|
UFL/COEL-94/007
PERDIDO KEY BEACH NOURISHMENT PROJECT:
GULF ISLANDS NATIONAL SEASHORE
1993 Annual Report
Emre N. Otay
and
Robert G. Dean
July, 1994
Sponsor:
Department of the Navy
Southern Division
Naval Facilities Engineering Command
Charleston, SC 29411-0068
1
REPORT DOCUMENTATION PAGE
1. port go. 2. 3. R cipent'*s ccessLon No.
4. Title and Subtitle 3. Report Date
PERDIDO KEY BEACH NOURISHMENT PROJECT: GULF ISLANDS July 1994
NATIONAL SEASHORE
1993 Annual Report
7. &utbor(s) 8. Perforrtan Organiation Report No.
Emre N. Otay and Robert G. Dean UFL/COEL-94/007
9. Perfomung Ora nizatioa name and Address 10. Project/Task/Uork Unit go.
Coastal and Oceanographic Engineering Department
University of Florida 1. Contrc or rnt o.
336 Weil Hall
N62467-89-C-0500
Gainesville, FL 32611 N62467-
13. Type of Report
12. Sponsoring Orgenizatioo Name and Address
Department of the Navy Annual Report
Southern Division
Naval Facilities Engineering Command
Charleston, SC 29411-0068 14.
15. Supplementary Notes
16. Abscract
This report is the fourth annual report in a continuing series documenting a field project
within the Gulf Islands National Seashore at Perdido Key, Florida. The field project includes
the monitoring of a number of physical parameters related to the evolution of the Perdido Key
beach nourishment project. Approximately 4.1 million m3 of dredge spoil from Pensacola Pass
were placed upon approximately 7 km of the Gulf of Mexico beaches and 3 million m3 offshore
of Perdido Key between November, 1989, and October, 1991.
Beach profile data describing the evolution of the nourished beach are included, as well
as wave, current, tide, wind, temperature, and rainfall data to describe the forces influencing
the evolution. Data describing the sediment sizes throughout the project area are also included.
A brief discussion of the data is included with an emphasis on evolution of the beach and
offshore nourishment.
17. Originator's Iey Words 18. Availability Sttement
Beach nourishment
Sediment transport
Shoreline response
19. U. S. Security Classit. of the Report 20. U. S. Security Classif. of This Pale 21. No. of Pages 22. Price
Unclassified Unclassified 253
r ......
UFL/COEL-94-007
PERDIDO KEY BEACH NOURISHMENT PROJECT:
GULF ISLANDS NATIONAL SEASHORE
1993 Annual Report
Submitted to:
Department of the Navy
Southern Division
Naval Facilities Engineering Command
Charleston, SC 29411-0068
Prepared by:
Emre N. Otay
Robert G. Dean
Coastal and Oceanographic Engineering Department
University of Florida
Gainesville, FL 32611
July, 1994
I
TABLE OF CONTENTS
LIST OF FIGURES iv
LIST OF TABLES vi
1 INTRODUCTION 1
2 DATA COLLECTION 4
2.1 Hydrographic and Topographic Surveys........................................ .......... 4
2.2 Wave/Current/Tide Data ........................................................................... 7
2.3 Sand Samples ............................................................................................... 8
2.4 W weather Data ............................................................................................... 8
2.5 Photographic Documentation ................................................................... 9
3 PROFILE NOURISHMENT 9
3.1 Volumetric Changes and Migration of the Placed Material........................ 11
3.2 Lateral Spreading and Surface Smoothing of Bed Features.......................... 14
3.3 Sheltering Effect on Beach Nourishment ......................................................... 16
4 DISCUSSION 18
4.1 Profile Equilibration and Cross- Shore Sediment Transport ...................... 18
4.2 Concentration of Fines ............................................................................. 27
4.3 Sedim ent Characteristics ................................................................................
5 REFERENCES
APPENDIX I: BEACH and OFFSHORE PROFILES
APPENDIX H: WAVE, CURRENT, and TIDE DATA
January, 1993 May, 1994
APPENDIX III: GRAIN SIZE DISTRIBUTIONS
APPENDIX IV: METEOROLOGICAL DATA
January, 1993 June, 1994
III-1
IV-1
LIST OF FIGURES
FIGURE PAGE
1 Site location chart ........................................................................ .... 2
2 Components of beach nourishment monitoring project .................... 3
3 Evolution of the profile nourishment between October, 1992 and
December, 1993 ................................................... ..................... 10
4 Offshore Mound: Cross-sectional area and center of gravity ............ 11
5 Offshore Mound: Volumetric changes relative to October, 1992 ..... 12
6 Offshore Mound: On/offshore migration of center of gravity
relative to October, 1992 .............................................. .......... 13
7 Offshore Mound: Landward edge at range R-50 ............................. 15
8 Offshore Mound: Evolution of bed shape ................................... 16
9 Evolution of dry beach width since completion of beach
nourishm ent ................................................................................. ...... 18
10 Movement of -4 m contour since completion of beach nourishment 19
11 Average of profiles within nourished area. Averages based on
profiles at R-45, R-46, R-48, R-50, R-52, R-54, R-56 and R-58 ...... 20
FIGURE PAGE
12 Cross-shore sediment transport within nourished area, based on
average profiles shown in Figure 11 from September, 1990 to
N ovem ber, 1993 ............................................................................. 21
13 Average of profiles west of nourished area. Averages based on
profiles at R-30, R-32, R-34, R-36 and R-38 ................................. 22
14 Cross-shore sediment transport west of nourished area, based on
average profiles shown in Figure 13 from September, 1990 to
N ovem ber, 1993 ............................................................................. 23
15 Average of profiles within protected beach nourishment. Averages
based on profiles at R-50, R-52, R-54, R-56, R-58 and R-60 ........... 24
16 Cross-shore sediment transport within protected beach
nourishment, based on average profiles shown in Figure 15 from
September, 1990 to November, 1993 .............................................. 25
17 Average of profiles within unprotected beach nourishment.
Averages based on profiles at R-43, R-44, R-45, R-46, R-61, R-62
and R -63 ............................................................................................ 26
18 Cross-shore sediment transport within unprotected beach
nourishment, based on average profiles shown in Figure 17 from 26
September, 1990 to November, 1993 ..............................................
19 Percentage of fines for 5 m samples for all years of study................. 27
FIGURE PAGE
20 Percentage of fines for 8 m samples for all years of study................. 28
21 Longshore distribution of D50 for November, 1993 (solid line) with
envelope (dashed line) of sizes for all years of study ..................... 29
22 Longshore averaged cross-shore distribution of Ds,. Temporal
variation for all years of study ........................................................ 30
LIST OF TABLES
PAGE
Chronology of Perdido Key field efforts .....................................
Chronology of Perdido Key field efforts (cont'd) ........................
TABLE
1
1
Draft
PERDIDO KEY BEACH NOURISHMENT PROJECT:
GULF ISLANDS NATIONAL SEASHORE
1993 ANNUAL REPORT
1 INTRODUCTION
This report is one in a series of annual summaries of a continuing field project within
Gulf Islands National Seashore at Perdido Key, Florida (Figure 1). Between November 1989 and
September 1990 approximately 4.1 million m3 of dredge material were placed along the eastern 7
km of the Gulf of Mexico shoreline of Perdido Key. From September 1990 to October 1991, an
additional approximately 3 million m3 of material were placed as an underwater deposit ("profile
nourishment") with pre-placement depths ranging from 5 m to 6.5 m. This deposit commenced at
an approximate offshore distance of 500 m and extended up to 1300 m from the
post-nourishment shoreline, between DNR Monuments R-50 and R-60, extending approximately
4 km in the longshore direction (see Figure 2).
Earlier reports (Work et al. 1990a, 1990b, 1991a, 1991b, 1991c, 1992a and Otay & Dean
1993) discussed the site and physical data collection methods in detail. The focus of this report
will be the results of the field work and physical data collection for 1993. The data describe
topographic and bathymetric changes of the area, waves, currents, tides, sediment sizes, winds,
temperatures and rainfall. In addition to the beach nourishment, a significant portion of this
year's report has been dedicated to the analysis of the profile nourishment data and the
interpretation of the findings.
C9
tto
10
Figure 1: Site location chart
\to
Figure 1: Site location chart
METEOROLOGICAL
STATION ..:
/
CD
0
0
CD
0
o
0
0.
0
c1r
0-
Ct
0
NOTE:
R-40 is FLORIDA DEPARTMENT OFNATURAL
RESOURCES MONUMENTED "RANGE 40"
0 1 2 3 4 5 km
I I'
2 DATA COLLECTION
The study area and the data collection sites are shown in Figure 2. Table 1 presents a
chronological summary of the ongoing field efforts since commencement of the project. A
discussion of the data collection and analysis methods can be found in previous reports; only a
brief summary will be included here.
