Establishment of a coastal setback line in Florida


Purpura, J.A.

Proceedings of the Coastal Engineering Conference 13(2): 1599-1615

1972


CHAPTER
88
ESTABLISHMENT
OF
A
COASTAL
SETBACK
LINE
IN
FLORIDA
By
James
A.
Purpura
Associate
Professor
Coastal
and
Oceanographic
Engineering
Laboratory
University
of
Florida,
Gainesville,
Florida,
U.
S.
A.
ABSTRACT
The
Florida
Legislature
passed
a
law
in
1971
requiring
the
establishment
of
coastal
construction
setback
lines
on
a
county
basis
along
the
sand
beaches
of
the
State
of
Florida
fronting
on
the
Atlantic
Ocean
and
the
Gulf
of
Mexico.
Florida's
beach
areas
(valued
in
$
billions)
are
being
developed
at
an
accelerated
rate,
however
the
coastline
is
in
a
general
state
of
serious
erosion.
These
factors
combine
to
make
implementation
of
the
above
law
extremely
urgent.
The
Coastal
and
Oceanographic
Department
of
the
University
of
Florida
has
a
contract
with
the
Florida
Department
of
Natural
Resources
to
furnish
a
comprehensive
engineering
study
of
the
various
coastal
counties
of
Florida
in
order
to
provide
the
technical
information
and
make
recommendations
for
the
establishment
of
such
setback
lines.
A
typical
coastal
county
study
is
described.
The
study
included
historical
data
related
to
shoreline
stability,
field
measurements,
computations
and
evaluation
of
all
pertinent
factors.
Some
factors
considered
were
dune
elevations,
foreshore-offshore
slopes,
erosion
trends,
storm
surge,
vegetation
bluff
line,
wave
setup,
uprush,coastal
structures
and
upland
development.
Analysis
of
the
pertinent
factors
resulted
in
formulation
of
criteria
that
were
applied
in
recommendation
of
the
setback
line.
The
criteria-
application
is
described
along
with
adoption
procedures
as
required
by
law.
I.
INTRODUCTION
Chapter
161.053,
Florida
Statutes,
enacted
by
the
1971
session
of
the
State
Legislature,
provides
that
the
Department
of
Natural
Resources
(Governor
and
Cabinet)
shall
set
a
Coastal
Construction
Setback
Line
along
the
Gulf
and
Atlantic
shores
of
the
State.
This
law
prohibits
any
construction,
excavation,
damage
to
dunes
or
vegetation
and
driving
of
vehicles
on
dunes,
seaward
of
the
established
setback
line.
The
purpose
of
this
law
is
the
protection
of
upland
properties
and
the
control
of
beach
erosion
by
preservation
of
the
natural
beach-dune
system.
This
law
states
that
the
setting
of
this
line
shall
be
based
on
data
resulting
from
comprehensive
engineering
and
topographic-hydrographic
surveys,
erosion
trends,
predictable
storm
tides,
wave
runup,
the
vegetation
bluff
line,
and
other
technical
data.
Subsequently,
the
Department
of
Natural
Resources,
through
the
Bureau
of
Beaches
and
Shores,
entered
into
a
contract
with
the
Coastal
and
Oceanographic
Engineering
Department
of
the
University
of
Florida's
College
of
Engineering
for
the
required
studies
and
surveys.
1599
1600
COASTAL
ENGINEERING
II.
PROBLEM
BACKGROUND
Florida's
coastline
has
been
considered
one
of
the
most
beautiful
recreational
areas
in
the
world.
It
has
over
800
miles
of
sand
beaches
fronting
the
Atlantic
Ocean
and
the
Gulf
of
Mexico.
It
has
beautiful
dune
formations,
clean
white
sand
and
a
sub-tropical
climate
which
attracts
over
25
million
tourists
per
year.
Its
sandy
beaches
backed
by
dunes
constitute
a
natural
defense
against
the
sea.
The
beach
area
is
highly
dynamic,
and
seasonal
fluctuations
of
the
shoreline
are
a
normal
occurrence,
However,
Florida
is
subjected
to
winter
northeast
storm
and
tropical
hurricanes,
and
abnormal
assaults
on
the
coast-
line
may
result
in
severe
erosion
or
wild
fluctuations.
