W&M ScholarWorks Dissertations, Theses, and Masters Projects Theses, Dissertations, & Master Projects 1990 Beach Forms Induced by Coastal Structures Forming Embayments in Fetch-Limited Environments Jian Hua Li College of William and Mary - Virginia Institute of Marine Science Follow this and additional works at: https://scholarworks.wm.edu/etd Part of the Ocean Engineering Commons, and the Oceanography Commons Recommended Citation Li, Jian Hua, "Beach Forms Induced by Coastal Structures Forming Embayments in Fetch-Limited Environments" (1990). Dissertations, Theses, and Masters Projects. Paper 1539617617. https://dx.doi.org/doi:10.25773/v5-ys6f-4f09 This Thesis is brought to you for free and open access by the Theses, Dissertations, & Master Projects at W&M ScholarWorks. It has been accepted for inclusion in Dissertations, Theses, and Masters Projects by an authorized administrator of W&M ScholarWorks. For more information, please contact [email protected]. BEACH FORMS INDUCED BY COASTAL STRUCTURES FORMING EMBAYMENTS IN FETCH-LIMITED ENVIRONMENTS A Thesis Presented to The Faculty of the School of Marine Science The College of William and Mary in Virginia In Partial Fulfillment of the Requirements for the Degree of Master of Arts by Jian Hua Li August,1990 f LIBRARY \ / of the i VIRGINIA INSTITUTE \ of \ m m m scie n c e / APPROVAL SHEET This thesis is submitted in partial fulfillment of the requirements for the degree of master of arts in Marine Science Jian Hua Li Approved, August 199 0 ^ * p L. Donelson Wright, Ph.D. Committee Chairman/Advisor Robert J . Byrne U Ph.D . Diazober •h.D. Evon P. Ruzecki, Ph.D. DEDICATION This thesis is dedicated to my wife iii CONTENTS Acknowledgement....................................................... v List of tables....................................................... vi List of figures..................................................... vii List of symbols.............................. ix Abstract.................................. xi 1. Introduc t ion....................................................... 2 2. General background................................................. 7 2.1. Major previous studies on profiles............................ 7 2.2. A brief review on plan beach form models................. 14 3. Data and Methodology.............................................. 21 3.1. Surveys and data sets on beach profiles and photography............................ 21 3.2. Data sets on plan—view beach forms........................... 28 3.3. Sediment data................................................ 29 3.4. Methods of wave hindcasting.................................. 29 3.5. Methods on wave refraction and diffraction...................32 4. Field site descriptions........................................... 36 5. Results of profile and sediment analysis..........................44 5.1. Results of field profile measurements........................44 5.2. Sediment characteristics in the study area...................60 6. Discussions and Conclusions — Profiles............................63 6.1. The general characteristics........ 63 6.2. The mechanisms of profile development........................71 6.3. Beach slope and sediments.................................... 77 6.4. Profile variations with seasons/wave climate.................85 6.5. Sediment distributions along profiles........................85 7. Results of plan-view beach form measurements......................89 7.1. Circular bay beach forms.................................... .89 7.2. Spiral bay beach forms....................................... 93 7.3. Irregular bay beach forms.................................... 97 8. Discussions and conclusions — plan beach forms....................99 8.1. General characteristics......................................99 8.2. Plan form and Wave refraction.............................. 101 8.3. Plan form and Wave diffraction............................. 104 8.4. Wave reflection............................................. 108 9. Future study considerations......................................Ill APPENDIX A: Calculations of A, m and er.............................112 APPENDIX B: A few of examples of enlarged profiles..................118 APPENDIX C: Results of bay measurements in Spring'90.................126 APPENDIX D: Plots of field measured profiles....................... 135 REFERENCES CITED.................................................... 183 VITA .............................................................. 