# Shoreline Change Rate Estimates Gulf County April 2001

Prepared by: Emmett R. Foster1 

## Jenny Cheng2 1Office of Beaches & Coastal Systems Florida Dept. of Environmental Protection Tallahassee, FL 2Beaches & Shores Resource Center Florida State University Tallahassee, FL 

# Report No. BCS-01-02 Florida Department of Environmental Protection Office of Beaches and Coastal Systems

# FOREWORD This report was prepared to provide shoreline change rate estimates to assist in regulatory programs and beach management planning efforts. In particular, there is a need to assist project managers within the Office of Beaches and Coastal Systems in ranking proposed beach management projects for State of Florida funding support. Efforts were made in developing the rate estimates to consider and take into account the influences of coastal structures and sand fill placements on shoreline change. However, these influences can be very complex and extensive analysis and consideration of such influences was beyond the scope of this work. Shoreline change analyses performed for other specific purposes, such as for establishing 30-year erosion projections pursuant to paragraph 161.053(6), F.S., should be developed in accordance with appropriate and applicable procedures for that specific purpose, although these reports may be relevant in that regard. This report was prepared by Emmett Foster, P. E., of the Office of Beaches and Coastal Systems, and Jenny Cheng of the Beaches and Shores Resource Center. Mr. Foster is the author and editor of the text, calculations, and base graphics. Ms. Cheng formatted and assembled the report, detailed the graphics, plotted the profiles, and assisted with outlining and referencing. The shoreline change rate estimates are based on the best available data at the time of report preparation. Updates to the report will be performed as new data becomes available and as staff workload allows. APPROVED BY Alfred B. Devereaux, Jr., Director Office of Beaches and Coastal Systems

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# TABLE OF CONTENTS 1 EXECUTIVE SUMMARY...............................1 2 INTRODUCTION .................................2 3 REGIONAL SETTING................................3 3.1 Study Area.................................3 3.2 Coastal Setting ...............................3 3.2.1 Geomorphology ..........................3 3.2.2 Waves and Tides..........................5 3.2.3 Longshore Transport ........................6 3.2.4 Storms ...............................6 3.3 Inlets....................................7 3.3.1 Entrance Channel To St. Joseph Bay ................7 3.3.2 Indian Pass.............................7 3.4 Engineering projects ............................7 4 METHODS.....................................8 5 SHORELINE CHANGE ...............................9 5.1 Northwest segment, R-1 to R-31 ......................9 5.2 St. Joseph Peninsula Segment, R-32 to R-115................9 5.3 Cape to Indian Pass Segment, R-119 to R-162. . . . . . . . . . . . . . . 14 6 REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 7 APPENDICES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 7.1 Appendix A: Shoreline Change Rate Estimates. . . . . . . . . . . . . . . 19 7.2 Appendix B: Stack Plots. . . . . . . . . . . . . . . . . . . . . . . . . . 25 7.3 Appendix C: Profile Plots . . . . . . . . . . . . . . . . . . . . . . . . . 52

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# LIST OF FIGURES Figure 1. Study area showing Gulf County, Florida. ....................4 Figure 2. Plan view map of Gulf County, Florida (from R-1 to R-31), comparing years 1934, 1973, 10-12/1983, and 1997.. . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Figure 3. Shoreline rate of change estimates for Bay County, Florida (from R-1 to R-97). . 11 Figure 4. Plan view map of Gulf County, Florida (from R-32 to R-115), comparing years 1868, 1934, and 1997.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Figure 5. Shoreline rate of change estimates for Gulf County, Florida (from R-32 to R-115).13 Figure 6. Plan view map of Gulf County, Florida (from R-119 to R-162), comparing years 1934, 1973, 12/1983, and 1997.. . . . . . . . . . . . . . . . . . . . . . . . . 15 Figure 7. Shoreline rate of change estimates for Gulf County, Florida (from R-119 to R-162). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16


# LIST OF TABLES Table A-1. Shoreline change rate estimates for Gulf County, Florida.. . . . . . . . . . . 20

# 1 EXECUTIVE SUMMARY Gulf County may be considered to be moderately developed. It can be divided into three distinct coastal segments. The northwest segment, R-1 to R-31, on the mainland adjacent to Mexico Beach, has been mildly accretional at + 1.5 to +5 ft/yr. The segment between Cape San Blas and Indian Pass, R-120 to R-162, has been highly accretional in the western portion, mildly accretional in the center to eastern portion, and highly unstable in the easternmost zone affected by Indian Pass. This latter zone, R-153 to R-161, experiences random, large-scale, beach width changes due to ebb shoal changes at the Pass. The middle segment is St. Joseph Peninsula, extending from Point St. Joseph to Cape San Blas. The northern half is St. Joseph Peninsula State Park, which is mildly erosional from R-41 to R-75 at 0 ft/yr to -2 ft/yr, but strongly accretional along the entire northern Point from R-32 to R-40. The Point is affected by dredging and filling from the USACOE navigational project. The southern half of the Peninsula progresses from moderately erosional, -2 ft/yr near the park entrance at R-75, to extremely erosional at the Cape, up to -43 ft/yr. The “stump hole” area near R-105 has been eroding between -10 ft/yr and -15 ft/yr. The landform comprising the point of the Cape (R-114 to R-118 ) was largely washed away by storms in the mid and late 1990’s. However, it was a relatively new landform that formed probably in the late 1940’s to mid 1960’s. It is unknown whether it will re-form to the same extent.

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# 2 INTRODUCTION This work is part of an ongoing project to develop up-to-date shoreline erosion rate estimates for the Florida sandy beach coastline. The shoreline referred to is the approximate Mean High Water (MHW) elevation contour. The information compiled and analyses conducted are intended to provide quantitative and qualitative information on a county-by-county basis that may be used to assist in beach management planning, coastal regulation, and general shoreline analysis work. Quantitative erosion information will be focused on providing erosion estimates relative to currently active coastal processes in those places where no renourishment projects exist. Where renourishment or other similar sand fill projects of size exist, erosion rate estimates for the pre-project conditions will be attempted where possible. It is beyond the scope of these reports to analyze renourishment project performance. In such cases, erosion is a combination of initial onshore-offshore adjustments, lateral diffusion, structural interaction, and the "background erosion" process. Because the conditions that affect erosion are being frequently altered (e.g. inlets, shoals, and armoring additions/subtractions), pre-project erosion estimates are useful primarily in a historical sense and in showing what led to the need for the artificial nourishment. The data used for this analysis is from the Office of Beaches and Coastal Systems Historic Shoreline Database. The database includes beach and offshore profile field surveys, digitized historical shoreline and bathymetric maps, aerial photographs from the Office files, and numerous graphical representations of the data, all within a common set of horizontal and vertical controls. This database was developed and quality controlled by engineers in the Research, Analysis and Policy Section and is continually updated as time and workload allows. Beach profiles were surveyed by the Coastal Data Acquisition Section and, in some cases, by private firms, the latter usually related to the monitoring of coastal erosion control projects. It is beyond the scope of this report to investigate possible actions that may be necessary to prevent or curb shoreline erosion. Where appropriate, however, recommended actions may be suggested or previous, unsuccessful attempts may be pointed out in an effort to help guide the reader towards a better understanding of the dynamics of the coastline and future trends in shoreline change.