Sand
dunes
are
nature's
"insurance"
in
these
instances.
Although
showing
the
scars
of
battle
(scarps),
nature
usually
provides
a
healing
or
rebuilding
time
before
the
next
abnormal
onslaught.
In
undeveloped
beach
areas
bounded
by
natural
dunes,
the
shoreline
fluctuations
are
not
readily
apparent
to
the
casual
observer.
Thus,
parts
of
Florida's
coastline
have
been
considered
relatively
free
of
beach
erosion
and
fluctuations.
However,
coastal
development
by
man
encroach-
ing
on
the
dynamic
beach
area
provides
"reference
point"
whereby
natural
shore-
line
fluctuations
and
beach
erosion
becomes
readily
apparent.
Recent
history
(geologically
speaking)
has
shown
that
Florida's
shorelines
are
in
a
general
state
of
natural
erosion
(submergence),
due
mainly
to
a
rise
in
sea
level.
But
man's
actions
have
and
still
are
the
biggest
contributing
factor
to
the
State's
shoreline
problems.
Development
of
the
coastline
has
progressed
at
an
ever
increasing
pace.
Unfortunately,
with
a
complete
lack
of
or
poor
zoning
laws,
man
has
encroached
on
the
beaches
and
in
the
process
has
hampered
or
destroyed
nature's
defense
against
the
sea.
In
fact,
development
has,
in
many
instances,
magnified
erosive
forces
(vertical
seawalls),
inhibited
natural
rebuilding
processes
and
placed
older
existing
structures,
once
relatively
safe,
in
jeopardy.
Sections
of
the
natural
dune
line
have
been
removed
and/or
flattened
and
in
many
instances,
structures
have
been
erected
in
front
of
existing
dunes.
Large
portions
of
the
coastline
and
development
worth
billions
of
dollars
are
now
subjected
to
flooding
by
storm
tides
as
a
result
of
these
practices.
The
"improvement"
and
construction
of
several
inlets
around
the
coastline
has
further
aggravated
shoreline
problems.
As
a
consequence
of
man's
encroachment,
destructive
actions
and
magnifi-
cation
of
erosive
forces
we
now
find
that
Florida
has
a
serious
beach
erosion
problem.
A
forewarning
of
this
problem
was
pointed
out
in
a
1962
publication'
of
the
Coastal
Engineering
Laboratory
of
the
University
of
Florida.
The
problem
has
been
increasingly
apparent
as
further
development,
above
normal
tides
and
wave
conditions,
have
caused
extensive
damage
to
coastal
structures
and
dune
formations.
III.
SETBACK
LINE
INVESTIGATION
The
location
of
a
setback
line
from
a
coastal
engineering
point
of
view
depends
upon
certain
physical
conditions.
Factors
to
be
considered
in
a
broad
sense
are
shoreline
stability
(fluctuations,
erosion
trends)
and
topography
as
FLORIDA
SETBACK
LINE
1601
related
to
storm/hurricane
tides
and
wave
action.
To
properly
evaluate
shoreline
stability,
there
is
a
need
for
historical
data
of
long
duration.
The
first
step
in
a
study
is
to
survey
the
area
in
question
to
determine
the
need,
if
any,
for
a
setback
line.
If
the
need
is
established,
all
available
historical
data
should
be
collected,
and
a
topographic
and
hydrographic
survey
of
the
area
should
be
carried
out.
1.
Study
Area
Based
on
existing
shoreline
conditions,
and
at
the
request
of
local
officials,
the
Bureau
of
Beaches
and
Shores
designated
Martin
County
as
the
first
county
in
which
the
required
studies
would
be
made.
The
study
area
consists
of
22
miles
of
Atlantic
Ocean
beachfront
dissected
by
St.
Lucie
Inlet,
a
major
tidal
inlet.
The
area
consists
of
barrier
islands,
namely
Hutchinson
Island
between
the
north
Martin
County
line
and
St.
Lucie
Inlet
and
Jupiter
Island
from
St.
Lucie
Inlet
to
the
Palm
Beach
County
Line.
The
locality
is
shown
on
USC
&
GS
charts
Nos.
846,
1247,
1248
and
Figure
1
of
this
report.
