Citation
Third Progress report

Material Information

Title:
Third Progress report
Series Title:
Progress report -- Tidal inlet management at Jupiter Inlet
Alternate Title:
UFL/COEL (University of Florida. Coastal and Oceanographic Engineering Laboratory) ; 91/002
Creator:
Mehta
Publisher:
Coastal and Oceanographic Engineering Department, Univeristy of Florida
Publication Date:

Subjects

Subjects / Keywords:
Jupiter Inlet (Fla) ( LCSH )
Tidal inlets -- Florida
Genre:
serial ( sobekcm )
Spatial Coverage:
North America -- United States of America -- Florida -- Jupiter Inlet

Notes

Funding:
This publication is being made available as part of the report series written by the faculty, staff, and students of the Coastal and Oceanographic Program of the Department of Civil and Coastal Engineering.

Record Information

Source Institution:
University of Florida
Holding Location:
University of Florida
Rights Management:
All rights reserved, Board of Trustees of the University of Florida

Full Text
UFL/COEL-91/002

TIDAL INLET MANAGEMENT AT JUPITER INLET: THIRD PROGRESS REPORT
by
A. J. Mehta C. L. Montague R. J. Thieke L.-H. Lin and
E. J. Hayter
January 1991
Sponsor: Jupiter Inlet District 400 North Delaware Boulevard Jupiter, FL 33458




REPORT DOCUMENTATION PAGE
reportt No. .3. Recipients Accession No.
4.Title end Subtitle 5. Report Date
TIDAL INLET MANAGEMENT AT JUPITER INLET: January 1991
THIRD PROGRESS REPORT 6.
7. Author(s) A. J. Mehta L.-H. Lin A. fois Or ztioO Rport No.
C. L. Montague and UFL/COEL-91/002
R. J. Thieke E.J. Hayter
9. Perforuing Organization Nu e and-Address 10. ProJec/Taak/Work Unit No.
Coastal and Oceanographic Engineering Department
University of Florida 11. Contract or Grant go.
336 Weil Hall C89-002
Gainesville, FL 32611 13. Type of Report
12. Sponsoring organizations Nam and Address
Jupiter Inlet District Commission Third Progress Report
400 North Delaware Boulevard
Jupiter, FL 33458
15. Supplementary Notes
16. Abstract
This third progress report summarizes progress in the ongoing Jupiter Inlet
management study, particularly covering the three month period 10/6/90 through 1/5/91. However, the findings reported in the second progress report form an
integral part of this report.
Here we report several "firsts" as far as studies on coastal processes
relevant to Jupiter Inlet are concerned. For the first time a data base on the wave climate off Jupiter Inlet is beginning to develop as data are retrieved from the directional wave gage. Commensurate with these data and 20 year wave hindcast information from the Corps of Engineers' Wave Information Study, we have developed preliminary statistics for the distribution of littoral drift rates in
the study area.
Based on a recently conducted field study we show conclusively that sand
in transported around the south jetty of the inlet even when the waves are from the northeast. This observation is in agreement with the model prediction of eddy circulations that are generated next to the downdrift beach south of the south jetty. We have briefly referred to these model predictions in the second progress report. For the first time we also report here field measurements of flood and ebb flow currents near the inlet which indicate eddy currents that can transport sand towards the inlet around the south jetty even during ebb flows. The measured
17. Orlginator's:Key Uords 18. Availability Statemf t
Hydrodynamics Jupiter Inletl Littoral drift
Loxahatchee River
Salinity intrusion
19. U. S. Security Classif. of the Report 20. U. S. Security Classif. of This Page 21 No. of Pages 22. price
Unclassified Unclassified 132

1 1




flow patterns near the inlet indicate significant disparities between flood and ebb flows, pointing to mechanisms which result in the exchange of water masses between the Loxahatchee River and the shallow open sea near the inlet. These flow patterns as well govern the modes of sand transfer around the inlet and the influx of sand into the interior traps and shoals.
Issues related to the potential mining of the ebb shoal have led us to develop a new protocol for tests to be carried out in the physical model which has been constructed to study the offshore issues including possible modifications to the inlet mouth as well as shallow dredged channels for offshore navigation. A similar, parallel test protocol has been developed for the mathematical modeling of the offshore area.
We report preliminary results from mathematical modeling of flows and salinity distributions in the Loxahatchee River. These simulations will be used to determine the transport and settling of sand within the inlet, trap efficiencies, and to calculate the amount of sand that is transported westward of the railroad bridge. In the second progress report we reported sedimentological parameters for the bottom of the estuary, and noted that the sedimentological study suggested that the flood shoal has continued to grow over the years. Additional evidence reported here confirms this trend, although further indicates that within the past decade the flood shoal growth has apparently slowed down.
Inlet engineering considerations are identified for protecting or enhancing critical marine habitats in the vicinity of Jupiter Inlet east of the railroad bridge. These habitats include nearshore rocky outcroppings, sea turtle nesting beaches, seagrasses, and mangroves. The occurrence of seagrasses and mangroves is documented in this study. In addition, the aforementioned salinity model will help predict the impact of inlet management alternatives on freshwater wetlands from salt transport up the northwest fork of the Loxahatchee River.
The main inlet engineering consideration for rocky outcroppings is protection of those rocks with well-developed biological communities. Few such rocks are within the zone of inlet influence, however, besides those actually used in jetty construction. For sea turtle nesting the goal is to maintain throughout the nesting season, a wide, gently sloping beach without steep scarps or berms. The sand should be of similar texture and compaction as that occurring naturally on beaches in the vicinity. The main considerations for mangroves east of the railroad bridge are water level, tidal range, and intertidal topographic slope. Mangroves occupy low wave-energy, sedimentary intertidal zones where winter temperatures remain above freezing. Gentle slopes and higher tidal ranges increase the extent of the intertidal zone and therefore the area suitable for mangrove growth. Rises in mean water level will shift the position of the intertidal zone landward, falls will shift it toward the center of channels. Since slopes may increase toward channels, falls in water level can result in smaller intertidal zones. Engineering considerations for seagrasses east of the railroad bridge include water level, tidal range, subtidal bathymetric slope, and water clarity. Patterns of water circulation between clear ocean water and turbid land runoff are important determinants of water clarity. Seagrasses east of the railroad bridge occur between the limits of exposure to air on the shallow side of seagrass beds and lack of light on the deep side. The bathymetric slope between these extremes is the major determinant of the size of the bed. Gentle slopes and continually high water clarity would likely result in extensive coverage of subtidal areas by seagrasses.




UFL/COEL-91/002

TIDAL INLET MANAGEMENT AT JUPITER INLET:
THIRD PROGRESS REPORT
by
A.J. Mehta
C.L. Montague
R.J. Thieke
L.-H. Lin and

E.J. Hayter
Sponsor:
Jupiter Inlet District
400 North Delaware Boulevard
Jupiter, FL 33458

January, 1991




TABLE OF CONTENTS

LIST OF FIGURES ........ ..................

LIST OF TABLES

10

I. INTRODUCTION ........ ..................
II. WAVE INFORMATION ...............
2.1 Instrument Deployment ..........
2.2 Data Analysis ..............
2.3 Results . . . . . . .
III. SAND TRANSPORT NEAR INLET MOUTH .......
3.1. Field Measurements: Sand Tracer Studies
3.2. Modeling of Longshore Transport .......
3.2.1. Transport Modeling Techniques .
3.2.2. WIS Wave Hindcast Model .....
3.2.3. Predicted Longshore Transport and
Statistics . .... ........
3.2.4. Shoreline Evolution ......

. .. 33
. .. 33
. .. 35
. .. 35
. .. 37
. .. 38
. .. 53

IV. INLET NEARFIELD STUDY AND MATHEMATICAL MODELING .
4.1 Nearfield Study ..............
4.1.1 Introduction ......
4.1.2 Drogue Test Technique ............
4.1.3 Description of Field Framework . .
4.1.4 Results ...... ................
4.2 Mathematical Study ..... ..............

V. PHYSICAL MODELING OF INLET NEARFIELD . .

. . . .. 71

5.1 Introduction ... .............
5.2 Model Limits .... ............
5.3 Model Scales .... ............
5.4 Waves and Currents ............
5.5 Extreme High Water Levels ... 5.6 Model Construction ... ........
5.7 Model Calibration and Measurements 5.8 Objectives of Measurements ... 5.9 Proposals to be Tested ........

VI. MATHEMATICAL MODELING OF INLET INTERIOR .
6.1 Physical Input Requirements ...
6.1.1 Bathymetry .........
6.1.2 Tides and Currents .....
6.1.3 Salinity ..........
6.1.4 Sedimentation ... ........




6.2 Hydrodynamic Modeling of Loxahatchee River
Estuary . . . . . . . . .
6.2.1 Introduction
6.2.2 Model Description .... ............
6.2.3 Model Application .... ............
6.2.4 Model Results ..... ..............

VII. ENVIRONMENTAL CONSIDERATIONS FOR INLET DESIGN ...
7.1 Offshore Rocky Outcroppings ...........
7.2 Sea Turtle Nesting .......... ...........
7.3 Estuarine Intertidal and Submersed Vegetation .
7.3.1 Mangroves in the Study Area ............
7.3.2 Engineering Considerations for Mangroves
7.3.3 Seagrasses in the Study Area . . ...
7.3.4 Engineering Considerations for Seagrasses .
7.4 Salinity Intrusion ....... .................
VIII. REFERENCES .....................

88 88 89 93

. 95

112
112 113 115 115
117 118 118 121
125




LIST OF FIGURES

FIGURE PAGE
1.1 Technical issues, physical impact studies and ecological
impact studies for Jupiter Inlet management plan . . 14
2.1 Jupiter wave data for March, 1990: (a) Modal period, TM;
(b) Significant wave height, H113; (c) Wave direction; (d) Wave spreading parameters Si and S2 ; (e) Current
velocity, UC; (f) Current direction, 6c and (g) Tide .18
2.2 Jupiter wave data for April, 1990: (a) Modal period, Tm;
(b) Significant wave height, H113; (c) Wave direction; (d) Wave spreading parameters Y.1 and S2 ; (e) Current
velocity, UC; (f) Current direction, 0c; and (g) Tide .20
2.3 Jupiter wave data for May, 1990: (a) Modal period, TMI
(b) Significant wave height, H113; (c) Tide. ........22
2.4 Jupiter wave data for June, 1990: (a) Modal period, Tmi
(b) Significant wave height, H113; (c) Tide. ........23
2.5 Jupiter wave data for July, 1990: (a) Modal period, TMin
(b) Significant wave height, H1,3; (c) Tide. ........24
2.6 Jupiter wave data for August, 1990: (a) Modal period, TM;
(b) Significant wave height, H113; (c) Wave direction;
(d) Wave spreading parameters Y1 and S2 ; (e) Current
velocity, UC; (f) Current direction, 0c and (g) Tide .25
2.7 Jupiter wave data for September, 1990: (a) Modal period,
T im; (b) Significant wave height, H1/3; (c) Wave
direction; (d) Wave spreading parameters S1 and S,; (e) Current velocity, UC; (f) Current direction, 6c;
and (g) Tide .......................27
2.8 Jupiter wave data for October, 1990: (a) Modal period, TM;
(b) Significant wave height, H113; Cc) Wave direction;
(d) Wave spreading parameters Y1 and S2' ; e) Current
velocity, UC; (f) Current direction, Od and (g) Tide .29
2.9 Jupiter wave data for November, 1990: (a) Modal period,
T M; Cb) Significant wave height, H1/3; (c) Wave
direction; (d) Wave spreading parameters S1 and S~ ; (e) Current velocity, Ud; (f) Current direction, 6cl
and (g) Tide .......................31
3.1 Approximate sample locations with number of colored
grains recovered and d50, December, 1990 ..........54




