• TABLE OF CONTENTS
HIDE
 Cover
 Title Page
 Dedication
 Acknowledgement
 Table of Contents
 List of Tables
 List of Figures
 List of symbols
 Abstract
 Introduction
 Evolution of ebb tidal shoals
 Methodology
 Results and analysis
 Conclusions and recommendation...
 Appendix A: Influence of wave...
 Appendix B: Florida's East Coast...
 References






Group Title: UFL/COEL (University of Florida. Coastal and Oceanographic Engineering Laboratory) ; 86/017
Title: Inlet ebb shoal volumes related to coastal physical parameters
CITATION PAGE IMAGE ZOOMABLE
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STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00076165/00001
 Material Information
Title: Inlet ebb shoal volumes related to coastal physical parameters
Series Title: UFLCOEL
Physical Description: xiv, 115 leaves : ill. maps ; 28 cm.
Language: English
Creator: Marino, James N., 1956-
University of Florida -- Coastal and Oceanographic Engineering Laboratory
Publication Date: 1986
 Subjects
Subject: Inlets -- Florida   ( lcsh )
Coast changes -- Florida   ( lcsh )
Coast changes -- Atlantic Coast (U.S.)   ( lcsh )
Coastal and Oceanographic Engineering thesis M.S
Coastal and Oceanographic Engineering -- Dissertations, Academic -- UF
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Thesis: Thesis (M. Eng.)--University of Florida, 1986.
Bibliography: Includes bibliographical references (leaves 111-114).
Statement of Responsibility: by James N. Marino.
General Note: Typescript.
General Note: Vita.
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
Bibliographic ID: UF00076165
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved, Board of Trustees of the University of Florida
Resource Identifier: oclc - 16440029

Table of Contents
    Cover
        Cover
    Title Page
        Title Page
    Dedication
        Dedication
    Acknowledgement
        Acknowledgement 1
        Acknowledgement 2
    Table of Contents
        Table of Contents 1
        Table of Contents 2
    List of Tables
        List of Tables
    List of Figures
        List of Figures 1
        List of Figures 2
    List of symbols
        Unnumbered ( 11 )
        Unnumbered ( 12 )
        Unnumbered ( 13 )
    Abstract
        Abstract 1
        Abstract 2
    Introduction
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
    Evolution of ebb tidal shoals
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
    Methodology
        Page 23
        Page 24
        Page 25
        Page 26
        Page 27
        Page 28
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
        Page 36
        Page 37
    Results and analysis
        Page 38
        Page 39
        Page 40
        Page 41
        Page 42
        Page 43
        Page 44
        Page 45
        Page 46
        Page 47
        Page 48
        Page 49
        Page 50
        Page 51
        Page 52
        Page 53
        Page 54
        Page 55
        Page 56
        Page 57
        Page 58
        Page 59
        Page 60
        Page 61
        Page 62
        Page 63
        Page 64
        Page 65
        Page 66
    Conclusions and recommendations
        Page 67
        Page 68
        Page 69
    Appendix A: Influence of wave energy
        Page 70
        Page 71
        Page 72
    Appendix B: Florida's East Coast inlets
        Page 73
        Page 74
        Page 75
        Page 76
        Page 77
        Page 78
        Page 79
        Page 80
        Page 81
        Page 82
        Page 83
        Page 84
        Page 85
        Page 86
        Page 87
        Page 88
        Page 89
        Page 90
        Page 91
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        Page 94
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        Page 96
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        Page 103
        Page 104
        Page 105
        Page 106
        Page 107
        Page 108
        Page 109
        Page 110
    References
        Page 111
        Page 112
        Page 113
        Page 114
Full Text




UFL/COEL-86\017


INLET EBB SHOAL VOLUMES RELATED TO COASTAL
PHYSICAL PARAMETERS




by



James N. Marino






Thesis


1986
















INLET EBB SHOAL VOLUMES RELATED
TO COASTAL PHYSICAL PARAMETERS








By

JAMES N. MARINO


A THESIS PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN
PARTIAL FULFILLMENT OF THE REQUIREMENTS
FOR THE DEGREE OF MASTER OF ENGINEERING



UNIVERSITY OF FLORIDA


1986




























To my wife,

whom I love for her support

through yet another phase of my career.


To my parents,

for giving me the opportunity to develop my own character.














ACKNOWLEDGEMENTS

Many people have contributed to this work, giving of

themselves and their time. Above all, the author expresses

his gratitude to Dr. A. J. Mehta, chairman of the

supervisory committee, and to the other members of the

committee: Dr. H. Wang and Dr. R. G. Dean. Particular

thanks go to Mr. C. P. Jones for his much needed help and

sharing his insight.

Others have helped by providing information necessary

for the completion of this thesis, including Administration

Inc., Jupiter--Mr. C. Christian and Ms. L. R. MacDonald;

Coastal Planning and Engineering, Boca Raton--Mr. N.

H. Beumel; Department of Environmental Resources Management,

Miami--Mr. D. Ettman; Florida Oceanographic Society, Inc.,

Stuart--Mr. M. D. Perry; Ft. Pierce Port and Airport

Authority--Mr. M. Baggett; Gee and Jenson, West Palm Beach

--Mr. J. S. Yeend; Ponce de Leon Port Authority--Mr. D. M.

O'Brien; Port-Everglades Port Authority--Mr. R. T. Clapp;

Sebastian Inlet Tax District Commission--Mr. T. W. Smith and

Ms. J. Farrington; U.S. Army Corps of Engineers,

Jacksonville District--Mr. J. Lillycrop, Ms. B. Lancaster,

Mr. C. Stevens, Mr. R. Murphy, and Mr. Wm. Ivey.


iii








Special thanks go to Ms. Lillean Pieter for her

graphics, to Ms. Cynthia Vey for her technical typing

advice, and to Ms. Lucille Lehman and Ms. Helen Twedell for

their unending support in the Coastal Engineering Archives.

Gratitude is due to the United States Army and the

State of Florida Department of Natural Resources for their

financial support. Much of this research was funded under

DNR contract C3470.

My sincere thanks go to my peers who have helped me

with so much, particularly Mr. D. Mann and Mr. E. Cervantes

with whom I began this study.















TABLE OF CONTENTS

Page

ACKNOWLEDGEMENTS ................................. iii

LIST OF TABLES ................................... vii

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

LIST OF SYMBOLS......................... ......... x

ABSTRACT............ ............ .. ................ xiii

CHAPTERS

I. INTRODUCTION.. ................ .... .......... 1

Rationale.................................. 1
Objectives................................. 3
Coastal Physical Parameters................ 3
General Physical Environment .............. 6

II. EVOLUTION OF EBB TIDAL SHOALS.............. 12

Introductory Note.......................... 12
St. Augustine Inlet........................ 14
St. Lucie Inlet............................ 16
Boca Raton Inlet...................... ... 19
Conclusion................................ 21

III. METHODOLOGY .... .......................... 23

Dimensional Analysis................... 23
Ebb Shoal Volume.......................... 29
Tidal Prism .............. ......... .... 32
Cross-Sectional Area, Width, and Depth..... 34
Wave Energy ......................********. 34
Volume vs. Prism Relationship............. 36

IV. RESULTS AND ANALYSIS............ 0......... 38

Physical Parameters....................*.. 38
Comparison of Volumes........... .......... 39
Regression Analysis ........... ............ 56
Results of Dimensional Analysis............ 58
Discussion..........................************.. 63









V. CONCLUSIONS AND RECOMMENDATIONS............. 67

Conclusions........... ...... ........... 67
Recommendations............................ 68

APPENDICES

A. INFLUENCE OF WAVE ENERGY................... 70

B. FLORIDA'S EAST COAST INLETS................ 73

St. Marys Entrance ....................... 75
Nassau Sound.................................. 77
Ft. George/St. Johns Inlet................. 79
St. Augustine Inlet..................... 81
Matanzas Inlet............................ 83
Ponce de Leon Inlet....................... 85
Port Canaveral Entrance.................. 87
Sebastian Inlet .............. ............. 89
Ft. Pierce Inlet.. ................... ...... 91
St. Lucie Inlet............................. 93
Jupiter Inlet.............................. 95
Lake Worth Inlet........................... 97
South Lake Worth Inlet...................... 99
Boca Raton Inlet........................... 101
Hillsboro Inlet............................ 103
Port Everglades Inlet...................... 105
Bakers Haulover Inlet...................... 107
Government Cut...... ....................... 109

