• TABLE OF CONTENTS
HIDE
 Front Cover
 Title Page
 Abstract
 Table of Contents
 List of Illustrations
 Introduction
 Past hurricane activity
 Historical shoreline responses
 Physical characteristics of Hurricane...
 Comparison of Hurricane Elena to...
 Effects of Hurricane Elena
 Conclusions
 References cited






Group Title: Technical paper / Florida Sea Grant College Program ; no. 49
Title: Effect of Hurricane Elena on Florida's marsh-dominated coast
CITATION PDF VIEWER PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00076000/00001
 Material Information
Title: Effect of Hurricane Elena on Florida's marsh-dominated coast Pasco, Hermando, and Citrus Counties
Series Title: Technical paper Florida Sea Grant College
Physical Description: 33 p. : ill. ; 28 cm.
Language: English
Creator: Hine, Albert C
Florida Sea Grant College
Publisher: Florida Sea Grant Extension Program
Place of Publication: Gainesville Fla
Publication Date: 1987
 Subjects
Subject: Hurricane Elena, 1985   ( lcsh )
Hurricane damage -- Florida   ( lcsh )
Marshes -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Bibliography: p. 33.
Statement of Responsibility: Albert C. Hine ... et al..
General Note: Grant NA85AA-D-SG059.
Funding: This collection includes items related to Florida’s environments, ecosystems, and species. It includes the subcollections of Florida Cooperative Fish and Wildlife Research Unit project documents, the Florida Sea Grant technical series, the Florida Geological Survey series, the Howard T. Odum Center for Wetland technical reports, and other entities devoted to the study and preservation of Florida's natural resources. This collection includes items related to Florida’s environments, ecosystems, and species. It includes the subcollections of Florida Cooperative Fish and Wildlife Research Unit project documents, the Florida Sea Grant technical series, the Florida Geological Survey series, the Howard T. Odum Center for Wetland technical reports, and other entities devoted to the study and preservation of Florida's natural resources. This collection includes items related to Florida’s environments, ecosystems, and species. It includes the subcollections of Florida Cooperative Fish and Wildlife Research Unit project documents, the Florida Sea Grant technical series, the Florida Geological Survey series, the Howard T. Odum Center for Wetland technical reports, and other entities devoted to the study and preservation of Florida's natural resources. This collection includes items related to Florida’s environments, ecosystems, and species. It includes the subcollections of Florida Cooperative Fish and Wildlife Research Unit project documents, the Florida Sea Grant technical series, the Florida Geological Survey series, the Howard T. Odum Center for Wetland technical reports, and other entities devoted to the study and preservation of Florida's natural resources.
 Record Information
Bibliographic ID: UF00076000
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 - 17445075

Downloads

This item has the following downloads:

PDF ( PDF )


Table of Contents
    Front Cover
        Front Cover
    Title Page
        Title Page
    Abstract
        Abstract
    Table of Contents
        Table of Contents
    List of Illustrations
        List of Illustrations
    Introduction
        Page 1
        Page 2
        Page 3
    Past hurricane activity
        Page 4
        Page 3
        Page 5
        Page 6
        Page 7
        Page 8
    Historical shoreline responses
        Page 9
    Physical characteristics of Hurricane Elena
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
    Comparison of Hurricane Elena to Hurricane Kate
        Page 19
    Effects of Hurricane Elena
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
        Page 25
        Page 26
        Page 27
        Page 28
        Page 29
        Page 30
        Page 31
    Conclusions
        Page 32
    References cited
        Page 33
Full Text



4. .i" EFFECTOF, N IR1C4NREEE44, SN@

SFRIM 'S Nd MRN0 TDf ("43
P4MSG, 4Nf4 N, K NR W C IfC IE


~ltsi::~Y Mb
...US*W Een


Do
DIk


ailo l F,*i oS::wQ-* : ^.*^ :. ,: '
vid L MeL Ms
el eka .p


9 1. :,., ,- ? i, ,,'. : ft W W..... .


'wi;fiMn 6la ::: i ..:;::












EFFECT OF HURRICANE ELENA ON
FLORIDA'S MARSH-DOMINATED COAST:
PASCO, HERNANDO, AND CITRUS COUNTIES





Albert C. Hine
Mark W. Evans
David L. Mearns
Daniel F. Belknap*


Department of Marine Science
University of South Florida
St. Petersburg, FL 33701


*Department of Geological Sciences
110 Boardman Hall
University of Maine
Orono, ME 04469




Project No. IR-85-14
Grant No. NA85AA-D-SG059



Technical Papers are duplicated in limited quantities for specialized audiences
requiring rapid access to information. They are published with limited editing
and without formal review by the Florida Sea Grant College Program. Content is
the sole responsibility of the author. This paper was developed by the Florida
Sea Grant College Program with support from NOAA Office of Sea Grant, U.S.
Department of Commerce, grant number NA85AA-D-SG059. It was published by the
Sea Grant Extension Program which functions as a component of the Florida
Cooperative Extension Service, John T. Woeste, Dean, in conducting Cooperative
Extension work in Agriculture, Home Economics, and marine Sciences, State of
Florida, U.S. Department of Commerce, and Boards of County Cnmmissioners,
cooperating. Printed and distributed in furtherance of the Acts of Congress of
May 8 and June 14, 1914. The Florida Sea Grant College is an Equal
Employment-Affirmative Action employer authorized to provide research,
educational information and other services only to individuals and institutions
that function without regard to race, color, sex, or national origin.



TECHNICAL PAPER NO. 49
March 1987
Price $3.00










EFFECTS OF HURRICANE ELENA ON FLORIDA'S MARSH-DOMINATED,
OPEN-MARINE COASTLINE: PASCO, HERNANDO, AND CITRUS COUNTRY COAST

ABSTRACT

During late August and early September, 1985, Hurricane Elena passed
erratically through the Gulf of Mexico, threatening landfall across the
west-central Florida coast. This class 3 (maximum winds were 110 knots)
hurricane's unusual path caused it to remain approximately stationary
about 100 km off the west-central coast of Florida for 36 hours.
Eventually, Elena passed off to the west-northwest making landfall along
the Mississippi coast. Hurricane Elena caused the largest evacuation in
U.S. history of people from coastal lowlands. This storm also caused
widespread property damage and is one of the most expensive storms on
record.

Hurricane Elena occurred just as a detailed geologic reconnaissance
of a three country sector of Florida's open-marine, marsh-dominated coast
was completed. Hurricane Elena provided an excellent opportunity to
examine the effect of high energy events on this type of coast. The
Pasco, Hernando, and Citrus County coast is distinctly different from the
sandy barrier island coast to the south which sustained heavier damage
from Elena. The marsh coast has a very low regional gradient, low wave
energy, low sediment input, and is largely controlled by underlying
antecedent, karstified rock topography.