3.2 March-April, 1990 wave roses for station at Jupiter.
Note that H refers to significant wave height.
Percents refer to frequency (%) of waves from a
given direction.....................55
3.3 August-September, 1990 wave roses for station at
Jupiter..........................55
3.4 October-November, 1990 wave roses for station at
Jupiter..........................55
3.5 Cumulative longshore transport at Jupiter Inlet
calculated from WIS hindcast data for year 1967
(Increasing volume implies southward transport) . . 56
3.6 Log-normal probability plot of annual longshore
transport magnitudes (southward and northward) from
WIS hindcasts for the period 1956-1975. .........57
3.7 Beach south of Jupiter Inlet on April 18, 1990, a
month before beach fill..................58
3.8 Beach south of Jupiter Inlet on June 1, 1990, soon
after beach fill .....................58
3.9 Beach south of Jupiter Inlet on December 5, 1990, six
months after beach fill..................59
4.1 Ebb flow velocity vectors at Jupiter Inlet measured
on August 15, 1990 ....................65
4.2 Details of ebb flow corresponding to Fig. 4.1 .......66
4.3 Flood flow velocity vectors at Jupiter Inlet measured
on August 14, 1990 ....................67
4.4 Details of flood flow corresponding to Fig. 4.3 . . 68
4.5 Slack tide velocity vectors of f Jupiter Inlet measured
on August 14, 1990 ....................69
4.6 Offshore bathymetry showing the proposed sand borrow
area to be investigated in the mathematical model . 70
5.1(a) :Jupiter model layout and locations of observation
points .. .. .. .. ... ... .. ... ....78
5.1(b) Photograph showing the physical model of Jupiter
Inlet.........................79
5.2 Deep water wave directions in Jupiter Inlet area
(CERC data) .. .. .. .. .. ... ... ... .. ..80




5.3 Schematic drawings showing the proposed experimental
conditions.........................81
5.4 Proposed dredging of borrow area and two options of
navigation channel . .. .. .. .. .. ... .....83
6.1 High and low slack water salinity distributions in the
Loxahatchee River estuary on February 26 and 27, 1975
(Chiu, 1975). Station numbers refer to Fig. 4.11 in
Mehta et al., 1990a....................97
6.2 Comparison of Flood shoals in the interior (-2 ft
contour): U.S.G.S., 1980-81 and Law Environmental
Inc., 1990.........................98
6.3 Flood shoal area variation with year based on
sketches provided by U.S.G.S., 1980-81. .........99
6.4. Extent (length) of flood shoal penetration relative
to the Florida East Coast Railroad bridge as a
function of year......................10
6.5 Loxahatchee River estuary showing model boundaries . 101
6.6 Finite element grid of the Loxahatchee river estuary 102
6.7 Recorded water surface elevations at indicated
stations on February 25, 1975 ..............103
6.8 Comparison of predicted and measured velocities at
Station C-i.......................104
6.9 Comparison of predicted and measured velocities at
Station C-4.......................105
6.10 Comparison of predicted and measured velocities at
Station C-5.......................106
6.11 Comparison of predicted and measured velocities at
Station C-6.......................107
6.12 Velocity vector plot of predicted ebb flow field at
11 AM on February 25, 1975. .............. 108
6.13 Velocity vector plot (scale not included) of
simulated flood flow field at 3 PM on February 25,
1975.............................10
6.14 Velocity vector plot of tidally-averaged flow field
on February 25, 1975....................110




6.15 Comparison of simulated and measured salinity
distribution at low water slack in the Loxahatchee
Riverestuary ........ ..................... .ii
7.1 Submerged rocky outcroppings in the vicinity of
Jupiter Inlet (adapted from Continental Shelf
Associates (1987, 1989a, 1989b) .... ............ 122
7.2 Location of quadrats for measurement of mangrove
characteristics in the Loxahatchee River estuary,
east of the railroad bridge ..... .............. 123
7.3 Location of major seagrass beds and core samples
removed for biomass measurement in the Loxahatchee
River estuary, east of the railroad bridge .. ....... ..124




LIST OF TABLES
TABLE PAGE
3.1 January distribution of wave heights H and wave angles
o (in percent) at 10-meter contour from WIS hindcast
for period 1956-1975 39
3.2 February distribution of wave heights H and wave angles
o (in percent) at 10-meter contour from WIS hindcast
for period 1956-1975 40
3.3 March distribution of wave heights H and wave angles
o (in percent) at 10-meter contour from WIS hindcast
for period 1956-1975 41
3.4 April distribution of wave heights H and wave angles
0 (in percent) at 10-meter contour from WIS hindcast
for period 1956-1975 42
3.5 May distribution of wave heights H and wave angles
0 (in percent) at 10-meter contour from WIS hindcast
for period 1956-1975 43
3.6 June distribution of wave heights H and wave angles
0 (in percent) at 10-meter contour from WIS hindcast
for period 1956-1975 44
3.7 July distribution of wave heights H and wave angles
0 (in percent) at 10-meter contour from WIS hindcast
for period 1956-1975 45
3.8 August distribution of wave heights H and wave angles
0 (in percent) at 10-meter contour from WIS hindcast
for period 1956-1975 46
3.9 September distribution of wave heights H and wave
angles 0 (in percent) at 10-meter contour from WIS
hindcast for period 1956-1975 . . . . . . 47
3.10 October distribution of wave heights H and wave angles
0 (in percent) at 10-meter contour from WIS hindcast
for period 1956-1975 48
3.11 November distribution of wave heights H and wave
angles 0 (in percent) at 10-meter contour from WIS
hindcast for period 1956-1975 . . . . . . 49
3.12 December distribution of wave heights H and wave
angles 0 (in percent) at 10-meter contour from WIS
hindcast for period 1956-1975 . . . . . . 50




3.13 Longshore transport values Q and distribution for
20 year period 1956-1975 as calculated from WIS
wave hindcast data.6.1 JID and Army Corps dredging
records for Jupiter Inlet ..... ............... 51
6.1 JID and Army Corps dredging records for Jupiter
Inlet .......... ......................... 86
7.1 Characteristics of mangroves in the Loxahatchee
River estuary, Florida, east of the railroad bridge
and US Highway 1. Top line: main study area.
Bottom line: north of Highway 707 bridge to Jupiter
Island ......... ..................... . . 116




TIDAL INLET MANAGEMENT AT JUPITER INLET: THIRD PROGRESS REPORT by
A.J. Mehta, C.L. Montague, R.J. Thieke, L.-H. Lin and E.J. Hayter
SUMMARY
This third progress report summarizes progress in the ongoing
Jupiter Inlet management study, particularly covering the three month period 10/6/90 through 1/5/91. However, the findings reported in the second progress report form an integral part of this report.
Here we report several "firsts" as far as studies on coastal processes relevant to Jupiter Inlet are concerned. For the first
time a data base on the wave climate off Jupiter Inlet is beginning to develop as data are retrieved from the directional wave gage.
Commensurate with these data and 20 year wave hindcast information from the Corps of Engineers' Wave Information Study, we have developed preliminary statistics for the distribution of littoral drift rates in the study area.
Based on a recently conducted field study we show conclusively that sand in transported around the south jetty of the inlet even
when the waves are from the northeast. This observation is in agreement with the model prediction of eddy circulations that are generated next to the downdrift beach south of the south jetty. We
have briefly referred to these model predictions in the second progress report. For the first time we also report here field measurements of flood and ebb flow currents near the inlet which indicate eddy currents that can transport sand towards the inlet
around the south jetty even during ebb flows. The measured flow patterns near the inlet indicate significant disparities between
flood and ebb flows, pointing to mechanisms which result in the exchange of water masses between the Loxahatchee River and the shallow open sea near the inlet. These flow patterns as well govern the modes of sand transfer around the inlet and the influx of sand into the interior traps and shoals.
Issues related to the potential mining of the ebb shoal have
led us to develop a new protocol f or tests to be carried out in the physical model which has been constructed to study the offshore




issues including possible modifications to the inlet mouth as well
as shallow dredged channels for offshore navigation. A similar, parallel test protocol has been developed for the mathematical modeling of the offshore area.
We report preliminary results from mathematical modeling of flows and salinity distributions in the Loxahatchee River. These
simulations will be used to determine the transport and settling of sand within the inlet, trap efficiencies, and to calculate the amount of sand that is transported westward of the railroad bridge. In the second progress report we reported sedimentological
parameters for the bottom of the estuary, and noted that the sedimentological study suggested that the flood shoal has continued to grow over the years. Additional evidence reported here confirms this trend, although further indicates that within the past decade the flood shoal growth has apparently slowed down.
Inlet engineering considerations are identified for protecting or enhancing critical marine habitats in the vicinity of Jupiter Inlet east of the railroad bridge. These habitats include
nearshore rocky outcroppings, sea turtle nesting beaches, seagrasses, and mangroves. The occurrence of seagrasses and
mangroves is documented in this study. In addition, the
aforementioned salinity model will help predict the impact of inlet management alternatives on freshwater wetlands from salt transport up the northwest fork of the Loxahatchee River.
The main inlet engineering consideration for rocky outcroppings is protection of those rocks with well-developed biological communities. Few such rocks are within the zone of inlet influence, however, besides those actually used in jetty construction. For sea turtle nesting the goal is to maintain throughout the nesting season, a wide, gently sloping beach without steep scarps or berms. The sand should be of similar texture and
compaction cis that occurring naturally on beaches in the vicinity. The main considerations for mangroves east of the railroad bridge
are water level, tidal range, and intertidal topographic slope. Mangroves occupy low wave-energy, sedimentary intertidal zones where winter temperatures remain above freezing. Gentle slopes and




higher tidal ranges increase the extent of the intertidal zone and therefore the area suitable for mangrove growth. Rises in mean water level will shift the position of the intertidal zone landward, falls will shift it toward the center of channels. Since slopes may increase toward channels, falls in water level can result in smaller intertidal zones. Engineering considerations for seagrasses east of the railroad bridge include water level, tidal range, subtidal bathymetric slope, and water clarity. Patterns of water circulation between clear ocean water and turbid land runoff are important determinants of water clarity. Seagrasses east of the railroad bridge occur between the limits of exposure to air on the shallow side of seagrass beds and lack of light on the deep side. The bathymetric slope between these extremes is the major determinant of the size of the bed. Gentle slopes and continually high water clarity would likely result in extensive coverage of subtidal areas by seagrasses.




I. INTRODUCTION
This report summarizes progress in the ongoing study on the management of Jupiter Inlet, particularly covering the three month period 10/6/90 through 1/5/91. However, considering the extensive prior coverage to the study given in the first two progress reports (Mehta et al., 1990a,b), all the material included here in must be viewed in conjunction with the two previous reports, especially the second.
Recognizing the importance of the technical issues in the overall study plan summarized in Fig. 2 from the second progress report (Mehta et al.,1990b), that plan is reproduced here as Fig. 1.1. Section 2 provides collected offshore wave information, which is crucial to the technical issues related to downdrift erosion, navigational safety and ebb shoal mining. Section 3 deals with the understanding of sand movement adjacent to the inlet mouth and development of littoral drift statistics. These are of particular interest to the problem of downdrift erosion and interior sedimentation, especially for the operation of the sand trap sand transfer. Section 4 pertains to the measurement and mathematical modeling of currents in the inlet nearfield, as related to the problem of downdrift erosion and ebb shoal mining. Section 5 deals with the physical modeling of the nearfield for the same two technical issues. Section 6 describes mathematical modeling of the inlet interior, which is essential for examining sedimentation problems within the inlet. Finally, Section 7 addresses ecological issues and impacts associated with the four principal technical issues noted in Fig. 1.1.




Downdrift Navigational Interior Ebb Shoal
Technical Beach Safet Sedimentation Dredging
Issues Erosion (Marinas, Traps, Impact on
Flood Shoal) Beach
Navigational Inlet Design Dredging Aids Alternatives Schedule
Physical
Impacts
Salinity Turbidity Tidal Range Upstream
Fj Fluctuations in Interior and Mean I Salt Transport
* Nest Washout Exterior
* Sand Compaction Turbidity
* Nest Burial Sand Transport
* Beach Avoidance and Deposition by Turtles of Dredged
Ecological Turtle
Impacts Entrainment
Impactsin Dredge
Submerged Intertidal Fresh Water Sea Turtle Nearshore Rocky
Vegetation Vegetation Habitat and Nesting and Outcropping
Drinking Water Dredging (Burial and Production
Mortality of Attached Ecosystem)
Fig. 1.1. Technical issues, physical impact studies and ecological impact studies for
Jupiter Inlet management plan.




