National Assessment Of Shoreline Change: Part 1 Historical Shoreline Changes And Associated Coastal Land Loss Along The U.S. Gulf Of Mexico Robert A. Morton, Tara L. Miller, and Laura J. Moore Open-File Report 2004-1043 U.S. Department of the Interior U.S. Geological Survey National Assessment Of Shoreline Change: Part 1 Historical Shoreline Changes And Associated Coastal Land Loss Along The U.S. Gulf Of Mexico Robert A. Morton, Tara L. Miller, and Laura J. Moore Open File Report 2004-1043 U.S. Geological Survey Center for Coastal and Watershed Studies St. Petersburg, FL 33701 This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards. Any use of trade names is for descriptive purposes only and does not imply endorsement by the U.S.Government. Morton, Robert A., Miller, Tara L., and Moore, Laura J., 2004, National assessment of shoreline change: Part 1: Historical shoreline changes and associated coastal land loss along the U.S. Gulf of Mexico: U.S. Geological Survey Open-file Report 2004-1043, 45p. U.S. Department of the Interior U.S. Geological Survey Open-File Report 2004-1043 i Contents EXECUTIVE SUMMARY..............................................................................................................................................................................4 INTRODUCTION ..........................................................................................................................................................................................4 U.S. Geological Survey National Assessment of Shoreline Change.........................................................................................4 Disclaimer ...........................................................................................................................................................................................5 Acknowledgments.............................................................................................................................................................................5 THE ROLE OF STATE AND FEDERAL GOVERNMENTS..........................................................................................................................5 PRIOR NATIONAL AND GULF COAST SHORELINE ASSESSMENTS..................................................................................................6 METHODS OF ANALYZING SHORELINE CHANGE.................................................................................................................................6 Compilation of Historical Shorelines ..............................................................................................................................................6 Delineation of a Modern (lidar-derived) Shoreline ......................................................................................................................7 Geographic Information System (GIS) Procedures .....................................................................................................................9 Calculation and Presentation of Rates of Change .....................................................................................................................10 Shoreline Definitions and Beach Alterations that Influence Rates of Change ..................................................................... 11 Shoreline Definitions.............................................................................................................................................................. 11 Human Activities.....................................................................................................................................................................12 Reliability of the Results .................................................................................................................................................................12 GEOMORPHOLOGY OF THE GULF COAST REGION .............................................................................................................................14 Gulf of Mexico Mainland Shores ..................................................................................................................................................16 Bays and Lagoons ...........................................................................................................................................................................16 Barrier Islands..................................................................................................................................................................................16 Origin and Evolution of Barriers ...........................................................................................................................................16 Morphologies of Gulf Coast Barrier Islands.......................................................................................................................18 Chenier Plain ....................................................................................................................................................................................20 Tidal Inlets.........................................................................................................................................................................................20 GEOLOGIC HISTORY AND SETTING ......................................................................................................................................................20 Climate ...............................................................................................................................................................................................21 Coastal Processes...........................................................................................................................................................................21 Sand Sources ...................................................................................................................................................................................24 GENERAL CHARACTERISTICS OF THE GULF SHORES BY STATE.....................................................................................................25 HISTORY OF INFRASTRUCTURE DEVELOPMENT ...............................................................................................................................26 SHORELINE CHANGE AND COASTAL LAND LOSS .............................................................................................................................27 West Florida......................................................................................................................................................................................27 Alabama ............................................................................................................................................................................................29 Mississippi ........................................................................................................................................................................................29 Louisiana ........................................................................................................................................................................................... 31 Texas ............................................................................................................................................................................................... 31 HUMAN RESPONSES TO COASTAL EROSION AND LAND LOSS.....................................................................................................32 DISCUSSION AND FURTHER CONSIDERATIONS ...............................................................................................................................38 Summary of Shoreline Changes....................................................................................................................................................38 Planned Updates and Related Research.....................................................................................................................................38 Influence of Human Activities .......................................................................................................................................................39 REFERENCES ............................................................................................................................................................................................39 Open-File Report 2004-1043 ii Open-File Report 2004-1043 iii Figures Figure 1. Example of a lidar profile from September 26, 1997 at Kitty Hawk, North Carolina for (a) the entire cross-shore region and (b) an expanded view of the foreshore region. .....................................................................9 Figure 2. Examples of common conditions where transects are eliminated in the absence of four shoreline intersections. .............................................................................................................................................. 11 Figure 3. Index map of the Gulf Coast region...................................................................................................................................15 Figure 4. Common coastal landforms of the Gulf Coast region. ...................................................................................................16