Hurricane Elena had very little impact upon the natural and human
structures along the marsh coast. There are several reasons for this:
(1) the storm never came closer than 81 km to the west central Florida
Gulf coast: (2) the dominant winds in the study area were never sustained
above hurricane.force (74 kts); (3) the dominant winds were
alongshore/even slightly offshore; (4) the storm surge peaked at only 2m
above MSL; (5) the marsh grasses absorbed wave energy and retarded
erosion; (6) much of the coast has rock exposed or nearly exposed; and
(7) there are relatively few people and few buildings/seawalls near the
Gulf compared to the sandy coastlines.

The observed effects were: (1) some coastal erosion in the southern
part of the study area (Bayonet Point, Pasco County); (2) development of
small overwash fans penetrating seaward marshes; (3) flattening down of
marsh grasses; (4) redistribution of small, nearshore sand bodies; (5)
extensive Juncus wracks in high marsh areas; and (6) breakage of dead
mangroves (killed by earlier freezes).

The response of open-marine, marsh coasts to a direct strike by a
major hurricane is still unknown. Storms like Hurricane Elena have a
recurring frequency of 10 years. In the future, the combined effect of a
greater sea-level rise with a class 5 hurricane could have much more
,devastating effects.












TABLE OF CONTENTS


Page


ABSTRACT . . . . . .

TABLE OF CONTENTS . . . . .

LIST OF ILLUSTRATIONS . . . .

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

INTRODUCTION . . ... . .

BACKGROUND GEOLOGIC INFORMATION . . .

PAST HURRICANE ACTIVITY . . . .

HISTORICAL SHORELINE RESPONSES . . .

PHYSICAL CHARACTERISTICS OF HURRICANE ELENA . .

Storm Formation and Storm Track . . .

Wind Circulation, Water Levels, Waves. . .

COMPARISON OF HURRICANE ELENA TO HURRICANE KATE .

EFFECTS OF HURRICANE ELENA . . .

CONCLUSIONS . . . . .

REFERENCES CITED . . . . .


iii


. . i

. 1ii

. iii

. . iii











. . 1


. . 3

. . 9
. . 9

. . 9

. . 13

. . 19

. . 19

. . 32

. . 33










LIST OF ILLUSTRATIONS


Page


Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure 8.
Figure 9.
Figure 10.

Figure 11.
Figure 12.
Figure 13A.
Figure 13B.
Figure 14A.
Figure 14B.
Figure 15.
Figure 16.
Figure 17.
Figure 18.
Figure 19.
Figure 20.
Figure 21.
Figure 22.


Location map of study area . . .
Calculated storm surge curves . . .
Hurricane track lines . . . .
Tracks of Hurricanes Agnes and Alma . .
Fluctuations in water level/spring discharge .
Tracks of 1985 hurricanes . . .
Detailed track of Elena/wind/pressure data .
Space image of Elena . . . .
Wind distribution map . . . .
Water levels associated with Elena in
study area . . . .
Peak storm-tide elevation along coast .
Wave height/period for Elena at Clearwater .
Detailed track of Kate/wind/pressure data .
Water levels associated with Kate in study area
Wave height/period for Kate at Clearwater .
Wave height/period for Kate at Steinhatchee .
Aerial photo of small cuts in marsh/washover .
Aerial photo of new sand spit . .
Aerial photo of Juncus wrack . . .
Aerial photo of Juncus wrack . . .
Aerial photo of marsh island . . .
Aerial photo of marsh island area . .
Aerial photo of oyster reef . . .
Comparison of beach profiles . . .


LIST OF TABLES


Table 1. Hurricanes passing within 120 nautical miles of
Crystal River . . . .
Table 2. Preliminary best track-Hurricane Elena .
Table 3. Wind data from Withlacoochee Forest Center .
Table 4. Summary of North Atlantic tropical cyclone
statistics, 1985 . . . .


Page

.5
. 12
.16









INTRODUCTION

The purpose of this document is to assimilate the basic, physical
characteristics of Hurricane Elena, which threatened the west-central
coast of Florida in late August/early September of 1985, and to report on
the effects that this storm had on the open-marine, marsh-dominated
coastline of the Pasco, Hernando, and Citrus Counties. Several reports
have already been written concerning Hurricane Elena's effect on the
barrier island/barrier beach shores (Balsillie, 1985; Bodge and Kriebel,
1985), however, little has been mentioned concerning this storm's effect
on the sand-starved, northern Suncoast.

Hurricane Elena appeared in the Gulf of Mexico after the authors had
completed a major, detailed reconnaissance of this three county coastal
sector (Hine and Belknap, 1986). As a result, we had a firm
understanding concerning the major depositional processes, geomorphology,
and stratigraphy prior to the arrival of Elena. This helped considerably
in our assessment of the storm's impact.

BACKGROUND GEOLOGIC INFORMATION

The northwest Florida coast along the'Gulf of Mexico has been
recognized for some time as a unique coastal sector primarily due to its
relatively low wave energy and dominance by an open-marine marsh system
(Fig. 1). Indeed, many coastal scientists have-viewed this area as the
classic zero energy coast (Price, 1954; Tanner, 1960). Perhaps, as a
result of this coastline's outwardly monotonic appearance, its
unappetizing appeal to physically-oriented sedimentologists, and the
strong interest in sandy, barrier island coastlines resulting from
problems associated with human development the coastal geological
community has looked elsewhere for questions to address. As a result, an
enormous stretch of the Florida shoreline (32%), and.an important type of
coast have been ignored and have remained poorly understood including the
effects of storms. Indeed, even to this day, the State's Bureau of
Beaches and Shores, an agency charged with shoreline research, feels that
this biologically-dominated coast is beyond their purview. Only as the
result of a handful of studies by marsh biologists has this coastline
avoided escape from scientific inquiry.

The recent geologic research along this coast has shown that the
morphologic and stratigraphic complexity has resulted from a unique
interaction of a suite of physical, chemical, and biological processes
(Hine and Belknap, 1986).

Within just the southern 65 km, of this 300 km long non-barrier
island coastal sector, four major geomorphologic subdivisions have been
distinguished: (1) berm ridge shoreline, (2) marsh peninsula shoreline,
(3) marsh archipelago shoreline, and (4) shelf embayment shoreline (Fig.
1). These sharply contrasting coastal zones have resulted from the
interplay of five major processes/sedimentation controls: (1) antecedent
topography resulting from chemical dissolution of the exposed bedrock,
2) fresh-water discharge from springs, 3) low regional gradient/low wave













0 C D
w w
W 3 ^ P


m O
I c 0c 0
S > xc
S o <

z
0











HE .-O C


Figure 1. Location map of the Pasco, Hernando, and Citrus County






Figure ]. Location map of the Pasco, Hernando, and Citrus County
marsh-dominated coastline illustrating distribution of four basic
coastal morphologic sectors. r


PASCO
COUNTY










energy, (4) lack of sediment input, no relict sand supply, and (5)
rising sea level. The reader is referred to Hine and Belknap (1986) for
an in depth analysis of these geomorphic subdivisions. None of these
subdivisions appear to have inherited or presently display effects of
past hurricanes or tropical storms.