II. WAVE INFORMATION

2.1 Instrument Deployment
On March 7, 1990, a directional wave gage was installed at an offshore location, at a depth of approximately 8 meters below mean
sea level. Its coordinates are at 260 561 5511 N, 800 31 4911 W. The wave gage contains a pressure sensor and an electromagnetic current meter. These devices are used to measure the wave height, wave direction, and water surface level changes (tide) at the gage location. The gage is entirely self-contained and is bolted to a steel tripod anchored to the sea floor. The gage has sufficient data storage and battery power to be left in place for periods up to 3 months without servicing.
Wave, current and tide data have been recorded by gage from the date of installation (March 7, 1990) to the present, although
data since November 7, 1990 have not yet been retrieved form the in situ data storage system. Data were not collected from July 15 to
August 7 as during this period the gage unit had to be retrieved for service due to malfunction. On August, a new gage was installed. As a result of the malfunction, current data were not collected between April 17 to July 14.
2.2 Data Analysis
Wave data are recorded every six hours, at which time 17minute records of the water pressure and the two horizontal components of velocity are stored using a sampling rate of 1 Hz, resulting in a time series of 1024 data points. The pressure time series is used to determine the wave energy spectrum, from which the significant wave height and modal wave period (defined as the
period corresponding to the peak of the energy spectrum) are obtained.
The two horizontal components of flow velocity recorded by the current meter are used to detect the presence of any mean current as well as to determine the dominant wave direction and the wave energy spreading parameter. The determination of the wave
direction makes use of the fact that the orbits of the water




particles under a wave are aligned with the direction of wave travel. The dominant wave direction is the primary direction of the waves at the frequency corresponding to the peak of the energy spectrum (and hence the modal period).
The wave energy spreading parameter is contingent upon the directional distribution of the waves. It occurs as the power of a cosine-square function, and describes the directional distribution of the wave energy spectrum (Longuet-Higgins et al. 1963). A unidirectional sea wave condition will have large values
for the spreading parameter while a very confused sea will have low values for this parameter. Two types of spreading parameters can
be obtained. The first type, denoted as S,, is obtained from current and wave data. The second, denoted as S21 is obtained solely from current data. If the directional distribution of the
actual sea waves is truly identical to the cosine-square power function, then S1 =S2' In general, S2 is greater than S,.
2.3 Results
The basic statistics of wave, current and tide measurements from the offshore gage location are summarized in Figures 2.1 to 2.9. The wave statistics include time series of significant wave
height, H1,31 modal period, T., wave direction, and spreading parameters, S and S2 The basic current and tide statistics include time series of current strength, U., and current direction, and the changes of water surface elevation (tide) at the gage location. It is seen that storm waves coming from east-northeast
were frequent and large during the period of data collection except those at the summer season (June, July and August). Waves
generally approaching the shore with wide directional spreading of energy are evident from the observed large spreading parameters. However, large waves are seen to be more unidirectional as they approach the shore.
The measured current information indicates that current strength is overall large, on order of 0.2 to 0.8 m/sec, except in summer. However, current direction measurements at the location indicate that the current were southbound in March and April but




more northbound in August, September and October. This could be
the result of the influence of large scale oceanic circulation pattern near Jupiter Inlet.




_ 20
0
0
S15
1 IL

1 5 10 15 20 25 30

1 5 10 15 20 25 30
March, 1990
(c)
+ +
Ii I i i I I I 11.1.1 I1 11 w -d44 1 1 1

1 5 10 15 20 25 30

120
(n
z 60
c30
0

I
Fig. 2.1. Jupiter wave data for March, 1990: (a) Modal period, Tm;
(b) Significant wave height, H 3; (c) Wave direction; (d) Wave spreading parameters S1 and S2 ; (e) Current
velocity, Uc; (f) Current direction, Oc; and (g) Tide.

S,:+ S2:*

March, 1990
(d)

0 +
Ilk ++
+*~0 +*+
$F ~ 0 ++ ++ +o ++ f i III 11 ,0*S-t OvI+ I I+ t I I% f

I I




1. O
0.8

0.6 0.4

E 0.2
0.0
_ w
0
ON
0
ZE Os
w

If I
March, 1990
- (e) +

+ +
+ +
+

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 I f I I
1 5 10 15 20 25 30

I I I I I I i S 5 10 s15 20 25 30
March, 1990
(g)
- (9)I
I J I I I I I I

Fig. 2.1. Continued.

+ + + +-+
+

+
+

+
March, 1990
(f)
++ +
+ 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

,




20
0
e April, 1990
is (a)
E
o

10
0
0
0 I I 51 I I 110 I 1 I 1 I I I I I t I
1 5 10 15 20 25 30
4
April, 1990
(b)
1 5 10 15 20 25 30
S+S
z
b April, 1990
IE (C)
U r=
+ ++
-H-4 ++ -H- -Hf1R W I 10 *I I+l+l1II I I I [ i llI
1 5 10 15 20 25 30
120
cg 90 w April, 1990
a6 .(d)
Z0 +
0!I I I I I I I 0 I II
0 ~ ~ ~ + 1++ 1 iii
1 5 10 15 20 25 30
Fig. 2.2. Jupiter wave data for April, 1990: (a) Modal period, TIm;
(b) Significant wave height, H 13; (c) Wave direction; (d) Wave spreading parameters S' and S2 ; (e) Current
velocity, Uc; (f) Current direction, Oc; and (g) Tide.




1.0 o0.8
E
00.6 I-
Z 0.4 LLI
n0.2
0.0
0
U
0
O, N oN
0 ZE
0
Os
2
2

Fig. 2.2. Continued.

tI
April, 1990
(e)
S++ + ++
++ + +
+
+ 4I I I 1 I 1 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
April, 1990
(f)
+
+ +
1 5 10 15 20 25 30
April, 1990
(g)
1 1I 1 1 1 1 1 1 1 I1 11fI I1 11II I1 I I I I I I1




__ 20
0
0) May, 1990
U)(a)
15
E
d 10
0
1= 5
1 5 10 15 20 25 30
4
May, 1990
(b)
E
I"
0
1 5 10 15 20 25 30
2
W0
1 5 10 15 20 25 30
Fig. 2.3. Jupiter wave data for May, 1990: (a) Modal period, Tm,
(b) Significant wave height, H1,3; (c) Tide.




20
June, 1990
s (a)
10
t5
15 10 15 20 25 30
June, 1990
3 (b)
2
0

0 1 1 1I I i l l I IIIII I
1 5 10 15 20 25 30
2
June, 1990
1 -(c)
0
-1
- 2 f I I I I I I I I I I I I I 1 1 1 1 1 1 t I I I I
5 10 15 20 25 30
2
Fig. 2.4. Jupiter wave data for June, 1990: (a) Modal period, Tm,
(b) Significant wave height, H 13; (c) Tide.




__ 20
U) 1
E
d 10
0 =- 5 LU
Cw

1 5 10 15 20 25 30

July, 1990,
(b)
5 10 15 20 25 30
July, 1990
(C)

Fig. 2.5. Jupiter wave data for July, 1990: (a) Modal period, TmI
(b) Significant wave height, H 13; (c) Tide.




S20
0 C)
a
15
E
-*
6 10
O
0
3
2
0
W

1 5 10 15 20 25 30
August,1990 SJ+,S2,

Fig. 2.6.

Jupiter wave data for August, 1990: (a) Modal period, Tm;
(b) Significant wave height, HV3; (c) Wave direction; (d) Wave spreading parameters S, and S2 ; (e) Current velocity, Uc; (f) Current direction, Oc; and (g) Tide.

1 5 10 15 20 25 30
August, 1990
(b)
1 5 10 15 20 25 30

H
120 CO go
0 Z 60
0

August, 1990
(c)
+
, ,. 4 A I 4__ _A __

August, 1990
(d)

00 00 +
+ ( + 4 4 < P ++ to
I I "I t + I++ I

-- v

S:+ S2:>




August, 1990
- (e)
I I I I 1
-wIIt +

1 5 10 15 20 25 30

I I t I I I I I I I I I I I I I I I I I I I I I
5 10 15 20 25 30
August, 1990
(g)
I I I I I I I I I f I I 1 I I I I I I I I I 1

Fig. 2.6. Continued.

1.0 0.8
0.6
0.4 0.2

L1. O0
N
0.
O
0
2E
0
a
2

August, 1990
(y)

+ -*+(+.++ ++ ++
+ 0 + +




1 5 10 15 20 25 30
Sept., 1990
(c)
I I I I I I I+m-i I --t 1 I 1 1 I =[

Fig. 2.7.

1 5 10 15 20 25 30
Jupiter wave data for September, 1990: (a) Modal period,
Tmn; (b) Significant wave height, H1.3; (c) Wave direction;
(d) Wave spreading parameters SI and S2 ; (e) Current velocity, UC; (f) Current direction, 8c; and (g) Tide.

Sept., 1990
(a)

20
(
*10
0
0
CC s
. 0
14
3
E
- 2 I,

120
C"go Cf)
I
Z 0 so
'-39




1 5 10 15 20 25 30
++ +++
.+i+ + ++ + ++
+ +'
Sept., 1990
(g)
I I I I I I I I I l I

Fig. 2.7. Continued.

_ 1.0
0
" 0.8
E
0.6 I
Z 0.4 LU CC 0.2 L0.0

w
o
0
N Z E
0
Ps
w
25




20
0
10
O
C 5
0 aL
Iw

2
E
0
H
o N
Z OE
120
0 Z 60 C1 30

0

1 5 10 15 20 25 30
1,
Oct., 1990
(c)
I1 i+4'f+"YL I I I II j
S5 10 15 20 25 30
Oct., 1990 + + + + s
-0 0 + + S + +
+ ++ + 0s/e +
- 4- 0+ ++ + +
0+0 ~+ + + + 0+'o
+ + + + + ++ + + + + 0
+ + ++ +*4. + + +'
* +0 + ++~s'' -"+
4+*. + + + + + + + ++ ++ ++ + + ++ +0+
4 + + + 0! -++1
l+ t i l l I It I I I I I 1 i i 1 I 1 1 fI
1 5 10 15 20 25 30

Fig. 2.8. Jupiter wave data for October, 1990: (a) Modal period,
T ; (b) Significant wave height, H 1/3; (c) Wave direction; (d) Wave spreading parameters S1 and S2 ; (e) Current
velocity, Uc; (f) Current direction, Oc; and (g) Tide.

Oct., 1990
- (a)
f + 1
- i i 1 1 1 1 l ii 1 1 1 1 ? I




1.0
0
S0.8
E
0 0.6
I
Z 0.14
0.2
0.0

1 5 10 15 20 25 30

+ + ++
+ +
Oct., 1990
(f)

++ + + +
+ ++ + + + ++
++ + + ++

I t I l I I I I I I I I I ., I l l
5 10 15 20 25 30
Oct., 1990
(g)

Fig. 2.8. Continued.




20 'O t15
E
I
Ft 10
0
4
3

I I t I I I 1 I I I I 1 I 1 I I 1 I !I I I I! I I
5 10 15 20 25 30
,Nov., 1990
(C)
5 10 15 20 25 30
S1:+ S2:e +o +*
+ Nov., 1990
++ (d)
+ +
-F+ ++ ++
+ +
I I I I I 1 I 1 I I I I I I I

Fig. 2.9.

Jupiter wave data for November, 1990: (a) Modal period,
Tm; (b) Significant wave height, H13; (c) Wave direction;
(d) Wave spreading parameters S1 and S2 ; (e) Current Velocity, Uc; (f) Current direction, Oc; and (g) Tide.

Nov., 1990
(a)
I I I f I I I I t I 1
1 5 10 15 20 25 30
LNov., 1990
(b)

W
120
04 90 UI)
Z60 1 0:

i i I




1.0 I I
0
+ Nov., 1990
0.8 + (e)
0.6
I
Z 0.4
0.2
4- +
0.0 I IT 1? 1 I 1iii,
1 5 10 15 20 25 30
0
L + + + Nov., 1990
0 N+ +f
+- ++ + (
O +
ZF E ++ +- + 0 4.
-- s
LU
1 5 10 15 20 2530
2
Nov., 1990
1 (g)
S0
-1
- 2 I I I I I I I I I I I I I I I
1 5 10 15 20 25 30
Fig. 2.9. Continued.