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# 3 REGIONAL SETTING 3.1 Study Area Gulf County is located in northwest Florida (see Figure 1) on the Gulf of Mexico. It includes three distinct open coast segments. The first is a 5.9 mile (9.5 km) shoreline segment extending from the Bay County line southeastward. It is exposed to Gulf waves entering the gap between St. Joseph Point and the Crooked Islands of Bay County. The second segment is St. Joseph Peninsula, approximately 16 miles (25.7 km) in length, extending from Cape San Blas to St. Joseph Point. It is the most exposed to higher wave energy of the three segments. The third segment, approximately 8.5 miles (13.7 km) in length, extends from Cape San Blas eastward to Indian Pass and the Franklin County line. It is within an embayment bounded by two large offshore shoal systems: those off Cape San Blas on the west, and those off Cape St. George on the east. There are 162 sequentially numbered DEP survey reference points, generally referred to as "R" monuments, spaced approximately 1,000 ft (300 m) apart. This report uses these reference points to locate various items within the study area. Gulf County is considered to be moderately developed with a combination of single family and multifamily dwellings. There is no coastal armoring of significance, with the exception of a rock revetment fronting the road between approximately R-105 and R-106.5 on St. Joseph Peninsula, an area commonly referred to as “stump hole”. There is only one significantly sized public park area, St. Joseph Peninsula State Park, which comprises the northern half of St. Joseph Peninsula. There is also a large parcel of federal land including the point area of Cape San Blas, with public access. 3.2 Coastal Setting 3.2.1 Geomorphology Coastal Gulf County has a complex geomorphology. The barrier islands of Gulf County and western Franklin County, including St. Joseph Peninsula, and the extensive shoals of Cape San Blas and Cape St. George, and the islands within the embayment between them, all appear to be related to a complex deltaic history of the Apalachicola River. It is well beyond the scope of this report to try to explain how the islands came to be where they are today. The authors are aware of no convincing geologic study of the area. It is important to note the presence of the –3–

## –4– St. Joseph Bay



## Gulf of Mexico Lake Wimico Franklin County Franklin Count y

30

98 98 98

71 71

30A

30A 30E R-1

R-10 R-20 R-30 R-40 R-50 R-60

R-70

R-80

R-90

R-100 R-110 R-120R-130 R-140 R-150 R-160 

### Cape San Blas Indian Pass St. Joseph Point
Port St. Joe 

# GULF COUNTY LOCATION MAP

N

012 3 4 0 1 2 3 4 5 6 Miles Kilometers SCALE Bay County

Federal Land St. Joseph Peninsula State Park St. Joseph Peninsula



## Figure 1. Study area showing Gulf County, Florida.

## extensive offshore shoals because they refract and diffract the wave energy reaching the study area, controlling the wave climate inbetween and to either side of Cape San Blas and Cape St. George. These major shoals can be viewed in any navigational chart of the area and in the historic bathymetric maps (e. g. in the DEP Historic Shoreline Database). There are two other items of significance to note . First, there are extensive peat deposits just below a surface veneer of sand between approximately R-100 and R-113. Second, sand in that area and eastward to San Blas and all the way to Indian Pass, appears finer and darker in color than on St. Joseph Peninsula in general. The peat is noted because it is not sand and therefore erodes differently. It has probably been a significant factor in preventing an island break-through with a new inlet in the R-105 area, thus far. The sand difference is noted because it strongly suggests different sources of material and possibly different directions of net transport. 3.2.2 Waves and Tides The shoreline segment extending from R-1 to R-31, because of its’ location at the entrance to St. Joseph Bay, is affected primarily by waves out of the west and northwest, as refracted and diffracted through the gap between the Crooked Islands (in Bay County) and St. Joseph Point. Tide gauges at Mexico Beach (in Bay County), at St. Joseph Point, and at Port St. Joe indicate diurnal tides with mean tidal ranges of 1.19 ft (.36m), 1.16 ft (.35m), and 1.15 ft (.35), respectively, all very similar (NOS 1988). Most of the shoreline of St. Joseph Peninsula is affected primarily by waves out of the south-southwest, the longest fetch direction. The U. S. Army Corps of Engineers WIS station37 located at 62 ft (19m) depth offshore of the Peninsula, experienced a mean significant wave height of 2.0 ft (0.6 m) and a mean period of 4 seconds, 1976-1995. The shoreline between Cape San Blas and Indian Pass, due to its location within an embayment bordered by two capes and their extensive shoal systems, is affected most frequently by waves out of the south-southeast. The U. S. Army Corps of Engineers WIS Station 36, located at 62 ft (19 m) depth offshore this area and inbetween the two large shoal systems, experienced a mean significant wave height of 2.3 ft (0.7 m) and a mean period of 4 seconds, 1976-1995.