2.1 Hydrographic and Topographic Surveys
The survey equipment and methodology used were unchanged from previous surveys.
The beach profiles were surveyed to approximate water depths of 4 to 5 m employing standard
rod-and-level techniques, by first wading and then swimming over the deeper portions of the
profiles. The offshore profile was surveyed by a boat equipped with a fathometer to measure
depths and a microwave rangefinder system to measure horizontal distances. The profile lines
were surveyed from the same monuments and azimuth values as in the previous surveys.
During the 1993 annual survey, twenty-five Gulf profiles were surveyed by boat, and an
additional eight have been surveyed to wading/swimming depth (generally 4-5 m) only, in order
to improve spatial resolution of the evolution of the beach nourishment. In addition to the yearly
Gulf surveys, twenty-three Bay profiles, out of which seventeen reached the water, were
surveyed by wading as was done in November 1989, before the nourishment. A total of twelve
surveys have been conducted to date: The annual bathymetric surveys of 11/89, 9/90, 10/91,
10/92 and 11/93 and the additional wading/swimming surveys of 1/91, 5/91, 9/91, 1/92, 6/92,
1/93 and 5/93. Data from the five annual surveys are presented in Appendix I.
Table 1: Chronology of Perdido Key field efforts
Date Task
10/28-11/1/89
11/17/89
1/18/90
1/29/90
1/30/90
3/7-3/9/90
5/2/99
6/24/90
8/8/90
8/17/90
9/22-9/26/90
12/6/90
1/29-2/3/91
5/15-5/16/91
5/28-6/1/91
6/18-6/19/91
7/29-7/30/91
9/10/91
9/28-10/2/91
10/12-10/20/91
Pre-nourishment survey:
Wading/swimming profiles (Gulf and Bay) Offshore bathymetry
Sand samples, photos
Placement of nourishment material begins
Wave gage tripod and standalone gage installed
Tide gage with small stilling well installed at Ft. Pickens Pier, Santa Rosa Island
Mechanical (analog) weather station installed
Large stilling well installed for Ft. Pickens tide gage
56 sand samples collected, to replace those destroyed or not collected during
pre-nourishment survey
Standalone wave data collection package replaced with new package
Digital weather station installed
Standalone wave data collection package replaced with new package
Placement of nourishment material completed
First post-nourishment survey:
Wading/swimming profiles (Gulf side)
Offshore bathymetry
Sand samples, photos
Standalone wave data collection package replaced with new package
Ft. Pickens pier tide gage re-surveyed
Wading/swimming profile survey (Gulf side)
Sand samples
Wave gage cable re-buried
Wading/swimming profile survey (Gulf side)
Sand samples
Shore-connected wave gage removed; cable cut
Standalone wave gage installed
Wind vane and anemometer replaced
Standalone wave gage removed
Fresh standalone wave gage installed
Wading/swimming profile survey (Gulf side)
Sand samples, photos
Reattached Ft. Pickens pier tide gage
yearly survey:
Wading/swimming profiles (Gulf side)
Offshore bathymetry
Installed heavyweight data/power cable for wave gage
Replaced standalone wave gage near Ranger Station
Installed shore-connected wave gage near Ranger Station
Sand samples, photos
Table 1: Chronology of Perdido Key field efforts (cont'd)
Date
10/23-10/24/91
1/16-1/22/92
4/15-4/16/92
7/8/92
10/17-10/20/92
10/27-10/29/92
1/22-1/25/93
5/14-5/18/93
10/15-10/17/93
11/13-11/16/93
12/8-12/10/93
Task
Replaced shore-connected wave gage near Ranger Station
Wading/swimming profiles (Gulf side)
Replaced wind vane/anemometer
Replaced shore-connected wave gage near Ranger Station
Replaced standalone wave gage near Ranger Station
Replaced shore-connected wave gage near Ranger Station
Removed standalone wave gage from Ranger Station
Installed new standalone wave gage near Caucus Shoal
Replaced shore-connected wave gage near Ranger Station
Replaced standalone wave gage near Caucus Shoal
yearly survey:
Wading/swimming profiles (Gulf side)
Replaced shore-connected wave gage near Ranger Station
Replaced standalone wave gage near Caucus Shoal
Sand samples, photos
Replaced weather station
bathymetric survey of range lines (Gulf side)
bathymetric survey of "Profile Nourishment"
Wading/swimming profiles (Gulf side)
Cleaned shore-connected wave gage near Ranger Station
Replaced standalone wave gage near Caucus Shoal
Reset weather station
Wading/swimming profiles (Gulf side)
Bathymetric survey of 8 lines along "Profile Nourishment"
Bathymetric survey of "Profile Nourishment"
Wading/swimming surveys of beach cusps
Cleaned shore-connected wave gage near Ranger Station
Replaced standalone wave gage near Caucus Shoal
Reset weather station
yearly survey:
Wading/swimming profiles (Bay side)
Reset weather station
yearly survey:
Wading/swimming profiles (Gulf side)
Sand samples, photos
Reset weather station
yearly survey:
bathymetric survey of range lines (Gulf side)
bathymetric survey of "Profile Nourishment"
2.2 Wave/Current/Tide Data
Waves, currents and tides are measured at two stations, one located offshore from the
Ranger Station near DNR Monument R-34, and the other on Caucus Shoal near R-62. Both
stations comprise P-U-V type electronic gages mounted on tetrapod shaped steel frames placed
on the ocean floor. The P-U-V gages consist of two electronic sensors; a pressure transducer and
an electromagnetic current meter. Raw data include a pressure signal and two velocity signals
measured on a horizontal plane perpendicular to each other. All signals are collected once every
6 hours at 1 Hz sampling frequency for a 17 minute duration.
The gage near the Ranger Station is connected by a cable to a shore station which serves
as a link for the remote control operation. The P-U-V data from this gage can be retrieved from
the University of Florida via telephone. The gage near Caucus Shoal carries a self contained
storage device which can store data until divers retrieve the package every 3-4 months.
Additional information about wave packages can be found in previous reports by Work et al.,
1990 and 1991.
The P-U-V data are analyzed using directional spectrum methods to obtain wave height,
wave period, wave direction, tide, current velocity and current direction. The computed wave,
current and tide parameters are presented in Appendix II for the period of January 1993 to May
1994. There are seven plots per month for each gage. The first four plots present wave related
parameters. These are: Wave period, significant wave height, modal wave direction and the
spreading parameters of the wave spectrum. Wave information is followed by current and tide
variables presented in three plots which show the current velocity, mean current direction and the
tidal elevation.
2.3 Sand Samples
Sand samples are collected at eight locations along the profiles: Dune, mid-beach, berm,
beachface, -1 m, -2 m, -5 m and -8 m. Details about the sampling locations and methodology can
be found in the previous reports by Work et al., 1990 and 1991.
Grain size distributions have been determined by mechanical sieve analysis of each
sample, using a series of twelve U.S. standard sieves with mesh numbers 10, 20, 30, 40, 50, 60,
70, 80, 100, 120, 140, 160. The analysis results are presented in Appendix III. Each figure shows
grain size distributions at a particular location for different sample years. Several characteristic
parameters of the grain size statistics have been analyzed, such as the median diameter (D0 ),
mean diameter, sorting index, skewness and kurtosis. In this report only the D50 results are
presented. Other parameters can be obtained from the authors. A further discussion on sediment
characteristics and spatial/temporal variations in grain sizes can be found in Chapter 4.
2.4 Weather Data
The current weather station has been operating since October 1992 with a locally
installed data acquisition unit and a storage device. The station can be controlled remotely from
the University of Florida and the stored data can be retrieved via telephone. The data acquisition
unit consists of electronic sensors to measure wind velocity, wind direction, air temperature and
rainfall. Data are sampled at 1 Hz frequency and the mean, minimum and maximum values over
a user defined interval are saved in the storage device. The optimum interval was found as two
hours considering the storage capacity and the retrieval time of stored data in case of system
malfunction. Approximately once a week stored data are retrieved into a computer at the
University of Florida via telephone. Appendix IV presents the analyzed data in biweekly time
series of wind velocity, wind direction, air temperature and rainfall.
2.5 Photographic Documentation
Oblique color ground photography has been taken throughout the study to document
changes as the nourished beach evolves. Photography is conducted in conjunction with each
survey. Three photos are generally taken along each profile, viewing to the left along the beach,
perpendicular to the beach and to the right along the beach. The reader may contact the authors
regarding availability of the photographs.
3 PROFILE NOURISHMENT
As shown in Figure 2 the "profile nourishment" is located between DNR Monuments
R-50 and R-60. Starting with the Fall survey of 1992, six of the survey lines encompassed the
profile nourishment area. The measurement efforts have included an extension of the profile
lines in the area of profile nourishment and additional bathymetric surveys "blanketing" the area.