PAST HURRICANE ACTIVITY

Ho and Tracey (1975) have presented a descriptive summary of 13
hurricanes that have caused widespread damage along the Florida Gulf
coast from Cape San Bias to St. Petersburg Beach from 1837 to 1972. From
these data and observations, they have calculated storm surge (storm
tide) frequency curves from the 500 year, 100 year, 50 year, and 10 year
recurring hurricane (Fig. 2). In addition, Table 1 is a listing of
tropical storms or hurricanes that have passed within 216 km (120 nm) of
Crystal River. Figure 3 illustrates the tracks of some of these storms.

The storm surge is a rapid rise in normal water level due to reduced
atmospheric pressure and to wind stress piling water up against an open
coastline (U.S. Army Coastal Engineering Research Center, 1973). An
extreme example is that of Hurricane Camille, a class 5 hurricane, which
struck the northern coast of the Gulf of Mexico in 1969. The maximum
elevation of the storm surge was 7.6 m (25 ft) above mean low water and
that a surge greater than 3 m (9.8 ft) extended over approximately 88 km
(55 mi) of coastline. Even more important, this great storm surge
reached its peak in less than 5 hours-starting from a point about 75 cm
(2.4 ft) below mean low water, thus rising a total of 8.35 m (27.4 ft).

The historical hurricane data for our study area does not indicate
that a storm surge of similar magnitude as Hurricane Camille has occurred
(Fig. 4). However, the 1842 hurricane was shown to have a storm surge of
approximately 5.5 m (18 ft) at Cedar Key a point just to the north of
our field area. This 1842 storm has a predicted recurring
frequency of 200 years. Figure 4 shows the tracks of two more recently
occurring hurricanes (Alma, 1966; Agnes, 1972) causing storm surges at
Cedar Key. Each had a storm surge of approximately 3 m (9.8 ft) and both
have a recurring frequency of 26 years. Both passed offshore. Had they
tracked directly over Cedar Key, the storm surges would have undoubtedly
been higher. Hurricane Elena's highest measured surge along this coast
was 2 m (Fig. 10) which, when plotted on the graph in Figure 4, would
indicate that a storm similar to Elena would recur about every 10 years.

It is interesting to note (Fig. 5) how hurricane storm surges affect
the freshwater discharge at Crystal River springs. Note that the water
level curve and the spring discharge curve are negatively correlated -
that is, minimum spring discharge occurs during maximum elevation of the
storm surge. Maximum spring discharge occurs either before or after the
storm surge during low water conditions.
















STUDY


I-


0 50 100


DISTANCE IN NAUTICAL MILES ALONG COAST

Figure 2. Calculated storm surge (storm wind tide) curves for the study
area and neighboring coastline for the largest storm occurring statisti-
cally every 10, 50, 100, and 500 years (data from Ho and Tracey, 1975).
With a measured storm surge of 2m at Bayport in Hernando County, the re-
curring frequency of such a flooding event lies between 20 and 30 years on
this graph.


AREA


C-C,
1-


0
(3
a3
CO
w
La
w Z
0.0
-wI
.

150


I- 1










energy, (4) lack of sediment input, no relict sand supply, and (5)
rising sea level. The reader is referred to Hine and Belknap (1986) for
an in depth analysis of these geomorphic subdivisions. None of these
subdivisions appear to have inherited or presently display effects of
past hurricanes or tropical storms.

PAST HURRICANE ACTIVITY

Ho and Tracey (1975) have presented a descriptive summary of 13
hurricanes that have caused widespread damage along the Florida Gulf
coast from Cape San Bias to St. Petersburg Beach from 1837 to 1972. From
these data and observations, they have calculated storm surge (storm
tide) frequency curves from the 500 year, 100 year, 50 year, and 10 year
recurring hurricane (Fig. 2). In addition, Table 1 is a listing of
tropical storms or hurricanes that have passed within 216 km (120 nm) of
Crystal River. Figure 3 illustrates the tracks of some of these storms.

The storm surge is a rapid rise in normal water level due to reduced
atmospheric pressure and to wind stress piling water up against an open
coastline (U.S. Army Coastal Engineering Research Center, 1973). An
extreme example is that of Hurricane Camille, a class 5 hurricane, which
struck the northern coast of the Gulf of Mexico in 1969. The maximum
elevation of the storm surge was 7.6 m (25 ft) above mean low water and
that a surge greater than 3 m (9.8 ft) extended over approximately 88 km
(55 mi) of coastline. Even more important, this great storm surge
reached its peak in less than 5 hours-starting from a point about 75 cm
(2.4 ft) below mean low water, thus rising a total of 8.35 m (27.4 ft).

The historical hurricane data for our study area does not indicate
that a storm surge of similar magnitude as Hurricane Camille has occurred
(Fig. 4). However, the 1842 hurricane was shown to have a storm surge of
approximately 5.5 m (18 ft) at Cedar Key a point just to the north of
our field area. This 1842 storm has a predicted recurring
frequency of 200 years. Figure 4 shows the tracks of two more recently
occurring hurricanes (Alma, 1966; Agnes, 1972) causing storm surges at
Cedar Key. Each had a storm surge of approximately 3 m (9.8 ft) and both
have a recurring frequency of 26 years. Both passed offshore. Had they
tracked directly over Cedar Key, the storm surges would have undoubtedly
been higher. Hurricane Elena's highest measured surge along this coast
was 2 m (Fig. 10) which, when plotted on the graph in Figure 4, would
indicate that a storm similar to Elena would recur about every 10 years.

It is interesting to note (Fig. 5) how hurricane storm surges affect
the freshwater discharge at Crystal River springs. Note that the water
level curve and the spring discharge curve are negatively correlated -
that is, minimum spring discharge occurs during maximum elevation of the
storm surge. Maximum spring discharge occurs either before or after the
storm surge during low water conditions.









TABLE 1

HURRICANES PASSING WITHIN 120 NAUTICAL MILES
OF CRYSTAL RIVER: 1886-1981


Date of Closest
Point of Approach


Distance of Closest
Point of Approach
(nautical miles)


1886-June 21
1886-July 1
1886-July 19
1888-Oct. 11
1893-June 16
1893-August 27
1894-Sept. 26
1894-Oct. 9
1896-Sept. 29
1898-Aug. 2
1898-Oct. 2
1899-Aug. 2
1921-Oct. 26
1925-Dec. 1
1926-July 28
1928-Sept. 17
1935-Sept. 4
1939-Aug. 12
1941-Oct. 7
1944-Oct. 19
1945-June 24
1945-Sept. 16
1947-Oct. 15
1949-Aug. 27
1950-Sept. 7 (Easy)
1950-Oct. 19 (King)
1960-Sept. 11 (Donna)
1964-Sept. 10 (Dora)
1966-June 10 (Alma)
1968-Oct. 19 (Gladys)
1979-Sept. 4 (David)


Notes: 1 Maximum sustained wind speed near storm center
is within 120 nautical miles of Crystal River.
necessarily the wind speed recorded at Crystal


while storm center
This is not
River.