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## 3.2.3 Longshore Transport Net longshore transport in the R-1 to R-31 segment is from northwest to southeast, as evidenced by accretion on the north side of Mexico Beach Inlet (in Bay County), and the deposition of sand in this segment as wave energy from the Gulf dissipates. Net longshore transport along the majority of St. Joseph Peninsula is from south to north, consistent with the direction of longest wave fetch and the observed growth of St. Joseph Point (and probably its’ shoals). In the area closest to the Cape itself, the R-110 to R-117 area, the net direction is likely southward, as evidenced by aerial photos showing refracted waves, and sand being transported into the adjacent east side of the Cape. Sand in the Cape area and eastward appears finer and darker in color than elsewhere on the Peninsula. It is probable that a point where net transport direction changes on the Peninsula exists in the vicinity of R-100 to R-110, due to shoal sheltering and refraction around the shoals off Cape San Blas. The above interpretation of net northerly transport over most of St. Joseph Peninsula is consistent with the totality of available information. It is also the only physical explanation that matches the observed shoreline erosion pattern between approximately R-107 and R-75, as determined by a numerical modeling study by Foster (1991). In that study it was shown that the tapered pattern of higher erosion to lesser erosion, south to north, in that area is a sand supply deficit-induced erosion pattern equivalent to those found elsewhere in the state downdrift of inlet jetties. Net longshore transport along the Cape San Blas to Indian Pass shoreline segment is observed to be west to east on the immediate east side of Cape San Blas. It is further observed to be east to west in the vicinity of both Indian Pass and West Pass ( in Franklin County), as evidenced by the ebb shoal locations at those inlets. It is uncertain what the net direction of littoral transport is inbetween the two observed areas. 3.2.4 Storms Hurricanes in this area occur frequently and both the storms and their effects can remain in the area for long periods of time. However, storms are just peaks in the total normal wind and wave climate record. Experience and observations indicate that severe storms can temporarily disrupt or obscure the longer term erosion pattern, perhaps for up to a decade. In some situations, if a major factor such as the sand supply is altered, or if an inlet is significantly changed, coastal processes can be permanently affected by a storm. Two major storms in recent history were Hurricane Opal in 1995 and Hurricane Kate in 1985. Both caused significant dune erosion and added to ongoing beach erosion. The regional effects of recent hurricanes have been discussed by Leadon (1999) and Leadon et al (1998). –6–

## 3.3 Inlets 3.3.1 Entrance Channel To St. Joseph Bay The Entrance Channel to St. Joseph Bay is a federal navigation project that is regularly dredged, and has a controlling effect on the northernmost tip of St. Joseph Peninsula. Before 1970, all of the dredged sand was disposed of in deep water (Dean & O’Brien, 1987). Since that time there have been several placements of sand offshore, nearshore, and onto St. Joseph Point. 3.3.2 Indian Pass This inlet separates the eastern end of Gulf County from St. Vincent Island (National Wildlife Refuge) in Franklin County. It is navigable by small boats. There is a large ebb shoal along the western Gulf County side which supplies sand to the beaches there and westward. The shoals change frequently and randomly, affecting the shoaling, refraction, and diffraction conditions. It will be seen that most of the shoreline in the vicinity of the shoal has been experiencing frequent random large-scale beach width changes. 3.4 Engineering projects The only significant beach fill placements have occurred in a remote undeveloped area, St. Joseph Point, in conjunction with navigation channel dredging, as discussed in a previous section. The only significant coastal armoring structure is the approximately 1500 ft (450m) long rock revetment fronting the frequently washed out road section between R-105 and R-106.5, in the “stump hole” area of St. Joseph Peninsula. This was constructed in 1996 or 1997 after Hurricane Opal.

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# 4 METHODS A shoreline change analysis to satisfy the report objectives was performed using the methodology initially developed by Foster and Savage (1989) and Foster (1992). In brief, within the often nonlinear record of shoreline change versus time by reference points, segments are identified, consistent with observed coastal processes, in which the erosion is relatively constant or can reasonably be approximated as such. Three different rate calculation methods are applied to these approximately linear shoreline change versus time segments: the rate averaging, least squares, and end-point methods. These results are first averaged alongshore and then averaged across the three calculation methods to achieve a consensus average, not dependent on any single rate calculation method. This is because each calculation method has relative advantages and disadvantages. If time segments are selected reasonably well, the differences between rate methods will be minimal. In certain simplified situations it may be better to use a single rate calculation method, such as the end-point method, as necessity and reason dictate. If the averaging is done properly it will achieve results representative of the unaveraged data but will not be overly affected by individual point variability. In many cases rates from longer and shorter time periods are calculated for comparison purposes (e.g., to show possible progression of an erosion pattern over time or to show that the use of more recent data, which is generally of higher accuracy, yields essentially the same results as the data in a comparative longer time period). Visual tools used for analysis generally include plan views of shorelines oriented and scaled to emphasize shoreline width changes as well as sometimes subtle but important shoreline orientation differences or geologic features within a county or reach. This analysis is also dependent on the shoreline location versus time plots with overlapping axes, known as "stack plots" because several data plots are stacked in sequence to better see a pattern in the data (Appendix B). There are also representative beach profile plots (Appendix C).

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# 5 SHORELINE CHANGE In this report it has been helpful to divide coastal Gulf County into three segments, northwest to southeast. The first two segments are separated by St. Joseph’s Bay Entrance Channel and the Bay entrance itself. The second and third segments are separated by the point of Cape San Blas. 5.1 Northwest segment, R-1 to R-31 Figure 2 shows this zone in plan view with selected historic shorelines. Shoreline (MHW) change rate estimates are provided in Figure 3 and Table A-1 (Appendix A). This zone receives sand from the northwest, and as wave energy diminishes further inside the Bay entrance, sand is deposited on the beachface. The R-1 to R-31 area has therefore been moderately accretional overall, with rates ranging from +2.0 ft/yr up to +5.0 ft/yr in the 1973-1997 time period. In the plan view, there are two particular areas of pronounced deposition, in the vicinity of R-16 to R-20, and R-28 to R-30. It is suspected that this is due to an uncommon wave pattern effect, but aerial photos of the area showing actual attacking waves have so far not been found. A series of aerial photos were reviewed. However, the lack of photos with waves could be taken as an indication of the area normally having a relatively mild wave climate. 5.2 St. Joseph Peninsula Segment, R-32 to R-115 The northern half of the Peninsula, R-32 to R-75, is a state park, as previously noted. By far, most of the erosion occurs southeast of the park. This is shown in the plan view of Figure 4 and the rate estimates of Figure 5. In the latter figure, there is a distinct change in the erosion pattern in the vicinity of R-105 to R-107. The erosion rate estimate at R-105 of -12.5 ft/yr tapers progressively down to -2.0 ft/yr at R-75, the park boundary. However, south of R-105 the erosion rates increase sharply to -43 ft/yr at R-113. It is to be noted that points from R-114 to R-118 no longer exist, the tip of the Cape having been reconfigured in 1995 by Hurricane Opal, and by later storms. The transition in the erosion pattern in the vicinity of R-105 to R-107 is suspected as being due to the change in net transport direction which likely occurs in that vicinity, –9–

## – 10 – 0 5000 10000 15000 20000 25000 30000 35000

2000 2500 3000 3500 4000 4500 5000 5500 6000 Distance along baseline (ft)

Distance from baseline (ft)

Gulf County Plan View Plot Northwest Segment
Baseline Origin: N 337000 E 1715000 AZIMUTH 150 Deg CW from N R-25 R-30
R-20 R-15 R-10 R-5 R-1 Gulf of Mexico St. Joseph Bay
Land Monuments 1934 1973 10-12/1983 1997Figure 2. Plan view map of Gulf County, Florida (from R-1 to R-31), comparing years 1934, 1973, 10-12/1983, and 1997.