III. SAND TRANSPORT NEAR INLET MOUTH
The current progress in the study of the sediment transport
patterns in the exterior portion of Jupiter Inlet and along the south beach is presented in two parts. The first part details the
results of a follow-up field experiment employing sand tracers (for a description of the first experiment see Mehta et al., 1990b) The second part describes the application of wave hindcast models
to develop a statistical description of the longshore sediment transport in the vicinity of the inlet.
3.1. Field Measurements: Sand Tracer Studies
Two sand tracer field experiments were conducted during June 1990 and, as noted, the results presented in the second progress report (Mehta et al. 1990Ob) The experiments occurred during typical summer wave conditions, with the predominant wave direction from the southeast. To complement these experiments, an additional tracer study was conducted in December 1990 in an effort to reveal
changes in sediment pathways during winter conditions in which the predominant wave direction is from the northeast.
An additional lot of colored sand (orange) was prepared to distinguish this test from the red and green sand tracer tests carried out in June. The grain size distribution was again matched to that of the dredged material placed on the south beach in May 1990, as described in the second progress report:
15% of sand: d > 0.85 mm
70% of sand: 0.52 mm < d < 0.85 mm 15% of sand: 0.38 mm < d < 0.52 mm
The general procedure employed was as described in the second progress report, with a "wind sock" style sand trap again placed within the inlet. In addition, a second identical trap was prepared, to be placed on the south beach well south of the inlet to monitor the motion of sand downcoast.
On December 5 1990, approximately 250 pounds of orange sand was place in the same shallow water location roughly 20-40 yards




south of the south jetty. The sand was placed at 1700 hr, which corresponded to low tide although at the time the flow was still
ebbing 'slightly. The following morning, December 6 1990, the sand trap was installed in the inlet in the same manner and at the same
location as in the previous experiment. Because of restricted daylight, although low tide was approximately at 0500 hr and slack
water roughly one and a half hours later, the trap was not actually installed until 0840 hr.
The tidal range for the day was moderately high at 2.8 feet, and observations at the site showed high waves (over 5 feet) with
a predominant direction from the northeast. An attempt was made to install the second trap in the surf zone along the south beach, but the intense breaking wave conditions prevented this installation. The trap within the inlet performed successfully and was monitored
throughout the flood tide. The trap was removed at high slack tide at 1345 hr. Hand samples were taken at various locations within
the inlet and along the south beach throughout the flood tide (0850-1425 hr) .
Analysis showed that the trap retained 36 pounds of sand, as compared with the 10 pounds retained on June 19, 1990. The median
diameter (d5O) of this sand was 0.50 mm, which is somewhat larger than the median diameter of 0.36 mm collected during the June 19 study. of this amount, 50 grains of orange sand were recovered,
indicating that south beach sand was moving into the inlet even though observations indicated wave incidence from the northeast. This was confirmed by the analysis of the hand samples as well, although these also indicated a substantial motion of dyed sand southward along the beach as might have been expected. Hand
samples had an average weight of 2.5 pounds. Locations of the trap and the hand samples (with number of colored grains found and the median grain diameter of each sample) are given in Fig. 3.1.
The sediment pathways both into the inlet and downcast are clearly indicated. The time scale of this sediment movement is relatively'short, since all of the observed motion occurred in the space of just under two complete tidal cycles, although it should be mentioned that this study was performed under somewhat severe




wave conditions. Note also that both red and green grains f rom the June 1990 experiments were recovered, indicating that although substantial sediment motion occurs, some sediment remains in the system for long time periods. This entire set of tracer studies shows that south beach sand moves into the inlet during periods of wave activity from the southeast and apparently from the northeast as well (this will be confirmed upon recovery of wave data). The latter phenomenon may have resulted strictly from the combination of moderately large tidal range and vigorous sediment suspension due to high wave activity. The larger grain sizes and increased weight of material retained in the trap suggest higher suspended
sediment concentrations than in the June studies. It is not
possible from these results to deduce whether sediment motion into
the inlet from the south beach will generally occur under northeast wave incidence. However the fact that it does occur (particularly
when transport rates are the highest) is an important consideration in the evaluation of possible design alterations to the existing
south jetty, commensurate with the efficiency of placement of beach fill from the sand traps.
3.2. Modeling of Longshore Transport
3.2.1. Transport Modeling Techniques
Longshore transport rates can be evaluated using a number of techniques, with the primary methods considered to be (in order of preference):
1. Deposition rates at a total littoral barrier
2. Volume changes indicated by hydrographic surveys
3. Empirical estimation from wave conditions
operating estimates of littoral drift in the Jupiter Inlet vicinity, as reviewed by Mehta et al. (1990a), have built largely
on the first technique (U.S. Army Corps of Engineers, 1966), resulting iLn an estimate of 230,000 cubic yards per year of net transport lin the southerly direction. This estimate traces




originally from accretion rates measured at Lake Worth Inlet over
a 26 year period (1929-1955) following the construction of the jetties (U.S. Army Corps of Engineers, 1956). It is well
recognized however that this net annual drift is the product of a highly episodic process, in which the majority of the total
transport may occur in a relatively small number of events. A
measure of this variability is essential for the proper design and operation of bypassing systems or the scheduling of maintenance dredging.
To account for the seasonal and long-term variability in longshore sediment transport, an empirical estimation of the
transport based on wave conditions was to be employed. Since there was not a sufficient amount of directional wave data available at
Jupiter Inlet, the following data sources/methods were considered:
a) U.S. Naval Weather Service Command Summary of Synoptic Meteorological Observations (SSMO) : use of existing ship wave
observations in the Atlantic.
b) Wave Hindcast from wind data at West Palm Beach Airport
c) U.S. Army Corps of Engineers Wave Information Study (WIS)
Hindcast Model
It should be noted that the SSMO data often lack extreme wave conditions since ships are typically routed away from bad weather,
thus not providing precisely the information necessary to reliably forecast episodic transport events. Walton (1973) used SSMO data
to develop littoral drift estimates at various points along the Florida shoreline, but recommended not employing this technique for points on Ithe coast from Jupiter Inlet southward. Significant
variability was seen in the annual transport along this region of the coast. For these reasons SSMO data were not used to establish coastal wave conditions at the inlet. Hindcasting waves from the
West Palm Beach Airport wind data were also ruled out since the station was on land, subject to possible land/sea breeze effects




and not capable of yielding information on swell from offshore storms. Such information is provided by the WIS hindcasting models, which were adopted accordingly.
3.2.2. WIS Wave Hindcast Model
The U.S. Army Corps of Engineers Waterways Experiment Station Wave Information Study (WIS) was begun in 1976. The Atlantic Ocean coast was divided into three regions to be treated by three programs or "phases" with Phase I being the deep ocean, Phase II being the U.S. continental shelf zone, and Phase III being the nearshore zone at approximately the 10-meter contour.
In Phase I (Corsen et al., 1981), historical surface pressure and wind data gathered from ships and national weather service charts were used to numerically hindcast deep water wave conditions. These data were collected for every three hour period for the entire 20 year period 1956-1975. This long data record makes this the ideal source since 20 years might be considered the minimum length of record to extract adequate longshore transport statistics. In Phase II (Brooks and Corsen, 1984), deep water wave information was transferred across the shelf zone and modified due to refraction, diffraction, shoaling and bottom friction. The results have been reported for a number of Phase II stations along the Atlantic coast (e.g. station #67 for Jupiter Inlet). The Phase III program (Thompson and Jensen, 1989) then extended the transformation to particular points on the 10-meter contour along the coast, each with a distinct shoreline orientation (e.g. sector #156 for Jupiter Inlet). The output wave heights and directions from these programs were then carried to the breakpoint by a simple Snell's law refraction calculation to yield a breaking wave height and a breaking wave angle measured from the normal to the shoreline. These two quantities serve as the input for standard empirical computations of longshore transport such as that given in the Shore Protection Manual (SPM) (U.S. Army Corps of Engineers, 1984). During the final transformation over the short region from the 10-meter contour to the breakpoint, bottom friction and local wind effects on the existing waves are ignored.




The WIS program output provided wave heights and directions at the 10-meter contour, which were then compared to existing wave data. Since there were not available directional wave data at Jupiter Inlet for the period 1956-1975, and there is no hindcast
information to compare with the directional data collected in 1990, only a very general comparison is afforded. Monthly distributions
of hindcast wave height and angle from the normal for the entire 20 year period were tabulated and are shown in Tables 3.1-3.12. These statistics can be compared with actual wave data collected at Jupiter Inlet in the months of March, April, August, September, October and November of 1990 and shown in the wave roses in Figs. 3.2-3.4. Note that the November wave rose only represents five days of data and hence shows very little spread. In addition, the wave rose directions are azimuth, and the normal to the shore at Jupiter lies roughly along the direction of 250 degrees. Although there is no strict reason why the 1990 data (a single realization)
should reproduce the statistical averages for 20 years, the two data sets compare quite reasonably in terms of predominant wave direction, general directional spread and particularly in the percentage occurrence of the various wave heights.
3.2.3. Predicted Longshore Transport and Statistics
With a reasonable estimate of wave conditions at the 10-meter contour provided by the WIS hindcast data, the previously outlined computations were carried out to first provide wave conditions at breaking and then to calculate the associated longshore transport
rate for each 3 hour time interval over the 20 year period. Because of the enormous scatter in longshore transport data used to develop empirical transport relationships, the average net annual
transport Ifor the 20 year period was computed and a constant calibration factor applied to the SPM formula to roughly yield the accepted value of 230,000 net cubic yards per year southward. The
summary of the 20 year transport data are given in Table 3.13, which shows the net transport, southward transport (positive), northward transport (negative) and the percentage of time for that year that the transport was southward, northward or zero. Although




Table 3.1. January distribution of wave heights H and wave
angles 0 (in percent) at 10-meter contour from WIS
hindcast for period 1956-1975.
Hklm lm 3m
0>300 4.38 0.00 0.00 0.00
200<0:300 2.66 0.04 0.00 0.00
100<0:200 19.03 2.46 0.04 0.00
00 <0<100 36.47 26.98 3.33 0.63
-10a<0<00 3.37 0.04 0.00 0.00
-200 <0<-100 0.02 0.00 0.00 0.00
-300<0:-200 0.00 0.00 0.00 0.00
05-300 0.56 0.00 0.00 0.00




Table 3.2.

February distribution of wave heights H and wave angles 8 (in percent) at 10-meter contour from WIS hindcast for period 1956-1975.

H3m
0>300 3.92 0.00 0.00 0.00
200<0<300 4.91 0.00 0.00 0.00
100<0200 19.65 1.68 0.00 0.00
00 <8100 37.08 25.49 3.08 0.63
-100<000 2.94 0.04 0.00 0.00
-200<80<-100 0.00 0.00 0.00 0.00
-300<0<-200 0.00 0.00 0.00 0.00
0<-300 1.22 0.00 0.00 0.00




Table 3.3.

March distribution of wave heights H and wave angles 0 (in percent) at 10-meter contour from WIS hindcast for period 1956-1975.

H3m
0>300 4.80 0.07 0.00 0.00
200<0:300 2.17 0.18 0.02 0.00
100 <0200 24.03 1.81 0.13 0.09
00<8<100 37.26 25.53 2.21 0.15
-100<0o0 0.53 0.00 0.00 0.00
-200 <0-100 1.02 0.00 0.00 0.00
-300 <0-200 0.00 0.00 0.00 0.00
09-300 0.56 0.00 0.00 0.00




Table 3.4.

April distribution of wave heights H and wave angles 0 (in percent) at 10-meter contour from WIS hindcast for period 1956-1975.

H3m
0>300 2.28 0.00 0.00 0.00
200<0:300 2.37 0.00 0.00 0.00
100 <09200 29.42 0.02 0.00 0.00
00<05100 36.58 26.39 2.06 0.00
-100 <0 00 0.42 0.00 0.00 0.00
-200 <0:-100 0.00 0.00 0.00 0.00
-300 <0:-200 0.00 0.00 0.00 0.00
0<-300 0.46 0.00 0.00 0.00




Table 3.5.

May distribution of wave heights H and wave angles 0 (in percent) at 10-meter contour from WIS hindcast for period 1956-1975.

H3m
0>300 2.68 0.00 0.00 0.00
200<0<300 7.90 0.00 0.00 0.00
100 <0200 14.66 0.00 0.00 0.00
00<0<100 55.54 14.82 0.60 0.00
-100<0o0 3.41 0.00 0.00 0.00
-200<0<-100 0.00 0.00 0.00 0.00
-300<80<-200 0.00 0.00 0.00 0.00
09-300 0.38 0.00 0.00 0.00




Table 3.6.

June distribution of wave heights H and wave angles 0 (in percent) at 10-meter contour from WIS hindcast for period 1956-1975.

H3m
0>300 3.71 0.00 0.00 0.00
200<0<300 2.42 0.00 0.00 0.00
100 <09200 11.48 0.19 0.00 0.00
00<0<100 67.29 10.44 0.96 0.23
-100 <0500 2.88 0.00 0.00 0.00
-200<0<-100 0.00 0.00 0.00 0.00
-300<09-200 0.00 0.00 0.00 0.00
0 -300 0.42 0.00 0.00 0.00

I I




Table 3.7.

July distribution of wave heights H and wave angles 0 (in percent) at 10-meter contour from WIS hindcast for period 1956-1975.

Hlm lm3m
0>300 0.97 0.00 0.00 0.00
200 <0300 0.67 0.00 0.00 0.00
100 <0200 18.61 0.00 0.00 0.00
00 <05100 69.61 3.47 0.04 0.00
-100<0o00 7.38 0.00 0.00 0.00
-200 <0-100 0.00 0.00 0.00 0.00
-300 <0-200 0.00 0.00 0.00 0.00
0!-300 0.26 0.00 0.00 0.00




Table 3.8.

