFL-B2 for Julian Day 200 to 260, 1991. a) Surface velocities; b) bottom velocities 80

4.18 The primary harmonic ellipses at UFL-B3 for Julian Day 200 to 260, 1991. a) Surface velocities; b) bottom velocities 82

IX 4.19 The primary harmonic ellipses at UFL-B4 for Julian Day 200 to 260, 1991. a) Surface velocities; b) bottom velocities 84

4.20 The frequency response curve for the Chebychev II, 48 hour low pass filter 88

4.21 a) The filtered alongshore and cross-shore winds versus the filtered water surface elevation at USGS-04 for Julian Day 255 to 285, 1990; b) The coherence between wind vector components spaced at 30 degree increments and the filtered water surface elevation at USGS-04 90

4.22 a) The filtered alongshore and cross-shore winds versus the filtered water surface elevation at USGS-06 for Julian Day 200 to 250, 1991. b) The coherence between wind vector components spaced at 30 degree increments and the filtered water surface elevation at USGS-06 92

4.23 The filtered wind speed components compared to the current vector components at UFL-Bl, Julian Day 200 to 260. a) North-south wind component compared to the bottom and surface north-south current component; b) east-west wind component compared to the bottom and surface east- west current component 93

4.24 The coherence between the filtered bottom current vector components and the filtered wind vector components at 30 degree spac- ings from 190 to 340 degrees, UFL-Bl, Julian Day 200 to 260. a) north-south currents; b) east-west currents 96

4.25 The coherence between the filtered surface current vector components and the filtered wind vector components at 30 degree spac- ings from 190 to 340 degrees, UFL-Bl, Julian Day 200 to 260. a) north-south currents; b) east-west currents 97

4.26 The filtered wind speed components compared to the current vector components at UFL-B2, Julian Day 200 to 260. a) North-south wind component compared to the bottom and surface north-south current component; b) east-west wind component compared to the bottom and surface east-west current component 98

4.27 The filtered wind speed components compared to the current vector components at UFL-B3, Julian Day 200 to 260. a) North-south wind component compared to the bottom and surface north-south current component; b) east-west wind component compared to the bottom and surface east-west current component 99

4.28 The filtered wind speed components compared to the current vector components at UFL-B4, Julian Day 200 to 260. a) North-south wind component compared to the bottom and surface north-south current component; b) east-west wind component compared to the bottom and surface east-west current component 100

X 4.29 The measured discharge compared with the measured water surface elevation at Roberts Bay and Blackburn Bay (solid line is the water surface elevation, broken lines are discharge), a) Julian Day 204 to 206, 1991; b) Julian Day 224 to 226, 1991 101

4.30 The measured discharge compared with the measured water surface elevations, a) New Pass and Big Pass, Julian Day 148, 1992; b) Longboat Pass and Anna Maria Sound, Julian Day 149, 1992. 103

4.31 The measured freshwater inflows to the Sarasota Bay System, Ju-

lian Day 200 to 260, 1991. a) Manatee River; b) Walker Creek. . 107

4.32 a) The surface salinity at UFL-Bl from Julian Day 200 to 250, 1991; b) The bottom salinity at UFL-Bl from Julian Day 200 to 250, 1991; c) The surface minus bottom salinity at UFL-Bl from Julian Day 200 to 250, 1991 110

4.33 a) The surface salinity at UFL-B2 from Julian Day 200 to 250, 1991; b) The bottom salinity at UFL-B2 from Julian Day 200 to 250, 199l; c) The surface minus bottom salinity at UFL-B2 from Julian Day 200 to 250, 1991 Ill

4.34 a) The surface salinity at UFL-B3 from Julian Day 200 to 250, 1991; b) The bottom salinity at UFL-B3 from Julian Day 200 to 250, 199l; c) The surface minus bottom salinity at UFL-B3 from Julian Day 200 to 250, 1991 112

4.35 a) The surface salinity at UFL-B4 from Julian Day 200 to 250, 1991; b) The bottom salinity at UFL-B4 from Julian Day 200 to 250, 1991; c) The surface minus bottom salinity at UFL-B4 from Julian Day 200 to 250, 1991 114

5.1 An idealized representation of the Sigma transformation 126

5.2 An Idealized Boundary Fitted Transformation 131

5.3 Cartesian vs. Curvilinear Coordinate Systems 132

6.1 The curvilinear grid utilized with the numerical model CH3D. . . 138

6.2 The model bathymetry within Anna Maria Sound, Sarasota Bay, Roberts Bay and the northern offshore region 140

6.3 The model bathymetry within Little Sarasota Bay, Blackburn Bay and the southern offshore region 141

6.4 A comparison of the measured wind speed components at UFL- Bl, UFL-B2, UFL-B3 and UFL-B4. a) East-west component; b) north-south component 145

6.5 A comparison of the measured and simulated water surface elevations, Julian Day 200 to 230, 1991. a) USGS-04; b) USGS-05; c) USGS-06; d) USGS-07 149

XI 6.6 A comparison of the measured and simulated current components at station UFL-Bl, Julian Day 200 to 230, 1991. a) Bottom east-west; b) surface east-west; c) bottom north-south; d) surface north-south 151

6.7 A comparison of the measured and simulated current components at station UFL-B2, Julian Day 200 to 230, 1991. a) Bottom east-west; b) surface east-west; c) bottom north-south; d) surface north-south 154

6.8 A comparison of the measured and simulated current components at station UFL-B3, Julian Day 200 to 230, 1991. a) Bottom east-west; b) surface east-west; c) bottom north-south; d) surface north-south 155

6.9 A comparison of the measured and simulated current components at station UFL-B4, Julian Day 200 to 230, 1991. a) Bottom east-west; b) surface east-west; c) bottom north-south; d) surface north-south 157

6.10 A comparison of the measured and simulated form numbers and overtide ratios for the tides at USGS-04, USGS-05, USGS-06 and USGS-07, Julian Day 200 to 230, 1991 165

6.11 A comparison between the simulated and measured water surface elevations, Julian Day 200 to 230, 1991. a) USGS-04; b) USGS-05; c) USGS-06; d) USGS-07 175

6.1