REFERENCES......................... ...... ...... 111

BIOGRAPHICAL SKETCH .............................. 115















LIST OF TABLES


Page

TABLE

I-1 Origin of Florida's East Coast Inlets..... 4

IV-1 St. Marys Entrance........................ 40

IV-2 Nassau Sound.............. ................ 41

IV-3 Ft. George/St. Johns Inlet................ 42

IV-4 St. Augustine Inlet....................... 43

IV-5 Matanzas Inlet.......................... 44

IV-6 Ponce de Leon Inlet....................... 45

IV-7 Port Canaveral Entrance.................. 46

IV-8 Sebastian Inlet........................... 47

IV-9 Ft. Pierce Inlet ......................... 48

IV-10 St. Lucie Inlet........................... 49

IV-11 Jupiter Inlet............................ 50

IV-12 Lake Worth Inlet...................... ... 41

IV-13 South Lake Worth Inlet..................... 52

IV-14 Boca Raton Inlet.......................... 53

IV-15 Bakers Haulover Inlet.................... 54

IV-16 Dimensionless Parameters.................. 59

IV-17 W/D versus V Comparison.................. 63

IV-18 Shear Stress Comparison.................. 65


vii
















LIST OF FIGURES


FIGURE

I-1 COASTLINE DISTANCE VS. WAVE ENERGY........ 8

1-2 COASTLINE DISTANCE VS. SHELF WIDTH........ 9

I-3 COASTLINE DISTANCE VS. TIDE RANGE......... 10

I-4 COASTLINE DISTANCE VS. NET SOUTHERLY
LITTORAL DRIFT RATE ..................... 11

II-1 ST. AUGUSTINE SHORELINE AND SHOAL
COMPARISON, 1937, 1975.................. 15

11-2 ST. LUCIE SHORELINE AND SHOAL COMPARISON,
1883, 1948, 1970.... ....... ......... ...... 17

II-3 BOCA RATON SHORELINE AND SHOAL COMPARISON,
1883, 1929, 1979............. ............. 20

IV-1 COMPARISON OF VOLUME ESTIMATES............ 55

IV-2 COMPARISON OF LINEAR REGRESSION ANALYSIS
RESULTS.......... ....... ............. ...... 57

IV-3 PLOT OF V/P VS. W/D WITH RESPECT TO Ac/ao2 61

A-I PLOT OF V/P VS. Hs2Tw2/ao2T2 WITH RESPECT
TO W/D................................... 72

B-1 ST. MARYS ENTRANCE, 1975.................. 76

B-2 NASSAU SOUND, 1954......................... 78

B-3 FT. GEORGE/ST. JOHNS INLET, 1978.......... 80

B-4 ST. AUGUSTINE INLET, 1979................ 82

B-5 MATANZAS INLET, 1978..................... 84


viii










Paae
FIGURE

B-6 PONCE DE LEON INLET, 1974................. 86

B-7 PORT CANAVERAL ENTRANCE, 1979............. 88

B-8 SEBASTIAN INLET, 1974.................. 90

B-9 FT. PIERCE INLET, 1975.................... 92

B-10 ST. LUCIE INLET, 1964.................... 94

B-11 JUPITER INLET, 1978............. ... 96

B-12 LAKE WORTH INLET, 1967................... 98

B-13 SOUTH LAKE WORTH INLET, 1979.............. 100

B-14 BOCA RATON INLET, 1981.................... 102

B-15 HILLSBORO INLET, 1961.................... 104

B-16 PORT EVERGLADES INLET, 1978............... 106

B-17 BAKERS HAULOVER INLET, 1969............... 108

B-18 GOVERNMENT CUT, 1978...................... 110















LIST OF SYMBOLS


a: Equal to log b

ab: Bay spring tidal amplitude

ao: Ocean spring tidal amplitude

Ab: Bay surface area; Maximum water particle displacement

Ac: Inlet cross-sectional area

b: Linear regression coefficient

CK: Prism correction coefficient defined by Keulegan

d: Water depth

ds: Bed roughness

D: Inlet depth at throat

Et: Tidal energy

E,: Wave energy

fc: Friction factor due to current

fw: Friction factor due to waves

ft: Feet

F: Force

g: Acceleration due to gravity

Hs: Significant wave height

L: Length; Wave length

Lo: Deep-water wave length

m: Meter; Number of fundamental dimensions; Linear
regression coefficient



x


I










mm: Millimeter

M: Littoral drift rate

n: Number of selected, governing physical quantities

N: Newton

Nij: Number of occurences in both the i- and j-domain

P: Spring tidal prism

PH: Hydraulic prism

PV: Volumetric prism

s: Offshore bottom slope

sec: second

SUM: Summation

T: Tidal period; Time

Tj: Wave period in the j-domain

T,: Weighted mean wave period

Ua: Alongshore current

uc: Water velocity due to currents

uw: Water velocity due to waves

V: Ebb shoal volume

Vmax:Cross-sectional inlet average maximum velocity
ws: Sediment settling velocity

W: Inlet width at throat

x: Equal to log P

R: Mean value of x

y: Equal to log V

7: Mean value of y


xi










yr: Year

p: Density of seawater

T : Shear stress due to currents

T : Shear stress due to waves


xii














Abstract of Thesis Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Master of Engineering



INLET EBB SHOAL VOLUMES RELATED
TO COASTAL PHYSICAL PARAMETERS

By
JAMES NICHOLAS MARINO

DECEMBER 1986
Chairman: Dr. A. J. Mehta
Major Department: Coastal and Oceanographic Engineering

Tidal inlets impact significantly on the local coastal

sedimentary budget. The general nature of inlet ebb shoal

development was examined through three case studies on the

east coast of Florida. Next, the ebb shoal volumes of the

eighteen inlet systems on the east coast of Florida were

estimated. Finally, the degree to which various coastal

physical parameters influence the ebb shoal volume was

investigated.

The case studies were those of St. Augustine,

St. Lucie and Boca Raton Inlets. It was found that ebb

shoals at these inlets evolved in quite different manners.

There is a general trend of decreasing ebb shoal volume from

north to south. A total of 420 million cubic meters of

sediment are found to reside in the ebb shoals of



xiii


------"










the eighteen inlet systems. Of that total, 83% resides in

four northernmost inlet systems. The ebb shoal volume, V, is

found to depend on the spring tidal prism, P, the inlet

width/depth ratio, W/D, the flow cross-sectional area, Ac,

and the tidal amplitude, ao. The effect of the width/depth

ratio on the ebb shoal volume signifies the role of both

inlet current and waves in influencing ebb shoal

development, as observed previously by Walton and Adams.








'Cairman


























xiv















CHAPTER I
INTRODUCTION

Rationale

Tidal inlets impact significantly on the local coastal

environment. The inlet provides access to sheltered harbors

from strong ocean currents and waves, to both the commercial

and recreational user. The ebb tidal shoal is one of the

most dominant features of a coastal inlet.

The ebb shoal occurs at an inlet when sediment is

trapped offshore of the mouth due to various coastal

physical processes. The sediment is removed from the

littoral drift and deposited typically in a crescent- or

kidney-shaped formation. Once the shoal has developedit

can serve as a bridge of sorts, transporting material from

the updrift beach to the downdrift side, when conditions

permit. Since the shoal is typically a much shallower area

than its surrounding region, it also serves as an energy

dissipator. As ocean waves approach the shore, they break

and dissipate their energies in the shallow water regions.

If the shoal causes these waves to break offshore, then the

local beach or coastline is in effect sheltered from the

erosional impact of these waves.









If the shoal is significantly large, it is a possible

source of sediment for beach nourishment. Several factors

impact on the feasibility of using this material in beach

renourishment projects. One must consider the relative

amounts of material needed and that which is available.

Ideally, the material used for the fill should be of the

same or greater coarseness than that of the native material.

After the factors have been considered, the accessibility of

the area needs to be taken into account. Whereas, flood or

bay shoals may have been ruled out because of possible

detrimental environmental effects and distant offshore

troughs ruled out because of the lack of quantity or quality

of material and transport problems, the ebb shoals can pose

a different kind of problem. The dredge or device used to

collect the material from the shoal may very likely be

subject to extreme breaking wave conditions. An additional

consideration before determining whether or not the ebb

shoal should be used for renourishment is the effect that

its removal will have on the local wave climate. If the

shoal had been sheltering the coast, how will its removal

change the erosional patterns? Should only part of the shoal

be removed? How will its removal impact on navigation? These

are some of the questions which must be considered in the

determining the best course of action to be taken with

regard to ebb shoals.










Objectives

The objectives of this study were three-fold. First,

the general nature of ebb shoal development was examined

with reference to three inlet systems on the east coast of

Florida. Next, the ebb shoal volumes at eighteen coastal

inlet systems, also along Florida's east coast, were

estimated. Finally, the degree to which significant coastal

physical parameters are related to ebb shoal volumes was

investigated.

Each of the eighteen inlet systems is unique in its own

way. Although an "ideal" ebb shoal can be drawn graphically

or developed in a laboratory, rarely can one be found in

nature. This holds true for the east coast of Florida. The

origins of all eighteen systems are summarized in Table I-1.

This table details the origin of each inlet, whether natural

or man-made, the year in which it was opened and.when

jetties were constructed, if any.


Coastal Physical Parameters

This study will investigate the following parameters

and their relationship to ebb shoal volume, V, spring tidal

prism, P, inlet cross-sectional area, Ac, inlet width, W,

inlet depth, D, spring tide amplitude, ao. Several other

physical parameters characterize the ebb shoal; however,

only these more significant ones are examined in this study.










Table I-1. Origin of Florida's East Coast Inlets

Inlet Origin Remarks

St. Marys natural jettied 1881-1904

Nassau Sound natural


Ft. George/St. Johns natural

St. Augustine man-made


Matanzas

Ponce de Leon

Port Canaveral


Sebastian


Ft. Pierce


St. Lucie


Jupiter

Lake Worth


South Lake Worth


Boca Raton


Hillsboro

Port Everglades


natural

natural

man-made


man-made


man-made


man-made


natural

man-made


man-made


man-made


natural

man-made


jettied 1881

opened in 1940, 4 km
north of natural
inlet; jettied 1941,
1957



jettied 1968-1971

opened in 1950;
jettied 1953-1954

opened in 1948;
jettied 1952,1955

opened in 1921;
jettied 1921

opened in 1892;
jettied 1926-1929,
1982

jettied 1922

opened in 1917;
jettied 1918-1925

opened in 1927;
jettied 1927

opened in 1925;
jettied 1930-1931

jettied 1952,1966

opened in 1926;
jettied 1926-1928;
replaced two nearby
inlets










Table I-1--continued

Inlet

Bakers Haulover



Government Cut


Origin

man-made



man-made


Remarks

opened in 1925;
jettied 1925,1975,
1986

opened in 1902;
jettied 1902,1907


Source: Marino and Mehta (1986)









Each of the parameters has been studied at one time or

another by other investigators, but never collectively.

Relevant previous work is utilized and presented in this

study. A dimensional analysis approach is used to determine

which parameters best explain trends and relationships that

are found with respect to the inlet ebb shoals on Florida's

east coast.


General Physical Environment

The general physical environmental condition along the

east coast of Florida would serve as useful background

information prior to examining the possible relationships

between the various selected parameters and the ebb shoal

volumes. Figures I-1 through I-4 depict the following

coastal environmental parameters versus coastline distance

along the east coast of Florida, from St. Marys.Entrance to

Government Cut: wave energy, shelf width, tide range, and

net littoral drift rate. The derivation of the wave energy

data is covered in Chapter III. The shelf width data are

obtained from National Ocean Survey (NOS) nautical charts.

The tide range data are the spring tide values taken from

the National Ocean Survey (NOS) Tide Tables. The littoral

drift rate data are taken from the U.S. Army Corps of

Engineers (1967).

Figure I-1 shows a somewhat higher wave energy defined

as HsTw2, where Hs is the significant wave height and Tw











is the wave period in the northern eleven inlet systems. The

wave energy parameter, Hs2T2 decreases most noticeably

between Jupiter Inlet and Lake Worth Inlet. The shadow

effect caused by the Bahama Islands may be the most

significant factor in that respect.

Figure I-2 depicts the constant narrowing of the shelf

width from north to south. The shelf width remains nearly

constant from Lake Worth Inlet to the south. Figure I-3

shows that the spring tide range in the northern inlets is

somewhat higher than in those from Sebastian Inlet to the

south. Figure I-4 depicts the general, although not uniform,

decrease in the net littoral drift rate from north to south.

The data presented subsequently in this study are

derived primarily from charts and survey maps of the

National Ocean Survey, the U.S. Army Corps of Engineers and

from reports of the University of Florida. Aerial

photographs supplemented the information from these sources.