The profiles from the extended survey lines in November, 1993 are presented in Appendix I from
R-50 through R-60. The additional data from "blanketing" surveys in October, 1992, May, 1993
and December, 1993 were interpolated into a 1 km by 5 km grid system. Figure 3 displays a
gray-scale map of the results for different surveys. Darker areas in the figure indicate deeper
sections whereas the elevated bathymetry of the profile nourishment are shown as lighter
shading. Snapshots from 92/10, 93/05 and 93/12 show qualitatively, the distributions of depths in
the mound area. Note that each snapshot is a result of analyzed survey data collected
approximately seven months apart.
The results presented in the following sections of this report are obtained from the
analysis of bathymetric surveys of the extended range lines only. A more comprehensive study
focusing on the special surveys which blanket the nearshore berm area is in progress. Three
aspects of the profile nourishment were evaluated: (1) The volumetric changes and migration of
migration of the placed material, (2) the lateral spreading and the evolution of surface features of
the bed, and (3) the sheltering effect of the underwater placed material on the leeward beaches.
Offshore Mound: 92/10
-500
S-1000
2-
0
0
4:
(I)
500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Shore Parallel [m]
Offshore Mound: 93/05
500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Shore Parallel [m]
Offshore Mound: 93/12
500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Shore Parallel [m]
Figure 3: Evolution of the profile nourishment between October, 1992 and December, 1993.
-1500-
0
--
-1500
.0
a-
o
-1500-
0
CE
S-1000g
a)
o
-1500--
0
3.1 Volumetric Changes and Migration of the Placed Material
Six survey lines encompassing the offshore mound were analyzed to calculate
volumetric changes and the movements of the center of gravity of the placed material. Figure 4
presents a general picture of the relative changes in the cross-sectional berm area and the
position of center of gravity from the completion of the placement in October, 1991 to the last
survey in November, 1993.
Offshore Mound: Changes in Center of Gravity and Area
62 i i i i i
60- 3 2 1
58- 1 324
56- 3J
54 1: 91/10
2: 92/10
52 3: 93/05
4: 93/11
50
I I I I I I I I
920 940
<---Onshore---
960 980 1000 1020 1040
Distance from Monument [m]
1060 1080 1100
---Offshore--->
Figure 4: Offshore mound: Cross-sectional area and center of gravity characteristics
Each bar in Figure 4 represents the cross-sectional area of the mound for a particular
time and location. The height of the bar is a relative measure of the magnitude of the
cross-sectional area such that longer bars indicate larger amounts of material. The position of the
bars along the horizontal axis determines the cross-shore location of the center of gravity of the
corresponding section. As is evident from these results, there is no clear indication of significant
cross-shore movement of the center of gravity.
Data presented in Figures 5, 6 and 7 were computed in quantities relative to October,
1992 survey because that was the first complete set of profiles to fully cover the berm section in
all of the six range lines. Figure 5 shows volumetric changes of the underwater placed material
based on six profiles relative to October, 1992.
Offshore Mound: Volumetric Changes
55
Range No.
Figure 5: Offshore mound: Volumetric changes relative to October, 1992.
Measured volumetric changes, distributed across the entire section, are equivalent to an
average vertical change of 5 cm which is in the same order of magnitude as the vertical survey
accuracy determined in a study on nearshore measurement techniques and accuracies (Otay and
Dean, 1994). A similar result was found for the movement of center of gravities in Figure 6. The
horizontal displacements were found to range within approximately 10 m which is again within
the limits of the horizontal accuracy as found by Otay and Dean (1994).
Offshore Mound: Center of Gravity
..... 91/10
S- -92/10
-- 93/05
93/11
\ N \ / .
\ /
51 52 53 54 55
Range No.
56 57 58 59 60
Figure 6: Offshore mound: On/offshore migration of center of gravity relative to October, 1992
Although it is theoretically possible to improve the measurement accuracy by adjustment
of the data or applying other high accuracy surveying techniques, it appears that the magnitudes
-10
-15
5'
0
2.5 Photographic Documentation
Oblique color ground photography has been taken throughout the study to document
changes as the nourished beach evolves. Photography is conducted in conjunction with each
survey. Three photos are generally taken along each profile, viewing to the left along the beach,
perpendicular to the beach and to the right along the beach. The reader may contact the authors
regarding availability of the photographs.
3 PROFILE NOURISHMENT
As shown in Figure 2 the "profile nourishment" is located between DNR Monuments
R-50 and R-60. Starting with the Fall survey of 1992, six of the survey lines encompassed the
profile nourishment area. The measurement efforts have included an extension of the profile
lines in the area of profile nourishment and additional bathymetric surveys "blanketing" the area.
The profiles from the extended survey lines in November, 1993 are presented in Appendix I from
R-50 through R-60. The additional data from "blanketing" surveys in October, 1992, May, 1993
and December, 1993 were interpolated into a 1 km by 5 km grid system. Figure 3 displays a
gray-scale map of the results for different surveys. Darker areas in the figure indicate deeper
sections whereas the elevated bathymetry of the profile nourishment are shown as lighter
shading. Snapshots from 92/10, 93/05 and 93/12 show qualitatively, the distributions of depths in
the mound area. Note that each snapshot is a result of analyzed survey data collected
approximately seven months apart.
The results presented in the following sections of this report are obtained from the
analysis of bathymetric surveys of the extended range lines only. A more comprehensive study
focusing on the special surveys which blanket the nearshore berm area is in progress. Three
aspects of the profile nourishment were evaluated: (1) The volumetric changes and migration of
of the changes will remain small relative to those occurring in the beach nourishment portion of
the project because of more energetic conditions and thus smaller time scales of the transport
processes in the vicinity of the beach nourishment and surf zone. For future monitoring plans of
the offshore mound a longer observational time scale would be appropriate.
3.2 Lateral Spreading and Surface Smoothing of Bed Features
Based upon analysis of the profile nourishment data, it appears that there may be a small
net landward movement of the underwater berm forming the profile nourishment; however, most
of the evolution is apparent as a "spreading out" of the placed material. To address the question
of lateral spreading the landward edge of the placed material was examined and corresponding
volume changes and displacement of center of gravities were calculated. Analysis of mound
profiles indicated certain evidence for the lateral spreading although it was not conclusive
mainly because the computed differences were very small compared to measured quantities.
Figure 7 shows one of the six sections (R-50) with a more consistent evolutionary trend. In this
figure, the increase of the area above the 90/09 profile and the monotonic landward migration of
the center of gravity of the section are evidence for the lateral spreading of the underwater
mound in the cross-shore direction. The rates of change of both the position of center of gravity
and the cross-sectional area decrease in consecutive years of project evolution. In general terms
this is a strong indication of a diffusive process; however, the magnitudes are small and are
almost within measurement accuracy.
Perdido Key: R-50
,-5.8
o
. -5.9
LU
730 740 750 760 770 780 790
Distance from Monument [m]
Figure 7: Offshore mound: Landward edge at range R-50.
To study the evolution of the surface features of the sand bed a spectral analysis
technique was applied to the mound profile data. The advantage of this method is that certain
features which cannot be detected in the spatial domain become very obvious once the signal is
transformed to the wave number domain using Fourier Transformation techniques. Analogous to
this are the common applications of Frequency Spectrum in Digital Signal Analysis of time
series. When applied to batymetric data, this method allows different types of bed undulations,
varying from small ripples to large dunes, to be separated in the spectral domain and studied
individually for their evolution. At six profiles the wave number spectra were obtained for
different survey data and the resulting spectral energies are plotted in Figure 8. Since higher
spectral energy means more bed undulation the drop in spectral energy over the time indicates a
consistent reduction of bed irregularities and a relatively rapid smoothening of the sand bed
along each section of the profile nourishment.
Offshore Mound: Spectral Energy of Bed Shape
E
CM 6
I 4
CD
E 2
w 0
aCD
E
Z
-2
a(
.
0)
w
55
Range No.