2 Highest storm intensity category achieved within 138 statute miles
of Crystal River.


Source: National Hurricane Center, Miami.


Wind1
Speed
(mph)


Storm2
Intensity
Category


104
48
42
10
39
89
74
85
22
89
108
96
87
99
19
32
43
77
112
45
49
50
111
16
37
9
77
7
67
47
87


95
97
98
97
86
119
100
102
107
75
98
77
101
81
81
118
95
79
87
75
97
93
76
87
125
76
116
115
98
81
98










HISTORY OF HURRICANE ACTIVITY IN THE
WITHLACOOCHEE REGION


SOURCE: Federal Emergency Management Agency Flood Insurance Studies.

Figure 3. Hurricane track lines affecting the Withlacoochee Regional
Planning area 1886 to 1979 (Withlacoochee Regional Planning Council,
1984).


68,600 :
4:
a6















































Figure 4. Map indicating tracks of Hurricanes Agnes and Alma-two storms whose surge or wind
tide have affected the study area in recent times. Insert shows high water marks of past
hurricanes plotted on calculated curve for storms of different return periods (different
size/strength hurricanes) for Cedar Key. (Data from Ho and Tracey, 1975). On the inset
graph, a storm surge of 2m at Bayport yields a recurring frequency of about 10 years.













































E 0-

u>


Uj
30





-30-:



6 10


Figure 5. Fluctuations in water
charge from Crystal River (upper
Hurricane Agnes.


HURRICANE
--m--- AGNES
I 7I OFFSHORE




WATER LEVEL
A~~ \^


16 20
JUNE 1972 .


level (lower diagram) and water dis-
diagram) during passage offshore of










HISTORICAL SHORELINE CHANGES

Shoreline changes in the study area show wide variability, from
unmeasureable stability over 37 years, (period over which aerial
photographs were compared and measured) to more than 100 m (328 ft) of

shoreline erosion. The agent which causes the greatest change is clearly
human dredge and fill. Not all segments of the shoreline move
simultaneously. Some remain stable for decades. This is probably
indicative of the ability of marsh and oyster reef communities to keep up
with rising sea level, unless devastated by a major storm. We would
expect much greater evidence of erosion after a major hurricane. Of the
natural shoreline segments that show erosion, there is a remarkable
similarity in their rates of erosion, about one half meter (20 in) per
year: 58 cm/yr (23 in/yr: Crystal Bay; 55 cm/yr (22 in/yr): Ozello; 42
cm/yr (16 in/yr): Bayport; and 44 cm/yr (17 in/yr): Bayonet Point. The
oyster reefs in Crystal Bay also fit this scheme, showing 33 cm/yr (13
in/yr) change on the outer reefs and 53 cm/yr (21 in/yr) on the inner
reefs, where changes occurred.

When compared to the potential rates of shoreline retreat estimated
from sea-level rise, these rates seem somewhat small. The geologic rate
of shoreline retreat should have averaged some 2.7 m/yr (8.9 ft/yr) over
the past 3000 years, and based on the tide gauge data for the past 60
years, shoreline retreat should have been four times faster than that.
This last point suggests that widespread shoreline changes may occur
during the direct passage of a major hurricane.

PHYSICAL CHARACTERISTICS OF HURRICANE ELENA

Storm Formation and Storm Track
The formation of the weather system that led to the development of
Hurricane Elena occurred as an organized cloud pattern passing out of the
Sahara Desert on August 23,1985. This system rapidly tracked across the
Atlantic Ocean, but did not become a tropical storm until August 27 as it
was approaching Cuba (Fig. 6). With the discovery of 50 knot winds on
August 28 by a reconnaissance aircraft, the low pressure system was named
Tropical Storm Elena. Tropical Storm Elena rapidly became Hurricane
Elena on August 29 as it entered the Gulf of Mexico. The Hurricane
continued to track in a northwesterly direction until an extratropical
frontal trough moving across the continental U. S. caused Elena to stop
and drift slowly toward the east for a 36 hour period spanning August 31
to September 1 (Fig. 7). As.atmospheric pressure began to increase over
the eastern United States, Hurricane Elena resumed its track toward the
northwest and began to strengthen as well. By late afternoon on
September 1 (see Table 2), the atmospheric pressure at the center of the
Hurricane was at its lowest (951 mb-measured) and maximum winds were
calculated to be 110 knots (Class 3 on Saffir/Simpson scale).. Hurricane
Elena passed over the Mississippi coast near Biloxi on September 2 and
was downgraded to tropical storm status late that afternoon (Information
gathered from a preliminary report generated by the National Hurricane
Center).










HISTORICAL SHORELINE CHANGES

Shoreline changes in the study area show wide variability, from
unmeasureable stability over 37 years, (period over which aerial
photographs were compared and measured) to more than 100 m (328 ft) of

shoreline erosion. The agent which causes the greatest change is clearly
human dredge and fill. Not all segments of the shoreline move
simultaneously. Some remain stable for decades. This is probably
indicative of the ability of marsh and oyster reef communities to keep up
with rising sea level, unless devastated by a major storm. We would
expect much greater evidence of erosion after a major hurricane. Of the
natural shoreline segments that show erosion, there is a remarkable
similarity in their rates of erosion, about one half meter (20 in) per
year: 58 cm/yr (23 in/yr: Crystal Bay; 55 cm/yr (22 in/yr): Ozello; 42
cm/yr (16 in/yr): Bayport; and 44 cm/yr (17 in/yr): Bayonet Point. The
oyster reefs in Crystal Bay also fit this scheme, showing 33 cm/yr (13
in/yr) change on the outer reefs and 53 cm/yr (21 in/yr) on the inner
reefs, where changes occurred.

When compared to the potential rates of shoreline retreat estimated
from sea-level rise, these rates seem somewhat small. The geologic rate
of shoreline retreat should have averaged some 2.7 m/yr (8.9 ft/yr) over
the past 3000 years, and based on the tide gauge data for the past 60
years, shoreline retreat should have been four times faster than that.
This last point suggests that widespread shoreline changes may occur
during the direct passage of a major hurricane.

PHYSICAL CHARACTERISTICS OF HURRICANE ELENA

Storm Formation and Storm Track
The formation of the weather system that led to the development of
Hurricane Elena occurred as an organized cloud pattern passing out of the
Sahara Desert on August 23,1985. This system rapidly tracked across the
Atlantic Ocean, but did not become a tropical storm until August 27 as it
was approaching Cuba (Fig. 6). With the discovery of 50 knot winds on
August 28 by a reconnaissance aircraft, the low pressure system was named
Tropical Storm Elena. Tropical Storm Elena rapidly became Hurricane
Elena on August 29 as it entered the Gulf of Mexico. The Hurricane
continued to track in a northwesterly direction until an extratropical
frontal trough moving across the continental U. S. caused Elena to stop
and drift slowly toward the east for a 36 hour period spanning August 31
to September 1 (Fig. 7). As.atmospheric pressure began to increase over
the eastern United States, Hurricane Elena resumed its track toward the
northwest and began to strengthen as well. By late afternoon on
September 1 (see Table 2), the atmospheric pressure at the center of the
Hurricane was at its lowest (951 mb-measured) and maximum winds were
calculated to be 110 knots (Class 3 on Saffir/Simpson scale).. Hurricane
Elena passed over the Mississippi coast near Biloxi on September 2 and
was downgraded to tropical storm status late that afternoon (Information
gathered from a preliminary report generated by the National Hurricane
Center).