No field measurements or observations were made as a part of

this study. Personal visits were made to each of the inlets

and their respective controlling agencies, in an effort to

gain the most recent information.














o Hindcost Data
A CDN Dato
N.4


01 0
""a a-0 <
I-
20 oc


20 0
X" 0
mo LI o


o" o a.
S9A o? LAI r .
' fl rl 3 ...0
w w No +" '4

L It II
=r C
>w CI L 3 A cu




SI I I I I I


C0 100 200 300 400 500

DISTANCE (km)


FIGURE I-1. COASTLINE DISTANCE VS. WAVE ENERGY































0

o


r VtA C+
U' 1

I L I I
ZC 0 C K
' c O C H




I I


200


'U

D


0*

-*. 0
r+
Ft
C1 3 v
3 3 3 3
"1 :y a

i I T


300 400 500

DISTANCE (km)


FIGURE 1-2. COASTLINE DISTANCE VS. SHELF WIDTH


w
0
o
nr
nj i


w o
G'3


r+n
Ft W" 2
crn

M
m
to'


ro(
w



I I


I

r















C)
o0

2. -

0 0 <-
w g 3
o 0
0 0, 0 0 0
0 0

o 0o" C o 0
-u A o o o ao0

SI I I I



) 100 200 300 400 500
DISTANCE (km)
OC -0 a# m I D




100 200 300 400 500
DISTANCE (kmn)


FIGURE 1-3. COASTLINE DISTANCE VS. TIDE RANGE

















S400




0 -U
pq I



b II a lb l. -
oo

2 0 0 cc

S0; IIk
200- o







DISTANCE (ki()
FIGURE -4. COASTLINE DISTANCE VS. NET SOUTHERLY LITTORAL DRIFT RATE
oo 100 c CC, Ir < -2. =r \
&+ 0 I i r-
z Q L W a no



-0 100 200 300 400 500














CHAPTER II
EVOLUTION OF EBB TIDAL SHOALS

Introductory Note
To trace the evolution of an inlet ebb shoal, a time

history of the inlet must be studied. Man-made or artificial

inlets were chosen that have been opened in relatively

modern times. The inlets of St. Augustine, St. Lucie and

Boca Raton were selected as case studies. Each has a unique

history and helps in explaining differences in evolutionary

trends as well as difficulties which are typically

encountered in precisely determining the shoal volume at any

particular point in time.

Much work has been done in the laboratory concerning

the development of ebb tidal shoals. This work includes, but

is not limited to, that done by Mayor-Mora (1977), Ozsoy

(1986), and Sill, Fisher. and Whiteside (1981). The Mayor-

Mora study conducted a series of idealized movable-bed tidal

inlet model tests. A significant conclusion found in that

study shows that as the tidal prism increases the inlet area

also increases, as was found by O'Brien (1969) and Jarrett

(1976). Ozsoy studied the mass transport by turbulent jets

issuing from tidal inlets through a mathematical model.

Important conclusions from this study are that the sediments









supplied by littoral processes are then entrained into the

tidal residual circulation and finally deposited in the

shoals and that the pattern of deposition depends on bottom

friction, slope, inlet current intensity, and the size of

sediment. The Sill, Fisher and Whiteside study was designed

to evaluate the appropriateness of the ebb jet hypothesis in

a laboratory model. Primary conclusions drawn from this

study state that the equilibrium shoal length and width

increase in direct proportion to the average inlet velocity

at the point of initiation of ebb jet, and that inlet width

and "critical" sediment velocity are appropriate scale

factors for laboratory shoals. Each of these represent

controlled environments and the variables are limited.

Unfortunately, that is not the case in nature.

The three inlets chosen differ from each other not so

much as in the way they were opened, but in how each local

coastline reacted to its opening. The effects of jetties,

dredging and longshore sediment transport become evident in

the investigation. St. Augustine Inlet was cut 4 kilometers

north of an existing inlet in 1941. St. Lucie Inlet was

created by local residents in 1892, to serve as a connecting

channel between the Indian River and the Atlantic Ocean.

Boca Raton Inlet is considered a man-made inlet although it

existed as a natural inlet from time to time prior to its








stabilization in 1925, according to Strock and Associates

(1983a).


St. Augustine Inlet
Figure II-i depicts both the previously (1937) existing

shoreline and shoal patterns with that of the present (1975)

for St. Augustine Inlet (U.S. Army Corps of Engineers,

1977). Locations A and B on the figure represent the areas

through which the old, natural inlet meandered, prior to the

new inlet opening at location C, in 1940. The shoal contour

lines delineate significant levels of sediment deposition

above the ideal beach profile, in feet (lft=0.305m). The

ideal profile is defined as the the natural beach profile

in that local area, as if the inlet were not present. For

example, any area outside the 5 ft (1.5 m) contour line

would have a deposition above the assumed ideal profile of

less than 5 ft (1.5 m). The area within the 5 ft (1.5 m)

contour would have deposition of greater than 5 ft (1.5 m)

above the ideal profile, up to the 10 ft (3.1 m) contour and

so forth. The exact volumes and methods used in determining

those volumes are covered in Chapters III and IV. It can be

seen in Figure II-1 that as a result of the opening of a new

inlet, the previously existing ebb shoal was caused to

migrate. The old shoal formation moved both westward, to

form what is now known as Conch Island, and northward to the

new inlet. The old inlet, which was located at location B in




























S---- 1975 Shoreline
B ---- 1937Shoreline
5' / 1975 Shoal Contours
"/ / -- -- 1937 Shoal Contours

I \ / Shcol Contour Conversion
/ I It. 0.305 m

10'
\ /. / 5" /
:' : ^ .



S?
5 -. .- Scale -elr

FIGURE II-1. ST. AUGUSTINE SHORELINE AND SHOAL
COMPARISON, 1937, 1975









1937, was completely closed by 1957. The present shoal is

rather elongated as opposed to crescent-shaped. This is

believed to be due to the presence of a predominant

longshore current to the south. The narrowest part of the

shoal seen directly east of the inlet is evidence of the

dredging done by sidecast dredges through the shoal area

since 1940. The large bulge adjacent to the south jetty is a

direct result of the jetty being constructed in 1957. The

shoreline since construction has moved eastward

approximately 750 meters adjacent to the jetty. This is

evidence of jetty sand-trapping during periodic seasonal

reversals of the littoral drift.


St. Lucie Inlet

St. Lucie Inlet is depicted in Figure 11-2. Walton

(1974a) presents several individual charts which have been

overlayed here to show the dramatic effect of the opening of

a new inlet on the coastline. The figure shows the

approximately 1000 meter retreat of the shoreline at the

south side of the inlet. The majority of this retreat

occurred prior to 1948, as is seen in the figure.

No shoal existed prior to the inlet being opened in

1892. It is seen that the shoal is divided into two lobes

rather than a single elongated shoal. The southern lobe is

situated directly over the location of the pre-construction

shoreline. It is believed that much of the material present








































197OShoreline "
-- -1948Shoreline
----- 1883Shoreline
Shoal Contours

Shoal Contour Corwersion


0 500 1000
Scale meters


FIGURE 11-2. ST. LUCIE SHORELINE AND SHOAL
COMPARISON, 1883, 1949, 1970









in this shoal was once a part of the shoreline prior to its

erosion and migration westward. The division of the two

lobes is maintained by periodic dredging of a channel

through the shoal. In the last 20 years approximately

382,000 cubic meters of dredge material has been deposited

in the vicinity of the south lobe (Florida Oceanographic

Society, 1982).

There is strong evidence that, although the shoreline

has retreated significantly, not all of the sand has eroded

and lost to the downdrift beaches. A close examination of

the land area suggests that the northern part of Jupiter

Island (south of the inlet) has migrated westward as sand

has washed through the inlet and deposited in the lagoon

area behind the island. The land areas presented in Figure

II-1 were planimetered to determine the approximate areas

involved. The land area present in 1883 was 2.2 million

square meters, while it is found to be 2.7 million square

meters in 1970. While this computation of areas does not

necessarily correspond to representative volumes, it does

give some idea as to where a significant amount of the sand

seems to have gone.

Further compounding the shoal development issue is the
existence of a reef which runs parallel to the coastline

approximately 1000 meters offshore. The reef had caused a

natural tidal current to form that ran from the inlet to the









south according to the Florida Oceanographic Society (1982).

This fact lends further credibility to the observation

regarding sand being washed into the inlet during flood tide

and being deposited on the lagoonal side of Jupiter Island.

The construction of a south jetty in 1980-1982 has since

diverted this tidal current eastward.


Boca Raton Inlet

Boca Raton Inlet, depicted in Figure II-3, is unique in

that it was closed during a storm as recently as 1967.

Again, an examination of this inlet shows clearly the effect

of jetties and the longshore current on shoal formation. The

shoreline has not eroded nor retreated with the same

severity as seen at St. Lucie. The elongated shape of the

shoal in the southerly direction depicts the influence of

the predominant littoral drift. The net longshore transport

rate in the southerly direction is reported to be between

90,000 and 170,000 m3/yr according to the U.S. Army Corps of

Engineers (1967).

The inlet was opened by dredging in 1925 and jetties

were emplaced in 1930. The inlet has had a history of

continual shoaling. The jetties were relatively short and

acted as little more than retaining walls, particularly on

the north side. In 1975 the north jetty was extended 55

meters to the east. In. 1980, a 20 meter weir section was

constructed. The south jetty was reinforced and extended












N
















5'



19


1979 Shoreline
1929 Shoreline
1883 Shoreline
1979 Shoal Contours


Shoal Contour Conversion
I ft = 0.305 m


600


900


FIGURE 11-3.