Figure 8: Offshore mound: Evolution of bed shape
3.3 Sheltering Effect on Beach Nourishment
When the profile nourishment project was first designed, one of the underlying concepts
was that the nearshore berm should provide some protection of the beach portion of the
nourished material by reducing the incoming wave energy. On the other hand, providing too
much blockage would cause unwanted sediment deposition in the sheltered zone of the beach,
similar to salient and/or tombolo formation in the leeside of offshore breakwaters which could
cause adverse effects to adjacent portions of the beach and therefore should be prevented. In the
Perdido Key Profile Nourishment Project the water depth within the placement area was reduced
by 1.5 to 2.0 m to result in depths of approximately 4 m relative to NGVD. Theoretically, the
reduced water column above the berm would allow most of the incoming wave energy to pass
through undisturbed under the region's regular wave climate. Only in severe sea conditions
would a significant fraction of wave energy be filtered mainly by wave breaking over the berm,
allowing less destructive forcing at the shoreface. The calculation of the optimum size and
location of the placement is an engineering challenge which is extremely sensitive to local wave
climate and topography. The initial placement of the beach nourishment material resulted in a
shoreline advancement of approximately 150 m into the Gulf of Mexico between
DNR-Monuments R-42 and R-64. Figure 9 shows the measured planform evolution for different
surveys. The measured shoreline recession was largest in the first year, from September, 1990 to
October, 1991 and it decreases consistently in the following years. The planform evolution and
comparison of the presented field data with analytic solutions using longshore diffusivity
models have been discussed in detail by Work (1992b). Prior to November, 1993 there was no
significant evidence in the profile data to support the sheltering effect of the profile nourishment.
However, the November 1993 data indicated a clear reduction of shoreline recession between
DNR-Monuments R-50 and R-60, which are the approximate limits of the nearshore berm.
Beyond these range lines the shoreline receded at reasonable rates as it would without the
offshore sheltering. A strong hypothesis is that the shoreline stabilization occurred due to the
sheltering effect of the offshore mound for this latter period. However, it is difficult to explain
why similar sheltering effects were not associated with previous intersurvey periods.
Perdido Key Beach Nourishment
Planform Evolution
600 ... .....
30 40 50 60
Range Number
Figure 9: Evolution of dry beach width since completion of beach nourishment.
4 DISCUSSION
Several features of the monitoring program, based on data collected during the last year
merit discussion as presented below.
4.1 Profile Equilibration and Cross-Shore Sediment Transport
With the exception noted previously, since completion of the beach nourishment project,
a consistent shoreline recession and profile equilibration have been observed. Within the beach
nourishment area the shoreline recession rate has been steadily decreasing, whereas the -4 m
contour has been monotonically moving seaward along the entire beach as shown in Figure 10.
The net result of the simultaneous recession of the upper and advancement of the lower portions
of the profile is a reduction of the initially steep slope of the nourished profiles.
Perdido Key Beach Nourishment
Movement of -4m Contour
-50
O O
z
E
50
0400
30
40 50 60
Range Number
Figure 10: Movement of -4 m contour since completion of beach nourishment.
In addition to the planform evolution results, the average of profiles within the nourished
area (Figure 11) contains useful information. The beachface slope has not changed since the first
post-nourishment survey in September, 1990. The profile slope seaward of the offshore bar has
gradually reduced although it has not yet reached the equilibrium slope of the prenourished
profile. The bar which has been steadily developing during the first two years of post-nourisment
is not shown clearly in the average of profiles of November, 1993. The main reason is the
missing survey points in the breaking zone due to severe wave conditions during the
wading/swimming survey in November, 1993 and the effects of the averaging process which
smoothes bar features that are located at different seaward locations.
Average Profiles Within Nourished Area
-300 -200 -100 0 100 200
Distance from Sep.90 Waterline [m]
Figure 11: Average of profiles within nourished area. Averages based on profiles at R-45,
R-46, R-48, R-50, R-52, R-54, R-56 and R-58.
Since the previous survey in October, 1992, the cross-shore sediment transport rates
within the nourished area were reduced significantly mainly because of the reasons discussed in
section 3.3. Figure 12 shows the distribution of transport rates across the profile. The seaward
shift of the peak transport rate for the Oct.92 Nov.93 period is because of the seaward displaced
hinge point between the two profiles from which the transport was computed. Strictly
interpreted, the negative transport at the seaward end indicates a net inflow of volume to the
nourished area, possibly due to the sheltering of the offshore mound.
Cross-shore Transport Rate Within Nourished Area
0 I I
S.... Sep.90 Oct.91
0 ----Oct.91 -Oct.92
: Oct.92 Nov.93
-0
n -------
-20L
-20
0
-150 -100 -50 0 50 100 150 200 250
Distance from Sep.90 Waterline [m]
Figure 12: Cross-shore sediment transport within nourished area, based on average
profiles shown in Figure 11 from September, 1990 to November, 1993.
Outside the beach nourishment, significant shoreline recession and beach erosion were
measured in November, 1993, with the severe erosion at DNR-Monument R-30 near the western
boundary of the project where the shoreline recession measured up to 25 m. According to Figure
13, the net shoreline recession west of the nourishment reached 20 m during the four years of
monitoring. More than half of it took place during the last year. As Figure 14 points out, most of
the eroded material from the upper portions of the profile was transported across the offshore bar
and deposited over the deeper sections of the profile. Again, the missing bar in the November,
1993 profile is due to incomplete coverage of the breaking zone during the wading/swimming
.\
I I . .
survey and the smearing effects noted earlier. The positive value of the transport at the seaward
end indicates a net volumetric loss of sediment from this area.
Average Profiles West of Nourished Area
Distance from Sep.90 Waterline [m]
Figure 13: Average of profiles west of nourished area. Averages
R-30, R-32, R-34, R-36 and R-38.
based on profiles at
With the addition of the second phase of nourishment as an underwater mound of
sediment, it was expected that the littoral processes in the vicinity of the inner surfzone and the
beach face would be affected to some degree. The portion of the beach sheltered directly by the
offshore mound would obviously be affected at the highest level. Between DNR-Monuments
R-50 and R-60, where the profile nourishment was located, the shoreline recession has been
stabilized as discussed earlier and appears to have experienced a net volumetric gain. Under
these new physical constraints a secondary categorization between the two different sections of
the beach nourishment area became necessary. The portion of the nourished beach between R-50
and R-60 is called the "protected" beach nourishment since the underwater mound sheltering this
area acts like an offshore breakwater. Areas outside these ranges but still inside the beach
nourishment limits are called the "unprotected" beach nourishment. The following Figures 15
through 18 compare the evolution of these two groups of profiles.
Cross-shore Transport Rate West of Nourished Area
40 ,- -, ,\ -
30
.... ... ... ... .. ...... ......... ......
20-
10- I
...\ Sep.90 Oct.91
-10- Oct.91 Oct.92
\ Oct.92 Nov.93
-20-
I I **
-100 -50 0
50 100 150 200 250 300 350 400
Distance from Sep.90 Waterline [m]
Figure 14: Cross-shore sediment transport west of nourished area, based on average
profiles shown in Figure 13 from September, 1990 to November, 1993.
One of the more obvious differences between the two groups is the erosion of the beach
face. Along the protected profiles, the dry beach width was reduced by an average of 35 m (see
Figure 15), whereas the unprotected profiles receded 60 m since first post-nourishment survey in
September, 1990 (see Figure 17). Some of this difference (presently unknown) is due to the well
known effect of increased erosion near the ends of a beach nourishment project.
Average Profiles Within Protected Beach Nourishment
Distance from Sep.90 Waterline [m]
Figure 15: Average of profiles within protected beach nourishment. Averages based on
profiles at R-50, R-52, R-54, R-56, R-58 and R-60.
Qualitatively, both groups of profiles have experienced erosion near the break point and
deposition at the deeper portions of the sloping profile during the most recent year of monitoring.
However, from a quantitative point of view, the two groups differ substantially. The average
volumetric rates of sediment transport, based on interpretation of Figures 16 and 18 for the
period from October, 1991 to November, 1993, yield 15 m3/m/year loss in the protected area and
50 m3/m/year loss in the unprotected area. These numbers represent total losses within the active
zone, reaching approximately 100 m offshore from the September, 1990 waterline. The linear
increase in transport rates beyond the active zone may be caused by small consistent errors in the
vertical datum. In interpreting these results, it is important to note that the magnitudes of
shoreline recession and beach erosion for the unprotected portion of the beach nourishment
incorporate effects of accelerated erosion rates at the lateral boundaries of the nourishment as
predicted by the longshore diffusivity solution. Thus the relatively small erosion rates in the
protected area are not only due to the sheltering effect of the offshore mound but also because of
the central location of these profiles relative to the boundaries of the beach nourishment project.
Cross-shore Transport Rate Within Protected Beach Nourishment
> 30
3
I-
s
: 20
lO
r)
-10 I I
-200 -150 -100 -50 0 50 100 150 200 250 300
Distance from Sep.90 Waterline [m]
Figure 16: Cross-shore sediment transport within protected beach nourishment, based on
average profiles shown in Figure 15 from September, 1990 to November, 1993.
25
..... Sep.90 Oct.91
--Oct.91 Oct.92
/ Oct.92 Nov.93
I
\' :
"\ i'
/
Average Profiles Within Unprotected Beach Nourishment
-250 -200 -150 -100 -50 0 50 100 150 200 250
Distance from Sep.90 Waterline [m]
Figure 17: Average of profiles within unprotected beach nourishment. Averages based on
profiles at R-43, R-44, R-45, R-46, R-61, R-62 and R-63.