## – 11 – 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

-50 -45 -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 DEP Reference Points

Rate Estimate (ft/yr)

Gulf County Shoreline Rates of Change Northwest Segment

Accretion ErosionFigure 3. Shoreline rate of change estimates for Bay County, Florida (from R-1 to R-97).

## – 12 – 0 10000 20000 30000 40000 50000 60000 70000 80000 90000

5000 10000 15000 20000 Distance along baseline (ft)

Distance from baseline (ft) Gulf County Plan View Plot St. Joseph Peninsula Segment
Baseline Origin: N 320000 E 1695000 AZIMUTH 162 Deg CW from N R-60 R-55 R-45 R-50 R-40 R-85

R-35 R-32 R-75 R-70 R-65 R-80 R-90 R-95 R-100 R-105 R-110 R-115


### Gulf of Mexico St. Joseph Peninsula Monuments 1868 1934 1997 Cape San BlasFigure 4. Plan view map of Gulf County, Florida (from R-32 to R-115), comparing years 1868, 1934, and 1997.

## – 13 – 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115

-50 -45 -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 DEP Reference Points

Rate Estimate (ft/yr)

Gulf County Shoreline Rates of Change St. Joseph Peninsula Segment

Accretion Erosion Affected by Dredging and Filling St. Joseph Peninsula State Park Progressive Erosion Similar to Inlet-Induced Pattern Increased Erosion Closer to CapeFigure 5. Shoreline rate of change estimates for Gulf County, Florida (from R-32 to R-115).

## as previously discussed. Waves from the southeast are refracted and diffracted by the Cape shoals, resulting in a net transport change in direction. It may also be of interest to note that our historic data indicates that the large landform that existed as the tip of the Cape, from R-113 to R-119, from sometime prior to 1973 to 1995, was a relatively new landform. It did not exist in 1934 or 1868. It likely formed gradually in the late 1940’s to early 1960’s, judging by the extensive vegetation cover in 1973 aerial photos. It is also noted that because of it’s relatively sudden appearance as a large landform, it may have developed as an emergent shoal as well as from longshore transport. It appears that a foundation of shoal material developed over a long time, and was shown in that location in the 1943 historic bathymetry map of the area (in the DEP Historic Shoreline Database). The point was washed out by storms in the mid to late 1990’s. Whether it will re-form again is unknown. A last item of possible interest concerns the possibility of one or more breakthroughs of the Peninsula in the future as very high erosion continues to make the land particularly narrow at two locations, R-105/106 and R-101/102. No one can say when or how, but an eventual breakthrough is more likely than not. It will probably occur during a hurricane. The peat deposits have most likely helped delay the event. The preventive ability of the revetment is unknown. All erosion on the Peninsula and towards the Cape will likely increase drastically in the event of a breakthrough, due to a landward sink effect and a major change in the sand supply. It is also possible a breakthrough will eventually occur at R-71/73, the site of an old inlet channel (Eagle Harbor area). 5.3 Cape to Indian Pass Segment, R-119 to R-162 Figure 6 shows the area in plan view and Figure 7 is a plot of the rate of change estimates. Receiving sand from both ends has been beneficial for this segment, which has been generally accretional, particularly in the western part, R-119 to about R-135. The eastern portion, R-135 to R-150, has been mildly accretional, particularly in recent decades. The dominant process at the eastern end is the Indian Pass ebb shoal interaction with the shoreline. The result has been random, large-scale beach width changes between R-161 and R-153, and an occasional erosion pocket in the R-152 to R-153 area. The rates calculated for this entire area are not reliable in either hindcast or forecast, and result primarily from the last surveys of 1997 and 1998 showing an accretion event rather than an erosion episode. While it may be possible that in the very long term there will be net accretion, it cannot be relied upon anytime soon. For example, if we only had data through 1983, it would not have predicted the 1997 condition in this area. A reasonable recommendation for this area is to keep development landward of the historic zone of beach width fluctuations. – 14 –

## – 15 – 0 5000 10000 15000 20000 25000 30000 35000 40000 45000

3000 4000 5000 6000 7000 8000 9000 10000 11000 Distance along baseline (ft)

Distance from baseline (ft)

Gulf County Plan View Plot Cape to Indian Pass Segment Baseline Origin: N 240000 E 1730000 AZIMUTH 90 Deg CW from N Monuments 1997 12/1983 1973 1934 R-160

R-150

R-125 R-140R-145

R-120 R-130 R-135

R-155 R-162 Gulf of Mexico Indian Pass

Cape San BlasFigure 6. Plan view map of Gulf County, Florida (from R-119 to R-162), comparing years 1934, 1973, 12/1983, and 1997.

## – 16 – 120 122 124 126 128 130 132 134 136 138 140 142 144 146 148 150 152 154 156 158 160 162

-50 -45 -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 DEP Reference Points

Rate Estimate (ft/yr)

Gulf County Shoreline Rates of Change Cape to Indian Pass Segment

Accretion Erosion Generally Accretionary Random Large-scale Beach Width FluctuationsFigure 7. Shoreline rate of change estimates for Gulf County, Florida (from R-119 to R-162).

