UFL/COEL-92/008 HISTORICAL SHORELINE RESPONSE TO INLET MODIFICATIONS AND SEA LEVEL RISE by Jonathan R. H. Grant Thesis May 1992 HISTORICAL SHORELINE RESPONSE TO INLET MODIFICATIONS AND SEA LEVEL RISE By JONATHAN R. H. GRANT A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ENGINEERING UNIVERSITY OF FLORIDA 1992 ACKNOWLEDGEMENTS I would like to thank my advisor, Dr. Robert Dean, for all of his assistance and utmost patience in helping me complete this thesis. The assistance of my other committee members, Dr. Ashish Mehta and Dr. Daniel Hanes, is greatly appreciated. I would like to thank Cynthia Vey, Sandra Bivins, Becky Hudson, Helen Twedell and Sabarna Malakar for their patience, humor and help in transforming my research into a thesis. I would also like to thank all of the professors who have taught me so much outside of my research work. This work was sponsored by Florida Sea Grant, whose continued support of coastal re- search is appreciated. The data used in this study were supplied by the Florida Department of Natural Resources. Special thanks goes to Emmett Foster (of FDNR) for taking the time to help furnish the most up to date shoreline data. The salvation of my sanity is the result of all my friends in Gainesville, to whom I am indebted. Thanks to all my fellow Coastals: Steve, Sam (my initial tutor to graduate school), Paul, Phil D., Jei and Mike and especially Mark and Phil H. (of G. H. and Assoc.). Katia, Pete, Pete, Shannon and Annie are responsible for all my nonengineering, activities and their friendship and help in creating the Florida Four will never be forgotten. Finally, I would like to thank my brother, Dr. William "Boo" Grant for showing me that the ocean could be more than just a playground. I wish he could be here to see me accomplish that. ii TABLE OF CONTENTS ACKNOWLEDGEMENTS ................................ ii LIST OF FIGURES .................................... v LIST OF TABLES ...... ................................. xi ABSTRACT .................... ..................... xii CHAPTERS 1 INTRODUCTION ..................... ............ 1 1.1 Purpose of this Study ...... ............ ........... 1 1.2 Scope. ...................................... 2 2 APPROACH .................................... 7 2.1 Review of Available Data ........................... 7 2.2 Erosion at Inlets ................... ............. 9 2.2.1 Erosion at Modified Inlets .................... 10 2.2.2 The Updrift and Downdrift Extent of the Influence of Inlets . 14 2.3 Sea Level Rise ..... ... .......... ... .... 19 3 METHODOLOGY ................... ............... 23 3.1 Introduction .................... .............. 23 3.2 Shoreline Change Rates ............................ 23 3.2.1 Inlet Influenced Shoreline Segments . .... 24 3.2.2 The Coast of Florida ......................... 24 3.3 Sea Level Changes ............................. 25 4 RESULTS ...................................... 28 4.1 Introduction .................................... 28 4.2 East Coast Inlets ............................... 28 4.2.1 St. Augustine Inlet ................... ....... 28 4.2.2 Matanzas Inlet .................... ........... 32 4.2.3 Ponce de Leon Inlet ................... ....... 32 iii 4.2.4 Port Canaveral Entrance ....................... 36 4.2.5 Sebastian Inlet ............................ 40 4.2.6 Ft. Pierce Inlet ............................ 43 4.2.7 St. Lucie Inlet ... ... ... ..... ... ....... 47 4.2.8 Jupiter Inlet ....... ........ ... ... ..... .. 51 4.2.9 Lake Worth Inlet ................... ........ 54 4.2.10 South Lake Worth Inlet ....................... 57 4.2.11 Boca Raton Inlet .......................... 60 4.2.12 Hillsboro Inlet ................. ... ........ 63 4.2.13 Port Everglades Entrance . .. ... 67 4.2.14 Bakers Haulover Inlet ......................... 70 4.3 West Coast Inlets ............................... 73 4.3.1 Pensacola Pass ............................ 73 4.3.2 East Pass (Destin Harbor) ...................... 75 4.3.3 St. Andrews Bay Entrance Channel (Panama City) . ... 79 4.3.4 Mexico Beach Inlet ................... ....... 83 4.3.5 Venice Inlet ................... .......... 83 4.4 Counties .................... .............. 88 4.4.1 East Coast ................... ... ......... 88 4.4.2 W est Coast .............................. 90 4.5 Florida's Coastline .............................. 90 4.6 Effects of Inlets ................... .............. 92 4.7 Sea Level Rise ................... ..... .......... 97 5 SUMMARY AND CONCLUSIONS ....................... 104 REFERENCES .................... ................ 107 APPENDIX ...................................... .. 110 A.1 Introduction ...................... ....... ......... 