Cross-shore Transport Rate Within Unprotected Beach Nourishment
300
Figure 18: Cross-shore sediment transport within unprotected beach nourishment, based
on average profiles shown in Figure 17 from September, 1990 to November, 1993.
Perdido Key Beach Nourishment
Planform Evolution
600 ... .....
30 40 50 60
Range Number
Figure 9: Evolution of dry beach width since completion of beach nourishment.
4 DISCUSSION
Several features of the monitoring program, based on data collected during the last year
merit discussion as presented below.
4.1 Profile Equilibration and Cross-Shore Sediment Transport
With the exception noted previously, since completion of the beach nourishment project,
a consistent shoreline recession and profile equilibration have been observed. Within the beach
nourishment area the shoreline recession rate has been steadily decreasing, whereas the -4 m
contour has been monotonically moving seaward along the entire beach as shown in Figure 10.
The net result of the simultaneous recession of the upper and advancement of the lower portions
of the profile is a reduction of the initially steep slope of the nourished profiles.
4.2 Concentration of Fines
The distribution of fines, located primarily between Ranges R-42 and R-58, is shown in
Figures 19 and 20 respectively, for the various sampling events at 5 m and 8 m water depths, and
appears to be decreasing with time. The origin of these fines is the Pleistocene mud deposits that
were excavated in the dredging operation. The decrease of fines with time is to be expected due
to suspension during energetic wave events which causes suspension of the fines and distribution
over wide areas. However the interpretation of the suspension and transport of fines must be
tempered with the understanding that the distribution can be somewhat "spotty" due to
concentrating in local depressions and thus the data must be interpreted in the "aggregate" sense
rather than on the basis of individual samples.
5 m Sand Samples
Percentage Finer than 0.0097 mm
A4 f~P\
IUU
, 80
0D
i1 60
4--
| 40
a 20
0
- - -- ----- --------- -- -----------------
-- -- -- --- -- -- -- -- -- -- -- --- -- -- -- -- -- -
I i i i- -- --- - - i -- -
30 34 38 42 44 46 50 54 58 61 63 65 67
Range Number increasing towards East
I = Nov.'89 O Sep.'90 i Oct.'91 M Oct.'92 M Nov.'93
Figure 19: Percentage of fines for 5 m samples for all years of study.
8 m Sand Samples
Percentage Finer than 0.0097 mm
100
180 ------------------------ ---------------------------------
80 ------------------- ----------------------
40 g ------------------------ ---------------------------------
60..
CL 20 1- --------- -------------- -----------------------_-- _------
80
a 2 0 . . . . . . . . . ..,
30 34 38 42 44 46 50 54 58 61 63 65 67
Range Number increasing towards East
~CZ Nov.'89 = Sep.'90 IM Oct.'91 m Oct.'92 MI Nov.'93
Figure 20: Percentage of fines for 8 m samples for all years of study.
4.3 Sediment Characteristics
Sediment characteristics (Do,) are summarized in Figure 21 for the dune, mid-beach,
berm, beach face, Im, 2m, 5m and 8m samples. The solid line in each of these figures represents
the November, 1993 median diameters and the dotted lines represent the envelope of the
measured size distributions including pre-nourishment. It is seen that in general the wet samples
of 1993 had sediment sizes nearer to the lower limit of the envelope than the upper limit. An
opposite trend was observed for the landward samples collected between the dune up to the -1 m.
Here the size distributions of 1993 sediments fell between the upper and lower limits of the
envelope.
Spatial Distribution of Median Diameter
Dune Mid Beach
0.5
'T .. 0.4
0.3
0L
30 40 50 60
Range Number
Berm
.4
.2
.1
30 40 50 60
Range Number
0.
30 40 50 60
Range Number
Beach Face
40 50
Range Number
Spatial Distribution of Median Diameter
.5
1.2
1.1
0
30 40 50 60
Range Number
-5 m
1.5
1.4 ... ". *
1.2 ""
1.1
30 40 50 60
Range Number
1.4
1.3
1.2
).1
0
30 40 50 60
Range Number
-8 m
1.5
).4
1.2
1.1
30 40 50 60
Range Number
Figure 21: Longshore distribution of D50 for November, 1993 (solid line) with envelope
(dashed lines) of sizes for 1989, 1990, 1991, 1992 and 1993.
Crosshore Distribution of D50
Longshore averaged for All Years
0.5
E 0.4
E 0.4 --------- -- ---------------------
N 0.3 --- -- -- --
II)
c 0.2 -2-
E
-00.1 -1 -
c)
0 0_) ll_
dune berm -1 m -5 m
mid-beach beachface -2 m -8 m
[ Nov.'890 Sep.'90O Oct.'91 Oct.'92 Nov.'93
Figure 22: Longshore averaged cross-shore distribution of D50. Temporal variation for all
years of study.
4 REFERENCES
Otay, E.N., and Dean, R.G., 1993. "Perdido Key Beach Nourishment Project: Gulf Islands
National Seashore. 1992 Annual Report." Coastal and Oceanographic Engineering
Department, University of Florida, Gainesville, Florida. September, 1993. COEL 93/005.
Otay, E.N., and Dean, R.G., 1994. "Nearshore Surveying: Accuracy and Techniques for
Improvement." Submitted to J. Surveying Engrg., ASCE.
Work, P.A., Lin, L.-H., and Dean, R.G., 1990a. "Perdido Key Beach Nourishment Project: Gulf
Islands National Seashore. Pre- Nourishment Survey, Conducted October 28 November
1989." Coastal and Oceanographic Engineering Department, University of Florida,
Gainesville, Florida. April 30, 1990. COEL 90/006.
Work, P.A., Lin, L.-H., and Dean, R.G., 1990b. "Perdido Key Beach Nourishment Project: Gulf
Islands National Seashore. First Progress Report." Coastal and Oceanographic
Engineering Department, University of Florida, Gainesville, Florida. August 27, 1990.
COEL 90/009.
Work, P.A., Lin, L.-H., and Dean, R.G., 1991a. "Perdido Key Beach Nourishment Project: Gulf
Islands National Seashore. First Post- Nourishment Survey Conducted September
22-26, 1990." Coastal and Oceanographic Engineering Department, University of
Florida, Gainesville, Florida. January, 1991. COEL 91/003.
Work, P.A., Lin, L.-H., and Dean, R.G., 1991b. "Perdido Key Beach Nourishment Project: Gulf
Islands National Seashore. 1990 Annual Report." Coastal and Oceanographic
Engineering Department, University of Florida, Gainesville, Florida. January, 1991.
COEL 91/004.
Work, P.A., Charles, L., and Dean, R.G., 1991c. "Perdido Key Beach Historical Summary and
Interpretation of Monitoring Programs.." Coastal and Oceanographic Engineering
Department, University of Florida, Gainesville, Florida. January, 1991. COEL 91/009.
Work, P.A., and Dean, R.G., 1992a. "Perdido Key Beach Nourishment Project: Gulf Islands
National Seashore. 1991 Annual Report." Coastal and Oceanographic Engineering
Department, University of Florida, Gainesville, Florida. July, 1992. COEL 92/012.
Work, P.A., 1992b. "Sediment Transport Processes at a Nourished Beach." Ph.D. Dissertation,
Coastal and Oceanographic Engineering Department, University of Florida, Gainesville,
Florida. December, 1992. COEL TR/087.
APPENDIX I
BEACH and OFFSHORE PROFILES
Notes: 1) All elevations are in meters, relative to NGVD.
2) Horizontal origin is the survey monument, with distances toward
the Gulf of Mexico defined as positive.
3) Reported bearings are for observer standing on monument,
looking offshore along survey line.
Perdido Key: Range 30 Azimuth 170 degrees
a0
CD
-4
-6-
I.-tI
0 100
~-4-
200 300 400 500 600 700 800 900 1000
Distance from Monument [m]
Perdido Key: Range 32 Azimuth 170 degrees
8
Nov.89
C 6 Sep.90
Oct.91
Oct.92
a 4-
S- Nov.93
0
02
CD
S 0 \.