Scale meters
BOCA RATON SHORELINE AND SHOAL
COMPARISON, 1883, 1929, 1979


0 300


~~~~~~~










landward to prevent flanking. In an examination of aerial

photographs from Strock and Associates (1983a), it can be

seen how the lengthening of the north jetty has forced the

shoal to form approximately 250 meters away from the inlet

mouth. With the help of a dredge which by-passes material

from within the inlet, the inlet has not shoaled since 1967.

Further examination of aerial photographs reveals that the

ebb shoal serves as a moderately efficient sand by-passing

bridge, since no channel is dredged through it.


Conclusion

These three inlets are mere examples of how ebb shoals

form and how the coastline reacts and adjusts due to the

formation of an inlet. It can be seen that by constructing

jetties of sufficient length to stabilize an inlet, as was

done at St. Augustine and Boca Raton, the shoals are

maintained a significant distance away from the inlet. It

can also be observed that dredging significantly affects the

shape of the shoal. At St. Lucie and St. Augustine the

shoals are divided into two distinct lobes, where there are

channels dredged, rather than one large mass as is the case

with the Boca Raton, where there is no dredged channel. In

all three cases, the great majority of the shoal area is

located to the southeast of the inlet mouth. This is

apparently due to the effect of the predominant longshore

current along the coast (see Figure 1-4).






22


Each of the eighteen inlet systems identified have

their own unique features. The remainder of this study deals

with estimating the ebb shoal volumes associated with those

inlets and in explaining how the various physical parameters

are related to those volumes.















CHAPTER III
METHODOLOGY


Dimensional Analysis

One approach to determine which parameters are

important in characterizing the ebb shoal volume is through

appropriate non-dimensional governing variables, using the

procedure of dimensional analysis. The basic objective in

dimensional analysis is to reduce the number of separate

governing variables involved to a smaller number of

independent dimensionless parameters. This procedure was

originally presented in 1915 by Buckingham and summarized in

Roberson and Crowe (1975). The Buckingham Pi Theorem shows

that the number of independent dimensionless parameters

needed to correlate the variables in a given process is

equal to n m, where n is the number of selected, governing

physical quantities and m is the number of fundamental

dimensions.

The process is started by identifying those variables

that are significant to the problem. In the most general

sense, the following variables may be selected as having a

bearing upon the ebb shoal volume: the (maximum) inlet

current velocity, Vmax, inlet width, W, inlet depth, D,tidal









range or amplitude, ao, tidal period, T, wave height, Hs,

wave period, Tw, alongshore current, ua, offshore bottom

slope, s, acceleration due to gravity, g, density of

saltwater,p and sediment settling velocity, ws. Some of

these parameters have been previously noted by other

researchers including Dean and Walton (1973), Walton and

Adams (1976), Sill, Fisher and Whiteside (1981), and Ozsoy

(1986). Considering, however, the Florida east coast

environment (as described in Chapter I) and practical limits

imposed by the availability and accuracy of data used, only

the more significant of these variables could be considered;

these may be combined to form a functional relationship

which can be written as

f(V,P,W,D,Ew,Et,ao2,s) = 0 (1)
where V is the ebb shoal volume, P is the spring tidal

prism, W is the inlet width at the throat, D is the inlet

depth, Ew is the wave energy, Et is the tidal energy, ao is

the spring tide amplitude, and s is the offshore bottom

slope. The slope, s, may be excluded in the derivation of

dimensionless parameters. The slope, s, was obtained by

measuring the perpendicular distance offshore to the 10

meter depth contour and dividing that distance by the depth.

This was done in all but the northern three inlets, where

the 6 meter contour was used due the complex nature of the

offshore bathymetry in the area. NOS charts 11467, 11472,









11476, 11485, 11488, and 11489 were used to obtain this

information. The slope was eliminated from further

discussion since all the values (presented in Tables IV-1

through IV-15) lie in a very narrow range, between 0.3 and

1.0 degrees. Furthermore, the ratio of the standard

deviation to the mean was found to be significantly small

(0.34).

Thus, the functional relationship is reduced to

f(V,P,W,D,Ew,Et,ao2) = 0 (2)

with seven physical quantities. Of the three possible

fundamental dimensions, force, F, length, L, and time, T, F

and L are present. Therefore, there are n m = 5

dimensionless parameters or Pi-terms. Choosing Ew and W as

the repeating variables, which include F and L, the first

Pi-term can be expressed as a product of the repeating

variables to unknown exponents and any one other variable to

the first power:

Pil = (Ewx) (WY) (V) (3)

Since Pil is now dimensionless, the requirement of

dimensional homogeneity yields

FOL0 = (FxL-x) (LY) (L3) (4)

Equating exponents yields

F: 0 = x (5)

and


L: 0 = -x + y + 3








or y = -3. Therefore,


Pi1 = V/W3
This procedure is repeated for the next four Pi-terms:


Pi2 = (EX) (WY) (P)


FOLO = (FXL-X) (LY) (L3)


(9)


yielding


F: 0 = x


L: 0 = -x + y + 3


(10)


(11)


or y = -3. Therefore,

Pi2 = P/W3

Pi3 = (EX) (WY) (D)
and

FOL0 = (FXL-X) (LY) (L)


(12)

(13)


(14)


yielding


F: 0 = x


L: 0 = -x + y +


(15)


(16)


or y = -1. Therefore,

Pi3 = D/W
Pi4 = (EX) (WY) (ao2)
and

FOLO = (FXL-x) (LY) (L2)


(17)

(18)


(19)


yielding


and


and


and










F: 0 = x (20)
and

L: 0 = -x + y + 2 (21)

or y = -2. Therefore,

Pi4 = ao /W2 142)

Pi5 = (EwX) (wY) (Et) (23)

and

FO0L = (FXL-x) (LY) (FL-1) (24)

yielding

F: 0 = x + 1 (25)
and

L: 0 = -x + y 1 (26)

or x = -1 and y = 0. Therefore,

Pi5 = Et/Ew (27)
According to the rules of dimensional analysis some re-

arranging is authorized. The Pi3-term is raised to the -1 to

yield

Pi3 = W/D (28)
The Pi3-term is divided by the Pi4-term to yield

Pi4 = Ac/ao2 (29)

Finally, the Pi5-term is raised to the -1 to yield

Pi5 = Ew/Et (30)

These, along with the original Pil- and Pi2-terms yield the

following functional relationship:

f(V/W3,p/W3,W/D,Ac/ao2,Ew/Et) = 0 (31)










The fifth Pi-term can be eliminated from further

consideration for the reason that follows. The wave energy,

Ew, values lie in the same range as defined by Walton and

Adams (1976). Walton and Adams state that if the values of

the wave energy parameter Hs2T 2 are between approximately 3

and 30 m2sec2, then the wave energy climate is considered to

be "moderate" (as opposed to "high" for values greater than

30 m2sec2 and "low" for values less than 3 m2sec2). The wave

energy values as presented in Tables IV-1 through IV-15 for

the east coast of Florida all fall within that range. This

study compares the ebb shoal volume to prism relationship

with that presented by Walton and Adams (1976). Since Walton

and Adams related that V/P ratio to the Ew parameter solely,

and not the Ew/Et ratio, it is essential that this study

rely on the same criteria for comparison. The Ew-term can be

considered as being predominant in this ratio, because it is

more widely varying. Since the wave energies all lie within

the moderate range, the energy parameter, Ew/Et, is

eliminated from further consideration. An alternate

explanation of the elimination of the energy parameter is

given in Appendix A. There it is shown that within the

"moderate" energy band, Florida's east coast inlet shoal

volumes showed no identifiable relationship to the ratio of

wave energy to tidal energy.









This leaves the following functional relationship to be

further examined for significant trends:

V/W3 = f(p/w3,W/D,Ac/ao2) (32)
These parameters are related to the kinematic aspects of the

tidal inlets. A dynamic analysis involves the consideration

of forces acting on the fluid particles in motion with

respect to one another. Shearing forces are important in the

analysis (Yuan, 1967). The shear stresses involved and their

effects are examined in detail, in Chapter IV. Additional

dynamic aspects are considered in Appendix A, when comparing

the energy parameter, Ew/Et, relative to V, P and W/D. Thus

the ebb shoal volume V, is seen to be dependent on the

spring tidal prism, P, the inlet aspect ratio (width to

depth), W/D, and the ratio Ac/ao2. This last parameter has

been used by O'Brien and Clark (1973) for characterizing

inlet-bay hydraulics, particularly as it relates to the size

of the inlet-bay system, and the manner in which bay filling

through tide occurs. The next step is to determine the

actual values of the parameters involved.


Ebb Shoal Volume

The ebb shoals include most of the stored sediment at

an inlet. The inlets under consideration presented several

different problems in the details of analysis, but in every

case, the basic technique applied for ebb shoal volume

estimation was that developed by Dean and Walton (1973), for









differentiating between the sands making up the ebb shoal

and those of the coast proper. The technique is explained in

detail in that reference and is summarized in this report.

NOS nautical charts and hydrographic sheets were used for

each of the eighteen inlet systems. The steps taken to

estimate the volumes of sand residing in the ebb shoal are

as follows:

1. Construct idealized, no-inlet contour lines.

2. Impose a 305 meter (1000 foot) square grid system on

the chart and calculate differences between actual

depth and idealized no-inlet depth at grid line

intersections.

3. Average depth differences at intersections and

record in center of block.

4. Compute volume of sand in outer shoal by summing

averaged block depth differences and multiply by

9.29x104 meters2 (106 feet2).

This technique worked well in most instances; however

some adjustments had to be made in cases where conditions

were less than "ideal". Two significant problems were the

existence of offshore reefs in southern Florida and the the

existence of large, natural offshore shoals between St.

Marys Entrance and St. Johns River Inlet. In their simplest

description, the offshore contour lines updrift and

downdrift of the inlet would be shore-parallel, and









represent the idealized no-inlet condition. In the case of

Nassau Sound, there were no parallel contour lines which

appeared to fit the idealized description. Hence, the value

of the ebb shoal volume used was taken from Dean and Walton

(1973). In the case of the southern inlets, from Ft. Pierce

to Government Cut, consideration had to be given to reef

formations. As an example, the contour lines at Ft. Pierce

updrift and downdrift of the inlet were not at the same

distances from the shoreline. The idealized contours were

therefore drawn by interpolation between the updrift and

downdrift sides. In the case of three inlets, Hillsboro, Pt.

Everglades, and Government Cut, the presence of offshore

reefs and associated shoals made the estimation of the ebb

shoal volumes too complex. These inlets were, therefore,

eliminated from further consideration. Chronological