Martin
County
has
a
long
history
of
beach
erosion
and/or
storm
damage
to
its
Atlantic
Coastline.
Jupiter
Island
has
been
noted
for
severe
beach
erosion
problems
and
Hutchinson
Island
has
suffered
from
erosion
and
damage
especially
during
hurricanes
and
northeast
storms.
Testimony
and
exhibits
presented
at
a
prestudy
public
hearing
in
Stuart
on
October
6,
1971
described
some
of
the
erosion
and
damage
problems
that
have
occurred
in
the
past.
Of
particular
interest
was
the
account
of
the
August-September
1949
hurricane
as
reported
in
the
Stuart
News.
It
described
how
Martin
County's
"first
ocean
front
tourist
colony,"
at
Jensen
Beach
was
reduced
to
a
pile
of
rubble.
The
colony
was
described
as
5
deluxe,
reinforced
concrete
cottages.
Also
described
at
the
hearing
was
the
severe
erosion
south
of
the
inlet,
a
breakthrough
to
the
bay
at
Pecks
Lake
and
a
history
of
the
development
of
St.
Lucie
Inlet.
A
comprehensive
report
of
the
coastline
problem
in
Martin
County
has
been
issued
by
the
Department
of
the
Army,
Jacksonville
District,
Corps
of
Engineers
dated
September
16,
1968.
The
report
entitled,
Beach
Erosion
Control
Study
on
Martin
County,
Florida,
with
its
detailed
descriptions
and
historical
data
was
a
valuable
aid
in
the
study.
The
above
data
and
public
hearing,
confirmed
the
need
of
a
setback
line
in
Martin
County.
2.
Field
Programs
The
general
case
in
Florida
will
show
a
lack
of
historical
and
good
statistical
data
so,
therefore,
much
reliance
must
be
made
on
comprehensive
topo-hydro
field
studies
correlated
with
the
measured
physical
parameters
of
the
area.
A
comprehensive
field
investigation
of
the
study
area
was
carried
out
as
follows:
As
required
in
the
law,
monumented
stations
approximately
900
ft.
apart
were
placed
parallel
to
the
shoreline
(127
stations)
from
the
northern
county
line
along
the
coast
to
the
southern
county
line,
a
distance
of
approximately
twenty-two
miles.
(Figs.
2
and
3).
Each
station
was
carefully
1602
COASTAL
ENGINEERING
A
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FIGURE
1
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MAP
FIGUR
E 2
PR
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ST
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U
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FLORIDA
SETBACK
LINE
1603
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PROFIL
E
ST
ATIONS
1604
COASTAL
ENGINEERING
FLORIDA
SETBACK
LINE
1605
surveyed
in
and
tied
to
the
State
Plane
Coordinate
System.
Beach
profiles
from
the
back
of
the
dune
(where
existing)
to
a
wading
depth
were
completed
from
each
station.
Profiles
were
repeated
after
two
winter
storms
to
determine
profile
fluctuations.
An
automatic
tide
recorder
was
placed
in
operation
on
an
ocean
pier
and
recorded
continuously
during
the
study.
Using
targeted
stations
as
control,
stereoscopic
aerial
coverage
of
the
study
area
was
flown
and
mylar
reproductions
at
a
scale
of
1"
=
100'
were
obtained.
Approximately
40
offshore
soundings
from
the
beach
to
a
depth
of
about
30
ft.
were
completed.
Intensive
ground
coverage
was
carried
out
taking
special
note
of
beach
material
and
composition,
rock
strata,
vegetation-bluff-scarp
lines,
wave
uprush,
dune
stability
(blowout-gaps,
etc.),
existing
coastal
structures
and
their
behavior,
present
construction
and
upland
development.
All
of
this
data
was
carefully
recorded
and
supplemented
with
photographs.
IV.
PERTINENT
FACTORS
1.
Erosion
Trends
Historical
data
are
extremely
valuable
in
determining
the
shoreline
trend
and
erosion-accretion
rates
for
use
in
determining
a
setback
line
location.
Fortunately,
there
are
sounding
data
of
1882,
1928-1930,
1946
and
1964
for
Martin
County.
Much
use
was
also
made
of
historical
aerial
photographs,
local
news
stories,
local
land
surveys
and
public
testimony.