1* N TO A W r 0* 0 fl *L'
1965 NATIONAL HURRICANE CENTER
-"' ." "- ATLANTIC CARIBBEAN GULF OF MEXICO HURRICANE TRACK CHART
6 \ \. 4--. \ ,
4 0 2ge SA 0 1UG1 k\ ..-
S G S0 P I
A .

.... Jusse o.. ... 6 ....


.... 2,, IS-"
I*. O.-c 5 ., A \



I ,








--,-_ -/ --- -




.I. I... I U]














Figure 6. Tracks of the 1985 hurricanes0 Hurricane Elena is track #5 (National Climatic Data Center,
1985).
S- ------ > ,, / .. -. -.
Fi uonr 6. T o
01985).
AT SUWIAAACft SIGAA







\14
.i: I~- i SIP

i ~ I4






*1:1



30 "
S: 8/31 N



S28- 8/3 N 9/1 N ... "91
I--M
I-




0 :.
M +A
S-I
26-
N= NOON
M = MIDNIGHT 8/29 N

24
92 90 88 86 84 82 80
WEST LONGITUDE
1020
+120

1010- +110
-+100 -

1000- \ I/ -
/ -+ z
S\ /
L 990- -+80
c3c\ -+70 WJ
0/ +60 C
S980- +60 Ce

/ PRESSURE
S/ -+50so
970- /WINDSPEED
/ +40

960- +30
+20
950 I I I I
12 00 12 00 12 00 12 00 12 00 12 00 12 00 12 00 12 00 12 00 12 00
28 29 30 31 1 2 3 4 5 6
DATE-TIME (GMT)

Figure 7. Detailed track line of Hurricane Elena and atmospheric
pressure/wind speed through time.











TABLE 2

PRELIMINARY BEST TRACK HURRICANE ELENA

28 AUGUST 4 September 1985


TIME
DATE (GMT)

8/28 0000
0600
1200
1800
8/29 0000
0600
1200
1800
8/30 0000
0600
1200
1800
8/31 0000
0600
1200
1800
9/01 0000
0600
1200
1800
9/02 0000
0600
1200
1800
9/03 0000
0600
1200.
1800
9/04 0000
0600
1200
1800


Landfall at:


POSITION
LAT. LONG.


19.8
20.8
21.8
22.6
23.2
24.0
25.0
25.9
26.6
27.3
27.9
28.3
28.4
28.6
28.8
28.8
28.8
28.6
28.6
28.9
29.4
29.7
30.2
31.0
31.9
32.4
33.2
34.5
35.9
37.0
38.0
38.8


74.0
76.0
78.0
80.0
81.8
83.5
85.0
85.8
86.6
87.2
87.3
86.8
86.0
85.3
84.4
84.0
83.8
83.9
84.2
84.8
85.9
87.3
88.8
90.4
91.8
92.8
93.7
94.0
93.9
93.2
92.5
91.4


PRESSURE
(MB)


1012
1010
1008
1006
1004
1000
994
990
986
980
974
978
977
976
*975
974
971
965
961
954
953
957
959
990
1000
1004
1006
1008
1010
1010
1010
1010


WIND
(KT)


30
30
30
45
50
55
65
70
75
80
90
90
90
90
90
90
95
100
105
110
110
105
100
60
45
30
25
25
20
20
20
20


STAGE


Tropical Depression
11 II


II
Tropical
II
Hurricar
II
I!
II
I!
'I
II


II
1t
I1

II
'I
1I

Tropical
11
Tropical
II
II

I1
I1
II
11
11
Trpia
11
Trpia
11
11
11
11
11
11


II
Storm
11

ie
















Storm

Depression
I1
11
"!
"!


9/02 1300 30.4


89.2 959


Hurricane









It is important to note that Hurricane Elena's closest location to
the west-central Florida coast was 81 km (45 nm) from Cedar Key at
midnight between August 31 and September (Figs. 7, 8). Maximum wind
velocity associated with the storm at that time was 95 knots. By the
time Elena reached its peak wind velocity of 110 knots, the Hurricane was
165 km (91 nm) away and heading off to the west-northwest.

Of the 700 tropical storms and hurricanes that passed over or near
Florida since the late 1800's, no more than two dozen have had tracks as
erratic as Hurricane Elena. This slow and erratic movement by this
hurricane feigning landfall caused unusual problems for disaster
preparedness and emergency personnel (Bodge and Kriebel, 1985).

Wind Circulation, Water Levels, Waves
While Hurricane Elena was drifting offshore, the location and size
of the storm determined wind direction patterns along the coast (Fig. 9).
Since hurricanes have counterclockwise circulation in the northern
hemisphere and this particular hurricane was located roughly due west of
the study area, the dominant winds blew alongshore or even slightly
offshore. Further to the south, in Pinellas County, dominant winds were
onshore, blowing from the southwest. No doubt that this was a
contributing factor to the relatively large amount of damage done to the
sandy beaches, seawalls, and buildings located along that county's shore
(7.8 miles of destroyed or heavily damaged open-ocean seawalls). Even
though the Pasco, Hernando, and Citrus County coastline was located
closer to the storm than Pinellas County, the alongshore direction of the
winds prevented a higher storm surge from developing.

Maximum winds at Cedar Key were 87 knots during August 31. Peak
gusts at Clearwater and Tampa International Airport were 60 and 39 knots,
respectively (Bodge and Kriebel, 1985). Further inland, wind velocities
were reduced as shown by wind data from Brooksville, FL where maximum
sustained winds were only 20 knots with gusts up to 35 knots (Table 3).

Storm-tide driven water levels for the study area are shown in
Figure 10. Note that the highest water level was recorded at the Bayport
tide gauge (2m above mean sea level). Note that water levels remained
elevated for about a 32 hour period from 0000 hours August 31 to 0800-
hours September 1. Finally, a pre-storm water elevation (storm set-up)
can be seen during August 29 and 30 as Elena was approaching from
the west.

Along the entire Florida coast affected by Elena, peak storm tide
elevations are shown in Figure 11. Note the absence of data along the
marsh-dominated coast (Wakulla through Pasco County). The lone data
point is from Cedar Key in Levy County measured by an NOS (National Ocean
Survey) tide gauge. Peak water levels actually measured inside rooms in
a building fronting the open Gulf on Cedar Key indicated that the storm
surge reached 2.78 m (9.2 ft) above mean sea level (Bodge and Kriebel,
1985). The storm surge north of Cedar Keys was estimated to be only
about 30-60 cm (1-2 ft), probably due to the dominance of the offshore
blowing winds.