August distribution of wave heights H and wave angles 0 (in percent) at 10-meter contour from WIS hindcast for period 1956-1975.

H3m
0>300 2.66 0.00 0.00 0.00
200<0<300 1.19 0.00 0.00 0.00
100<0 200 20.08 0.00 0.00 0.00
00 <0<100 66.98 3.39 0.02 0.00
-10<0O0 5.54 0.00 0.00 0.00
-200<0<-100 0.00 0.00 0.00 0.00
-300 <0-200 0.00 0.00 0.00 0.00
09-300 0.14 0.00 0.00 0.00




Table 3.9.

September distribution of wave heights H and wave angles 0 (in percent) at 10-meter contour from WIS hindcast for period 1956-1975.

H3m
0>300 4.98 0.02 0.00 0.00
200<0<300 2.71 0.15 0.00 0.00
i0 <0<200 15.21 0.21 0.04 0.00
00<0100 53.15 16.73 1.77 0.23
-100<000 4.31 0.27 0.00 0.00
-20o<80-100 0.00 0.00 0.00 0.00
-300<0-200 0.00 0.00 0.00 0.00
09-300 0.27 0.00 0.00 0.00




Table 3.10. October distribution of wave heights H and wave angles 0 (in percent) at 10-meter contour from
WIS hindcast for period 1956-1975.
H3m
0>300 3.31 0.10 0.00 0.00
200<80<300 4.17 0.22 0.00 0.00
100 <0<200 15.42 0.75 0.00 0.00
00<0g100 37.30 24.50 7.88 0.14
-1006<00 5.48 0.56 0.00 0.00
-200 <0<-100 0.00 0.00 0.00 0.00
-300<0<-200 0.00 0.00 0.00 0.00
0.-300 0.16 0.00 0.00 0.00




Table 3.11. November distribution of wave heights H and wave
angles 0 (in percent) at 10-meter contour from
WIS hindcast for period 1956-1975.

H3m
0>300 3.77 0.08 0.00 0.00
200<0<300 4.42 0.02 0.00 0.00
100 <0<200 13.10 2.85 0.00 0.00
00<0<100 32.65 31.88 6.75 0.44
-100 <0 00 3.33 0.17 0.00 0.00
-200<0-100 0.00 0.00 0.00 0.00
-300<09-200 0.00 0.00 0.00 0.00
09-300 0.54 0.00 0.00 0.00




Table 3.12. December distribution of wave heights H and wave
angles 0 (in percent) at 10-meter contour from
WIS hindcast for period 1956-1975.
Hslm 1m3m
0>300 2.34 0.02 0.00 0.00
200<05300 1.86 0.10 0.00 0.00
100<0<200 22.30 3.73 0.00 0.00
00 <0<100 29.62 32.73 5.51 0.16
-10o <0500 1.27 0.16 0.00 0.00
-200 <0<-100 0.00 0.00 0.00 0.00
-300 <0-200 0.00 0.00 0.00 0.00
0 -300 0.20 0.00 0.00 0.00




Table 3.13.

Longshore transport values Q and distribution for 20 year period 1956-1975 as calculated from WIS wave hindcast data.

Transport (cu yds/yr) Distribution (%)
Year Qnet Qsouth Qnorth % south % north % zero

1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975

433,633 207,214 381,848 310,889 236,324 147,716 261,973 232,033 146,029 225,910 255,891 270,685 63,430 194,132 203,480 190,001 316,316 316,063 200,821 121,181

473,253 278,450 441,072 395,503 302,862 228,766 321,219 286,333 218,080 291,087 346,656 315,307 98,922 253,204 273,624 246,245 375,529 382,845 227,965 78,744

-39,621
-71,236
-59,223
-84,614
-66,538
-81,050
-59,245
-54,299
-72,050
-65,177
-90,766
-44,622
-35,492
-59,072
-70,143
-56,244
-59,214
-66,781
-27,144
-57,563

67.3 72.2 61.4 60.7
55.2 53.8 58.5
56.4 55.2
56.9 64.3 64.2 53.9
56.5 67.5 52.8 74.1 66.0 49.3
31.5

28.2 27.6
31.4 36.8 42.4 42.2 34.0 33.7 41.0 39.1 34.6 32.6 39.7
36.1 32.1 38.8
25.5 33.5
36.7 50.4

4.5 0.3 7.2
2.4 2.4 3.9 7.5
9.9 3.8 4.0 1.0 3.2 6.4 7.4 0.4 8.4 0.4 0.5 14.0 18.0

- i




it is clear that there is substantial variability even in the annual transport values, the truly episodic nature of the transport process is not revealed in the table. Consider the cumulative daily sum of the volume transported past a point for the year 1967 as shown in Fig. 3.5. It can be seen that the total net transport of 270,000 cubic yards for that year is largely the result of 5 or 6 major transport events, particularly those near day 80, 310 and 360 (most likely typical "northeaster" storms). Such events are
quite important when considering design options, and are only predicted through a statistical description of the transport process.
Weggel and Perlin (1988) and Weggel et al. (1988) have shown that longshore transport data from various locations reasonably approximate a log-normal probability distribution, and the statistics of such a distribution at a particular site could then be used to perform simulations of transport events. The calculated annual transport magnitudes in the southward and northward direction at Jupiter Inlet were ranked to determine exceedance probabilities (the probability that the transport will equal or exceed a given value) and plotted in log-normal fashion in Fig. 3.6. It is seen that the data largely approximate a lognormal distribution, with the notable exception of the extremely
low transport years of 1968 and 1975. Nevertheless it would appear that the log-normal distribution statistics would quite adequately reflect the overall transport process. However, the statistics of
the annual transports do not allow the modeling of the seasonal variations in transport rates and direction. Instead, calculations of monthly transport statistics for the 20 year period are being undertaken. Monthly means and standard deviations of the logarithmically transformed distributions of northward and southward transport are being calculated. In such a manner the transport is represented by six parameters: the monthly mean and standard deviation for northward and southward transport and the percentages of time during the month that the transport is in each direction.




The following process will allow simulation of daily transport events: A random number is selected to establish the direction of
transport for a given day, based on the calculated percentages. The appropriate transformed normal distribution (northward or
southward) f or that month is sampled to yield a daily transport. Daily interpolation between monthly means and standard deviations could also be accommodated. In such a manner a synthetic
"transport year" is readily generated. Synthetic transport data can then be produced for any length of record and used for design evaluation, for example, in the determination of storage and pumping capacities of potential sand bypassing systems.
3.2.4. Shoreline Evolution
The final addition to the statistical transport model for the
purposes of design evaluation is the incorporation of a "one-line" type model of shoreline evolution. Such models are typically based on only net rates of annual transport. Modifications will be made to use the model with a variable longshore transport provided by the statistical simulations. This will allow potential erosion of the immediate shoreline to near critical levels to be included as a criteria in the evaluation of design alternatives including the
improvement of the efficiency of the placement of beach fill, while fully accounting for the seasonal and episodic variability of the longshore transport.
The most recent placement of beach fill occurred over a two
week period ending on May 26, 1990, during which 85,000 cubic yards of sand were placed on the south beach. Fig. 3.7 shows the beach on April 18, about a month prior to the placement, while Fig. 3.8 shows the beach on June 1, soon after placement. Fig. 3.9 shows the beach on December 5, six months later. While in this case the
waterline is observed to have receded to its pre-fill position, the berm was actually substantially higher, as the volume of sand retained landward of the waterline was considerably greater on December 5, 1990, than on April 18, 1990.




6 orange
S 0.48 mm
0

-4 orange, 1 green
da = 0.62 mm

6 orange
da = 0.31

1upiter Inlet
No color
d a = 0.57 mm
;3 250 pounds orange sand placed
at 1700, 5 Decer-Der 1990.
5 orange, 1 green, 1 red
d., = 0.58 mm
. 5 orange
" a 0.32 mm
S20 orange, L green
S"O= 0.65 mm

No color d0=1.1 mm
3 orange S4 0.90 mm
Fig. 3.1. Approximate sample locations with number of colored
grains recovered and ds50, December, 1990.
54




Fig. 322.

March-April, 1990 wave roses for station at Jupiter. Note that Hs refers to significant wave height. Percents refer to frequency (%) of waves from a given direction.

Fig. 3.3. August-September, 1990 wave roses for station at Jupiter.
I

Fig. 3.4. October-November, 1990 wave roses for station at Jupiter.




300.00

~250.00
S200.00
0
0
1 150.00 ry
0
0
n
1 100.00
H
D
150.00

Fig. 3.5. Cumulative
calculated (Increasing

100.00

200.00
TIME (DAYS)

300.00

400.00

longshore transport at Jupiter Inlet from WIS hindcast data for year 1967 volume implies southward transport).




SOUTHWARD TRANSPORT

106
105-

* -,.
* ~

I I 2 4 6 0 8 0 9 0 9 9 9
104 1 510 204060 80 90 95 99

EXCEEDANCE PROBABILITY (%)
Fig. 3.6. Log-normal probability plot of annual longshore transport
magnitudes (southward and northward) from WIS hindcasts
for the period 1956-1975.
57

NORTHWARD *
TRANSPORT "

i I




Fig. 3.7. Beach south of Jupiter Inlet on April 18, 1990, a month
before beach fill.

Fig. 3.8. Beach south of Jupiter Inlet on June 1, 1990, soon after
beach fill.




Fig. 3.9. Beach south of Jupiter Inlet on December 5, 1990, six
months after beach fill.




IV. INLET NEARFIELD STUDY AND MATHEMATICAL MODELING
The offshore region of the inlet nearfield includes the area over which inlet flood and ebb currents play a measurable role and
interact with incoming waves and associated alongshore current. This interaction defines sand transport and the location, shape, volume and the movement of the ebb sand shoal. It also will be the
principal factor determining shore effects due to any mining of the offshore area for sand. The nearfield region is being studied through field work, mathematical simulation, and physical modeling. The first two are considered in this section. Physical modeling is discussed in the next section.
4.1 Nearfield Study
This field study was reported briefly in the second progress report (Mehta et al., 1990b); a fuller account is given here.
4.1.1 Introduction
In order to describe the current hydrodynamics at Jupiter Inlet, the current patterns and magnitudes were measured in the field by performing the floating drogue test. The drogue test
technique features tracing floating drogues which are carried
freely by currents on the water surface. The path and speed of the drogue's movement are then computed, which represent the pattern and strength of current flows. The results from the drogue test
will be used for the prediction of the sediment movement in the vicinity of the inlet.
It is generally known that the most dynamic influence of waves and tidal currents on sediment transport at Jupiter Inlet occurs when large waves approach from the southeast direction while tidal currents are at their peak strengths. Accordingly, to perform the field drogue test subject to southeast waves, a research crew from was sent to Jupiter Inlet on the August 14 and 15, 1990. The
accomplished field tasks included deploying reference buoys at sea, placing baseline makers on the beach adjacent to the inlet, and tracing free-motion styrofoam. floats by taking aerial photos of drogues from an airplane during the ebb, flood and slack tides.