Long
term
trends,
however,
do
not
always
indicate
the
short
term
fluctuations
that
occur
on
the
beach.
These
fluctuations
can
be
quite
large
in
magnitude
over
a
short
term
as
a
result
of
certain
tide-wave
conditions.
During
the
recent
surveys,
areas
of
the
county
shoreline
which
have
an
apparent
long
term
trend
of
stability
were,
noticed
to
suffer
quite
severe
erosion
with
subsequent
accretion-erosion
cycles.
These
cycles
are
dependent
on
wave
conditions,
however,
severe
damage
(i.e.
loss
of
vegetation,
structures,
etc.)
may
result
during
these
fluctuations.
2.
Wind-Waves-Tide
It
is
important
to
obtain
long
term
records
of
wind,
waves
and
tides
because
of
their
direct
bearing
on
the
coastline
stability.
This
is
especially
true
for
the
short
term
trends
or
fluctuations
of
the
beaches.
Florida's
coastline
suffers
from
severe
northeastern
storms
on
an
annual
basis.
These
storms
although
"normal",
can
in
many
instances,
if
long
enough
in
duration,
cause
considerably
more
beach
erosion
and
coastline
damage
than
many
hurricanes.
The
following
data
was
obtained
for
the
Martin
County
area.
Tides
-
Tide
records
in
this
area,
collected
from
previous
studies
and
currently
furnished
by
a
tide
recorder
at
Seminole
Shores
pier
on
Hutchinson
Island,
show
that
the
tide
is
semi-diurnal
with
a
rather
large
daily.
inequality.
Tide
tables
of
the
U.S.
Coast
and
Geodetic
Survey
list
the
average
tidal
range
for
the
ocean
tide
off
Martin
County
as
2.6
ft.
and
the
average
spring
tidal
range
as
3.0
ft.
The
actual
mean
sea
level
(MSL)
is
1.08
ft.
above
mean
low
1606
COASTAL
ENGINEERING
water
(MLW)
and
1.83
ft.
below
mean
high
water
(MHW)
(furnished
by
the
Army
Corps
of
Engineers,
Jacksonville
District).
Winds
-
The
most
comprehensive
offshore
wind
speed
and
direction
data
in
this
area
are
compiled
by
the
U.
S.
Naval
Weather
Service
Command.
According
to
this
publication,
85.5%
of
the
time
the
wind
speed
is
between
4
and
21
knots.
Wind
direction
frequencies
are
rather
evenly
distributed
among
the
eastern
semicircle
with
slightly
higher
frequency
from
east
(21.7%)
and
northeast
(16.7%).
Waves
-
In
accordance
with
the
wind
direction,
higher
percentage
of
waves
are
from
the
east
(22.4%)
and
northeast
(17.2%).
Waves
with
a
height
between
3
and
6
ft.
are
the
most
frequent
(48.4%).
Waves
higher
than
6
ft.
have
a
frequency
of
12.9%.
The
prevailing
wave
periods
are
between
3
and
4
sec.
(30.7%),
1
and
2
sec.
(26.0%)
and
5
and
6
sec.
(17.g%).
3.
Longshore
Current
and
Littoral
Drift
The
currents
which
affect
the
open
coast
are
the
longshore
currents
created
by
breaking
waves
at
an
angle
to
the
shore.
The
magnitude
of
the
longshore
current
depends
on
the
breaking
wave
characteristics,
breaking
angle
and
local
bottom
and
shore
configurations.
The
longshore
currents
are
responsible
for
sand
transport
along
the
coast.
For
the
study
area,
the
littoral
transport
is
generally
southward
during
the
period
September
through
February,
northward
from
June
through
August
and
directions
uncertain
during
the
rest
of
the
months.
The
predominant
or
net
littoral
drift
is
from
north
to
south
and
is
estimated
to
be
about
200,000
to
250,000
cu.
yds.
a
year
inside
the
20
ft.
contour.
4.
Storm
Surge
and
Wave
Setup
In
addition
to
the
astronomic
tide,
storms,
hurricanes
and
waves
are
capable
of
creating
extreme
high
water
levels,
especially
on
shallow
coastal
areas.
Storm
surge
is
the
vertical
rise
in
the
still
water
level
near
the
coast
caused
by
wind
stresses
on
the
water
surface.