-2-
-6 -
I 1- \--------
W \\' -
I I I I I I
0 200 400 600 800 1000
Distance from Monument [m]
Perdido Key: Range 34 Azimuth 165 degrees
I I I I
6-
,- -- Nov.89
S- -- Sep.90
S- Oct.91
4 Oct.92
S1-- Nov.93
S2-
O 4,
-61
00
N" -2
I I I I I I
0 200 400 600 800 1000
Distance from Monument [m]
0 =---^--------
Perdido Key: Range 36 Azimuth 165 degrees
I I I
4-
4---- Se-
-Oct
2 -- Oct
2--1
i ^ I- NO\
Oct
a a
Sz-
o o
CD .-2
(a
-4-
-6-
-200 0 200 400 600 800
Distance from Monument [m]
Perdido Key: Range 38 Azimuth 160 degrees
I I I I II
8 4- ---- Sep.90
Oct.91
Oct.92
-4 -
S 2- Nov.93
2
z0
CD
CD,
-4-
| ----
I I I I I I I
-200 0 200 400 600 800 1000
Distance from Monument [m]
Perdido Key: Range 40 Azimuth 160 degrees
6 -
J. Nov.89
4 -- Sep.90
4-
C Oct.91
S- Oct.92
-- Nov.93
2-
oo
0-
CD
-4 -'I
-6
-200 0 200 400 600 800 1000
Distance from Monument [m]
Perdido Key: Range 42 Azimuth 160 degrees
0 200 400 600 800
Distance from Monument [m]
1000
Perdido Key: Range 43 Azimuth 160 degrees
4-
IT)
CrD
P 2-
CD.
00
0
CD 9-2
o .
-d >
-4- '
6
t. 6 o ,
0 200 400 600 800 1000
Distance from Monument [m]
Perdido Key: Range 44 Azimuth 160 degrees
I I II
M 4 -
- --- Nov.89
S- -Sep.90
Oct.91
2 O Oct.92
"' / Nov.93
0 l
E c
-4-
Cd
S 5
4- 6- \,\
8 -8
I I I I I I I
-200 0 200 400 600 800 1000
Distance from Monument [m]
Perdido Key: Range 45 Azimuth 160 degrees
I I I I I
4-
-- Nov.89
S2- ----Sep.90
-- -Oct.91
'I. Oct.92
S-- Nov.93
8 i
0
o- -
CD E- \
S I I \
-4 I
CD,
-8
-200 0 200 400 600 800 1000
Distance from Monument [m]
Perdido Key: Range 46 Azimuth 165 degrees
0 200 400 600 800 1000 1200 1400 1600
Distance from Monument [m]
-200
Perdido Key: Range 48 Azimuth 165 degrees
0 200 400 600 800 1000 1200 1400
Distance from Monument [m]
-200
1600
Perdido Key: Range 50 Azimuth 165 degrees
I I I I I I I
a6-
( Q-- Nov.89
t 4-
S- Sep.90
Oct.91
Oct.92
2 .,, Nov.93
> ,
0
n- 0
-6
-8 -
I I 1 I I I I I I
-8-
0 200 400 600 800 1000 1200 1400 1600
Distance from Monument [m]
Perdido Key: Range 52 Azimuth 165 degrees
0 200
400 600 800 1000
Distance from Monument [m]
1200 1400 1600
-200
1800
Perdido Key: Range 54 Azimuth 165 degrees
I I I I I I I I
S4 Nov.89
-t - Sep.90
-44
I', Nov.93
S 5'0==^ ---- T-----------------------Oct.91--
SI\
0
o z
0
-4 -
t~n -6 -- -. .
0 200 400 600 800 1000 1200 1400 1600
Distance from Monument [m]
Perdido Key: Range 56 Azimuth 165 degrees
I I I I I I I I
4
t' l- Nov.89
CD
-04
Ej
(I
CD
I I I I I I I I I
\ --6-
0 200 400 600 800 1000 1200 1400 1600
Distance from Monument [m]
Perdido Key: Range 58 Azimuth 165 degrees
as-
4-
- -- Nov.89
S- Sep.90
-A Oct.91
2 ct.92
S\ -- Nov.93
0 >
o z
S-2-
L
t -4-
CD
-6
I I I I I I I I I
0 200 400 600 800 1000 1200 1400 1600
Distance from Monument [m]
Perdido Key: Range 60 Azimuth 165 degrees
I I I I I I I
' -- Nov.89
S- Sep.90
2-
S2,, Oct.91
S/ Oct.92
SI Nov.93
0 V
0-
o Z
o-2-
SD- 4
I -6- .
I I I
-6-
-200 0 200 400 600 800 1000 1200 1400 1600
Distance from Monument [m]
Perdido Key: Range 61 Azimuth 165 degrees
0 200 400 600 800 1000 1200 1400
Distance from Monument [m]
0-
1 -2
Cl
LU
-200
1600
Perdido Key: Range 62 Azimuth 165 degrees
5
-. 4
0
t 3
2-
S2 1-
" I1 ^ "
-3 \\
00
o z
S4c \
00
-2-
S-3-
-4-
0 200 400 600 800 1000
Distance from Monument [m]
Perdido Key: Range 63 Azimuth 165 degrees
Cr 4-
----- Nov.89
S- Sep.90
3 - Oct.91
Oct.92
2 ll / Nov.93
I .0
2 \ '
^ (~3 -
S z I ,
Cl
0 2 4 \ 00
0 f
i i-1
-2
,D' -3
-4
-5
0 200 400 600 800 1000 1200 1400
Distance from Monument [m]
Perdido Key: Range 64 Azimuth 170 degrees
I I I I I I I I
4-
Nov.89
S--- Sep.90
Oct.91
2 Oct.92
SNov.93
1
t0 o
-
C
0o L-
CD
0 200 400 600 800 1000 1200 1400 1600
Distance from Monument [m]
Distance from Monument [m]
Perdido Key: Range 65 Azimuth 105 degrees
4-
Nov.89
2
---- Sep.90
t.. -_- Oct.91
*0
0 Oct.92
S- Nov.93
-2-
E o
Sz
) -812
-10
-12
S- -14 -S -
-16
I I I I I I
0 200 400 600 800 1000
Distance from Monument [m]
Perdido Key: Range 66 Azimuth 105 degrees
5-
---- Sep.90
_- -- Oct.91
CO
0 0. Oct.92
\-- Nov.93
>
ot -
o -. : "
-15- V ,, -
I I I I I I
0 200 400 600 800 1000
Distance from Monument [m]
Perdido Key: Range 67 Azimuth 90 degrees
0 100 200
300 400 500 600 700 800 900 1000
Distance ftom Monument [m]
APPENDIX H
WAVE, CURRENT, and TIDE DATA
from Offshore Gages
located near Ranger Station and near Caucus Shoal
January, 1993 May, 1994
Representative Wave Period
Significant Wave Height
Central Wave Direction
Spreading Parameters
Mean Current Velocity
Mean Current Direction
Tidal Stage
Notes: 1) Mean wave direction, 6, is the direction that the wave is
heading. It is measured clockwise from magnetic north.
2) Mean current direction, 0o, is the direction toward which the
current is heading. It is measured clockwise from magnetic
north.
3) Horizontal axis denotes day of month.
4) Tidal datum is mean sea level.
PERDIDO KEY: RANGER STATION
20
15
Tm 10
(SEC)
5
0
12
9
6
0
1 10 15 20 25 30
,+ .
+ + + + + +
+ + .4- + + + + + ++
4.+
+ + + + +
+ +
+ + + +
SI t + I I I I I ++ +1+1
1 5 10 15 20 25 30
S,:+ S2:O
0
o 0 2
0
0 <0 00 < 0 0 ^ <
o...-^ ... ... ,- .. ... 6
1 5 10 15 20 25 30
JAN. ,1993
Figure II-1. Representative Wave Period, Significant Wave Height, Central Direction and
Spreading Parameters, January, 1993.
II-2
"i I III IIIIIIIIII
PERDIDO KEY: RANGER STATION
1.0
0.8
Uc 0.6
(M/S)
0.4
0.2
0.0
N
8c E
(DEG)
2
TI-2DE
(M) 0
-1
-2
*++N*-H- -W-O -H- -Ht "-+- -- -* 4 -- t4-- -- --tf .FS+1-t
+
+1+1+1+1+ 1+1+ .+I-I ++I + + + + +II+I+ I+I+I+ ++ I +
1 5 10 15 20 25 30
+
+ + +
+ + +
49-4+jt- 4+4--H- -+4l-t-HH1--14+# 4- *.*.+l4-H$4**tI4 +H-H1-4- 1+H-4+4W H4t H -+H -+
+ +
++ ++ ++ + +
+ + + +
1 5 10 15 20 25 30
S I I I I I I I II I I I I I I I I I I I I
1 5 10 15 20 25 30
JAN. 1993
Figure 11-2. Magnitude and Direction of Mean Current and Tidal Stage, January, 1993.
II-3
PERDIDO KEY: RANGER STATION
20
15
TM 10
(SEC)
5
0
1
0
N
N
SE
S
w
121
91
S 6'
3'
I I I II I 20 25 28I I I I I I
1 5 10 15 20 25 28
1 5 10 15 20 25 28
1 5 10 15 20 25 28
Si:+ S2:e
0 -
o 4
0 -
o 1 5 10 15 20 25 28. .