development at these inlets is presented in Appendix B.

Another problem to be worked out was in determining how

inlets, which were very wide or had significant offsets,

were to be dealt with. Where the updrift and downdrift sides

of the inlet were offset (or imbalanced) with respect to

each other, special consideration had to be given in

determining which grid pattern would be used. The best

solution was to reduce the size of the grid overlay from 305

meter square to 152 or 76 meter square. By using a smaller

grid less detail was lost in the vicinity of the inlet.




.'e










Once the idealized contours and the appropriate grid

size were selected, they were superimposed on the charts.

The depth differences between the actual and idealized no-

inlet contours were calculated to the nearest 0.3 meters (1

foot) at the intersection of grid lines. Depth differences

were then averaged for each grid square. These values were

added to give the total volume difference between the actual

and the idealized condition. The results are presented in

Tables IV-1 through IV-15.


Tidal Prism
The values selected for prism on the spring range of

tide were taken from published sources with the exception of

two inlets, South Lake Worth and Boca Raton. Three

techniques were found to have been used in literature for

the estimation of tidal prism. The techniques are the

Hydraulic Prism Method presented by Keulegan (1967), the

Cubature Method presented by Jarrett (1976), and the

Volumetric Prism Method.

The hydraulic prism is defined as

PH = (Vmax Ac T) / ( WCK) (33)
where Vmax is the cross-sectional average maximum velocity

of the tidal current through the inlet,.Ac is the inlet

cross-sectional area, T is the tide period (taken as 44,640

seconds for a semi-diurnal tide), and CK is a coefficient








developed by Keulegan (understood as 0.86 for this study).

This equation was used in estimating the prism values for

South Lake Worth and Boca Raton Inlets.

The Cubature Method for calculating tidal prisms takes

into account the time required for a tidal wave to propagate

through an inlet and into a bay (Jarrett, 1976). The method

divides the bay into areas which have approximately the same

phase range of tide, rather than assuming that the tide

rises and falls uniformly. The average surface area of each

sub-area is measured and multiplied by the phase range to

obtain the volume of water entering or leaving the sub-area

between succeeding periods of slack water. All of the sub-

area values are then summed to yield the tidal prism.

The volumetric method is simply stated by the

following

PV = 2 Ab ab (34)
where Ab is the area of the bay and ab is the bay tide

amplitude. The particular problem in using this relationship

arises from the difficulty in accurately estimating the bay

area. If the bay is of an irregular shape or is ill-defined,

it is difficult to correctly compute the area.

If data cannot be physically measured for use in these

prism formulas, then the NOS Tide Tables, Current Tables and

Navigation Charts can be used to obtain the velocity, inlet

cross-sectional area, bay area, and tidal amplitude data.










Cross-Sectional Area, Width and Depth

The cross-sectional area, width and depth values were

obtained from previous studies. The sources for these sets

of data are enumerated within Tables IV-1 through IV-15. It

should be noted that cross-sectional area was measured at

the inlet throat or the narrowest point. The width and depth

values were taken from previous studies for each inlet.

Where more than one source is noted, the values have been

combined by averaging to yield one value for the purpose of

this study.


Wave Energy
Wave energy is defined by Walton and Adams (1976) in

terms of the parameter, Hs 2T, where Hs is the wave height

and Tw is the wave period. This parameter is derived from

fundamental Airy Wave Theory. The wave energy per unit width

is represented by the expression

Ew = pgHs2L/8 (35)
where p is the density of seawater, g is the acceleration

due to gravity, Hs is the significant wave height, and L is

the wave length. Further, the deep-water wave length, Lo, is

related to the wave period, Tw, by the expression

Lo = gTw2/2n (36)
Lo is related to L through Table C-l, Coastal Engineering

Research Center, Shore Protection Manual (1984), as they are








both a function of water depth. Thus, the wave energy can be

conveniently represented as a function of Hs2Tw2. The tidal

energy parameter, ao2T2, can be derived in a similar

fashion. Here, ao is the tidal amplitude and T the period.

Jensen (1983) presents hindcast, shallow-water,

significant wave information covering a 20-year period. The

data are available for each of the East Coast inlets. The

average significant wave height, Hs, is given for each

location. However, the wave period is given in ten frequency

bands for each of ten wave height bands. These values were

combined to obtain a weighted mean period, Tw, using the

following expression

Tw = ((SUM Tj)(SUM Nij)] / (SUMij Nij) (37)
where SUM Tj is the summation of the values in each

frequency range, SUM Nij is the summation of the number of

occurrences of each frequency range and SUMij Nij is the

summation of the total number of occurrences for that

location. These data are plotted in Figure I-1 and the

values are presented in Tables IV-1 through IV-15.

University of Florida Coastal Data Network (CDN) values for

1984 are also given in Figure I-1. Even though these values

are only for a single year, they are useful for comparison

purposes. The values of Hs and Tw from these data were

derived in the same manner as previously described for T,,

however only five locations are available for use.








The values derived from the hindcast data are then

analyzed to determine which energy range they fit into, as

defined by Walton and Adams (1976). The ranges chosen to

describe mildly exposed, moderately exposed, and highly

exposed were 0.0-3.0, 3.0-30.0, and >30.0, respectively (in

m2sec2). The results are provided in Tables IV-1 through IV-

15.


Volume vs. Prism Relationship

The ebb shoal volume versus spring tidal prism

relationship presented by Walton and Adams (1976) was used

as the focus of this study's analysis. That study concluded

that there is a strong correlation between the volume of

sand stored in the ebb shoals of inlets with their

respective tidal prisms (and cross-sectional areas). The

wave energy parameter was used to explain the differences in

the correlation of these parameters. Of the three ranges of

energy, previously described, the mildly exposed coast

contained the largest volumes, while the highly exposed

coasts had the smallest volumes. Walton and Adams (1976)

found the volume/prism ratio to be a function of inlet

cross-sectional area and wave energy. A linear regression

analysis is conducted to determine a comparable volume/prism

relationship based on this study's data. The volume/prism

relationship derived from this analysis is then compared to

that presented by Walton and Adams (1976). The correlation










coefficient for each set of data is determined and compared

for relative accuracy (scatter).

This study takes that conclusion one step further to

determine which parameters explain the scatter of data

within the same relative wave energy range. The dimensional

analysis, previously discussed, revealed that the volume is

likely to be dependent upon the prism, the cross-sectional

area/tidal amplitude (squared) ratio and the width/depth

ratio when the wave energy is invariant, as shown in

equation (32). These parameters are used to determine what

physical trends exist and their degree of correlation.














CHAPTER IV
RESULTS AND ANALYSIS

Physical Parameters

Estimated and compiled values of each of the

parameters, V, P, A,, W, D, ao, s, Hs, Tw, and Hs2Tw2, are

presented in Tables IV-1 through IV-15. Each of these tables

represents the fifteen individual inlets under

consideration. The tables include the various sources from

which the data were derived. Where more than one source is

listed, the corresponding average value is presented in the

table. The volume estimates (with the exception of Nassau

Sound, as previously noted) list the source used and date.

The data are selected based on their appropriateness in

time, relative to the volume estimates. For example, at St.

Augustine Inlet, Walton and Adams (1976) present prism and

cross-sectional area data from 1954-1957, which is the

period when the inlet was undergoing migration from its old

southern location to the present northern location. More

recent data are available from Florida Coastal Engineers

(1976), which more closely meet with the 1979 chart used for

volume estimation. Although no sediment-related data are

listed specifically for each inlet, it may be noted here

that the sediment grain sizes range from 0.12mm to 0.52mm








along the coast. Thus the sediment is in the range of fine-

to medium-sized sand.

It should be noted that the dates corresponding to the

various parameters, in most cases, do not exactly coincide.

Effort was made in obtaining data based on dates as close to

each other as feasible, as explained in the case of St.

Augustine Inlet.


Comparison of Volumes
The ebb shoal volume estimates obtained in this study

and those values from the corresponding inlets in Walton and

Adams (1976) are plotted against one another in Figure IV-1.

This plot was made to ascertain whether the values for each

inlet obtained from two different sources were close enough

to permit further comparison of related parameters. An

inspection of the figure reveals that the values are

relatively close to each other. All of the values have a

relative error of 11% or less, except for the two smallest

values, i.e. those for Jupiter and Bakers Haulover inlets.

These values have relative errors exceeding 30%. This is

explained by the fact that these volumes are so small (less

than 500,000 cubic meters) that even a relatively small

deviation yields a large percentage error.









Table IV-1. St. Marys Entrance

Parameter Value Sources

V 95.1x106m3 NOS charts 11488,11502; 1975

P 154.0x106m3 Parchure (1982)

A, 12.4x103m2 Parchure (1982)

W 12.7x102m Parchure (1982)

D 9.5m Parchure (1982)

ao 2.1m NOS Tide Tables (1986)

s 0.30 NOS chart 11489; 1981

Hs 0.55m Jensen (1983)

Tw 6.0sec Jensen (1983)

Hs2Tw2 10.9m2sec2

Remark: Data from Parchure (1982) are compiled from O'Brien
and Clark (1974), Bruun (1958), Environmental Science and
Engineering (1980), Walton and Adams (1976), Hou (1974) and
Olsen (1977).










Table IV-2.

Parameter

V

P


Ac


W

D

ao

s

Hs


sTw
Hs2Tw2


Nassau Sound

Value

40.5x106m3

62.3x106m3


67.4x106m2


14.7x102m

4.6m

1.9m

0.70

0.56m

5.9sec

10.9m2sec2


Sources

Dean and Walton (1973)

Walton and Adams (1976;,
Jarrett (1976)

Walton and Adam (1376),
Jarrett (Q976)

Jarrett (1976)

Jarrett (1976)

NOS Tide Tables (1986)

NOS chart 11489; 1981

Jensen (1983)

Jensen (1983)






42

Table IV-3. Ft. George/St. Johns Inlet


Parameter

V

P


Ac


W
w


D


ao
S
s

Hs


Value

131.3x106m3

60.2x106m3


50.6x102m2


8.4x102m


13.7m


1.7m

0.80

0.69m


Sources

NOS chart 11488; 1978

Jarrett (1976),
Kojima and Hunt (1980)

Jarrett (1976),
Kojima and Hunt (1980)

Jarrett (1976),
Kojima and Hunt (1980)

Jarrett (1976),