190 iv ACKNOWLEDGEMENTS I would like to thank my major professor, Dr. L.D. Wright, for his continuing guidance during the past few years. Great thanks and appreciation are extended to all other members in my advisory committee for their help in this study. Special thanks to C. Scott Hardaway and George Thomas for their very close corporation in all field data collection. This special thanks also go to Dr. E.P. Ruzecki and Dr. R.J. Diaz for their very careful english correction on the text of this thesis. Finally, thanks to all the others in the Division of Geological and Benthic Oceanography for their continuing friendship and support. v LIST OF TABLES TABLE PAGE 1.1. The average erosion rate at study sites................. 4 3.1. Profiling and aerial photography schedule...................... 22 3.2. Profiling and aerial photography schedule...................... 22 3.3. Wave predictions by various methods............................ 31 5.1. Results of slope and sediment analysis......................... 45 5.2. Sediment size distribution along bay beaches................... 61 6.1. Surf scaling parameters in the study area...................... 69 -6;2. Bank erosion history and beach fill............................ 78 6.3. Field measured data and Sunamura's parameter................... 84 8.1. Summary table of beach forms.................................. 100 vi LIST OF FIGURES Figure Page 1.1. Virginia Chesapeake Bay and its river system................... 5 2.1. Plan of spiral beach, Sandy hook, New Jersey.................. 16 2.2. Logarithmic Spiral nomenclature (Yasso, 1965)................. 16 2.3. Definition sketch of logarithmic spiral........ 16 2.4. Typical prototype bay showing refracted orthogonals........... 17 2.5. A mathematical simulation of spiral beaches................... 17 3.1. Feature profiling method...................................... 24 3.2 through 3.8. Base maps with numbered profiles.............. 25—27 3.9. Wave diffraction diagram...................................... 35 4.1. Long term wind roses.......................................... 43 5.1 through 5.17 Plots of beach profiles. :^.................... 46—59 6.1. Comparisons of different models............................... 65 6.2. Comparisons of different models............................... 66 6.3. Reflective beach profile...................................... 68 6.4. Comparisons of beach profiles................................. 70 6.5. Beach slope prediction........................ 80—83 6.6. The distribution pattern of sediments............. 87 7.1. Breakwater system and its embayments at CHP....................90 7.2. Breakwater system and its embayments at HI2....................90 7.3. Breakwater system and its embayments at DMF....................91 7.4. Breakwater system and its embayments at WAL....................91 7.5. Photo showing the breakwaters and embayments at WAL........... 92 7.6. The spiral bay at SUM ................................... 94 7.7. Photo showing the general spiral bay shape at SUM............. 94 7.8. Breakwater system and Its embayments at NPS................... 95 7.9. Headlands and their bays at YTB............................... 96 7.10.Photo showing the headlands and bays at YTB....................96 vii List of figures continued: 7.11 .Headlands and the plan beach forms at HIH......................98 8.1. Wave refraction in waters with curved shorelines.............. 103 8.2. Wave refraction in circular bay......................... 105 8.3. Wave refraction in spiral bay................................. 105 8.4. Wave diffraction diagram for SUM.............................107 8.5. Wave reflections from breakwaters............................110 iix LIST OF SYMBOLS A — Scale factor in Bruun-Dean's model. a± — Incident wave amplitude. a — (l).The angle between a radius vector and tangent for a given logspiral, a constant; (2).Wind direction in effective fetch calculation; (3). The angle between wave crest and respective depth contour (wave refraction). B — The vertical increase in water depth. — Nearshore slope angle seaward from breaking waves. C — Wave phase speed (C-L/T). CQ — Wave phase speed in deep water. € — Wave reflectivity or surf-scaling parameter. E — Wave energy density, e — The base of Naperian logarithms. eE — Root—Mean—Square (RMS) error. D — Diameter of a sediment particle. D50 — Median grain size. D. — The average wave energy dissipation rate. Fff - Gravitational force parameter. Ff - Fluid force, g — Gravitational acceleration. Hb — Wave height at breaking, h — Water depth. hbo - Breaking depth before water level change. hb — Breaking depth after water level change. h. — The depth of effective motion of active profile. hDo — The original dune height above mean sea level. h ^ — The original breaking depth before water level rise. Hd — Wave height in the region affected by wave diffraction. H± — Incident wave height unaffected by diffraction. Hc - Wave height in deep water. Hr - Reflected wave height. hB — Water depth