# 6 REFERENCES Dean, R. G. and O’Brien, M. P., 1987. Florida’s West Coast Inlets: Shoreline Effects and Recommended Action. University of Florida, Coastal and Oceanographic Engineering Department, Gainesville, FL, UFL/COEL-87/018, 100 p. Foster, Emmett R., 1992. Thirty Year Erosion Projections in Florida: Project Overview and Status. In: Proceedings of the 23rd International Conference on Coastal Engineering, Venice, Italy. American Society of Civil Engineers (ASCE), NY, Vol. 2, pp. 2057-2070. Foster, Emmett R., 1991. Coastal Processes Near Cape San Blas, Florida: A Case Study Using Historic Data and Numerical Modeling. In: Proceedings of the Fourth Annual National Beach Preservation Technology Conference. Florida Shore and Beach Preservation Association, Tallahassee, FL, pp. 400-411. Foster, Emmett R. And Savage, Rebecca J., 1989. Methods of Historical Shoreline Analysis. In: Coastal Zone ‘89. American Society of Civil Engineers (ASCE), NY, Vol. 5, pp. 4434-4448. Leadon, Mark E., 1999. Beach, Dune and Offshore Profile Response to a Severe Storm Event. In: Kraus, N. C. And McDougal, W. G. (Eds), Coastal Sediments ‘99, Proceedings of the 4th International Symposium on Coastal Engineering and Science of Coastal Sediment Processes, Reston, VA. American Society of Civil Engineers (ASCE), NY, Vol.3, pp. 2534-2549. Leadon, M. E., Nguyen, N. T., and Clark, R. R., 1998. Hurricane Opal: beach and Dune Erosion and Structural damage Along the Panhandle Coastal of Florida. Florida Department of Environmental Protection, Bureau of Beaches and Coastal Systems, Tallahassee, FL, BBCS number 98-01. National Ocean Service, 1988. Published Tidal Benchmark Sheets. Available from World Wide Web <http://co-ops.nos.noaa.gov/bench.html>. ASCII format. Waterways Experiment Station [cited 1999]. Wave Information Study, Gulf of Mexico Phase I: 1976-1995. Vicksburg, MS: U.S. Army Corps of Engineers. Available from World Wide Web at Coastal Engineering Data Retrieval System (CEDRS) <http://bigfoot.wes.army.mil/u023.html>. ASCII format.
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# 7 APPENDICES

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## 7.1 Appendix A: Shoreline Change Rate Estimates Table A-1: This table and accompanying figure provide rates based on the method described in Section 4.

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## – 20 – Range Time Span Method Rounded Concensus

Average Comments RA LS EP 1 1973-1997 1.5 1.7 1.5 2 7 pt avg 2 1973-1997 2.4 2.4 2.4 2.5  3 1973-1997 2.6 2.7 3 2.5 4 1973-1997 2.8 2.9 2.9 2.5 5 1973-1997 3.4 3.4 3.3 3 6 1973-1997 3.3 3.5 3.3 3.5 7 1973-1997 2.4 2.6 2.3 3.5 8 1973-1997 4.4 4.1 4.2 3 9 1973-1997 3.2 3.6 5.3 3 10 1973-1997 2.5 2.8 3.1 3 11 1973-1997 2.1 2 2.5 3 12 1973-1997 2.1 1.8 2 2.5 13 1973-1997 1.9 2.3 2.4 2.5 14 1973-1997 3 3.3 3.4 3 15 1973-1997 2.7 2.4 2.6 3.5 16 1973-1997 3.2 2.6 2.9 4 17 1973-1997 4.6 4.4 5 4.5 18 1973-1997 7.2 7.3 7.5 4.5 19 1973-1997 6.2 6.1 6.2 4 20 1973-1997 5.7 5.9 5.9 3.5 21 1973-1997 1.3 1 1.5 3.5 22 1973-1997 -0.3 -1.6 -0.3 3 23 1973-1997 2.1 0.5 1.5 3 24 1973-1997 4.2 3.9 4.8 2.5 25 1973-1997 3.5 3.5 4.1 2.5 26 1973-1997 5.4 5.2 6.2 3.5 27 1973-1997 2.3 2.1 2.1 4 28 1973-1997 -0.2 -0.5 -0.2 4 7 pt avg 29 1973-1997 9.8 6.3 6.4 3.5 5 pt avg 30 1973-1997 5.6 5.7 5.3 5 3 pt avg 31 1973-1997 2.1 2.1 2.1 2 1 pt avg St. Joseph Bay Entrance 

## Table A-1. Shoreline change rate estimates for Gulf County, Florida.

## – 21 – Range Time Span Method Rounded Concensus

Average Comments RA LS EP 32 1973-1993 N/A 7.1 6.9 7 LS + EP only; No longshore avg 33 1973-1997 N/A 12.2 5.4 9 34 1973-1997 N/A 15.3 9.8 12.5 35 1973-1997 N/A 29.7 28.3 29 36 1973-1997 N/A 20.9 20 20.5 37 1973-1997 N/A 11.5 11.7 11.5 38 1973-1997 5 4 2.6 4 1 pt avg 39 1973-1997 3.3 2.3 2 3.5 3 pt avg 40 1973-1997 4.1 3.9 3.1 3 5 pt avg 41 1973-1997 3.3 3.4 3.1 1 7 pt avg 42 1973-1997 0.1 0.8 0.1 -0.5  43 1973-1997 -1.8 -1.9 -1.6 -0.5 44 1973-1993 -4.5 -4.3 -3 -0.5 45 1973-1993 -5.9 -6.4 -6.4 -1.5 46 1973-1997 1.4 1 2.3 -2 47 1973-1997 2.8 1.4 2.2 -2 48 1973-1997 -0.5 -1.5 -0.8 -1.5 49 1973-1997 -6.6 -6.2 -4.9 -0.5 50 1973-1997 -0.7 0 0.8 -1 51 1973-1997 -0.1 0.8 -0.1 -2 52 1973-1997 -0.4 0.1 1.5 -1.5 53 1973-1997 -3 -2.8 -2.7 -1 54 1973-1997 -3.6 -3.3 -3.6 -1.5 55 1973-1997 -0.1 0.3 -0.1 -1.5 56 1973-1997 -3.2 -1.3 -1.4 -1.5 57 1973-1997 -2 -2.1 -3.2 -1.5 58 1973-1997 1.1 1.7 -1.3 -1 59 1973-1997 -0.6 -1.1 -2.6 -2 60 1973-1997 0.7 -0.5 -1 -1.5 61 1973-1997 -1.7 -1.9 -2.6 -1.5 62 1973-1997 -3.3 -4.4 -5.8 -1.5 63 1973-1997 0.2 -0.6 -1.9 -1 64 1973-1997 -0.5 -0.1 -0.5 -1 