1 5 10 15 20 25 28
FEB. ,1993
Figure 11-3. Representative Wave Period, Significant Wave Height, Central Direction and
Spreading Parameters, February, 1993.
I
Uc
(M/S)
ec
(DEG)
PERDIDO KEY: RANGER STATION
I 4L
1 5 10 15 20 25 28
+ +
+
-
+ +
+4- ++
+ + +
-+H++H-4+ -+4 +1$-4+I--H+-t+ -H+*44 4- +4H- w"+ + 4 + 4+4F++
+1
II 10 15 I 25 28
1 5 10 15 20 25 28
1 5 10 15 20 25 28
FEB. ,1993
Figure 11-4. Magnitude and Direction of Mean Current and Tidal Stage, February, 1993.
II-5
+ + +
S 1 1 ,. 1 I l + ll- I I I I i+ I I
0.2 +-+-,+ -H
I" rl l l
+ + + +
I I I+ 1 I
PERDIDO KEY: RANGER STATION
1 5 10 15 20 25 30
+ f+. + + + +
++ + + +
+ + + + +
+
+++ +
+ + + + + + +
+ +. + +"+ +
S+ + + ++ + +
+ ++ + + +
+ + ++
0++ 11 +
1 5 10 15 20 25 30
S1:+ Sz2:
0 0
0
00
o 0 0
1 5 10 15 20 25 30
MAR. 1993
Figure 11-5. Representative Wave Period, Significant Wave Height, Central Direction and
Spreading Parameters, March, 1993.
11-6
20
15
Tn 10
(SEC)
5
0
4
3
6
3
II
SiIII II I IA 1 I I 11 1 1 1 111 11 1
+- +.
+ ++ ++ + + +%. +++- ++
+ + + + + 4
++ + + +
+
4- ++
++ +
niA n I I ,I
Uc 0.6
(M/S)
0.4
0.2.
0.0
H
MAR. ,1993
Figure 11-6. Magnitude and Direction of Mean Current and Tidal Stage, March, 1993.
II-7
1.0
0.8 -
PEROIDO KEY: RANGER STATION
n n i I II IH II
15 10 15 20 25 30
+ + +++ ++ 4++ ++ + + +
to+-++ + + + + 3+
%+++ + S +'(-+,+ + +
+ t++ + +
+ + ++
1 5 10 15 20 25 30
8c
(DEG)
ii,,,,,,, ii iiii II ii ll I
PERDIDO KEY: RRNGER STATION
20
15
Tn 10
(SEC)
5
0
4
3
0I n
1
9
6
3
1 5 10 15 20 25 30
+ +4 + +
+ +
++ + + +++ +++ +
+ + +
++ + ++ + +
S4. + + 4 ++ +
SI I I I I I I I I I I I I I 1 I 1 1 11+ 1
5 10 15 20 25 30
v Nt v v v v wS v v w w w A w
SO:+ S2:o
0
0 o
0
0 +
0
APR.,1993
Figure II-7. Representative Wave Period, Significant Wave Height, Central Direction and
Spreading Parameters, April, 1993.
II-8
I SR/i tII IIIIII
II
PERDIDO KEY: RANGER STATION
1.0
0.8
Uc 0.6
(M/S)
0.11
0.2
0.0
W
N
8c E
(DEG)
S
2
1
TIDE
(M)
0
-1
-2
I I I I I I I I I I I I I I I I I I I I I I I I I I I
1 5 10 15 20 25 30
APR.,1993
Figure II-8. Magnitude and Direction of Mean Current and Tidal Stage, April, 1993.
11-9
+
-4-
+
++ +- + + -H- -0.,- ++ + ++ +.+4 '""-+1 ++
+ + ++
I i++ i i I i+ i I+. +I i I I I I I I 1+ r- i" *t i
1 5 10 15 20 25 30
+F ++ + ++ + +
+ + +
!- + + + + .+ +.+ ++ +++ + +. + *4f
+
1 5 10 15 20 25 30
PERDIDO KEY: RANGER STAT LON
20
15
Tm 10
(SEC)
5
0
3
15 10 15 20 25 30
+ + ++ + +
++ ++ +
+ +
+ + + + ++ + + + +
- + + + + +
+ + +
.i 1- I I I + + 1 1 1 I 1 +1 4
1 5 10 15 20 25 30
MHY, 1993
Figure 11-9.
Representative Wave Period, Significant Wave Height, Central Direction and
Spreading Parameters, May, 1993.
II-10
1 5 10 15 20 25 30
S
120
90
S 60
30
a Lgg o
Si:+ S2:o
4 0 0
I~h~j~o Ofq I I I a* I~hC~BJfgl J A
---~" "-~ "~"""""' LYY UI--L -II1-1-I ~_Y-~------
PERDIDO KEY: RANGER STATION
+ 4+
+ +++ +.++ .
H-cH+M++ + + rl- q '-d++++-
+ + ++ + ++ ++-b ++
,I I I,+++t+ #++4 +-H-7 + 4- +
SI++++ I I I
1 5 10 15 20 25 30
w
N++ + + + + + +++ + + + + + +
N ++- +++ + --- + +
E + + + + + +
+ + + ++ ++ + + ++ +++++ "-. ++++o+++
S
14 I I I I I I I I I I I I I I I I I I I I I I I
1 5 10 15 20 25 30
0
M 0
S-
1 5 10 15 20 25 30
MAY, 1993
Figure II-10. Magnitude and Direction of Mean Current and Tidal Stage, May, 1993.
1.0
0.8
Uc 0.6
(M/S)
O.1,
0.2
0
8c
(DEG)
II-11
PERDIDO KEY: RANGER STATION
20
15
0
3
91
6
3
1 5 10 15 20 25
1 5 10 15 20 25 30
I I
+ +
+ + +
+ +
+ +
+ +
+ ++
+
+
1 5 10 15 20 25 30
Si:+ Sa:O
0
0 -
0
0 ,,..
1 5
25
JUN. ,1993
Figure II-11. Representative Wave Period, Significant Wave Height, Central Direction and
Spreading Parameters, June, 1993.
II-12
PERDIDO KEY: RANGER STATION
1.-0
0.8
Uc 0.6
(M/S)
0.4
0.2
0.0
8c
(DEG)
1+ + ++ ++ + ++ -+
+ ++++ + ++ -+ 4-
1 5 10 15 20 25 30
.+ + ++ + + +.I+ +
+
+ + +
++ +++ ++ +-
1 5 10 15 20 25 30
JUN. ,1993
Figure 11-12. Magnitude and Direction of Mean Current and Tidal Stage, June, 1993.
II-13
I 1 1 1 1 1 1 1 1 I I I I I I I I I I I I I I I I I
20
15
TH 10
(SEC)
5
0
3
PERDIDO KEY: RANGER STATION
-+
1 10 15 20 25 30I
1 5 10 15 20 25 30
1 5 10 s15 20 25 30
I I I I I I I I I I I I i l l I l l I l l lI l l
1 5 10 15 20 25 30
SS:+ S2:*
90
60
30 -
JUL.,1993
Figure 11-13. Representative Wave Period, Significant Wave Height, Central Direction and
Spreading Parameters, July, 1993.
II-14
t .. 6i 0 *I".. .l .. I. ... W 1 W I I I I I I I I I I I I I I I I
PERDIDO KEY: RANGER STATION
1.0
0.8
Uc 0.6
(M/S)
0.4
0.2
0.0
8c
(DEG)
i iI ii, I I I I I I I I I I I I I 30
1 5 10 15 20 25 30
1 5 10 15 20 25 30
JUL..1993
Figure 11-14. Magnitude and Direction of Mean Current and Tidal Stage, July, 1993.
11-15
I I I I I I I I I I I I I I I I I I I I I I I I I I I
-SHHtSHHH+H+H+tmtt~m+m~n~ttt+n-+t~
PERDIDO KEY: RANGER STATION
20
15
Tn 10
(SEC)
5
0
4
3
1
0
w
N
E
S
120
90
S 60
30
5 10 15 20 25 30
I I aI II I I i: i I I i i rI I II.-tt- i i
1 5 10 15 20 25 30
-^
+ ++
+ + + +
++ -+
++
1 5 10 15 20 25 30
S:+ S2:o
i i i i i i i i Fr w t*. H- it -j go i i i i i i i i r N- i- #9 w I
-
-
AUG. 1993
Figure 11-15. Representative Wave Period, Significant Wave Height, Central Direction and
Spreading Parameters, August, 1993.
II-16
PEROIDO KEY: RANGER STATION
Uc 0.6
(M/S)
0.4
0.2
0.0
H
AUG. 1993
Figure 11-16. Magnitude and Direction of Mean Current and Tidal Stage, August, 1993.
