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Natural and Anthropogenic Influences on the Morphodynamics of Sandy and Mixed Sand and Gravel Beaches Tiffany Roberts University of South Florida, [email protected]

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Natural and Anthropogenic Influences on the Morphodynamics of Sandy and Mixed Sand and Gravel Beaches Tiffany Roberts University of South Florida, Tmr813@Gmail.Com University of South Florida Scholar Commons Graduate Theses and Dissertations Graduate School January 2012 Natural and Anthropogenic Influences on the Morphodynamics of Sandy and Mixed Sand and Gravel Beaches Tiffany Roberts University of South Florida, [email protected] Follow this and additional works at: http://scholarcommons.usf.edu/etd Part of the American Studies Commons, Geology Commons, and the Geomorphology Commons Scholar Commons Citation Roberts, Tiffany, "Natural and Anthropogenic Influences on the Morphodynamics of Sandy and Mixed Sand and Gravel Beaches" (2012). Graduate Theses and Dissertations. http://scholarcommons.usf.edu/etd/4216 This Dissertation is brought to you for free and open access by the Graduate School at Scholar Commons. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Scholar Commons. For more information, please contact [email protected]. Natural and Anthropogenic Influences on the Morphodynamics of Sandy and Mixed Sand and Gravel Beaches by Tiffany M. Roberts A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Geology College of Arts and Sciences University of South Florida Major Professor: Ping Wang, Ph.D. Bogdan P. Onac, Ph.D. Nathaniel Plant, Ph.D. Jack A. Puleo, Ph.D. Julie D. Rosati, Ph.D. Date of Approval: July 12, 2012 Keywords: barrier island beaches, beach morphodynamics, beach nourishment, longshore sediment transport, cross-shore sediment transport. Copyright © 2012, Tiffany M. Roberts Dedication To my eternally supportive mother, Darlene, my brother and sister, Trey and Amber, my aunt Pat, and the friends who have been by my side through every challenge and triumph. In memory of Dr. Nicholas C. Kraus. Acknowledgements I would like to thank Dr. Ping Wang for being one of the most important and influential people in my academic, educational, and personal advancements. Over the last few years, Dr. Wang has not only been an active advisor and mentor, but also an invaluable friend. I also would like to thank one of my original committee members, Dr. Nicholas Kraus, who passed in 2011. His exuberance for the study of all sciences (not only coastal-related topics) and relentless fervor to approach every scientific inquiry with the utmost enthusiasm has influenced me to always do my best, and then try even harder. I would also like to thank my other committee members, Dr. Bogdan Onac (for both memorable field excursions and knowledge on carbonates and karst), Dr. Nathaniel Plant (for his support the last four years), Dr. Jack Puleo (for his role as a mentor and teacher both in the field and through writing papers helping to advance my scientific technique and prose; and for his contributions to the research presented in Chapter 4), and Dr. Julie Dean Rosati (for providing me with the same level of enthusiasm and support as her predecessor, Nick). I would also like to thank the many graduate and undergraduate students who have helped with field data acquisition over the years. I am grateful to Pinellas County, Delaware Department of Natural and Environmental Resources and Control, and USF for funding my research. And lastly, my deepest gratitude to the family and friends who have given me so much love, encouragement, and support during the last ten years of my collegiate endeavors. TABLE OF CONTENTS LIST OF TABLES iii LIST OF FIGURES iv ABSTRACT ix CHAPTER 1 INTRODUCTION 1 CHAPTER 2 GENERAL BACKGROUND: COASTAL MORPHOLOGY AND LITTORAL PROCESSES 3 2.1 The Coast 3 2.2 Beaches 4 2.3 Barrier Islands 8 2.4 Beach and Barrier Islands Depositional Environments 11 2.5 Tidal Inlets 12 2.6 Sandbars 14 2.7 Littoral Processes 16 2.8 Natural and Anthropogenic Influences 22 CHAPTER 3 FOUR-YEAR PERFORMANCE AND ASSOCIATED CONTROLLING FACTORS OF SEVERAL BEACH NOURISHMENT PROJECTS ALONG THREE ADJACENT BARRIER ISLANDS, WEST-CENTRAL FLORIDA, USA 25 3.1 Introduction 25 3.2 Study Area 28 3.3 2006 Beach Nourishment on Three Adjacent Barrier Islands 34 3.4 Post-Nourishment Monitoring and Evaluation Methods 40 3.5 Results and Discussion 42 3.5.1 Beach Morphology Changes 43 3.5.1.1 “Typical” Stable Profile 43 3.5.1.2 Monotonic Profile Located in a Divergent Zone 44 3.5.1.3 Headland Beach Profile 47 3.5.1.4 Profiles in Close Proximity to (Downdrift of) Structured Inlets or Jetties 48 3.5.1.5 Profiles near Shore Perpendicular Porous Structures 51 3.5.1.6 Profiles Landward of a Relict Dredge Pit 52 3.5.2 Beach Profile Volume Change 55 i 