The photos were taken as a time series with time for each photo being recorded.
Based on the aerial photos, drogue locations were computed in
accordance with the plan coordinates, and drogue velocities were calculated between each two consecutive time series photos. The
final composite drogue test data were then utilized to describe the field current flow characteristics near the inlet.
4.1.2 Drogue Test Technique
As noted the test consists in tracing styrofoam drogues which are floating free with currents on the water surface. The drogue has a four-leaf fan structure of approximately one quarter meters in diameter and length attached to its bottom, which helps induce
sufficiently large current drag. The advantage of employing the drogue test in the field is that several drogues can be released in the same run as long as the drogues are well distinguished in aerial photos. It is often helpful in distinguishing drogues in
the photos by painting the drogues with color that is different from the bright blue sea surface. It is also helpful if individual drogue is released with spacing large enough from the neighboring ones and aerial photos are taken over reasonably short time intervals. It is sometimes necessary to have several trial runs to see where it is best to release the drogues and how often aerial photos should be taken.
A disadvantage is that drogue locations are usually shown in
distortion as related to the reference points in the aerial photos. The distortion is a function of the sighting angle and the height of the camera. It is therefore necessary to correct or transform the droguellocations shown in aerial photos into plan coordinates that are in use.
The transformation of aerial photo plan information into the
actual horizontal plan is based on a linear mapping algorithm, which transforms location information between two rectangular
plans. According to this mapping algorithm, the actual drogue locations (x,y) are expressed as (Segerlind, 1976):




x=Nixi+NixJ+Nkxk (4.1)
y=Niyi+Njyj+Nkyk (4.2)
where (x,, y,), (xl, yj), (xk, Yk) are the locations of any three reference points selected on the actual horizontal plan, and N, N and Nk are functions of (x',y'), (x'1i, y'1), (x'j, y 'j), (x'k, Y'k) with the prime indicating the aerial photo plan coordinates. In the coordinate transformation process, the aerial photo plan coordinate system can be arbitrarily chosen. However, the
selection of the three reference points in the process is important. More accurate results are obtained from this coordinate mapping algorithm if the three reference points are properly selected so as to construct a triangle that includes as many drogues as possible in an aerial photo.
4.1.3 Description of Field Framework
For the test, a baseline was first chosen through DNR monuments R-12 and R-15, approximately parallel to the shoreline. The origin of the reference coordinates was located at R-12 with positive x direction pointing to R-15. The onshore reference makers were then established on the beach face, one located about 140 meters north of inlet's north jetty, and three others 335, 475 and 730 meters south of the south jetty. The offshore reference points were also established by deploying five anchored sea buoys aligned at a distance of 610 meters from the shoreline and 210 meters apart from each other. The anchored buoys were located with great accuracy by using a three point radar measuring system.
The drogue test was performed for the ebb and flood tide cases when the corresponding tidal currents were strong. One additional run was carried out at slack tide. The drogue diameter, the dimensions of the reference makers and the sea buoys were approximately equal to 1.5 meters. In order to have good
resolution of drogue images in the aerial photos, the airplane was maintained to fly at the height of 610 meters.




On August 14, the current study was concentrated on the flood tide case. Six drogues were first released in the nearshore area near the southside of south jetty, where erosion is significant.
Deployments of the drogues were then repeated in the nearshore areas to the east and the north of the inlet. The last run was in
the further offshore area and was for the slack tide case. A total six runs of the drogue test were performed on this day. During the entire test period, waves of about one-half meter height were observed approaching from the southeast direction.
On August 15, the study was performed for the ebb tide case.
Three drogues were first released just inside the inlet entrance at about peak ebb current. Three more runs were then conducted in the nearshore areas to the south, east and north of the inlet. During the test, small southeast waves were observed.
4.1.4 Results
Measured currents for the ebb tide case are shown in Fig. 4.1. These indicate a significant ebb plume heading in the east and northeast directions in the presence of small waves were arriving
from the southeast. Fig. 4.2 is a zoom of the currents patterns near the inlet shown in Fig. 4.1. A noteworthy observation is the
occurrence of a weak entraining flow towards the inlet near the south jetty.
Flood currents shown in Fig. 4.3 shows water being drawn into the inlet almost entirely from the southeast direction. The closeup in Fig. 4.4 shows water being drawn around the jetties, with a stronger current around the south jetty, consistent with the influence of waves. The effect of southeast waves in generating northbound currents is quite evident in Fig. 4.5, corresponding to the slack tide condition.
These particular sequence of tests are revealing in a number
of ways. Firstly, under southeasterly waves, inlet waters ebb towards the east and northeast, while flood waters are drawn from
the southeasterly direction. Furthermore, the ebb waters go further out of the inlet than the extent (around 600 m from the inlet) up to which flood waters are drawn in. These differences in the flood




and ebb flow patterns enable water mass exchanges and associated flushing of tidal waters of the Loxahatchee River. Secondly, both during flood as well as ebb flows, water is drawn into the inlet
around 'the south jetty. The likelihood of associated net sand transport in to the inlet as a result has been confirmed by the sand tracing tests described in Section 3.
4.2 Mathematical Study
Some aspects of this study including several selected offshore bathymetric grids with channel options and computational results were reported in the second progress report. Progress made since then is briefly noted here.
This study is being conducted in close coordination with the
physical model study of the inlet. Hence the protocol for input parameters for the physical model study described in the next section will apply to the mathematical study as well. The main point to be made here is that a new grid corresponding to the proposed dredging of the ebb shoal for sand mining will be added for studies on the effect of dredging on shoreline stability. The grid itself is shown in Fig. 4.6.




800

600 Sea Level: -0.3 m
400
q- c SEA
CE 200
U
U
0
CSouth North Jetty
LL.
C D
-200 -".
I M/SEC
- 00 I I I I I
-600 -400 -200 0 200 q400 600
LONGSHORE DISTANCE (M)

Fig. 4.1. Ebb flow velocity vectors at Jupiter Inlet measured on August 15, 1990.




250
200
150
LU too SEA
1--- ';.":'
U-)
C)
0
. North
f- .Jetty
-50 Suth Observation Date: 8/15/90
o Jetty Significant Wave Ht.: 0.37m
LL Mean Wave Period: 4.0 sec
L- Wave Direction: 2680
* Sea Level: -0.3 m
-150
I H/SEC
-200 I I I I I I I I I
-200 -150 -100 -50 0 50 100 150 200 250 300
LONGSHORE DISTANCE (M)

Fig. 4.2. Details of ebb flow corresponding to Fig. 4.1.




600
400
Li CJ
z SEA
CE
- 200
CO
o / South
-en
CD
LL.
-200 &
Observation Date: 8/14/90 Significant Wave Ht.: 0.45m Mean Wave Period: 4.0 sec Wave Direction: 273 1I M/SEC
Sea Level: -0.3 m
- 0 I I II
-600 -400 -200 0 200 400 600
LONGSHORE DISTANCE (M)
Fig. 4.3. Flood flow velocity vectors at Jupiter Inlet measured on August 14, 1990.




300
250
200
ISO
so
(9n
b-50
0'0
0 u. North
c "+ "Jetty
5 Observation Date: 8/14/90
Significant Wave Ht.: 0.45m Mean Wave Period: 4.0 sec
-100 Wave Direction: 2730
Sea Level: -0.3 m
- s o -l e
jupiter I letM/SEC
-200 -I I II I I I I I
-200 -150 -100 -50 0 50 100 150 200 250 300
LONGSHORE DISTANCE (M)

Fig. 4.4. Details of flood flow corresponding to Fig. 4.3.




600
400
>- qoo
SEA
LLJ CI
U
S200
(3-)
cn
Ca North
01 Jetty o eSouth Jtty
1-.. Observation Date: 8/14/90 ~LLU
U) osrainDae /49
,.-' /- -Significant Wave Ht.: 0.38m
U_ Mean Wave Period: 4.0 sec
C Wave Direction: 2700
-200 Sea Level: 0.0 m
I M/SEC
-400
-400 -200 0 200 400 600 800
LONGSHORE DISTANCE (M)

Slack tide velocity vectors off Jupiter Inlet measured on August 14, 1990.

Fig. 4.5.




00
f111 I f il IIII 1C1:ti~ T F d TF TFIF Yr iti+1 14 -f rli-t-4w lll
Fig. 4.6. Offshore bathymetry showing the proposed sand borrow area to be investigated in the
mathematical model.




V. PHYSICAL MODELING OF INLET NEARFIELD

5.1 Introduction
one of the components of the comprehensive study consists of construction of a physical model and conducting necessary experiments. Proposals are expected to be evolved from constructional modifications at the site, if any, and for a
possible dredging of an offshore navigational channel. In addition, potential impacts of mining sand from the proposed offshore borrow
area will be investigated in the model. The merits of various alternatives will be studied in the physical model. Details of the physical model and the proposed studies are given below.
5.2 Model Limits
The physical model study is essentially concerned with the localized area near the inlet. A stretch of about 0.8 mile-long shoreline on the north side and about 1 mile-long shoreline on the south side are therefore considered adequate for inclusion in the model. Since the depth of offshore navigation channel is expected to be only 10 feet, the seaward limit of model was extended to the 34 foot depth. The objective is to study the conditions on the
seaward side of the inlet. Hence the landward geometry of Jupiter Inlet is not included in the model. Instead, a 2 f eet wide
rectangular channel has been provided for carrying the flood and ebb tidal discharges. The model limits cover an approximate sea area of 1.8 miles by 1.0 mile.
5.3 Model Scales
Taking into account the relative importance and impact of tides and waves in the coastal processes at Jupiter and the scope
of the present physical model study, it was apparent that the model would have to be designed as a wave model. It was decided that instead of generating tides with a continuously varying water level and velocities, the effect of varying sea level would be simulated by providing equivalent flood and ebb discharges through the inlet at selected steady water levels in the model.




Wave models are generally geometrically similar, that is, the horizontal scale and the vertical scale are the same. The space available in the Coastal Engineering Laboratory of the University
of Florida for reproducing the area within the limits described earlier permitted a horizontal scale of 1:100 which is a good scale commonly adopted for wave models.
The limitations of instruments and the requirements of the physical model are as follows:
1. The capacitance wave gage can measure wave heights with a
resolution of 0. 2 mm. The wave height in the model needs to be large enough to permit accurate measurement with this
resolution.
2. The height of wave needs to be large enough to generate waveinduced currents of measurable magnitudes.
3. Water depth at the wave paddle needs to be sufficient to permit
generation of waves with a satisfactory water surface profile
without getting adversely affected by surface tension.
Since the depth of navigation channel is 10 feet and the maximum water depth at the seaward limit is 34 feet, the corresponding depths would be 1.2 inches and 4.1 inches respectively with a depth scale of 1:100. The model wave height
corresponding to 4 feet would be of the order of half an inch. These small-amplitude waves would likely be adversely affected by the surface tension effects. Generation of waves with a
satisfactory wave form is often difficult in a small water depth on the order of 4 inches due to the limitations of the mechanical wave paddle. Hence, taking into account these considerations, it was decided to provide a depth scale of 1:50 for the model in order to overcome the above difficulties. A horizontal scale of 1:100 and a vertical scale of 1:50 gives a distortion of 2, which is within acceptable limits for three dimensional wave basin models. The overall dimensions of the physical model are 90 feet by 48 feet (Figs. 5.1(a) and 5.1(b)).
With the above basic scales, the related derived scales are as follows..




Area 1: 10,000
Volume 1: 500,000
Discharge 1: 35,355
Time 1: 14.1
Velocity 1: 7.1
5.4 Waves and Currents
Fig. 5.2 shows the prevailing wave climate around Jupiter area (CERC data). The diagram expectedly shows three predominant directions, namely, northeast, east and southeast. Easterly waves
are almost normal to the general shoreline and hence are not responsible for measurable alongshore sediment transport. Waves from the northeast produce southerly littoral drift, whereas waves from the southeast produce northerly littoral drift. Hence these two directions have been selected for model wave simulation.
Field observations of flow patterns during flood and ebb phase of tide are shown in Figs. 4.1 to 4.4. These observations taken in August 1990 show that in addition to the in and out tidal flow through the Jupiter Inlet during flood and ebb, there is also an alongshore-cum-onshore flow which is roughly in the northwesterly direction. As noted in Section 4 of this report, the observations
shown in Figs. 4.1 to 4.4 were taken with drogues which were weighted to 1 meter depth. Hence these are essentially surface float observations. The flow directions are therefore governed partly by the influence of inlet and partly by the wave- and windinfluenced tidal surface currents. outlet gates have been provided in the southern and eastern boundaries of the model to enable simulation of the flow pattern observed at site.
5.5 Extreme High Water Levels
High winds and relatively large atmospheric pressure gradients associated with tropical storms and hurricanes can cause water levels in the ocean as well as inside the inlet to be much higher
than the astronomical levels predicted by the National Ocean Survey tide tables. Bruun et al. (1962) have predicted the return period




f or various storm surge levels as follows for the coastal region of North Palm Beach County:
Height Above msl Return Period (Years)
1.25 m or higher 6-7
1.5 12-14
2.0 20-22
2.5 34-36
3.0 58-60
3.5 100
In an area of high littoral drift as noted in Section 3 and
rapidly changing shoreline, coastal structures may have to be designed for a life of say 25 years because prediction of coastal situation after that time could be quite difficult and unreliable. Under this situation a maximum storm surge level of 7 feet (2.1 m) appears acceptable for design purposes. Any measurable sea level
rise has not been taken into account for the present purposes, since projected rise scenarios are speculative.
5.6 Model Construction
Sea bed surveys conducted in 1980 and 1986 formed the latest available data on bathymetry at Jupiter Inlet. A contour map of
the area was used for drawing cross-sectional profiles roughly perpendicular to the shoreline extending from the high water line
to the 3 4 feet depth in sea. These prof iles were drawn at an interval corresponding to about 3 to 4 feet in the model. Templates were cut out of 1/8 inch thick particle board
corresponding to the profiles reduced to a horizontal scale of 1:100 and a vertical scale of 1:50. Wooden battens 2 inch by 2 inch in size were nailed to the laboratory floor at the requisite locations where the templates were to be provided. All the
templates a ppropriate to the respective locations were then nailed in vertical position to the battens on f loor. Sand was f illed between all the templates. About one inch thick layer of cement mortar (1: 5 mix) was provided over the sand and the surface was




levelled to exactly correspond to the top of the templates. This procedure satisfactorily reproduced the shoreline and the sea bed topography. Smooth finish was not provided for the mortar surface
in order to provide a higher roughness essential for distorted models.
A 400 gallon per minute capacity pump has been provided for initial filling as well as for the operation of the model. After filling the model to the required sea level elevation, water will be pumped in the sea portion and let out of the basin by gravity through the channel upstream of the inlet in order to simulate the flood flow condition through the inlet. On the other hand, water
will be pumped upstream of the inlet to f low out to the sea through the inlet for simulating ebb flow. A steady water level will be
maintained in the sea by balancing the rates of inflow and outflow, whereas the required flow velocity through the inlet will be achieved by controlling the pump discharge.
Overflow weirs along the southern and eastern boundaries will be operated to the required extent in order to achieve the necessary strength of current in the sea portion. A flap type wave maker operated by a variable-speed electric motor will be used for generating regular waves of required height and period. The
position of wave maker will be shifted depending upon the direction of wave generation.
A water level sensor is provided in a gage well connected to
the inlet f or measurement of sea water level. An electronic multichannel data acquisition system will be used for measurement of waves and currents at different locations in the model.
5.7 Model Calibration and Measurements
The calibration of model will consist of the following:
1. Correct' simulation of the flood and ebb strength of flow through the inlet.
2. Adjlstinig the strength and direction of flow in the sea portion.
Experiments will be conducted with the following variable parameters:




Wave Direction: Waves will be generated from the northeast and
from the southeast direction.
Wave Height and Period: Regular waves corresponding to 4 feet and
6 feet heights with a period of 10 seconds will be generated
in the model.
Sea Water Level: Three water levels will be used, namely, low
water level, high water level and storm surge level (+7 ft
corresponding to a return period of 25 years).
i
The following observations will be made:
Waves: Wave heights will be measured at 12 locations shown in Fig. 5.1.
Currents: Direction and strength of current will be measured at 7
locations shown in Fig. 5.1.
In addition, weighted floats and water-soluble dye will be used to observing eddies and flow pattern. Also, wave-induced movement of
light-weight material injected in the near-shore zone will be studied for obtaining qualitative information on littoral transport.
5.8 Objectives of Measurements
1. Obtain data on wave-induced currents along the shoreline for
assessment of sediment transport capacity.
2. Obtain data on the change in flow pattern, current magnitude and
eddies caused by implementation of dredging and construction
proposals (jetties, ebb shoal mining, offshore channels).
3. Obtain data on the change in wave heights as a result of
implementation of dredging and construction proposals.
4. Evaluate relative merits and demerits of different alternatives.
5.9 Propos ls to be Tested
Two alignments of offshore approach channel, namely southeast channel and south channel, will be studied in the model along with extension of north and south jetties. Experimental conditions (Al
- A3, and B1 B3) are shown schematically in Fig. 5.3. As shown in Fig. 5'4, these two design channels alignments avoid the areas of




high magnetic anomalies (Baer and Throckmorton, 1990) that have been found in the vicinity of the inlet, indicative of the presence of cannons and anchors from shipwrecks.
Effect of dredging borrow area around the offshore ebb shoal as shown in Fig. 5.4 will be studied on the model. Experiments Al and Bi will be conducted with pre-dredged and post-dredged
conditions. If any significant changes in critical shore areas are noticed, other experiments will be repeated without and with simulation of dredging in the borrow area.




0 Locations of Current and Wave Observations

Fig. 5.1(a).

Jupiter model layout and locations of observation points.




Page
Missing or
Unavailable




.Not Recorded
0'-2'
2' -4
L-- 4'- 6'
___ 6'- 12' L.'.. No Waves from this Direction

Survey Area
February, 1967- June, 1968 Wave Heights

.00 M Not Recorded EM .02 10.06 M .03 M9 .07 EM .04 0 .08 = No Waves from this Direction

Note: Numbers Indicate the
Percentage of time

E
4.20
3.36 6.72

'66

Fig. 5.2.

February, 1967 June, 1968 Wave Steepness
Deep water wave directions in Jupiter Inlet area (CERC data).

I I




SERIES A: SOUTH-EAST CHANNEL

1 : Existing Jetties

A2-: Extension of
North Jetty
A3 : Extension of
South Jetty

SERIES B: SOUTH CHANNEL B1 : Existing Jetties

B2 : Extension of
North Jetty
B3 Extension of South Jetty

-- 0 600
*' Scale In Feet
Fig. 5.3. Schematic drawings showing the proposed experimental
conditions.




A4 :Extension of
\both jetties

A5 :Extension of
N South Jetty

B4 : Extension of
both jetties

B5 :Extension of
South Jetty

0 600
Scale In Feet

Fig. 5.3. Continued.




Borrow Area
1 7.5 ft
2 12.0 ft.
3 16.0 ft.
4 14.0 ft 5 20.0 ft.
6 20.0 ft.

0 100 200 500 Scale In Feet

Jetty

Fig. 5.4. Proposed dredging of borrow area and two options of navigation channel.




VI. MATHEMATICAL MODELING OF INLET INTERIOR
The purpose and scope of mathematical modeling of the interior waterbody was briefly described in the first progress report (Mehta et al., 1990a). The modeling effort is being carried out: 1) to simulate existing flow, salinity and sediment transport conditions within the inlet, and 2) to evaluate effects of potential modifications to the inlet on these processes. This section is divided in two parts. The first part deals with physical input parameters and related matters, while the second discusses model results.
6.1 Physical Input Requirements
6.1.1 Bathymetry
The finite element grid being used in modeling the interior area of the Loxahatchee River Estuary consists of 576 quadrilateral elements and 1970 nodes. The grid being used is shown in Fig. 7, Part I, Mehta, et al.(1990a), and also in Fig. 6.6 of this report. The bottom elevation at each node was obtained from a bathymetric map by the U.S.G.S. (McPherson, et al. 1982; and Fig. 6b, Part I, Mehta, et al., 1990a). By changing selected nodal elevations, it is possible to predict changes in the hydrodynamic/sediment regimes caused by changes in the estuary geometry, e.g. in size or number of sediment traps, or jetty modifications.
6.1.2 Tides and Currents
Simultaneous records of tides and currents at different locations throughout the estuary are necessary for calibrating the hydrodynamic model. Model calibration was performed using tidal and current records at five locations (stations 1,2,4,5 and 6 shown in Fig. 7.3, Part II, by Mehta et al., 1990a). These records are given in Figures 7.4, 7.11, and 7.12, Part II, by Mehta et.al. (1990a). See also Fig. 6.7 in this report. In addition to calibrating the model at these five points, further "fine-tuning" will be performed using tide and current records obtained by the University of Florida at the U.S. 1 bridge and at the Jupiter 84




Marina on the south side of the estuary (see Figs. 10a, l0b in Part I, by Mehta et al., 1990b).
6.1.3 Salinity
To model the salinity distribution in the estuary, data from Chiu (1975) was used. See also see Figs. 4.11, 4.12, and 4.13, in
Part II, by; Mehta et al. (1990a), and Fig. 6.1 in this report. Using the high and low water slack salinity distributions at stations 1
at the inlet mouth and the average of stations 15 and 16 in the northwest fork of the river, a range of salinity was calculated for the mouth and for the northwest fork (see Fig. 4.11, Part II, Mehta et al.,1990a). Using the range at each of these two boundaries, a
corresponding time variation in salinity for a tidal cycle was generated. This was done in order to allow the model to "read" data at five minute intervals at the two boundaries. Initial
conditions for salinity in the estuary were taken from salinity
profiles obtained at high water on 2/26/75 (see also Section 6.2.3). With two boundary points and initial conditions thus defined, the model uses the 2-D, depth-averaged advectiondispersion relationship for conservative constituents such as salt to calculate the salinity variations throughout the estuary. Flow
boundaries other than the two mentioned are considered to have zero net salinity flux, due to no measurable freshwater inflows.
6.1.4 Sedimentation
The computer model for sediment transport will be calibrated by adjusting the influx of sediment into the inlet mouth from the
sea until the sedimentation rates calculated using bottom trap dredging records of the U.S. Army Corps of Engineers and the Jupiter Inlet District match those predicted by the model.
Sedimentation rates will also be calculated by determining changes in sediment volumes from various surveys elsewhere in the estuary, particularly east of the railroad bridge.
A complete list of all recorded dredgings has been prepared and will be used to determine sedimentation rates in the inlet channel (see Table 6.1). Two bathymetric surveys were used to show 85




Table 6.1 J.I.D. and Army Corps Dredging Records for Jupiter Inlet

J.I.D. 1
CU. YRD.
(CU. METERS)
99,000 (75,690)
VOL. UNKNOWN VOL. UNKNOWN VOL. UNKNOWN VOL. UNKNOWN

ARMY CORPS 2 CU. YRD. (CU. METERS)

TOTAL CU. YRD. (CU.METER)
99,000 (75,690)

6/52 72,075
(55,110)

VOL. UNKNOWN

42,000 (32,110)
45,100 (34,410)

42,000 (32,110)
45,100 (34,410)

VOL. UNKNOWN

45,000 (34,410)

123,000 (94,040)

243,000 (185,790)

(34,410) 46,000 (35,170) 21,800 (12,750) 24,000 (18,350)
31,500 (24,080)

45,000

46,000 (35,170)
144,800 (110,700)
24,000 (18,350)
243,000 (185,790)
31,500 (24,080)

1Ron Dixon, Dixon and Associates Engineering, Inc. personal
2 communication.
Florida Inland Navigational District, Long Range Dredged Material Managment Plan for the ICWW in Palm Beach Co., Florida (December, 1989).

PROJECT YEAR

1922 1/31

11/36 9/47 7/48

72,075 (55,110)

1956 9/58
9/60 1961 8/62 1963 1964 1965 6/66 1967




Table 6.1. Continued

YEAR

J. I. D.

TOTAL

6/68 131,000
(100,160)

ARMY CORPS
-----------28,000
(21,400)
50,000 (38,230)
93,500
(71,490)
45,000 (34,410)
154,000 (117,740)

159,000 (121,560)
50,000 (38,230)
170,500 (130,356)
121,500 (92,890)
256,600 (92,890)
93,995 (71,860)
211,800 (161,930)
75,000 (57,340)
170,500 (130,360)
76,000 (58,110)
130,300 (99,620)
195,800
(149,700)
156,300 (119,500)
85,000
(64,990)

1969 8/70 9/72 5/75

77 000 (581870)
76,500 (58,490)
102,600
(78,440)

5/77 93,995
(71,860)

1979 11/81

93,000 (71,100)
75,000 (57,340)

118,800 (90,830)

1983 60,000
(45,870)

110,500
(84,480)

1985 1986 1987 1988 1990

76,000 (58,110)

130,300 (99,620)
130,300 (99,620)
87,000 (66,520)

65,500 (50,080)
69,300 (52,980)
85,000
(64,990)




the change in the flood shoal over a ten year period (see for example Fig. 6.2). Using drawings based on the interpretation of aerial photographs and two bathymetric surveys, comparisons of flood shoal area and length over years was made, as shown in Figs. 6.3 and 6.4, respectively. These data generally confirm the observation made in the second progress report (Mehta et al., 1990b) that the flood shoal has been growing over the years (at least since around 1964), although the rate of growth seems to have been slow during the past decade.
6.2 Hydrodynamic Modeling of Loxahatchee River Estuary
6.2.1 Introduction
This section presents the results from the hydrodynamic modeling (using a two-dimensional depth-averaged finite element model) of the Loxahatchee River estuary. The objectives achieved in this effort include:
(a) generation of the finite element grid to represent the Loxahatchee River estuary;
(b) formation of the input data set for the hydrodynamic model;
(c) calibration of the hydrodynamic model.
I
The hydrodynamic model predicts the two-dimensional (depthaveraged) velocity and salinity fields throughout the estuary, within the selected boundaries. Modeling results are presented in the form of velocity vector plots showing the predicted flow (i.e., velocity) field in the estuary, and plots showing comparisons between predicted and measured velocities and salinities. A
description of the numerical model is given next, followed by a description of model application and model results.