II-17
1.0
0.8 F
I I I I I I I I I I I' I I I I I I I I I I I4 I .
S 5 10 15 20 25 30
-- -I-
++
++
++ +
+
+ 5
+ ++ +
+
1 5 10 15 20 25 30
I I I I I I I I I I I I I I I I I I I I I I I I i I
8c
(DEG)
+ +*+ ++ I I ++
+ ,flC IJ .1 II -I I II
PERDIDO KEY: RANGER STATION
20
15
T" 10
(SEC)
5
0
1 5 10 15 20 25 3(
1
0
H
N
SE
S
120
90
S 60
30
0
I I I I "T -- IrI'' I I i I I I I I ,
S5 10 15 20 25 30
++ + +
+ + + + .. + + + +
+ ,- + + ,+ ,++
+ ++ +
++
+ +
4
+ + ++
++ +
+ ++ 4 1 1
1 5 10 15 20 25 30
S1:+ S2:4
-O
e
1 5 10 15 20 25 30
SEP. ,1993
Figure 11-17. Representative Wave Period, Significant Wave Height, Central Direction and
Spreading Parameters, September, 1993.
II-18
ja~il' I I II
I
PERDIDO KEY: RANGER STATION
1.0
0.8
Uc 0.6
(M/S)
0.4
0.2
0.0
N
Be
(DEG)
I I I I I I I I I I I I i a 1. i i i i a i i i
1 5 10 15 20 25 30
+4 +
+
+ + + +
+
+ + + -.--H- -4--. H-+-4 -9--H-44-+ --H"- +. +
+
1 5 10 15 20 25 30
I
SEP. ,1993
Figure 11-18. Magnitude and Direction of Mean Current and Tidal Stage, September, 1993.
II-19
Siii 111111111i IJ 1.11
+
S + + + +
S-4"+ .+ 0 -. +.. .+ .+4-++ +++H-, -I
. 3 .t u--tt ^.1 l l 1 T 1
PERDIDO KEY: RANGER STATION
20
15
TN 10
(SEC)
5
0
3
1 5 10 15 20 25 30
90
S 60
30
0'
1 5 10 15 20 25 30
S1:+ S2z:
o
o'o
o o
-o
a-^2^.yt^^.<^.. +
OCT. 1993
Figure 11-19. Representative Wave Period, Significant Wave Height, Central Direction and
Spreading Parameters, October, 1993.
II-20
I II II I I I I I II I*I I I II 11111111111I t
PERDIDO KEY: RANGER STATION
0.8
Uc 0.6
(M/S)
0. -
8c
(DEG)
'++ ++++ L +
1 5 10 15 20 25 30
a +Y- ++-
+4 + + ++ + +
+ ++
S+ +
+ ++ +
+
+
++ + + + + + ++ +
+ +
I I 10 15 20 25 30
1 5 10 s15 20 25 30
OCT. ,1993
Figure 11-20. Magnitude and Direction of Mean Current and Tidal Stage, October, 1993.
II-21
I I I II I I I I I I I I I I I I I I I I I I I I I I I I I
PERDIDO KET: RANGER STATION
20
15
Tn 10
(SEC)
5
0
3
3
120
90
S 60
30
1 5 10 15 20 25 30
+ +
++
1 5 10 15 20 25 30
NOV. .1993
Figure 11-21. Representative Wave Period, Significant Wave Height, Central Direction and
Spreading Parameters, November, 1993.
11-22
I I I I I I I I I I I I I I I I I I I I I
PERDIDO KEY: RANGER STATION
1.0
0.8
Uc 0.6
(M/S)
0.4
0.2
0.0
8c
(DEG)
15 10 15 20 25 30
+h- 4. +
+ + + +
+ + + + +++ +
++
+ ++ +0. +4l + +++++ + +H+
+
1 10 20 25 30
1 5 10 15 20 25 30
NOV. ,1993
Figure 11-22. Magnitude and Direction of Mean Current and Tidal Stage, November, 1993.
II-23
I I I I, I I I I I I I I I I I I I I
PERDIDO KEY: RANGER STATION
20
15
Tm 10
(SEC)
5
0
1
0
N
E E
S
H
120
90
S 60
30
0
1 5 10 15 20 25 30
+-- ++ +-. + + -,-
+ + ++ 4 H+..
.4J- +
+
+
+
I I I I I I I I I I I I I I I I I I I I I I I I I l I I I
1 5 10 15 20 25
DEC. .1993
Figure 11-23. Representative Wave Period, Significant Wave Height, Central Direction and
Spreading Parameters, December, 1993.
11-24
I I I I I I I I I I I I I I I I I I I I I I 1
PERDIDO KEY: RANGER STATION
+
*^ ,V^+^^ ^-^.^+
-H + + +
+ ,+++.0 + .+ + ,
pF I I I I I1- I T W- 1 i i 1 i 1"-],i i I 1 I 1 U I -'l I
1 5 10 15 20 25 30
+g+ + + +
+ + +
+4 + + -+ +++ + +
+ + ++ +
+ + +
1 I5 II I 5.1 20 25 301
1 5 10 15 20 25 30
DEC. ,1993
Figure 11-24. Magnitude and Direction of Mean Current and Tidal Stage, December, 1993.
II-25
0.8 -
8c
(DEG)
L I I I I I
SI I I I I I I I I I I I I I I I I I I I I I I I I I I I I I
Uc 0.6 -
(M/S)
0.4 -
PEROIDO KEY: RANGER STATION
20
15
Tn 10
(SEC)
5
0
3
3
120
90
S 60
1 5 10 15 20 25 30
1 5 10 15 20 25 30
+ +
+
1 5 10 15 20 25 30
S,:+ S2:o
o
o o
o o o
o 0
~~F~SO ~H0
JAN.,1994
Figure II-25. Representative Wave Period, Significant Wave Height, Central Direction and
Spreading Parameters, January, 1994.
II-26
PERDIDO KEY: RANGER STATION
0.8
Uc 0.6
(M/S)
0.4i
0.2 -
8c
(DEG)
15 10 15 20 25 30
+ + + +
+ + ++ + ++
+ + + .+"* ++
+ + + +
+ +I*
+
+
I liI I" I I I III + 1+ I I I I I+ I I I+
1 5 10 15 20 25 30
JAN.,1994
Figure 11-26. Magnitude and Direction of Mean Current and Tidal Stage, January, 1994.
II-27
+
+tF ^r,+^^
. + + ++ +,+
.+ +.+1. to- t+,
Ic++4 -+
PEROIDO KEY: RANGER STATION
20
15
Tm 10
(SEC)
5
0
1
0
W
N
9 E
S
W
120
90
S 60
30
S10 15 20 25 28
1 5 10 15 20 25 28
+ + + +p g +H 4 4++
1 + ++++ +N" + + 4++-+ +
++
-"I
25 2
15 10 15 20 25 28
FEB. .1994
Figure II-27. Representative Wave Period, Significant Wave Height, Central Direction and
Spreading Parameters, February, 1994.
II-28
I
25 28
PERDIDO KEY: RANGER STATION
0.81-
Uc 0.6
(M/S)
0.2 -
8c
(DEG)
H-
+ +
iH i+A~
++41a.L 4+ _++F + 4+
4.4+4j, 44 -+
1 4 1 +
1 5 10 15 20 25 28
+++ '+ + + + +
++ + + + + +
S + ++ + + + + + +
+ ++ ++
+ + +
+ +
1 5+ + + + 4-4-
+4-
1 I I I I I II I I I s 20 25 28II
1 5 10 15 20 25 28
1 5 10 15 20 25 28
+ +
FEB.,1994
Figure 1-28. Magnitude and Direction of Mean Current and Tidal Stage, February, 1994.
II-29
PERDIDO KEY: RANGER STATION
20
15
Tn 10
(SEC)
5
0
H
N
SE
S
H
120
90
S 60
30
0
1 5 10 15 20 25 30
1 5 10 15 20 25 30
1 5 10
MAR. ,1994
Figure 11-29. Representative Wave Period, Significant Wave Height, Central Direction and
Spreading Parameters, March, 1994.
11-30
PEODIDO KEY: RANGER STATION
1..0
0.8
Uc 0.6
(M/5)
0.4
0.2
0.0
N
+++
4."e
+
c++
l iI I I I rI I I I I 5ii I I3 II 14. Ii
1 5 10 15 20 25 30
MRR. .1994
Figure 11-30. Magnitude and Direction of Mean Current and Tidal Stage, March, 1994.
II-31
+ + 04. + + 4-+ -
1 5 10 15 20 25 30
-4- -I
8c
(DEG)
*4- +
S+ + + +
+ + + ++ +++ ++
+ +.- + +
I1 1 1 1 1 1 1 1 III II III I II III III II
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