No
reliable
records
are
available
of
water
levels
on
the
open
coast
during
major
hurricanes
which
have
occurred
in
the
past
few
decades.
In
a
study
of
storm
tides
in
Florida
2
,
the
Department
of
Coastal
and
Dceanographic
Engineering,
University
of
Florida
has
analyzed
the
normal
yearly
high
tides
and
high
water
levels
caused
by
hurricanes
and
expressed
the
results
as
frequency
of
occurrence
for
a
certain
water
level
to
be
equaled
or
exceeded.
In
that
study,
all
available
normal
and
storm
tide
data
before
1959
along
the
coast
of
Florida
were
analyzed
and
correlated
to
provide
the
tidal
level-frequency
information
for
the
open
coast
of
Florida.
Unfortunately
there
were
a
lack
of
data
for
the
study
area.
Thus
the
interpolated
storm
surge
frequencies
given
in
that
report
may
be
less
reliable
than
the
new
information
furnished
by
National
Oceanic
and
Atmospheric
Ad-
ministration
(NOAA).
For
this
reason,
it
is
chosen
to
adopt
the
NOAA's
information
for
use
in
this
study.
Figure
4
shows
the
storm
surge
elevation
and
frequency.
i
i i i i i
N
I i i I i
i 1
--------------....,.......................................
\
\
\
University,-.\
of
Florida
\\
N.
NOAA
,
....„......„..„.........
N.....
-......
-..-....._,
i i i
1 1 i i I I
I
I 1 I
i
0.001
0-002
0-005
0
01
0.02
0
05
0•I
0-2
average
number
of
occurrence
per
year
FIGURE
4
STORM
SURGE
FREQUENCIES
s
torm
s
urg
e
e
le
va
t
ion
a
bove
MS
L
in
ft.
10
9
8
5
4
3
2
0
H
N
I
'l
NO
VE
IH
S
VCI
I110
1,
4
Cr\
0
1608
COASTAL
ENGINEERING
For
comparison
the
interpolated
surge
elevation-frequency
curve
in
the
Univerversity
of
Florida's
report
is
also
shown
in
Figure
4
which
indicates
a
much
higher
trend.
In
view
of
the
documented
3
surge
of
8.5
ft.
(MSL)
in
St.
Lucie
River
caused
by
the
August
1949
hurricane,
the
curve
with
higher
surge
trend
may
prove
to
be
valid,
however,
the
newly
compiled
curve
by
NOAA
was
used
for
this
study.
Wave
setup
is
the
superelevation
of
the
water
surface
over
normal
surge
elevation
due
to
onshore
mass
transport
of
the
water
by
wave
action
alone.
There
is
no
record
of
wave
setup
for
this
area.
During
a"Standard
Hurricane"
such
as
Hurricane
Audrey
(1960),
the
wave
setup
is
estimated
to
be
about
2.0
ft.
in
the
study
area.
Another
factor
which
may
cause
an
increase
in
water
level
is
the
effect
of
rainfall.
Since
hurricanes
are
often
associated
with
ex-
cessive
rainfall,
an
increase
in
storm
tidal
levels
may
occur
in
coastal
areas
in
the
neighborhood
of
creeks,
rivers
and
inlets.
The
water
level
rise
due
to
reduced
atmospheric
pressure
associated
with
a
hurrican
is
considered
to
be
included
in
the
original
storm
tide
data.
5.
Wave
Uprush
Wave
uprush
is
the
rush
of
water
up
onto
the
beach
following
the
breaking
of
a
wave.
How
high
or
how
far
the
uprush
will
reach
depends
on
the
wave
characteristics
and
the
steepness
and
roughness
of
the
beach
surface.
Due
to
the
fact
that
each
beach
profile
is
highly
ir-
regular
in
shape
and
widely
varying
in
elevation
from
place
to
place,
the
wave
uprush
is
expected
to
vary
accordingly.
Since
a
setback
line
should
not
be
exposed
to
direct
wave
attack
of
a
certain
frequency,
the
uprush
would
be
a
minimum
elevation
(or
distance)
beyond
which
the
setback
line
should
be
located.
While
not
much
field
data
are
avail-
able,
laboratory
test
results
have
been
utilized
to
assist
in
uprush
computations.