6.2.2 Model Description
The numerical model, named STM-H, is a two-dimensional,
depth-averaged finite element model capable of predicting sediment transport in non-stratified (i.e. vertically well mixed) coastal waters. The model is limited to numerical simulation of
cohesionless sediment transport as bed load and suspended load. In order to better represent the irregular geometry of most coastal
waterway systems, a finite element method is used in STM-H to solve the depth-averaged flow and sediment transport equations. Eight
node quadratic isoparametric (curved-sided) elements, which can more closely represent geometric irregularities (i.e., shoreline configuration) than standard finite difference methods, are used for spatial discretization of the water system being modeled.
The model consists of semi-coupled hydrodynamic and sediment transport modules. At a given time-step, first the hydrodynamic
module is run to predict the two-dimensional flow field (which consists of the flow depth and depth-averaged horizontal velocity
components at every node) and the two-dimensional (depth-averaged) salinity field, and then the sediment transport module is run at the same time-step to predict (1) the sediment transport rate at every node in the finite element grid, and (2) the corresponding morphological changes (i.e. increase or decrease in bed elevation to account for predicted sedimentation or scour, respectively) at every node. It is in this manner that the hydrodynamic and sediment transport modules are effectively semi-coupled. This
allows the predicted morphological changes at each time-step to be used during the next time-step in calculating the new flow field.
Hydrodynamic Module: Given the STM-H model being a depth-averaged model, barotropic but not baroclinic circulation (due to salinity
or temperature stratification) is represented. However, baroclinic circulation is usually significant only when there is appreciable freshwater inflow resulting in partially mixed or stratified conditions Nevertheless, even under the typical low freshwater
inf low and vertically well-mixed conditions that occur in this estuary, Russell and Goodwin (1987) found that water circulation in




the Loxahatchee River estuary, as predicted by a two-dimensional depth-averaged hydrodynamic model, is dominated by freshwater inflow rather than by tidal forcing. As such, it is essential that the mixing of freshwater and sea water be adequately represented in modeling the hydrodynamics of this system. In the STM-H model this mixing, and therefore the resulting longitudinal salinity gradient, is modeled by solution of the advection-dispersion equation for a conservative constituent (i.e., dissolved salt). This equation is coupled to the equations solved in the hydrodynamic module. This allows the spatial density variation to be included in calculation of the flow field. In this manner the mixing and therefore
dilution of sea water by freshwater inflow is simulated.
Barotropic flow in estuaries is primarily generated by imbalances in water surface elevations between the ocean and estuary, and along the length of the estuary. Since these
elevation differences are primarily caused by astronomical tides, the flows are oscillatory in nature, with a semi-diurnal (12.42 hours) period on the east coast of the United States. Other
factors influencing vertically well-mixed estuarial flows, and which are represented in STM-H, are bottom friction, internal (or turbulent) shear stresses, surface shear stresses caused by winds, the Coriolis force, estuary bathymetry and shoreline geometry. The barotropic flow field is evaluated in the hydrodynamic module in STM-H by numerical solution (using the finite element method) of the shallow water equations, i.e., the two-dimensional, depth-averaged equations of continuity (Eq. 6. 1) and momentum (Eqs.
6.2-6.3), given as:
-h + +) +u_ + v_ = 0 (6.1)
a u "u u + g ba h 1 (U + 2 U
t uy +V ay g ax P x2 + y2) -x 0
90

_ -I




+v+ + ob + h _I v + v0(6where u, v = depth-averaged velocity components in the x- and ydirections, respectively; t = time; g = acceleration due to gravity; h = water depth; b = bottom elevation; p = water density; 6ij = turbulent exchange coefficient tensor; and r = external traction. Internal (turbulent) stresses are modeled in the momentum equations (Eqs. 6.2 and 6.3) using an eddy viscosity model. The turbulent exchange coefficient tensor is equal to the eddy viscosity tensor multiplied by the water density. The
external traction includes bottom and surface friction and the Coriolis force. The components of the external traction are given by:
_x gU(U2+v2)05 CW2cs+ 20vsin( C2h T(
-y 2 +V2)0 CW2sin* + 2Qusin4 (6.5)
Y C2 hh
where C = Chezy coefficient; = empirical wind shear coefficient; W = wind speed; = wind direction; n = angular speed of earth's rotation; 0 = local latitude. The first term on the right-handside of the above two equations represents bottom friction, the second term represents wind shear stress, and the last term represents the effect of the Coriolis force. Assumptions
incorporated in Eqs 6.1-6.3 include (1) the water is incompressible, (2) vertical variations in velocities are negligible, (3) external (i.e., bottom and surface) friction is uniformly distributed over depth, and (4) pressure is hydrostatic.




The hydrodynamic module is capable of simulating emergence and/or submergence of a particular portion or feature (e.g., mud flats) of the water system being modeled (as often occurs with the cited example over the duration of a tidal cycle). It does this by eliminating 'dry' nodes (i.e., nodes with less than 10 cm of water depth) from the grid to simulate emergence, and by adding 'wet' nodes (i.e., previously dry nodes with more than 30 cm of water depth) to the grid to simulate submergence.
I
Sediment Transport Module: Cohesionless sediment transport occurs when the hydrodynamic forces (i.e., bed shear) acting on sediment particles at the bed surface exceed the resisting forces of interparticle friction and gravity. Thus, estimation of sediment transport requires calculation of the flow induced bed shear stress (or shear velocity). The equation used in the sediment transport module in STM-H to calculate the bed shear stress is the following Darcy-Weisbach type relationship:
lC = lpfclulu (6.6)
where fc is the current friction factor, given by the well known relationship from turbulence theories (Christoffersen, 1982):
(2)1/2 = 2.5 .n( 11.04h) (6.7)
in which kN is Nikuradse's bed roughness.
Two methods for predicting the total sediment transport rate are incorporated in the sediment module. These are the Einstein methodology (Simons and Senturk, 1978) and the Ackers-White algorithm (Ackers and White, 1973). The latter is used only when the median diameter, d50, is greater than 0.04 mm. When d50 is greater than 0.04 mm, the normal procedure is to alternatively use both methods and compare the results.




When sediment transport away f rom a point is not equal to that towards the same point, erosion or deposition will occur causing changes in the bottom elevation. Erosion will result if there is a net transport of sediment away from the point, while deposition will occur if there is a net sediment transport towards it. Using
a control volume approach in two horizontal dimensions, Fahien (1983) presented a differential balance of sediment volume flux and accretion/scour. The sediment volume conservation equation is given by
ab aq. aqy = 0 (6.8)
at ax +l
where b = local bed surface elevation, and qx, qY = components of the sediment load (dry weight) transport per unit width in the x,
and x2 directions, respectively, as determined using either the Einstein or Ackers-White equation. Equation 8 is used in the sediment transport module to estimate the local (i.e., at each node) bottom elevation change resulting from net sediment transport to or away from a given location. The elevation change at each node during a single time step is computed after the hydrodynamic and sediment transport computations are completed. The predicted bathymetric changes at a given time step are used in the
hydrodynamic module during the next time step to predict the new flow field.
6.2.3 Model Application
The portion of the Loxahatchee River estuary modeled is
indicated in Fig. 6.5 (the area enclosed by the elongated H's which cross water boundaries in the inlet channel, north and south sections of the Intracoastal Waterway, and the north, northwest and southwest forks). These water boundaries were chosen because of their proximity to tide gage stations used during a study in 1975
by the University of Florida (Chiu, 1975). The finite element grid constructed to represent this estuarine system is given in Fig. 6.6. The grid is composed of 576 quadrilateral elements and 1970 nodes. The size of the elements was varied such that the
93




highest density of nodes occurred in the areas of expected high spatial velocity gradients.
Initial conditions used in the hydrodynamic module were zero velocity and constant water surface elevation at all nodes. The initial nodal salinity values were set equal to the average of the high water slack and low water slack salinity distributions measured in the Loxahatchee River from Station 1 to Station 16 on February 26, 1975 (Chiu, 1975) (station numbers refer to those used in the 1975 study; see Section 6.1.3). That is, the initial
salinity at the 1970 nodes decreased approximately linearly (with distance upstream from the inlet) from 34.5 ppt at the inlet mouth to 31.5 ppt at the grid boundary in the northwest fork. Since the salinities were not measured on the same day (they were measured the next day) as the tidal elevations and flow velocities, it was assumed that the salinity initial and boundary conditions for February 25, 1975 were the same as those measured on February 26.
Boundary conditions for the hydrodynamic module consisted of the recorded water surface elevations during the spring tide on February 25, 1975 (Chiu, 1975). The measured tides at Stations T-l, T-2, T-3, T-5, and T-6 used in the 1975 study (see also Fig. 7.3 in Mehta et al., 1990a) were used for the boundary conditions for the grid boundaries at the inlet mouth, north branch of the ICWW, south branch of the ICWW, north fork, and northwest fork, respectively. The measured tides at these six stations are shown in Fig. 6.7. The boundary conditions used for the southwest fork were assumed to be the same as those measured at Station T-6 in the northwest fork.
Since!continuous salinity profiles were not measured during the 1975 study (only high water slack and low water slack distributions in the Loxahatchee River were measured), boundary conditions for the salinity module had to be assumed. Sinusoidally varying (with a 12.42 hour period) boundary conditions were used for the grid boundaries at the inlet mouth and in the northwest fork. The amplitudes of the sine functions for the inlet mouth and northwest fork were taken to be one half the difference between the high water slack and low water slack salinities at Stations 1 and




I I

16, respectively. The mean sine function values at the two
boundaries were assumed to be equal to the average of the high water slack and low water slack salinities at Stations 1 and 16, respectively.
6.2.4 Model Results
Results to date consist of only a partial calibration of the
hydrodynamic and salinity modules. The measured velocities at Stations C-1, C-4, C-5 and C-6 (see Fig. 7.3 in Mehta et al., 1990a) were used to calibrate the hydrodynamic module by adjusting the bottom friction coefficients until the predicted nodal
velocities at those locations were in fair agreement with the measured velocities. The bottom friction coefficients, which have to be prescribed for each element, were varied spatially throughout the grid to account for increased roughness associated with piles and grass beds (Fonseca and Fisher, 1986). Comparison between measured and predicted velocities are shown in Figs. 6.8 6.11 for the four stations listed above. Because of the short period of time that has elapsed since the required data were supplied to the consultant, the model calibration is not yet complete. In
addition, very good agreement is probably not achievable because
the exact locations of the stations where the velocities were measured are not given in Chiu (1975). The nodes at which the predicted velocities are compared to the measured velocities are at best in the "general vicinity" of the stations. Nevertheless, as seen in Figs. 6.8 6.11, fair agreement has been achieved between the measured and predicted velocities.
Figures 6.12 and 6.13 show velocity vector plots of the predicted flow fields during an ebb tide (at 11 AM on February 25,
1975) and during a flood tide (at 3 PM on February 25, 1975). Because of the large number of nodes and the small scale of these
figures, a velocity vector is only plotted at every other node (i.e., 9851 velocity vectors are plotted on each figure). The velocity vector plot shown in Fig. 6.14 represents the tidally averaged flow field (i.e., averaged over 12.42 hours) on February 25, 1975. Note the prominent tidally averaged northward




flow in the north branch of the ICWW, and the upstream flow in both the northwest and southwest forks.
Figure 6.15 shows a comparison between the predicted and measured low water slack salinity distribution along the Loxahatchee River. As seen, fairly good agreement between the measured and predicted salinites is achieved.
Model calibration is continuing, and when complete, calibration of the sediment transport module will begin. The
latter will be performed by comparing predicted and measured sedimentation rates in the two sedimentation basins in the proximity of the confluence of the Loxahatchee River and the north branch of the ICWW.




30
20

10

30
20

10

0 1

Fig. 6.1.

I I I I I I I 2 3 4 5 6 7 8 DISTANCE IN MILES (from entrance of Inlet)

iigh and low slack water salinity distributions in the Loxahatchee River estuary on February 26 and 27, 1975 (Chiu, 1975). Station numbers refer to Fig. 4.11 in Mehta et al., 1990a.

**6 66. p
**
* 0.0* 0
High water slack *
0*
-0
2-26-75 10:00l
0*
II~ l III I I I I 1 11 1 1 I I I II II I I I I

I I I 1 I I I I I I

00.00 .00
0
Low water slack *
0.00
12-26-75-1 7:0
I*
III ll I I l l I I I ~ l I I I 11

P* **00
,,, ,,,* I
High water slack
_ Sampling Stations
2-27-75 11:00
23458789 1012131415 1 171810 2 21 92 It SN M 272 20 303M132 IlI I I l lI I I llI I I I I I I II II I I li t