Kojima and Hunt (1980)

NOS Tide Tables (1986)

NOS Chart 11489; 1981

Jensen (1983)


T, 6.2sec
Hs2Tw2 18.3m2sec2


Jensen (1983)


Remarks: The prism, cross-sectional area, width and depth
values for each individual inlet have been combined for the
two inlets to coincide with the combined volume calculation.
This is recognized as a potential source of error and is
considered in the analysis of these data. It is felt that
less error would occur in combining these values then in
attempting to divide the ebb shoal between the two inlets.









Table IV-4. St. Augustine

Parameter Value

V 83.3x106m3


P 81.6x106m3


Ac 46.1x102m2


W 3.4x102m


D 13.7m


ao 1.6m

s 0.80

Hs 0.72m

Tw 6.0sec

Hs2T 2 18.7m2sec2


43


Inlet

Sources

NOS charts 11486; 1979,
11488; 1978

Florida Coastal Engineers
(1976)

Florida Coastal Engineers
(1976)

Florida Coastal Engineers
(1976)

Florida Coastal Engineers
(1976)

NOS Tide Tables (1986)

NOS chart 11488; 1978

Jensen (1983)

Jensen (1983)









Table IV-5.

Parameter

V

P

Ac

w
W

D

ao


s
Hs

Tw

Hs 2 Tw2


Matanzas Inlet

Value

4.8x106m3

14.2x106m3

9.1x102m2

3.3x102m

2.7m

1.5m

0.80

0.72m

6.3sec

20.6m2sec2


Sources

NOS chart 11486; 1978

Mehta and Jones (1977)

Mehta and Jones (1977)

Mehta and Jones (1977)

Mehta and Jones (1977)

NOS Tide Tables (1986)

NOS chart 11485; 1974

Jensen (1983)

Jensen (1983)










Table IV-6. Ponce de Leon Inle

Parameter Value

V 17.0x106m3

P 16.3x106m3

Ac 11.7x102m2


3.1x102m

4.1m

0.8m

0.90

0.82m

6.3sec

26.7m2sec2


et

Sources

NOS chart 11485; 1974

Jones and Mehta (1978)

Jones and Mehta (1978),
Walton and Adams (1976)

Jones and Mehta (1978)

Jones and Mehta (1978)

NOS Tide Tables (1986)

NOS chart 11485; 1974

Jensen (1983)

Jensen (1983)


W

D

ao

s

Hs

Tw

Hs2w2










Table IV-7. Port Canaveral Entrance

Parameter Value

V 4.3x106m3 NOS cl

P 2.5x106m3 Hunt

Ac 22.3x102m2 Hunt

W 2.0xl02m Hunt

D 10.7m Hunt

ao 1.2m NOS T:

s 0.50 NOS cl

Hs 0.71m Jensez

T, 6.9sec Jensei

Hs2Tw2 24.0m2sec2


Sources

hart 11476; 1979

(1980)

(1980)

(1980)

(1980)

ide Tables (1986)

hart 11476; 1979

1 (1983)

1 (1983)








Table IV-8. Sebastian Inlet

Parameter Value Sources

V O.1x106m3 NOS chart 11472; 1981

P 8.5x106m3 Mehta, Adams and Jones (1976)

Ac 3.6x102m2 Mehta, Adams and Jones (1976)

W 1.4x102m Mehta, Adams and Jones (1976)

D 2.6m Mehta, Adams and Jones (1976)

ao 0.8m NOS Tide Tables (1986)

s 1.00 NOS chart 11472; 1981

Hs 0.80m Jensen (1983)

T, 6.7sec Jensen (1983)

HS2T2 28.7m2sec2

Remark: Prism data presented in Mehta, Adams and Jones
(1976) were taken from Bruun (1966).










Table IV-9.

Parameter

V

P


Ac


w

D

ao


Hs

Tws
Hs 2Tw 2


Ft. Pierce Inlet

Value

22.2x106m3

17.3x106m3


9.8x102m2


2.7x102m

4.2m

0.9m

0.60

0.78m

6.6sec

26.5m2sec2


Sources

NOS chart 11474; 1975

O'Brien and Clark (1973),
Jarrett (1976)

O'Brien and Clark (1973),
Jarrett (1976)

Jarrett (1976)

Jarrett (1976)

NOS Tide Tables (1986)

NOS chart 11472; 1981

Jensen (1983)

Jensen (1983)







49

Table IV-10. St. Lucie Inlet


Parameter


. ,


Value

16.4x106m3


16.4x106m3

13.9x102m2

5.5x102m


2.6m


Sources


NOS chart 11472; 1981,
USACE (1965)

Jarrett (1976)

Jarrett (1976), Walton (1974a)

Jarrett (1976), Walton (1974a)

Jarrett (1976), Walton (1974a)


l.lm


0.50

0.83m


NOS Tide Tables (1986)

NOS chart 11472; 1981

Jensen (1983)


T, 6.5sec Jensen (1983)
Hs2T2 29.1m2sec2

Remarks: Volume is calculated using the survey chart
presented by the U.S. Army Corps of Engineers, Jacksonville
District (1965) due to its smaller scale and greater detail.
Prism data from Jarrett are derived from the cubature method
and taken from the U.S. Army Corps of Engineers,
Jacksonville District (undated).


I /-









Table IV-11.

Parameter

V

P

Ac


Jupiter Inlet

Value

0.3x106m3

3.0x106m3

4.2x102m2


Sources
NOS chart 11472; 1981

Jarrett (1976)

Jarrett (1976),
Dean and Walton (1973)


W 1.0x102m Jarrett (1976)

D 2.8m Jarrett (1976)

ao 0.9m NOS Tide Tables (1986)

s 0.50 NOS chart 11472; 1981

Hs 0.82m Jensen (1983)

T, 6.4sec Jensen (1983)

H2T 2 27.5m2sec2

Remark: Prism data presented in Jarrett (1976) are derived
from the cubature method and taken from U.S. Army Corps of
Engineers, Jacksonville District (undated).










Table IV-12. Lake Worth Inlet


Parameter

V



P


Ac


W

D

ao

s

Hs


Value

2.9x106m3



28.4x106m3


13.5x102m2


2.9x102m

4.0m

0.8m

0.80

0.72m


Sources

NOS chart 11472; 1981,
COED, University of Florida
(1967)

Jarrett (1976),
O'Brien and Clark (1973)

Jarrett (1976),
O'Brien and Clark (1973)

Jarrett (1976)

Jarrett (1976)

NOS Tide Tables (1986)

NOS chart 11472; 1981

Jensen (1983)


5.3sec


Jensen (1983)


Hs2T2 14.6m2sec2

Remarks: Volume is calculated using a survey chart presented
by the Coastal and Oceanographic Engineering Department
University of Florida (1967), rather than NOS chart 11472
due to the smaller scale used, yielding greater detail and
therefore, less error. The prism data from Jarrett (1976)
include values reported by Bruun (1958) and the U.S. Army
Corps of Engineers, Jacksonville District (undated), along
with that from the cubature method.









Table IV-13. South Lake Worth


Parameter

V

P

Ac


W


D


ao

s


Value

1.lx106m3

3.1x106m3

1.0x102m2


0.3x102m


3.1m


0.9m

0.90


Sources

NOS chart 11467; 1978

Mock (1962)

CEL, University of Florida
(1964)

CEL, University of Florida
(1964)

CEL, University of Florida
(1964)

NOS Tide Tables (1986)

NOS chart 11467; 1978


0.68m

5.7sec


Jensen (1983)

Jensen (1983)


15.0m2sec2


Remark: The prism value is calculated using the mean maximum
velocity presented in Mock (1962) and the cross-sectional
area presented in Coastal Engineering Laboratory, University
of Florida (1964) with the hydraulic prism equation (24)
presented in Chapter III.


Hs2Tw2









Table IV-14. Boca Raton Inlet


Parameter

V


Value

0.8x106m3


5.5x106m3

1.8x102m2

0.5x102m

3.4m

0.8m

1.00

0.69m


Sources

NOS chart 11467; 1978,
Strock (1983a)

Strock (1983a)

Strock (1983a)

Strock (1983a)

Strock (1983a)

NOS Tide Tables (1986)

NOS chart 11467; 1978

Jensen (1983)


5.8sec


Jensen (1983)


H 2T 2 16.0m2sec2
sw


Remarks: The volume is calculated using the survey chart
presented by Strock (1983a) due to its smaller scale and
greater detail rather than the NOS chart 11467. The prism is
calculated using the mean maximum velocity and cross-
sectional area presented by Strock (1983a) with the
hydraulic prism equation (24) presented in Chapter III.


I









Table IV-15.

Parameter

V


Bakers Haulover

Value

0.5x106m3


Inlet


Sources

NOS chart 11467; 1978,
COED, University of Florida
(1969)


P 10.2x106m3 Jarrett (1976)

Ac 4.1x102m2 Jarrett (1976)

W 1.1xl02m Jarrett (1976)

D 3.6m Jarrett (1976)

ao 0.9m NOS Tide Tables (1986)

s 0.30 NOS chart 11467; 1978

Hs 0.53m Jensen (1983)

T, 4.3sec Jensen (1983)
Hs2Tw2 5.2m2sec2

Remark: The volume is calculated using the survey chart
presented by the Coastal and Oceanographic Engineering
Department, University of Florida (1969) due to its smaller
scale and greater detail than NOS chart 11467 (1978).















I i I I I I
E
10 St. Marys
100- x



Q 80- x St.Augustin
z


60-


tJ
5 40- Nassau Sound


y20- Ponce De Leon

Jupiter
0 Bakers Hulover ,
0O 20 40 60 80 100
VOLUME ESTIMATE- PRESENT
STUDY (x lOm3)

FIGURE IV-1. COMPARISON OF VOLUME ESTIMATES











Regression Analysis

Correlations were made of the inlets examined in this

study with the equation

V = bPm (38)
where V is the ebb shoal volume in cubic meters, P is the

spring tidal prism in cubic meters, and b and m are

coefficients to be determined through linear regression. The

equation can be written as

Y = a + mR (39)
where y = log V x = log P and a = log b.

Solve for m, using the expression:

m = SUM [(x x) (y y)] / SUM (x )2 (40)

yielding

m = 1.39 (41)

Then solve for a, using the expression:

a = y mx (42)
yielding

a = -3.25 or b = 5.59x10-4 (43)

Thus regression analysis yields the following

V = 5.59x10-4 p1.39 (44)

This equation is plotted on Figure IV-2, along with the

equation from Walton and Adams (1976) for moderate energy

environment. The indicated data points are those from this

study. Correlation coefficients for both sets of data were

computed to determine the relative accuracy.












100 I I I 1 1 1
50- V 559 x 104 P39 (Present Study)
V=6.08x 10t3 P '(Walton and Adams)

St. Marys/
E 10 y /
10 x St.Auqustine
0 7 NsNossu x Ft.George/
S/ Sound St. Johns
Lake Worth x '
L 4x Ft. Pierce
cr Bakers Houlover Ponce De Leon
1a. 10 an Matanzas
J 1. ebostion x
o 0.5- x
/1 Jupiter
x x South Lake Worth
7 x Pt. Canaveral

0.11,, --- .. I I I I----
I 0.5 1.0 5 10 50 100 500 000
EBB SHOAL VOLUMES (x Knrr1)
FIGURE IV-2. COMPARISON OF LINEAR REGRESSION
ANALYSIS RESULTS









An examination of Figure IV-2 reveals a considerable

spread of values. Although the data from Walton and Adams

(1976) are not plotted on this figure, a similar spread of

data exists. For prism values which are approximately equal

there is considerable scatter, even within the same wave

energy environment range as is presented here.

The correlation coefficient for data from this study is

0.75 and for Walton and Adams (1976) it is 0.80. These

values may be considered to be rather low, indicating

unsatisfactory correlation between the values. These

somewhat poor correlations suggest the possibility of

examining the influence of other parameters as expressed in

equation (23).

Results of Dimensional Analysis

The dimensional analysis, presented in Chapter III

yielded the following relationship to be examined for

trends:

V/W3f( P/W3, W/D, Ac/a02) (32)

Since V and P are both a function of W3, they will be

combined to form the ratio V/P for the discussion (although

it is noted that V and P are not linearly related). The

values of the three dimensionless parameters are contained

in Table IV-16.

The variability of each of these parameters may be

demonstrated by calculating the standard deviation of each









Table IV-16. Dimensionless

Inlet V/P

St. Marys 0.62

Nassau Sound 0.65

Ft. George/ 2.18
St. Johns

St. Augustine 1.02

Matanzas 0.34

Ponce de Leon 1.04

Port Canaveral 1.72

Sebastian 0.01

Ft. Pierce 1.28

St. Lucie 1.00

Jupiter 0.10

Lake Worth 0.10

South Lake Worth 0.35

Boca Raton 0.15

Bakers Haulover 0.05


set and dividing

are as follows


Parameters

W/D

133

320

61


25

123

*75

19

55

64

211

35

74

11

16

31


by their respective mean values. The values


V/P: Std Dev/Mean = 0.93 (45)

W/D: Std Dev/Mean = 1.01 (46)

Ac/ao2: Std Dev/Mean = 0.66 (47)

These relatively large values of the normalized

standard deviation are indicative of the fairly wide


Aao2(xl0-3)
2.8

1.9

1.7


1.8

0.4

2.0

1.6

0.6

1.2

1.2

0.5

2.3

0.1

0.2

0.5










variation of the three parameters. While such a variability

does not, by itself, imply correlation, the possibility of

correlation is suggested. It should be noted that since the

cross-sectional area is not directly related to the W/D

ratio, two inlets with identical areas can have widely

different aspect ratios. This situation is portrayed by

comparing St. Lucie and Lake Worth Inlets. In this case,

their cross-sectional areas are relatively equal, 13,900

square meters and 13,500 square meters, respectively.

However, their W/D ratios are 211 and 74, respectively.