## Table A-1. Shoreline change rate estimates for Gulf County, Florida.

## – 22 – Range Time Span Method Rounded Concensus

Average Comments RA LS EP 65 1973-1997 0.2 -0.4 0.2 -1 66 1973-1997 -0.6 0.4 -0.6 0 67 1973-1997 -0.3 -0.8 -0.3 -0.5 68 1973-1997 0.7 -1.7 -0.8 -1 69 1973-1997 0.7 1.1 2.1 -1 70 1973-1997 -3.5 -3.6 -4.4 -1.5 71 1973-1997 -1.5 -1.7 -2.1 -1.5 72 1973-1997 -2.4 -3.1 -3 -1.5 73 1973-1998 -4.3 -4.4 -3.5 -2.5 74 1973-1997 -0.3 -0.9 -0.3 -2 75 1973-1997 0.5 -0.3 1.6 -2 76 1973-1998 -3.5 -4.1 -4 -1.5 77 1973-1997 -2.1 -2.5 -3.1 -1 78 1973-1997 -0.2 0.3 -0.2 -1.5 79 1973-1997 -1.6 -0.7 -0.7 -2 80 1973-1998 -0.8 -0.9 -2.3 -1.5 81 1973-1998 -3.1 -2.4 -3.5 -1.5 82 1973-1997 -2.7 -0.4 -1.2 -1.5 83 1973-1997 -1 -0.5 -1 -1.5 84 1973-1998 -1 -1 -2.9 -2 85 1973-1997 -1.9 -1.6 -2.7 -1.5 86 1973-1997 -1 -0.9 -1.7 -1.5 87 1973-1998 -2.9 -2.1 -3.6 -2 88 1973-1997 -0.3 0.3 -0.3 -2 89 1973-1997 -3 -2.1 -3.2 -2 90 1973-1998 -4.3 -4.1 -5.7 -3 91 1973-1997 -0.9 -2 -0.9 -4 92 1973-1997 -2.6 -3.2 -1.8 -5.5 93 1973-1998 -8 -7.1 -7.4 -6 94 1973-1998 -7.9 -8.8 -8.7 -7.5 95 1973-1998 -9.5 -9.3 -9.8 -8 96 1973-1997 -11.7 -9.7 -7.7 -9 97 1973-1998 -12.6 -11.2 -12.1 -9.5 

## Table A-1. Shoreline change rate estimates for Gulf County, Florida.

## – 23 – Range Time Span Method Rounded Concensus

Average Comments RA LS EP 98 1973-1997 -8.9 -8 -5.9 -10.5 99 1973-1997 -7.6 -7.4 -6.9 -10.5 100 1973-1998 -12.8 -12.3 -14.4 -11 101 1973-1998 -12.5 -12.1 -13 -11 102 1973-1998 -11.2 -11.5 -11.5 -11.5 103 1973-1998 -13.2 -14 -13.5 -12 104 1973-1997 -10.7 -11.4 -11.4 -12 105 1973-1997 -10.3 -10.6 -9.3 -12.5 106 1973-1998 -14 -13.6 -13.4 -13.5 7 pt avg 107 1973-1997 -12.9 -12.3 -11.5 -14 5 pt avg 108 1973-1997 -17.4 -16.5 -15.4 -16.5 109 1973-1997 -19.6 -18.7 -17.7 -19 110 1973-1998 -20.2 -22.5 -21.4 -22 3 pt avg 111 1973-1997 -25.4 -25.4 -25.2 -27.5 112 1973-1997 -33.1 -35.9 -36.6 -37.5 113 1973-1997 -45.8 -54.3 -56.8 -43 114 1973-1993 -32.8 -43.8 -48.1 -46 115 1976-1993 -39.3 -48 -47.2 -45 1 pt avg Cape San Blas 119 1973-1998 28.9 21.7 33.1 28 1 pt avg 120 1973-1997 38.1 30 31.3 29.5 3 pt avg 121 1973-1997 31.1 27 25.9 27.5 5 pt avg 122 1973-1998 26.5 24.7 23.7 26 7 pt avg 123 1973-1998 26.9 22.3 20.8 25  124 1973-1997 24.8 23 22.1 22 125 1973-1997 22.5 22.3 21 20 126 1973-1998 19.1 19.1 17.6 18 127 1973-1996 15.4 16.1 15.7 16 128 1973-1998 13.5 13.3 12.6 13.5 129 1973-1997 9.6 10.9 9.1 11 130 1973-1997 8.1 8.4 7 8.5 131 1973-1997 6.7 6.6 5.1 6.5 132 1973-1998 5.5 5.2 3.5 5 

## Table A-1. Shoreline change rate estimates for Gulf County, Florida.

## – 24 – Range Time Span Method Rounded Concensus

Average Comments RA LS EP 133 1973-1997 3.5 3.2 2 3.5 134 1973-1997 2.4 3.3 1.6 2.5 135 1973-1997 0.6 2.6 0.6 2 136 1973-1998 -0.2 2 -0.2 1.5 137 1973-1998 0.5 1.7 0.5 1 138 1973-1998 0.2 1.1 0.2 1 139 1973-1998 0 1 0 1 140 1973-1998 0.7 1.4 0.7 1 141 1973-1998 0.6 1.5 0.7 0.5 142 1973-1998 2.1 1.7 1.2 0.5 143 1973-1998 0 1.6 0 1 144 1973-1998 -0.1 1.3 -0.6 1 145 1973-1998 0 1.3 0 1 146 1973-1998 1.6 2.7 0.9 1 147 1973-1998 2.4 2.3 1.4 1 148 1973-1998 1 1.7 0.7 1 7 pt avg 149 1973-1998 2.4 2 1.6 1 5 pt avg 150 1973-1998 0.9 1.4 -0.6 1 3 pt avg 151 1973-1998 0 0.3 0 0 1 pt avg 152 1973-1998 N/A N/A 0.1 0 EP only 153 1973-1998 N/A N/A 0.8 1 154 1934-1998 N/A -0.2 0.4 0 Average EP + LS; No longshore average 155 1934-1998 N/A 4.6 3.7 4 156 1934-1998 N/A 3.8 3 3.5 157 1934-1998 N/A 1 2.8 2 158 1934-1998 N/A 0.2 0.7 0.5 159 1934-1998 N/A -1 -1.5 -1.5 160 1934-1997 -2.7 -1.2 -1.7 -2 3 method average; No

longshore average 161 1934-1998 0 -0.2 0 0 162 1934-1984 -0.7 -0.6 -0.8 -0.5 

## Table A-1. Shoreline change rate estimates for Gulf County, Florida.

## 7.2 Appendix B: Stack Plots Stack plots from Historic Shoreline Database, Florida Department of Environmental Protection, Office of Beaches and Coastal Systems; slightly modified by authors.