For
a
complicated
beach
surface
with
changing
slopes,
the
composite
slope
method
has
proven
to
be
applicable.
Laboratory
tests
5
also
showed
rough
surfaces
could
reduce
uprush
considerably.
A
computer
program
was
developed
to
perform
the
calculations
of
uprush
on
each
of
the
profiles
by
employing
the
composite
slope
method.`'
Field
data
could
be
directly
fed
into
the
computer
which
would
compute
the
wave
uprush
under
any
given
wave
height
and
period
superimposed
on
any
water
level.
Many
different
water
levels
(surge
frequencies)
and
combinations
of
wave
periods
could
be
computed
in
an
extremely
fast,
efficient
manner.
6.
Topographical
Conditions
and
Existing
Structures
As
mentioned
in
Section
111-2,
Field
Program,
intensive
ground
surveys
were
carried
out.
Factors
such
as
beach
composition,
coastal
structures,
upland
development,
vegetation
(types-density),
visible
erosion
and/or
dune
damage
are
all
important
considerations.
Controlled,
vertical
aerial
photo-
graphs
of
the
coastline
were
flown
and
proved
to
be
extremely
valuable.
These
aerials
were
reproduced
on
mylar
sheets
at
a
scale
of
1"
=
100'
and
showed
the
position
of
each
permanent
monument
(profile
station)
as
well
as
the
state
plane
coordinate
lines.
FLORIDA
SETBACK
LINE
1609
V.
SETBACK
LINE
ANALYSIS
In
making
the
analysis
for
the
setback
line
the
objectives
were
two
fold.
To
prevent
beach
encroachment
that
would
endanger
the
natural
beach-dune
system
and
to
prevent
upland
development
from
being
unreasonably
subjected
to
great
or
irreparable
damage.
The
analysis
considered
these
factors:
topographic
features,
which
included
dune
elevation,
foreshore
and
offshore
slopes,
beach
material
and
width,
coastal
structures,
vegetation
and
bluff
lines;
the
dynamic
features,which
included
storm
surge
elevations,
erosion
rates,
wave
set
up
and
uprush,
tides
and
short
term
fluctuations
of
the
beach
profiles.
1.
Criteria
For
Martin
County
the
guidelines
and
standards
that
were
chosen
for
positioning
the
setback
line
are
as
follows:
A
storm
surge
of
4.2
ft.
MSL,
2.0
ft.
wave
setup
and
a
1.8
ft.
MSL
spring
tide
were
combined
in
the
determination
of
a
still
water
level
of
8.0
ft.
MSL
under
storm
conditions.
A
wind
wave
of
6.5
ft.
in
height
with
a
period
of
8.0
sec.
was
chosen
for
computing
the
uprush
by
composite
slope
method''
under
the
storm
condition
on
each
of
the
profiles.
This
will
yield
the
information
about
how
far
landward
the
uprush
may
reach.
Long
term
erosion
trends
were
compiled
for
each
profile
station
and
reduced
to
an
annual
average.
Short
term
fluctuations
were
used
to
determine
what
order
of
magnitude
may
be
expected
on
a
5
year
frequency.
Pertinent
topographical
features
(materials,
vegetation,
etc.)
were
incorporated
into
these
guidelines.
Existing
coastal
structures
and
upland
development
were
studied
for
efficiency,
durability,
continuity
and
affect
on
adjacent
properties.
2.
Application
Using
the
above
criteria,
the
uprush
limits
were
plotted
on
the
beach
profile
and
aerial
plans
as
a
first
approximation
of
the
setback
line.
A
minimum
distance
of
40
ft.
from
the
present
dynamic
beach
face
was
used
to
provide
for
the
extraordinary
beach
fluctuation.
This
distance
was
further
adjusted
to
the
annual
erosion
rate
using
a
further
setback
of
annual
rate
times
5
years.
A
minimum
distance
of
25
ft.
from
the
most
seaward
dune
crest
(if
present)
was
used
for
protection
of
the
dune
system.
Adjustment
of
coastal
structures
-
upland
development
was
then
applied
where
deemed
necessary.
Further
adjustment
was
made
to
avoid
discontinuity,
zig-zags
or
other
irregularities
which
showed
up
on
the
plotted
setback
line.