S-p.
/


Figure 8. Space image (GOES 6 satellite) of Hurricane Elena early
morning August 31, 1985. This location is about as close that the
storm came to the west-central Florida coast. The storm started to
move to the west as a result of the cold front moving off the Atlantic
coast (National Climatic Data Center, 1985).




















































Figure 9. Distribution of winds during August 30-September 2, 1985 at
three locations around the west Florida coast. Orientation of wind
direction illustrates general counter-clockwise circulation of Elena.
Unfortunately, no wind velocity measurements were available from the
Crystal River station. Note that in the Crystal River area, most of
the wind direction readings indicate an alongshore or slightly off-
shore orientation. The strongest winds in the Tampa area were onshore.










TABLE 3



WIND DATA FROM WITHLACOOCHEE FOREST CENTER, BROOKSVILLE, FL




DATE WIND DIRECTION SPEED


8-28-85 South East 12

8-29-85 East 10

8-30-85 East 8

8-31-85 East 20, G-35

9-1-85 South East 20

9-2-85 South East 12

9-3-85 South East 6

11-20-85 North East 10

11-21-85 South East 18

11-22-85 South West 12

11-23-85 North 1












S313V4


-I















































-w
00
L .j
> 0
oo

oa <


L1I


0


C rJ-
CU
W (0










S-









o,,










> ol
*O
CL

o '









*e 0
s-




> O



Sr












4.--
*0









O
0





US
>0
























S- "
04-
'C0






















oak
03






.- 03 =
E 0






In
SO

















0) 0 3
r- -L>
aUl i-
s-
+->O)!-
o *'- 3 C~ U
01,
.-=
01
Q ~
(U ,
L(0n
3 C S-
*r^-















a 2 0
0 -0
E o Bay Gull Franklin Taylor Dixie Levy o Pinellas a
o -V C
0-- ---- ,U a.no
I. | I I
Bodge and Kriebel (MSL) Few Sandy Beaches
O DNR Wrackline (NGVD)
14-
O Nickpoint Analysis (NGVD) O CoE, Mobile District, Tide Gauges (NGVD, preliminary)
S 12 A NOS Tide Gauges (MSL, NGVD, preliminary) V High Water "
Storm
Tide
10-
Elevation
o 0





2-

o .. I ..I . I I a I i,. ,
400 300 200 100 0
Distance (Miles)
Figure 11. Peak storm- feet) from Hurricane Elena along the Gulf coast of Florida
(Figure 9 of Balsillie, 1985).










To the south of the study area, maximum storm surge (1100 hrs,
August 31) at Clearwater was estimated to be 1.39 m (4.6 ft) above mean
sea level (Bodge and Kriebel, 1985).

Wave parameters (height and period) were recorded by the University
of Florida's Coastal Data Network station at Clearwater. Here, a peak
significant wave height of 2.48 m (8.2 ft) was measured at 1400 hours on
August 31 (Fig. 12). Corresponding wave period was 13 sec. Unfortunately,
the wave gauge at the Steinhatchee CDN station was not operating. Since
the regional gradient of the inner continental shelf is flatter in the
Pasco, Hernando, and Citrus County coastal area and the seafloor located
at a higher (shallower) elevation than those conditions off Clearwater,
one can only assume that wave heights were not as large along the
northern Suncoast.

COMPARISON OF HURRICANE ELENA TO HURRICANE KATE

Hurricane Kate passed over the central portion of the Gulf of Mexico
from November 20-22, 1986. Although this storm had similar dimensions as
Hurricane Elena (Fig. 13A) it passed by the Pasco, Hernando, and Citrus
County coastline further offshore (nearly 300 km seaward) and moved along
much more rapidly than Elena. The effects on the Pasco, Hernando, and
Citrus County coast were minimal. The storm surge associated with Kate
was only 60 cm (2 ft) higher than a normal spring high tide (Fig. 138).
Wave data for Hurricane Kate'from both the Clearwater and Steinhatchee
gauge are shown (Fig. 14A,B).

EFFECTS OF HURRICANE ELENA

Overall, around the Gulf of Mexico basin, the effect of Hurricane
Elena on human activity and property was dramatic. Approximately 537,000
people were evacuated from low-lying areas and housed in shelters. This
was the largest number ever recorded. Only four deaths were
reported-perhaps as a result of this large evacuation effort.

According to a preliminary, unpublished report from the National
Hurricane Center, insured losses from Hurricane Elena were the fourth
largest on record ($534,000,000 reported to the American Insurance
Services Group). This report was written before Hurricane Juan which
apparently caused more property damage than Elena (Table 4).

Within the Pasco, Hernando, and Citrus County coast, very little
damage was done to property. In addition, very little change occurred
along the natural coastline. There are a number of reasons for this:
(1) Elena never actually came ashore-the eye came within 81 km of Cedar
Key, (2) winds were generally from the south or alongshore, (3) the coast
was not subjected to hurricane force winds, (4) the resulting storm surge
was only 2 m above mean sea level, (5) the low shelf gradient prevented
generation/propagation of large storm waves, (6) the baffling effect by
marsh grasses, and (7) the relative low density of human habitation
within this broad, coastal marsh system.










To the south of the study area, maximum storm surge (1100 hrs,
August 31) at Clearwater was estimated to be 1.39 m (4.6 ft) above mean
sea level (Bodge and Kriebel, 1985).

Wave parameters (height and period) were recorded by the University
of Florida's Coastal Data Network station at Clearwater. Here, a peak
significant wave height of 2.48 m (8.2 ft) was measured at 1400 hours on
August 31 (Fig. 12). Corresponding wave period was 13 sec. Unfortunately,
the wave gauge at the Steinhatchee CDN station was not operating. Since
the regional gradient of the inner continental shelf is flatter in the
Pasco, Hernando, and Citrus County coastal area and the seafloor located
at a higher (shallower) elevation than those conditions off Clearwater,
one can only assume that wave heights were not as large along the
northern Suncoast.

COMPARISON OF HURRICANE ELENA TO HURRICANE KATE

Hurricane Kate passed over the central portion of the Gulf of Mexico
from November 20-22, 1986. Although this storm had similar dimensions as
Hurricane Elena (Fig. 13A) it passed by the Pasco, Hernando, and Citrus
County coastline further offshore (nearly 300 km seaward) and moved along
much more rapidly than Elena. The effects on the Pasco, Hernando, and
Citrus County coast were minimal. The storm surge associated with Kate
was only 60 cm (2 ft) higher than a normal spring high tide (Fig. 138).
Wave data for Hurricane Kate'from both the Clearwater and Steinhatchee
gauge are shown (Fig. 14A,B).

EFFECTS OF HURRICANE ELENA

Overall, around the Gulf of Mexico basin, the effect of Hurricane
Elena on human activity and property was dramatic. Approximately 537,000
people were evacuated from low-lying areas and housed in shelters. This
was the largest number ever recorded. Only four deaths were
reported-perhaps as a result of this large evacuation effort.