– 25 –

## – 26 – Historic MHW Distance vs. Time R-1 to R-8

Calendar Year 1850 1875 1900 1925 1950 1975 2000 2025 Distance from Reference Points (ft) (Plots overlap; 100 ft tick interval)

0 0 0 0 0 0 0 0 0 400 800 ID / Axis Location

R-8 R-7 R-6 R-5 R-4 R-3 R-2 R-1 Ref. pt.

## – 27 – Historic MHW Distance vs. Time R-9 to R-16

Calendar Year 1850 1875 1900 1925 1950 1975 2000 2025 Distance from Reference Points (ft) (Plots overlap; 100 ft tick interval)

0 0 0 0 0 0 0 0 0 400 800 ID / Axis Location

R-16 R-15 R-14 R-13 R-12 R-11 R-10 R-9 Ref. pt.

## – 28 – Historic MHW Distance vs. Time R-17 to R-24

Calendar Year 1850 1875 1900 1925 1950 1975 2000 2025 Distance from Reference Points (ft) (Plots overlap; 100 ft tick interval)

0 0 0 0 0 0 0 0 0 400 800 ID / Axis Location

R-24 R-23 R-22 R-21 R-20 R-19 R-18 R-17 Ref. pt.

## – 29 – Historic MHW Distance vs. Time R-25 to R-31

Calendar Year 1850 1875 1900 1925 1950 1975 2000 2025 Distance from Reference Points (ft) (Plots overlap; 100 ft tick interval)

0 0 0 0 0 0 0 0 0 400 800 ID / Axis Location

R-31 R-30 R-29 R-28 R-27 R-26 R-25 Ref. pt.

## – 30 – Historic MHW Distance vs. Time R-32 to R-33

Calendar Year 1850 1875 1900 1925 1950 1975 2000 2025 Distance from Reference Points (ft) (Plots overlap; 100 ft tick interval)

0 0 0 0 0 0 0 0 0 400 800 ID / Axis Location R-33 R-32 Ref. pt.

## – 31 – Historic MHW Distance vs. Time R-34 to R-38

Calendar Year 1850 1875 1900 1925 1950 1975 2000 2025 Distance from Reference Points (ft) (Plots overlap; 100 ft tick interval)

0 0 0 0 0 0 0 0 0 400 800 ID / Axis Location

R-38 R-37 R-36 R-35 R-34 Ref. pt.

## – 32 – Historic MHW Distance vs. Time R-39 to R-45

Calendar Year 1850 1875 1900 1925 1950 1975 2000 2025 Distance from Reference Points (ft) (Plots overlap; 100 ft tick interval)

0 0 0 0 0 0 0 0 0 400 800 ID / Axis Location

R-45 R-44 R-43 R-42 R-41 R-40 R-39 Ref. pt.

## – 33 – Historic MHW Distance vs. Time R-46 to R-53

Calendar Year 1850 1875 1900 1925 1950 1975 2000 2025 Distance from Reference Points (ft) (Plots overlap; 100 ft tick interval)

0 0 0 0 0 0 0 0 0 400 800 ID / Axis Location

R-53 R-52 R-51 R-50 R-49 R-48 R-47 R-46 Ref. pt.

## – 34 – Historic MHW Distance vs. Time R-54 to R-61

Calendar Year 1850 1875 1900 1925 1950 1975 2000 2025 Distance from Reference Points (ft) (Plots overlap; 100 ft tick interval)

0 0 0 0 0 0 0 0 0 400 800 ID / Axis Location

R-61 R-60 R-59 R-58 R-57 R-56 R-55 R-54 Ref. pt.

## – 35 – Historic MHW Distance vs. Time R-62 to R-68

Calendar Year 1850 1875 1900 1925 1950 1975 2000 2025 Distance from Reference Points (ft) (Plots overlap; 100 ft tick interval)

0 0 0 0 0 0 0 0 0 400 800 ID / Axis Location

R-68 R-67 R-66 R-65 R-64 R-63 R-62 Ref. pt.

## – 36 – Historic MHW Distance vs. Time R-69 to R-75

Calendar Year 1850 1875 1900 1925 1950 1975 2000 2025 Distance from Reference Points (ft) (Plots overlap; 100 ft tick interval)

0 0 0 0 0 0 0 0 0 400 800 ID / Axis Location

R-75 R-74 R-73 R-72 R-71 R-70 R-69 Ref. pt.

## – 37 – Historic MHW Distance vs. Time R-84 to R-91

Calendar Year 1850 1875 1900 1925 1950 1975 2000 2025 Distance from Reference Points (ft) (Plots overlap; 100 ft tick interval)

0 0 0 0 0 0 0 0 0 400 800 ID / Axis Location

R-91 R-90 R-89 R-88 R-87 R-86 R-85 R-84 Ref. pt.

## – 38 – Historic MHW Distance vs. Time R-92 to R-97

Calendar Year 1850 1875 1900 1925 1950 1975 2000 2025 Distance from Reference Points (ft) (Plots overlap; 100 ft tick interval)

0 0 0 0 0 0 0 0 0 400 800 ID / Axis Location

R-97 R-96 R-95 R-94 R-93 R-92 Ref. pt.

## – 39 – Historic MHW Distance vs. Time R-98 to R-104

Calendar Year 1850 1875 1900 1925 1950 1975 2000 2025 Distance from Reference Points (ft) (Plots overlap; 100 ft tick interval)

0 0 0 0 0 0 0 0 0 400 800 ID / Axis Location

R-104 R-103 R-102 R-101 R-100 R-99 R-98 Ref. pt.

## – 40 – Historic MHW Distance vs. Time R-105 to R-106

Calendar Year 1850 1875 1900 1925 1950 1975 2000 2025 Distance from Reference Points (ft) (Plots overlap; 100 ft tick interval)

0 0 0 0 0 0 0 0 0 400 800 ID / Axis Location

R-106 R-105 Ref. pt.

## – 41 – Historic MHW Distance vs. Time R-107 to R-108

Calendar Year 1850 1875 1900 1925 1950 1975 2000 2025 Distance from Reference Points (ft) (Plots overlap; 100 ft tick interval)

0 0 0 0 0 0 0 0 0 400 800 ID / Axis Location

R-108 R-107 Ref. pt.

## – 42 – Historic MHW Distance vs. Time R-109 to R-110

Calendar Year 1850 1875 1900 1925 1950 1975 2000 2025 Distance from Reference Points (ft) (Plots overlap; 100 ft tick interval)

0 0 0 0 0 0 0 0 0 400 800 ID / Axis Location

R-110 R-109 Ref. pt.

