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Overwash Controls on Barrier Island Morphodynamics During Storms

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Overwash Controls on Barrier Island Morphodynamics During Storms University of New Orleans ScholarWorks@UNO University of New Orleans Theses and Dissertations Dissertations and Theses Spring 5-19-2017 Overwash Controls on Barrier Island Morphodynamics during Storms Joshua H. Alarcon [email protected] Follow this and additional works at: https://scholarworks.uno.edu/td Part of the Geology Commons Recommended Citation Alarcon, Joshua H., "Overwash Controls on Barrier Island Morphodynamics during Storms" (2017). University of New Orleans Theses and Dissertations. 2289. https://scholarworks.uno.edu/td/2289 This Thesis is protected by copyright and/or related rights. It has been brought to you by ScholarWorks@UNO with permission from the rights-holder(s). You are free to use this Thesis in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights- holder(s) directly, unless additional rights are indicated by a Creative Commons license in the record and/or on the work itself. This Thesis has been accepted for inclusion in University of New Orleans Theses and Dissertations by an authorized administrator of ScholarWorks@UNO. For more information, please contact [email protected]. Overwash Controls on Barrier Island Morphodynamics during Storms A Thesis Submitted to the Graduate Faculty of the University of New Orleans In partial fulfillment of the Requirements for the degree of a Master of Science In Earth and Environmental Science By Joshua Holland Alarcon B.A. Tulane University, 2011 May 2017 Acknowledgements This master’s thesis is considered a major personal accomplishment and hopefully will serve as a stepping stone to further wonderful endeavors. The completion of this research would not have been possible without the support and guidance of my committee and others who contributed to the advancement of this research. I would first like to thank my major professor, Dr. Ioannis Georgiou, who has led me on a path of becoming a more driven, ambitious, and curious student. I owe my highest gratitude to Dr. Georgiou for instilling in me a higher level of knowledge and greater sense of appreciation for the world around me. I would also like to thank my committee members, Dr. Mark Kulp and Dr. Martin O’Connell for their continued support and guidance throughout this research as well as the Earth and Environmental Science Program. Special thanks also goes out to Mikkel Andersen who granted me permission to use MIKE 21 by DHI for the purpose of this research and to Kevin Hanegan who taught me a great deal of numerical modeling techniques in MIKE 21 that allowed me to fulfill my research requirements. Finally, I would like to thank my friends, family and colleagues who provided me with love, encouragement and support throughout my life. Thank you all! ii Table of Contents List of Figures ................................................................................................................................ iv List of Tables ...................................................................................................................................v Abstract .......................................................................................................................................... vi Introduction ......................................................................................................................................1 Background and Significance ..........................................................................................................3 Barriers .................................................................................................................................3 Shoreface..............................................................................................................................4 Overwash .............................................................................................................................7 Objective ............................................................................................................................12 Methods..........................................................................................................................................13 Model setup ........................................................................................................................13 Boundary Conditions .........................................................................................................13 Barrier morphology templates ...........................................................................................15 Experimental design...........................................................................................................18 Metrics for evaluating barrier response .............................................................................19 Results ............................................................................................................................................22 Upper shoreface .................................................................................................................22 Dune ...................................................................................................................................24 Backbarrier .........................................................................................................................33 Backbarrier lagoon .............................................................................................................33 Discussion ......................................................................................................................................34 Upper shoreface .................................................................................................................34 Dune ...................................................................................................................................36 Backbarrier .........................................................................................................................37 Backbarrier lagoon .............................................................................................................38 Profile evolution.................................................................................................................38 Summary and Conclusions ............................................................................................................43 Implications for barrier island restoration..........................................................................44 References ......................................................................................................................................45 Vita .................................................................................................................................................49 iii List of Figures Figure 1. Barrier Profile as defined by Dean and Dalrymple, 2004. ...............................................6 Figure 2. Seven barrier responses to overwash as proposed by Donnelly, 2007 ...........................11 Figure 3. Time series input files. ..................................................................................................14 Figure 4. The process of building a bathymetry from the master definition profile (.mdf). ..........16 Figure 5. Dune crest widths and shoreface slopes .........................................................................17 Figure 6. Profile change and Initial/Final profile for each shoreface slope on the low barrier dune crest ................................................................................................................................................23 Figure 7. Profile change and Initial/Final profile for each shoreface slope on the wide barrier dune crest ......................................................................................................................................26 Figure 8. Profile change and Initial/Final profile for each dune crest width on the gentle shoreface slope ...............................................................................................................................28 Figure 9. Profile change and Initial/Final profile for each dune crest width on the very steep shoreface slope ..............................................................................................................................29 Figure 10. Profile evolutions of the low barrier and wide crest width on the gentle shoreface slope .............................................................................................................................................30 Figure 11. Profile evolutions of the low barrier and wide crest width on the very steep shoreface slope ..............................................................................................................................................31 Figure 12. Profile change and Initial/Final profile for the low barrier and wide dune crest on the gentle slope for the twelve versus twenty-four day period ............................................................32 Figure 13. Profile Evolution for the gentle shoreface slope low barrier at hours 48, 72 and 110 .39 Figure 14. Profile Evolution for the very steep shoreface slope low barrier at hours 48, 72 and 110..................................................................................................................................................41
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