110 A.2 East Coast Counties ................... .......... 112 A.3 West Coast Counties ................... .......... 126 BIOGRAPHICAL SKETCH ................... ........... 140 iv LIST OF FIGURES 1.1 Location of inlets along the coast of Florida covered in this thesis in- cluding the location of tide gauges from which the sea level data were obtained. ... ........... ......... .. ... ..... 4 1.2 Location of counties examined in this thesis for shoreline change. 5 1.3 Approximate longshore sediment transport along the coast of Florida. 6 2.1 DNR monuments located in St. Johns County. 8 2.2 Longshore migration of a natural inlet. ... 11 2.3 Basic transfer process of sand at a natural inlet. ... 11 2.4 Shoreline changes due to placement of a shore normal littoral barrier. 13 2.5 Shoreline changes as a result of placing jetties at an inlet ........ 16 2.6 Definitions of the variables Ob, B, h. and . ... 20 3.1 Monthly mean sea level variations and long-term sea level data at the three locations on the east coast of Florida used in this study. Based on tide gauge data (from Hicks et al., 1983). .... 27 4.1 Historical shorelines for St. Augustine Inlet (from Marino, 1986). 30 4.2 Shoreline change rates before (1858-1937) and after (1943-1986) training St. Augustine Inlet. Change rates in feet per year. ... 31 4.3 Shoreline change rates before (1858-1924) and after (1937-1986) con- struction of the Rt. A1A bridge over Matanzas Inlet. Change rates in feet per year. ................... ... ........ .... 33 4.4 Shoreline change rates before (1873-1967) and after (1972-1989) training Ponce de Leon Inlet. Change rates in feet per year. .... 35 4.5 Ponce de Leon Inlet: South jetty alignment. Adapted from Jones and M ehta, 1978. .................. .............. 36 v 4.6 Shoreline change rates before (1874-1948) and after (1964-1986) training Port Canaveral. Change rates in feet per year. ... 38 4.7 Shoreline change rates for pre- (1964-1974) and post-nourishment (1976- 1986) of the south beach of Port Canaveral. The shoreline change rates for after training (see previous figure) are included for reference. Change rates in feet per year. ................... ......... 39 4.8 Historical shorelines for Sebastian Inlet. ... 41 4.9 Shoreline change rates after training (1948-1986) Sebastian Inlet. Change rates in feet per year. ................... ......... 42 4.10 Historical shorelines for Ft. Pierce Inlet. ..... 44 4.11 Shoreline change rates after training (1928-1987) Ft. Pierce Inlet. Change rates in feet per year. ................... ......... 45 4.12 Shoreline change rates for pre- (1928-1970) and post-nourishment (1972- 1987) of Ft. Pierce Inlet. Change rates in feet per year. ... 46 4.13 Historical shorelines for St. Lucie Inlet (from Marino, 1986). 49 4.14 Shoreline change rates after training (1928-1984) St. Lucie Inlet. Change rates in feet per year. ................... ......... 50 4.15 Historical shorelines for Jupiter Inlet. ... 52 4.16 Shoreline change rates after training (1927-1980) Jupiter Inlet. Change rates in feet per year. .... .......................... 53 4.17 Historical shorelines for Lake Worth Inlet. ... 55 4.18 Shoreline change rates after training (1928-1980) Lake Worth Inlet. Change rates in feet per year. Note that indicated downdrift accretion is due to recovery following south jetty construction. .... 56 4.19 South Lake Worth Inlet in 1969 ...................... 58 4.20 Shoreline change rates after training (1928-1980) South Lake Worth In- let. Change rates in feet per year. ..... 59 4.21 Historical shorelines for Boca Raton Inlet (from Marino, 1986) ... 61 4.22 Shoreline change rates after training (1942-1980) Boca Raton Inlet. Change rates in feet per year. ........... ...... .... ... 62 4.23 Hillsboro Inlet in 1967. ............................ 64 4.24 Shoreline change rates before (1883-1962) and after (1970-1985) jetty construction at Hillsboro Inlet. Change rates in feet per year. 65 vi 4.25 Shoreline change rates after construction (1935-1985) of initial training device (north rock groin) at Hillsboro Inlet. Change rates in feet per year. 66 4.26 Historical shorelines for Port Everglades Entrance. ... 68 4.27 Shoreline change rates after training (1935-1985) of Port Everglades En- trance. Change rates in feet per year. .... 69 4.28 Historical shorelines for Bakers Haulover Inlet. ... 71 4.29 Shoreline change rates after training (1927-1986) of Bakers Haulover Inlet. Downdrift shoreline includes shoreline change rates prior to Miami Beach nourishment (1927-1974). Change rates in feet per year. 72 4.30 Long term (1856-1978) shoreline change rates adjacent to Pensacola Pass. Change rates in feet per year. ....... 74 4.31 Historical shorelines for East Pass (Destin Harbor).