The parameters are plotted in Figure IV-3. An

examination of Figure IV-3 reveals a somewhat significant

trend with respect to the aspect ratio, W/D. Two zones can

be determined as is depicted by the dashed line. This line

is represented by the equation:

V/P = 0.0033 W/D + 1 (48)
This line, although clearly somewhat arbitrarily chosen,

divides the domain into two distinct zones with respect to

the values of Ac/ao2. V/P ratios will be greater than

predicted by equation (48) when Ac/ao2 is greater than 1000.

Likewise, V/P will be less than predicted by equation (48)

when Ac/ao2 is less than 1000. This relationship holds in 14

of 15 cases presented. In the case of Lake Worth Inlet, for

which the relationship does not hold, the V/P ratio is a low














Note: Numbers in Parentheses ( )
Represent Ac Volues xl0"3
ao


x (I.e


(20)
K


- 0.0033- +1


x(2.4 )


x (0.4)


x (0.2)
x (0.5) x(23)
(o. 5), tosl


100


150
W/D


x(1.2)


x (1.9)


A ( I.0)



o I


200


250


300


FIGURE IV-3. PLOT OF V/P VS. W/D WITH RESPECT TO Ac/a 2


I1 I -


2.0


x(1.7)


x(1.6)


1.5h


x(. 2)


1.0K


0.5
x (0.1)


I
1-j


350


I








0.10. From equation (44), a value of not less than 0.75

should be expected for the V/P ratio.

Equation (44) should be used mainly as an expedient

means of estimating the maximum or minimum volume stored in

the ebb shoals. The width and depth can be easily measured

in most field environments. The cross-sectional area can be

estimated from the width and depth. The tide range can be

found locally or derived from Tide Tables. The prism can be

estimated from the Prism Area Relationship, as presented

for example by O'Brien (1969)

Ac = 2.0x10-5 P (49)
With these parameters now known, the maximum or minimum

volume of sand stored in the shoals can be estimated within

the bounds of the two zones defined. For example, assume the

width of the inlet is 500 meters and the depth is 10 meters.

The cross-sectional area is then 5000 square meters. Assume

the tide range squared is 3.0 square meters. The Ac/ao2

value is 1666 which is greater than 1000. The prism is

estimated, using equation (49), to be 2.5x108 cubic meters.

From equation (48), we know that the V/P value must be

greater than 0.84. Therefore, the minimum volume estimated

to be stored in the ebb shoal is 2.1x108 cubic meters.

Results of Figure IV-3 imply that if the wave energy

and prism (and therefore cross-sectional area via O'Brien,

1969) are kept constant, then a greater W/D ratio will yield








a smaller volume and vice versa. This can be seen on a

relative basis by using Matanzas, Ponce de Leon and Ft.

Pierce as examples. These inlets have prism values of

14.2x106m3, 16.3x106m3, and 17.3x106m3, respectively. Their

cross-sectional areas are 910m2, 1170m2, and 980m2

respectively. These values may be considered as being

essentially constant for the present purpose. It can be

seen from Table IV-17 that as the W/D ratio decreases from

Matanzas to Ft. Pierce, the volume increases, lending

credibility to the hypothesis that volume is in fact a

function of not only prism (or cross-sectional area), but

also the aspect ratio, W/D.


Table IV-17. W/D versus V Comparison

Inlet W/D V(m3)

Matanzas 123 4.8x106

Ponce de Leon 75 17.0x106

Fort Pierce 64 22.2x106


Discussion

It would be difficult to find an ideal case in nature

where the wave energy, prism, area and tide are all

constant. However, this requirement may be further examined

through mathematical or physical modeling. Using a

relatively simple approach, the effect of varying W/D ratios

on the ebb shoal volume may be best realized by examining









the influence of the bed shear stress. The critical shear

stress is that value of the bed shear stress that is exerted

at the point of incipient motion. When the actual bed shear

stress exceeds the critical shear stress, the bed material

is put into motion.

Jonsson (1966) finds that the wave friction factor, fw,

is significantly larger than the current friction factor,

fc. The equations representing the shear stress due current,
Tc, and waves, Tw are

Tc = 0.5 p fc uc2 (50)
and

Tw = 0.5 p fw uw2 (51)
respectively, where p is the density of seawater, uc is the

water velocity due to current and uw is the water velocity

due to waves near the bed.

For the problem at hand, it is sufficient to consider

two inlets of the same cross-section, Ac, but having

different aspect ratios, W/D. Let inlet #1 be 3 meters deep

by 400 meters wide, and inlet #2 be 6 meters deep by 200

meters wide. Thus both inlets have a cross-sectional area of

1200 m2, but the corresponding aspect ratios are 133 and 33,

respectively. It can be shown that by virtue of equations

(33) and (49), the maximum ebb velocity through both the

inlets will be the same. Let us assume that the velocity,

uc, over the ebb shoal will as well be the same in both









cases, in spite of the differences in the flow depth over

the bar. Let uc be 0.3 m/sec, a representative value. Select

further, a representative wave height of 1 m and a wave

period of 7 sec applicable to ebb shoals at both inlets. For

current, a typical value of 4.1x10-3 may be selected for fc.

The magnitude of fw depends on the relative bottom

roughness, i.e. the maximum water particle displacement near

the bed, Ab, divided by the bed roughness, ds. fw was

estimated by using calculated Reynolds Numbers of 2.85x106

and 1.33x106 and corresponding Ab/ds values of 2264 and 1586

for inlets #1 and #2, respectively. The fw values are

estimated to be 8.0x10-3 and 9.0xl0-3 for inlets #1 and #2,

respectively.


Table IV-18. Shear Stress Comparison

D(m) c(/m2 (N/m2)
Inlet #1 3 0.18 3.23

Inlet #2 6 0.18 1.62


In Table IV-18, the current shear stress, Tc, and wave

shear stress, Tw, are given for the two inlets. It is

observed that in the case of both inlets, the wave shear

stress is dominant. Hence the precise selection of the

magnitude of uc for the inlets is not a matter of critical

importance, so long as reasonable values are selected. Since

the shear stress is greater in the shallower inlet, it is









more likely that the critical shear stress will be exceeded

there more often than in the deeper inlet. As the sand is

put into motion, it is moved by the longshore current and

wave forces back towards the shore. This movement of sand,

therefore, occurs more significantly in shallower inlets

than in deeper inlets, allowing the shoals of deeper inlets

to grow to greater volumes than those of shallow inlets.

This reasoning is in agreement with the conclusion of Walton

and Adams (1976). They state that more material is stored in

the shoals of low wave energy coasts than in high wave

energy coasts. This is because there is more energy

available to drive the sand back to shore in high energy

environment after being deposited as a shoal. In the present

study, the same relative wave energy environment was

considered, and the local effect of the shear stress caused

by incoming waves has been examined. The role of the aspect

ratio in determining the ebb shoal volume is thus shown to

be significant, along with the tidal prism and cross-

sectional area.














CHAPTER V
CONCLUSIONS AND RECOMMENDATIONS

Conclusions
A few important conclusions with respect to Florida's

east coast inlets are in order.

1. There is a general (but not uniform) trend of

decreasing ebb shoal volume from St. Marys Entrance

(95x106 cubic meters) south to Bakers Haulover Inlet

(0.5x106 cubic meters).

2. The total amount of material stored in the ebb shoals

of all eighteen inlet systems is 420x106 cubic meters.

Of that amount, approximately 83% resides in the ebb

shoals of the four northernmost inlet systems-- St.

Marys, Nassau Sound, Ft. George/St. Johns and St.

Augustine. None of the other inlets account for more

than 5% of the total volume, individually.

3. The east coast inlets of Florida all reside within the

moderate wave energy range as defined in Walton and

Adams (1976).

4. The volume of material found in the ebb shoals appears

to be a function of spring tidal prism, P, inlet area,

Ac, amplitude of tide, ao, and the inlet width to depth

ratio, W/D.









5. The influence of the W/D ratio appears to arise as a

result of the differing effect of wave-induced sand

transport at different depths over the ebb shoal.

6. Two distinct regions are defined by relating V/P to W/D

and Ac/ao2. For values of Ac/ao2 greater than 1000, the

V/P value will be greater than that predicted by the

equation V/P = 0.0033 W/D + 1, in most instances.

For values of Ac/ao2 less than 1000, the V/P value will

be less than that predicted by equation (48).


Recommendations
Throughout this investigation, many ideas came to mind

or were brought to the author's attention that could be used

to improve upon what has been presented within this text, in

the future. Some general comments should be made at this

time.

Ideally, the parameter values used for each inlet

should be compiled from identical periods of time. This

would eliminate problems arising from relating the ebb shoal

volume from one period with the prism or cross-sectional

area from another, and would add a significant degree of

confidence to the results. This, however, will not be an

easy task to perform.

The next logical step would be to collect these same

parameters from inlets of the Atlantic, Pacific and Gulf

Coasts of the United States and to analyze them in the same







69


manner as performed here. That analysis may prove to

reinforce those trends discovered in this study, or those

trends may prove to be unique to the east coast of Florida.

The use of an electronic digitizer to perform volume

calculations will save enormous amounts of time and add to

the accuracy of volume estimates. The data can then be more

easily stored, retrieved and updated.















APPENDIX A
INFLUENCE OF WAVE ENERGY


The wave energy parameter, Hs2Tw2, used by Walton and

Adams (1976), is useful in defining ranges of approximately

equivalent wave environments. It was concluded, through data

and arguments presented in Chapters III and IV, that the

wave energy environment for each of the inlets on the east

coast of Florida is of the moderate range. The wave energy

parameter, therefore, was eliminated from further

consideration as a determining factor of ebb shoal volumes

in the analysis. Had the wave energy of each inlet not been

found to lie in the same range, the parameter would have had

to be considered in the analysis. It is felt that such an

analysis may be beneficial in locating any similar trends to

those found in Chapter IV, regardless of wave environment.

A dimensional analysis similar to that performed in
2 2
Chapter III can be conducted using Hs2 T2. This analysis can

be shown to yield a characteristic nondimensional parameter

Hs2T 2 / a 2T2, where T is the tidal period. The

significance of this parameter is that it represents the

ratio of wave energy to tidal energy. If no waves are

present, the magnitude of this parameter would be zero.








Consequently, the magnitude of this parameter is an

indicator of the importance of waves relative to tide. The

functional relationship of interest is thus

V/W3 = f(P/W3, W/D, Hs2T2/ao2T2) (52)
This relationship is plotted in Figure A-i. An examination

of this figure does not yield any clear trends with respect