## – 43 – Historic MHW Distance vs. Time R-111 to R-112

Calendar Year 1850 1875 1900 1925 1950 1975 2000 2025 Distance from Reference Points (ft) (Plots overlap; 100 ft tick interval)

0 0 0 0 0 0 0 0 0 400 800 ID / Axis Location

R-112 R-111 Ref. pt.

## – 44 – Historic MHW Distance vs. Time R-113 to R-118

Calendar Year 1850 1875 1900 1925 1950 1975 2000 2025 Distance from Reference Points (ft) (Plots overlap; 100 ft tick interval)

0 0 0 0 0 0 0 0 0 400 800 ID / Axis Location

R-118 R-117 R-116 R-115 R-115 R-114 R-113 Ref. pt.

## – 45 – Historic MHW Distance vs. Time R-119

Calendar Year 1850 1875 1900 1925 1950 1975 2000 2025 Distance from Reference Points (ft) (Plots overlap; 100 ft tick interval)

0 0 0 0 0 0 0 0 0 400 800 ID / Axis Location R-119 Ref. pt.

## – 46 – Historic MHW Distance vs. Time R-120 to R-123

Calendar Year 1850 1875 1900 1925 1950 1975 2000 2025 Distance from Reference Points (ft) (Plots overlap; 100 ft tick interval)

0 0 0 0 0 0 0 0 0 400 800 ID / Axis Location

R-123 R-122 R-121 R-120 Ref. pt.

## – 47 – Historic MHW Distance vs. Time R-124 to R-131

Calendar Year 1850 1875 1900 1925 1950 1975 2000 2025 Distance from Reference Points (ft) (Plots overlap; 100 ft tick interval)

0 0 0 0 0 0 0 0 0 400 800 ID / Axis Location

R-131 R-130 R-129 R-128 R-127 R-126 R-125 R-124 Ref. pt.

## – 48 – Historic MHW Distance vs. Time R-132 to R-139

Calendar Year 1850 1875 1900 1925 1950 1975 2000 2025 Distance from Reference Points (ft) (Plots overlap; 100 ft tick interval)

0 0 0 0 0 0 0 0 0 400 800 ID / Axis Location

R-139 R-138 R-137 R-136 R-135 R-134 R-133 R-132 Ref. pt.

## – 49 – Historic MHW Distance vs. Time R-140 to R-147

Calendar Year 1850 1875 1900 1925 1950 1975 2000 2025 Distance from Reference Points (ft) (Plots overlap; 100 ft tick interval)

0 0 0 0 0 0 0 0 0 400 800 ID / Axis Location

R-147 R-146 R-145 R-144 R-143 R-142 R-141 R-140 Ref. pt.

## – 50 – Historic MHW Distance vs. Time R-148 to R-155

Calendar Year 1850 1875 1900 1925 1950 1975 2000 2025 Distance from Reference Points (ft) (Plots overlap; 100 ft tick interval)

0 0 0 0 0 0 0 0 0 400 800 ID / Axis Location

R-155 R-154 R-153 R-152 R-151 R-150 R-149 R-148 Ref. pt.

## – 51 – Historic MHW Distance vs. Time R-156 to R-162

Calendar Year 1850 1875 1900 1925 1950 1975 2000 2025 Distance from Reference Points (ft) (Plots overlap; 100 ft tick interval)

0 0 0 0 0 0 0 0 0 400 800 ID / Axis Location

R-162 R-161 R-160 R-159 R-158 R-157 R-156 Ref. pt.

## 7.3 Appendix C: Profile Plots

– 52 –

## – 53 – 

## Gulf County R-9

Distance from Monument (ft) -200 0 200 400 600 800 Elevation (ft NGVD)

-10 -5 0 5 10 15 20 25 30 1973 1984 1997

MHW 

## Gulf County R-1

Distance from Monument (ft) -200 0 200 400 600 800 Elevation (ft NGVD)

-10 -5 0 5 10 15 20 25 30 1973 1984 1997

MHW

## – 54 – 

## Gulf County R-30

Distance from Monument (ft) -200 0 200 400 600 800 Elevation (ft NGVD)

-10 -5 0 5 10 15 20 25 30 1973 1984 1997

MHW 

## Gulf County R-21

Distance from Monument (ft) -200 0 200 400 600 800 Elevation (ft NGVD)

-10 -5 0 5 10 15 20 25 30 1973 1984 1997

MHW

## – 55 – 

## Gulf County R-48

Distance from Monument (ft) -200 0 200 400 600 800 Elevation (ft NGVD)

-10 -5 0 5 10 15 20 25 30 1973 1984 1997

MHW 

## Gulf County R-39

Distance from Monument (ft) -300 -100 100 300 500 700 Elevation (ft NGVD)

-10 -5 0 5 10 15 20 25 30 1973 1984 1997

MHW

## – 56 – 

## Gulf County R-75

Distance from Monument (ft) -200 0 200 400 600 800 Elevation (ft NGVD)

-10 -5 0 5 10 15 20 25 30 1973 1984 1997

MHW 

## Gulf County R-60

Distance from Monument (ft) -400 -200 0 200 400 600 Elevation (ft NGVD)

-10 0 10 20 30 40 50 60 1973 1984 1997

MHW

## – 57 – 

## Gulf County R-120

Distance from Monument (ft) -400 0 400 800 1200 Elevation (ft NGVD)

-10 -5 0 5 10 15 20 25 30 1973 1984 1997

MHW 

## Gulf County R-93

Distance from Monument (ft) -400 -200 0 200 400 600 Elevation (ft NGVD)

-10 -5 0 5 10 15 20 25 30 1973 1984 1997

MHW

## – 58 – 

## Gulf County R-141

Distance from Monument (ft) -200 0 200 400 600 800 Elevation (ft NGVD)

-10 -5 0 5 10 15 20 25 30 1973 1984 1997

MHW 

## Gulf County R-129

Distance from Monument (ft) -300 -100 100 300 500 700 Elevation (ft NGVD)

-10 -5 0 5 10 15 20 25 30 1973 1984 1997

MHW

## – 59 – 

## Gulf County R-150

Distance from Monument (ft) -200 0 200 400 600 800 Elevation (ft NGVD)

-10 -5 0 5 10 15 20 25 30 1973 1984 1997

MHW



## Gulf County R-159

Distance from Monument (ft) -200 0 200 400 600 800 Elevation (ft NGVD)

-10 -5 0 5 10 15 20 25 30 1973 1984 1997

MHW