According to a preliminary, unpublished report from the National
Hurricane Center, insured losses from Hurricane Elena were the fourth
largest on record ($534,000,000 reported to the American Insurance
Services Group). This report was written before Hurricane Juan which
apparently caused more property damage than Elena (Table 4).

Within the Pasco, Hernando, and Citrus County coast, very little
damage was done to property. In addition, very little change occurred
along the natural coastline. There are a number of reasons for this:
(1) Elena never actually came ashore-the eye came within 81 km of Cedar
Key, (2) winds were generally from the south or alongshore, (3) the coast
was not subjected to hurricane force winds, (4) the resulting storm surge
was only 2 m above mean sea level, (5) the low shelf gradient prevented
generation/propagation of large storm waves, (6) the baffling effect by
marsh grasses, and (7) the relative low density of human habitation
within this broad, coastal marsh system.










SIGNIFICANT WAVE HEIGHT AND MODAL PERIOD
CLEARWATER, FLORIDA: HURRICANE ELENA
AUGUST 28-SEPTEMBER 2, 1985


0080 0800 1800 0000 0800 1600 0000 0800 1800 0000 0800 1600 0000 0800 1600 0000 0800
28 29 30 31 1 2


AUGUST


SEPTEMBER


EXPLANATION
-*- SIGNIFICANT


WAVE HEIGHT


e.... *.. MODAL PERIOD

Figure 12. Graph showing significant wave height and modal wave period from the Clearwater wave gauge
during Hurricane Elena. Note the long duration (nearly 48 hours) of the highest waves. This was probably
one of the contributing reasons why there was so much damage done to the sandy shoreline of Pinellas
County. This wave gauge is located out in approximately 13 m of water.






























WEST LONGITUDE


/ N

I \
/I I


/ V
/
/
/ WIND SPEED
/
I/

I I I I i I


PRESSURE


I I a I


I I I I I .


12 00 12 00 12 00 12 00
15 16 17 18


12 00 12 00 12 00 12 00 12 00 12 00 12 00
19 20 21 22 23 24


DATE-TIME (GMT)

Figure 13A. Track of Hurricane Kate and associated atmospheric pressure
and wind speed associated with that storm. This hurricane had a
relatively small impact on the marsh-dominated coastline.


1020


1010


1000


990


980


970


e-%
0
z
80 S

LU
60
60 CL



40



20


I a


af













HURRICANE KATE-TIDAL STAGE
NOVEMBER, 1985


.. *. ** 1.0


JL : .' \ a ,o s.V .
S.; '
I:I-






S\ \ BAYPORT

e .o 0800 1600 0000 0800 1600 0000 0800 1600 0000 !.. 1600 0000


22


23


0.:'
*0


BAYPORT ......
CRYSTAL RIVER---
ANCLOTE RIVER--


--0.5


Figure 13B. Water level measurements from Bayport, Anclote River, and Crystal River during Hurricane
Kate. The highest level recorded was slightly over Im at Crystal River. This storm tide was about 50%
of Hurricane Elena's storm tide.


000


-2L


I 00







SIGNIFICANT WAVE HEIGHT AND MODAL
PERIOD; CLEARWATER, FLORIDA
HURRICANE KATE NOVEMBER 1985


20 21 22 23


EXPLANATION
----- SIGNIFICANT WAVE HEIGHT
............ MODAL PERIOD

Figure 14A. Graph showing significant wave height and modal wave period from the Clearwater wave gauge
for Hurricane Kate. Wave height at this location from this hurricane was much lower than Hurricane Elena.


10
0
a
8

Co


a.
62


4

0
2






SIGNIFICANT WAVE HEIGHT
AND MODAL PERIOD; STEINHATCHEE, FLORIDA
HURRICANE KATE NOVEMBER 1985


I 1600 0000 0800 1600 0000 0800 1600 0000 0800
20 21 22 23


EXPLANATION
--- SIGNIFICANT WAVE HEIGHT
...*** MODAL PERIOD
Figure 14B. Graph showing significant wave height and modal wave period from the Steinhatchee wave gauge
for Hurricane Kate. This hurricane made landfall over the Apalachicola River delta just off to the west.
The close proximity of this wave gauge station the Hurricane Kate accounts for the relatively large waves
measured here (250 cm/8.25 ft).










TABLE 4

SUMMARY OF NORTH ATLANTIC TROPICAL CYCLONE STATISTICS, 1985
(CLARK AND CASE, 1986)


Maximum
Sustained
Winds (kn)


Lowest
Pressure
(mb)


U.S.
($ Damage)
(millions)


7/15-7/19

7/21-7/26

8/09-8/17

8/12-8/20

8/28-9/04

9/15-9/19

9/16-10/02

9/21-9/25

10/07-10/15

10/26-11/01

11/15-11/23


60

65

75

80

110

55

125

50

60

75

105.


996

1002

980

987

951

992

919

996

997

971

953


Tropical storm, wind speed 34-63 kn.


Tropical storm, wind speed 34-63 kn.
Hurricane, wind speed 64 kn or higher.

day begins at 0000 GMT.


Cyclone
Number


Name


Class1


Dates2
Dates


Deaths


ANA

BOB

CLAUDETTE

DANNY

ELENA

FABIAN

GLORIA

HENRI

ISABEL

JUAN

KATE


50

1250


900


1500

300


T:
H:
2The










In the Crystal River area, a local scientist living near the marsh
system west of the Salt River on Route C-44 claimed that his own house,
which is 1.5 m (5 ft) above sea level, was not flooded. In addition,
there was.very little erosion of the marsh islands and oyster bars. It
was observed, however, that the spoil banks associated with the Crystal
River nuclear power plant were noticeably eroded. Other observers noted
some wind damage (trees blown down), but concluded that coastal flooding
was little more than a normal spring tide. Flooding problems were more
the result of rainfall.

Our own observations from the ground and several overflights
generally coincided with the general conclusion that Hurricane Elena did
not make a significant impact upon the open-marine coastline.
Unfortunately, no vertical aerial photography was commissioned by State
agencies such as DOT or DNR right after the storm to assess storm impact.
We conducted two overflights from light aircraft. The basic observations
from these overflights are illustrated in Figures 15-21.

From south to north, we made the following observations from a low
altitude overflight made in September, 1985. Figure 15 illustrates two
new breaks or cuts made into the marsh forming small, sand-starved
washover fans (Pasco County). Figure 16 shows a submerged sand spit that
has enlarged as a result of waves breaking during the storm thus
transporting sands in an alongshore direction (Pasco County). Figures 17
and 18 show a prominent, new Juncus wrack in the higher marsh areas
(Hernando County). Figures 19 and 20 show dead mangrove plants (killed
by earlier freezes) and trees blown down by Elena's winds (Citrus
County). Figure 21 illustrates the top of an oyster bioherm in Crystal
Bay, seaward of the Crystal River. Very little change was seen on these
features except for the crest which had been modified by waves and
currents. The lightest portion of the crest represents new oyster shell
transport resulting from the storm.