to the three parameters. The data points tend to group

together without regard to parameter value. A possible

reason for this lack of correlation is the variable nature

of the energy parameter itself. The values of Hs T2 and

ao2T2 are averages of relatively widely varying (with time)

values, whereas the other parameters reflect averages of

comparatively less variable values. For a more definitive

conclusion concerning the influence of wave energy, it will

be essential to evaluate trends in Figure A-i using a much

larger data base involving wider variations in wave energy,

as was done by Walton and Adams (1976), although in a

different manner.
















I I I
Note:Numbers in Parentheses( )
Represent W/D Values





x (19)




X(64)


x(211)


X(123)


X(31) ,


PA --


x (I)


X(35)


X) 150

-t-'(2 x 1O
ao2T2
0


FIGURE A-i. PLOT OF V/P VS. H2 Tw2/ao2T
RESPECT TO W/D


250


x(61)


2001-


150t-


x(25)


x (75)


200


250


WITH


I -----~- -T-


I (55),


, (320)


x(7 16)
x( !)
















APPENDIX B
FLORIDA'S EAST COAST INLETS


A chronological development of Florida's east coast

inlets is presented to aid in the understanding of coastline

evolution. A brief description of the sections that follow

is appropriate at this time. There are nineteen inlets on

the east coast of Florida. However, as noted before, Ft.

George and St. Johns are considered together because these

two closely spaced inlets are characterized by a single

large ebb shoal, leaving eighteen inlet systems to be

examined. Each section is comprised of a brief history of

the inlet, including a summary of works and a figure

delineating ebb shoal volumes.

The figures depict the area of ebb shoal calculations

which are portrayed by rather straight, rectangular lines.

Within these areas, significant levels of deposition are

delineated. These levels are enclosed by contour lines

ranging from 5 to 20 ft (1.5 to 6.1 m), in increments of 5

ft (1.5 m). For example, any area outside the 5 ft (1.5 m)

contour line would have deposition above the assumed ideal

profile of less than 5 ft (1.5 m). The area within the 5 ft

(1.5 m) contour would imply deposition of greater than 5 ft








(1.5 m) above the ideal profile, up to the 10 ft (3.1 m)

contour, and so forth.

In all but the Ft. George/St. Johns Inlet system, the

contour lines are contained within the rectangular box. In

this case, the shoal system to the north of the inlet is

complicated by factors beyond the influence of the inlet

itself. The effect of those other factors are not addressed

in this study. Engineering judgement must be applied in

determining how much of this shoal is due to the inlet

processes and how much is due to other factors.

In all but three cases, the rectangular boxes which

contain the ebb shoal volumes are displayed. These three

cases are Nassau Sound, Port Everglades, and Government Cut.

Nassau Sound has a complex system of shoals which tend to

merge, to a varying degree, with the shoal systems to the

north and to the south. It was determined that Port

Everglades and Government Cut had shoals which could not be

accurately determined. This determination is complicated by

the presence of an extensive network of offshore reefs and

dredging of the channels, which makes total volume

calculations difficult, at best. At Hillsboro Inlet, a scour

hole or depression was found, giving rise to a negative

volume being recorded. Since Port Everglades, Hillsboro and

Government Cut did not have identifiable shoals, they were

not considered in the analysis portion of this study.









1. St Marys Entrance
An extensive history of this inlet is presented by

Parchure (1982) and is summarized here. Prior to the

stabilization of the channel by the construction of jetties,

St. Marys Entrance was fronted on its seaward side by a very

large bar formation which was cut by two relatively stable

channels. The deepest section of the inlet was believed to

be 20 meters, in the vicinity of Ft. Clinch. The bar was

located seaward of Amelia Island at a distance of 3.2

kilometers. The controlling depth was 2 meters below mean

low water (mlw).

In 1881, construction was begun on the jetties. Five

spur groins were installed along the westernmost shoreline

of Ft. Clinch to halt rapid recession at that point. Jetty

construction was completed in 1904. The two natural channels

had disappeared, leaving only a single entrance through the

inlet.

During the period 1905-1937, maintenance dredging and

jetty repair work was conducted on an as needed basis. In

1957, the entrance channel was realigned and deepened to 10

m, in connection with the King's Bay Army Terminal. In 1978-

79 the project depth for the navigation channel was

increased to 11-12 meters. The channel is presently 125

meters wide. The north jetty and south jetties are 5840

meters and 3415 meters in length, respectively.









Note I To'oi Vo!ume of Ebb Shool
Above !deal Profile= 95.1 x 106 Cu r

Note2 Isolirne Indncote Depth of Shoal
Above Ideal Profile


0 2000 4000
Scale : meters

FIGURE B-1. ST. MARYS ENTRANCE, 1975









2. Nassau Sound

Nassau Sound is a natural inlet that connects the

Nassau River and Amelia River to the Atlantic Ocean. It has

not been altered by dredging or the construction of jetties.

Over the last hundred years, major changes have been the

recession of Amelia Island to the north, the accretion of

Little Talbot Island to the south and the emergence of Bird

Island near Little Talbot Island. Nassau Sound is presently

1700 meters wide with variable depth. The maximum depth is 7

meters. There are many tidal flats in the inlet mouth.












Note I. Total Volume of Ebb Shoal
Above Ideal Profile =40.5 x 106cu.m.
(Dean and Walton, 1973)
Note 2. Limits of Study Area could not be
Set due to Complicated Shoaling
Patterns


1000


2000


FIGURE B-2. NASSAU SOUND, 1954


Scole: meters


4










3. Ft. George/St. Johns Inlet

Ft. George and St. Johns are natural inlets. Ft. George

has not been stabilized except by the presence of the north

jetty of the St. Johns River. In 1881, two jetties were

constructed at the St. Johns River inlet. The north jetty

was 2900 meters long and the south jetty was 2075 meters in

length. These jetties were submerged at the seaward end. In

1895, the jetties were lengthened to 3360 meters and 3230

meters, respectively.

In the early 1900's, the channel was dredged to 7

meters. This was completed in 1910 when authorization was

granted for deepening to 9 meters. In 1934, the north jetty

was capped with concrete and holes were plugged to make the

jetty less permeable. In 1937, the jetties were extended to

4360 meters and 3410 meters, respectively. The channel was

deepened to 13 meters, in 1965, in conjunction with the

Mayport Naval Air Station.

Ft. George Inlet has a variable bathymetry due to

shifting shoals. The main channel is approximately 2 meters

deep. Kojima and Hunt (1980) present a detailed history of

this inlet.










Note I Totol Volume of Lbt Shool
Above Ideal Protle 131.3 x 106Cu m

Note 2 Isolines Indcote Deoth of Shoal
Above Ideal Profile
Note3. Isolines of the North End of the Study
Area are left Open due to the
Complicated Shoal System which
Merges with that of Nassau Sound


( I ft.= 0305 m)

N














"-Limits of Study Area


0 2000 4000
Scole: meters


FIGURE B-3. FT. GEORGE/ST. JOHNS INLET, 1978









4. St. Augustine Inlet
St, Augustine existed as a natural inlet prior to its

stabilization in 1940. The inlet had meandered naturally

between two well-defined locations. The inlet was first

studied by the U.S. Army Corps of Engineers in 1887. In

1940, a new inlet was cut approximately 600 meters north of

North Point. In 1941, the north jetty was constructed. By

1946, the old inlet to the south showed signs of

deterioration and shoaling. The old ebb shoal bar had begun

to move shoreward to form Conch Island. In 1957, a south

jetty was constructed and the old inlet had almost

completely closed. In addition, the old inlet shoals and

bars had moved landward to form Conch Island as it is today.

A detailed study shows that accretion has occurred in all

regions, with no significant erosion until a point

approximately 6.5 kilometers south of the inlet in the

vicinity of St. Augustine Beach. A more detailed history of

the inlet can be found in Florida Coastal Engineers (1976).

The entrance channel is 60 meters wide and 5 meters deep.

The north and south jetties are 480 meters and 1130 meters

long, respectively.











Note I TotlG Volume of Ebb Shool
Above Ideal Profile-- 83 106 Luu

Note2. Isolines Indicole Deoth of Shoal
Above Ideal Profile

(lft.= 305m)


N













-s '










/ Limits of Study Area


0 :ODO 2000
Scowe meteri


FIGURE B-4. ST. AUGUSTINE INLET, 1979










5. Matanzas Inlet
Matanzas Inlet is a natural inlet located approximately

21 kilometers south of St. Augustine and 64 kilometers north

of Daytona.Beach. Much of the historical information which

follows is summarized from Mehta and Jones (1977).

A by-pass channel 2880 meters long through the marsh

west of the inlet was constructed to link the inlet with the

intracoastal waterway in 1932. In 1964, Hurricane Dora

struck the St. Johns County coastline on September 9th

causing widespread erosion, as well as the undermining of

the coast and structures. This hurricane was responsible for

the breakthrough at Rattlesnake Island which caused

significant changes in the area. The breakthrough had

widened to 75 meters by 1972. Erosion along both sides of

the inlet had taken place, although it was more significant

at Summer Haven. The breakthrough was closed, in 1976, with

the construction of a steel, sheet pile dike. A channel was

dredged through the shoal, in 1977, and 1000 meters of the

south beach was nourished. The inlet is approximately 290

meters wide with a maximum depth of 5-6 meters.












Total Volume of Ebb Shoal
Above Ideal Profile 4.8 x 106 cum

Ebb Shoal Depth Less Than 5ft.
Above Ideal Profile Throughout
Study Area


(I ft.=0305 m.)

N


Limits of Study Area


0 1000 2000
Scale: meter


FIGURE B-5. MATANZAS INLET, 1978









6. Ponce de Leon Inlet

The history of Ponce de Leon inlet goes back as far as

recorded documents by early Spanish settlers in the 1500's.

Much of the historical information which follows comes from

Jones arv Mehta (1978).

The early Spanish settlers sailed through the inlet as

early as 1513. It was named Mosquito Inlet at that time. The

first recorded depths were made in 1573. The reported depth

was between 1-2 meters. In 1765, the British surveyed the

inlet and reported depths of 2-3 meters. In 1883,

construction was begun on a lighthouse. In 1926, the inlet

was renamed Ponce de Leon. Construction of jetties was begun

in 1968. Each jetty was approximately 1200 meters in length.

The north jetty had a 550 meter weir section to produce an

impoundment basin. Jetty construction was completed in 1971.

A northeast storm breached a channel through the north side

shoal in 1973. This breach was closed by dredging in 1974.

In 1984, the north jetty weir section was closed. The inlet

is 490 meters wide at the jetty entrance and as narrow as

300 meters.inside the inlet shoals. The channel is 5 meters

deep and 60 meters wide.




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