3.5.2.1 Sand Key Profile-Volume Change 56 3.5.2.2 Treasure Island Profile-Volume Change 62 3.5.2.3 Long Key Profile-Volume Change 66 3.5.3 Contour Changes 68 3.5.3.1 Sand Key Contour Change 69 3.5.3.2 Treasure Island Contour Change 71 3.5.3.3 Long Key Contour Change 74 3.5.4 Performance and Controlling Factors of the 2006 Nourishment 74 3.6 Conclusions 83 CHAPTER 4 STORM-DRIVEN CYCLIC BEACH MORPHODYNAMICS OF A MIXED SAND AND GRAVEL BEACH ALONG THE MID- ATLANTIC COAST, USA 86 4.1 Introduction 86 4.2 Study Area 90 4.3 Methodology 93 4.4 Results 97 4.4.1 General Morphology and Sedimentology 97 4.4.2 Cyclic Beach Morphodynamics 102 4.4.2.1 Characteristics of Three Consecutive Storms in 2009 102 4.4.2.2 Storm-Induced Beach Morphology Changes 106 4.4.2.3 Pre- and Post-Nor’Ida Sediment Properties 110 4.4.2.4 Post-Storm Beach Recovery 116 4.5 Discussion 119 4.5.1 Sedimentological Characteristics of Storm and Post-Storm Deposits 119 4.5.2 Temporal Scales of Post-Storm Recovery 123 4.5.3 The Absence of a Nearshore Bar 124 4.5.4 A Storm-Driven Beach Cycle Model for Non-Barred Mixed Sand and Gravel Beaches 126 4.6 Conclusions 128 MAJOR CONCLUSIONS 130 REFERENCES 133 ABOUT THE AUTHOR End Page ii LIST OF TABLES Table 3.1 Overview of 2006 nourishment projects. Each fill segment is divided into individual projects, including information on construction date, total quantity placed, fill sediment grain size, design berm width, and volume density. 35 Table 3.2 Post-nourishment sediment volume change above four representative contours for each project area from 2006 to 2010. 77 Table 4.1 Cross-shore and longshore distribution of sediment characteristics. 101 iii LIST OF FIGURES Figure 2.1 The terminology used to describe the littoral zone in terms of hydrodynamic processes, such as wave and currents (A) and in terms of morphology (B). Modified from Komar (1998). 7 Figure 2.2 The Hayes model for barrier island morphology distinguishes two types: 1) wave-dominated and 2) mixed-energy. Modified from Davis and Hayes (1984). 10 Figure 2.3 Orbital motions of small-amplitude waves circular in deep water, elliptical in intermediate water, and linear in shallow water. Modified from Schwartz, M. (Ed.) (2005). 17 Figure 3.1 General location and bathymetric map of the study area, encompassing all three barrier islands in Pinellas County Map. White crosses indicate the location of example beach profiles discussed. 29 Figure 3.2 Idealized northerly approaching waves modeled in CMS-Wave for the study area, with Ho = 2 m and Tp = 7 s approaching from the NW (330º). 31 Figure 3.3 Idealized southerly approaching waves modeled in CMS-Wave for the study area, with Ho = 1 m and Tp = 6 s approaching from the SW (220º). 32 Figure 3.4 Interaction of waves with the large John’s Pass ebb-tidal shoal and the influence to adjacent beaches is modeled in CMS-Wave, with Ho = 2 m and Tp = 7 s approaching from the NW (330º). Also note, the higher waves reaching the southern portion of Treasure Island (Sunset Beach). 33 Figure 3.5 Project area locations and adjacent tidal inlets are identified on a bathymetric map of Sand Key. 37 Figure 3.6 Project area locations and adjacent tidal inlets are identified on a bathymetric map of Treasure Island. Inset: Google Earth image of the large John’s Pass ebb-tidal shoal and attachment point. 38 iv Figure 3.7 Project area locations and adjacent tidal inlets are identified on a bathymetric map of Long Key. 39 Figure 3.8 Example profile, R75, from Indian Rocks Beach on Sand Key illustrating the “typical” beach state. Note: 01/28/2006 is the pre- nourishment survey. 46 Figure 3.9 Example monotonic profile, R59, from the divergence zone at North Sand Key. Note: 04/13/2006 is the pre-nourishment survey. 46 Figure 3.10 Example profile R84 located at the apex of the Headland on Sand Key. Note: 08/01/2005 is the pre-nourishment survey. 48 Figure 3.11 Example profile LK3, located on Upham Beach, downdrift of the structured Blind Pass inlet completely blocking the littoral drift. Note: 03/26/2006 is the pre-nourishment survey. 50 Figure 3.12 Example profile R127, located on north Treasure Island, downdrift of the structured John’s Pass inlet, influenced by flood-tidal currents running along the beach. Note: 01/28/2006 is the pre- nourishment survey. 51 Figure 3.13 Example profile R104A, located on North Redington Beach (on Sand Key), with sandbar morphology interruption due to the presence of a nearby shore perpendicular porous structure. Note: 01/28/2006 is the pre-nourishment survey. 52 Figure 3.14 Example profile R140, located on Sunset Beach (Treasure Island), landward of a relict dredge pit. Note: 06/04/2006 is the pre- nourishment survey. Inset: Annual offshore bathymetric data shows no infilling of the nearshore dredge pit between 2007 and 2010.
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