We reoccupied two beach profile stations after the storm. The
northern station on Shell Island at the entrance to Crystal River showed
no change. The other profile (PC-2) located on Bayonet Point in Pasco
County did show measureable change (Figure 22). This station is along
the berm-ridge coastal sector. One can see that the berm-ridge has
migrated several meters onto the marsh surface. The most important
change is along the beachface and lower intertidal, shallow subtidal zone
where the profile has been lowered about 30 cm (1 ft). This represents a
lateral translation of the ravinement surface and a shoreline erosion of
about 7 m. Further seaward there is no change.

Along the berm-ridge coast, roots of dead mangroves'(from earlier
freezes) were nearly exposed indicating that this coastal sector did
undergo some shoreline retreat. This contrasts with the marsh
archipelago and shelf embayment coasts to the north which had little
change. One would expect this trend since the winds were more onshore
further to the south and also, the berm-ridge coast is less stabilized by
marsh plants/mangroves. The berm-ridge coast also has more sand which is
noncohesive and therefore more easily transportable than marsh sediments
which front the open Gulf further to the north.





























Figure 15. Low altitude, oblique aerial photo of marsh coast in Pasco
County illustrating two small cuts in seaward marsh and small, sand-
starved washover fans associated with them.


Figure 16. Low altitude, oblique aerial photo of a small, submerged
recurved spit that has been enlarged/lengthened by wave activity
associated with Hurricane Elena. Photo from northern Pasco County.






























Figure 17. Low altitude, oblique aerial photo of new, extensive Juncus
wrack in high marsh along Hernando County coast.


Figure 18. Low altitude, oblique aerial photo of Juncus wrack in marsh
along Hernando County coast. This new, prominent win-drow of marsh grass
was a ubiquitous feature seen from the air.









































Figure 19. Low altitude, oblique aerial photo of a marsh/dead mangrove island in the marsh archipelago
section of the Citrus County coast. Note the new erosion along the edge of the island in the lower center
of the photo. Also, note the broken limbs and trunks of the dead mangrove plants which has been killed by
earlier freezes.































Figure 20. Low altitude, oblique aerial photo within the marsh archi-
pelago coast of Citrus County showing that a number of trees that had
been blown down by the storm.


Figure 21. Low altitude, oblique aerial photo of an oyster reef in
Crystal Bay. The light area on the crest of the oyster bar resulted
from recent transport of oyster shells from storm currents.










PROFILE QC-2 BAYONET POINT, PASCO COUNTY


BERM RIDGE


GULF OF MEXICO



z- X x X -x x x x


--SALT MARSH


EXPLANATION

PROFILE STAKE LOCATIONS

*-* MAY 26, 1983 PROFILE
x-x OCTOBER 24, 1985
PROFILE


--NO CHANGE--


/ SAND LOSS


SAND GAIN


Figure 22. Two topographic beach profiles indicating coastal response to Hurricane Elena at Bayonet
Point, Pasco County. Note the lowering of the profile due to sand loss and the landward migration of
the berm-ridge. There is no change further seaward. These profiles indicate a net loss of sand. The
sand was transferred laterally out of this cross-section. These sediments may have been trapped by
nearby tidal creeks which act as small tidal inlets.


EAST


WEST


lOmn










CONCLUSIONS

1. Hurricane Elena, a class 3 hurricane (maximum winds 110 knots)
came within 81 km of the west-central Florida coast and remained offshore
for an unusually long period of time (about 36 hours). Although this
storm caused considerable damage to the beach and man-made structures
along sandy shorelines to the south, the marsh-dominated coast of Pasco,
Hernando, and Citrus Counties suffered relatively little ill effect.

2. There are a number of reasons for the small impact that Elena
had on this flat, sand-starved, biologically dominated coast: (1) the
storm never made landfall in the study area; (2) the dominant winds were
not hurricane force winds along this coast; (3) the winds were directed
alongshore; (4) the resulting storm surge was only 2m above MSL; (5) the
marsh grasses absorbed wave energy and the plant roots stabilized the
substrate; (6) there are numerous rock exposures along this coast; and
(7) there are relatively few people and man-made structures to injure or
to damage, respectively.

3. There was some shoreline erosion in the Bayonet Point area
(7-10m retreat). Marsh grasses were noticeably flattened/matted down;
Juncus wracks were deposited in the high marsh; several, small overwash
fans formed; nearshore sand accumulations were reconfigured; and dead
mangrove branches/trunks were broken. However, there was no noticeable
change in coastal morphology, no marsh islands disappeared, no oyster
bars were eroded, and no marsh hammocks were destroyed.

4. The response of this open-marine, marsh-dominated coast to a
major, class 5, hurricane making landfall is still unknown. Such an
event could be much more devastating than this coastal response to
Hurricane Elena. If sea level is to continue its increasing rate of
rise, the marsh coast could approach a state of drowning and be subject
to widespread erosion during the 100 year recurring hurricane.









REFERENCES CITED

Balsillie, J.H., 1985, Post-storm report: Hurricane Elena of 29 August
to 2 September 1985: Beaches and Shores Post-Storm Report No. 85-2,
Florida Department of Natural Resources, Tallahassee, 66 p.

Bodge, K.R., and Kriebel, D.L., 1985, Storm surge and wave damage along
Florida's Gulf coast from Hurricane Elena: Department of Coastal
and Oceanographic Engineering, University of Florida, Gainesville,
20 p.

Clarke, G.B. and Case, R.A., 1986, Annual data and verification
tabulation Atlantic tropical cyclones 1985: NOAA Technical
Memorandum, National Weather Service, National Hurricane Center 29,
123p.

Hine, A.C., and Belknap, D.F., 1986, Recent geological history and
modern sedimentary processes of the Pasco, Hernando, and Citrus
County coastline: west-central Florida: Florida Sea Grant College
Publication No. 79, University of Florida, Gainesville, 160p.

Ho, F.P., and Tracey, R.J., 1975, Storm tide frequency analysis for the
Gulf coast from Cape San Blas to St. Petersburg Beach: NOAA
Technical Memorandum, National Weather Service HYDRO-20, 34 p.

National Oceanographic and Atmospheric Administration (NOAA), 1985,
Storm data: National Climatic Center, Asheville, North Carolina, v.
27, no. 9, 47 p.

Price, W.A., 1954, Shoreline and coasts of the Gulf of Mexico: U.S.
Fish and Wildlife Service Fishery Bulletin 89, v. 55, p. 39-65.

Tanner, W.F., 1960, Florida coastal classification: Transactions of the
Gulf Coast Association of Geological Societies, v. 10, p. 259-266.

U.S. Army Coastal Engineering Research Center, 1973, Shore protection
manual, Volume 1: Superintendent of Documents, U.S. Government
Printing Office, Washington, D.C. 4-180p.

Withlacoohcee Regional Planning Council, 1984, Withlacoochee Hurricane
Evacuation Study: 134p.




University of Florida Home Page
© 2004 - 2010 University of Florida George A. Smathers Libraries.
All rights reserved.

Acceptable Use, Copyright, and Disclaimer Statement
Last updated October 10, 2010 - - mvs