1610
COASTAL
ENGINEERING
Figures
5
to
8
show
some
typical
profiles
with
the
setback
line
(SBL),
surge
level
(20
year
frequency,
see
V.1.),
and
computed
wave
uprush.
VI.
ADOPTION
OF
SETBACK
LINE
As
required
by
law,
a
public
hearing
in
Martin
County
was
held
prior
to
recommendation
to
the
Governor
and
Cabinet
for
adoption
of
the
line.
Prior
to
the
public
hearing,
notice
was
given
to
all
county
residents
and
interested
parties.
Plans
showing
the
recommended
setback
line
along
with
reports
and
other
supporting
data
were
placed
on
public
display
well
in
advance
of
the
hearing.
At
the
public
hearing
all
arguments
and
evidence
for
support
or
in
opposition
to
the
recommended
line
were
recorded
for
study
by
the
staff
of
the
Department
of
Natural
Resources.
As
a
result
of
the
hearing,
one
adjustment
to
the
line
was
made
by
the
hearing
officer.
The
line
was
recommended
to
the
Governor
and
Cabinet
for
adoption.
Further
arguments
and
evidence
were
presented
at
the
time.
The
setback
line
was
adopted
by
a
unanimous
vote.
A
legal
description
of
the
adopted
setback
line
was
then
recorded
at
the
Martin
County
Clerk
Office.
The
law
provides
for
variances
of
the
setback
line
to
be
granted
by
the
Oepartment
of
Natural
Resources
if
such
variances
are
fully
justified.
The
law
further
provides
that
the
setback
line
be
reviewed
at
five
year
intervals
or
sooner
if
proven
necessary.
ACKNOWLEDGEMENTS
This
study
is
supported
by
the
Bureau
of
Beaches
and
Shores,
Department
of
Natural
REsources,
Tallahassee,
Florida.
Bureau
Chief,
Mr.
W.
T.
Carlton
and
Engineer,
Mr.
William
Sensabaugh
provided
valuable
assistance
throughout
the
study.
Special
acknowledgement
belongs
to
Mr.
T.
Y.
Chiu
of
the
Coastal
and
Oceanographic
Research
Laboratory
who
spearheaded
the
office
work
force
and
personally
contributed
so
much
to
the
project.
Mr.
Hal
Bean,
Field
Supervisor
and
Mr.
Stan
Rising,
also
deserve
special
recognition
for
their
untiring
efforts
in
providing
field
data.
REFERENCES
1.
Bruun,
Morgan,
Purpura,
"Review
of
Beach
Erosion
and
Storm
Tide
Conditions
in
Florida,"
Technical
Progress
Report
#13,
EIES,
College
of
Engineering,
University
of
Florida,
1961-1962.
2.
"Storm
Tides
in
Florida
as
Related
to
Coastal
Topography,"
Bulletin
Series
No.
109,
Florida
Engineering
and
Industrial
Experiment
Station,
University
of
Florida,
1962.
3.
"Survey
Report,"
by
the
Corps
of
Engineers,
Jacksonville
District,
September
1961.
4.
Saville,
T.,
Jr.,
"Wave
Run-up
on
Composite
Slopes,"
Proc.
of
the
6th
Conference
on
Coastal
Engineering,
Council
of
Wave
Research,
University
FLORIDA
SETBACK
LINE
1611
of
California,
1958.
5.
Savage,
R.
P.,
"Wave
Run-up
on
Roughened
and
Permeable
Slopes,"
Proc.
of
ASCE,
Waterways
and
Harbors
Division,
WW3,
Paper
1640,
1958.
30
Range
No.
17
uprush
20
yr.
freq.
MHW
0
100
distance
in
ft.
200
300
20
10
E
--Oct.
12-13,
1971
survey
----Jan.
26,
1972
survey
0
2
-5
0
30
20
10
0
—5
O
N
I
NAA
NIO
NA
I
VI
S
V
OD
Range
No.
18
SBL
uprush
20
yr.
freq.
MHW
0
distance
in
ft.
L
100
200
300
FIGURE
5
BEACH
PROFILES
30
Range
No.
41
20
SBL
uprush
20
yr.
freq.
MHW
0
100
200
distance
in
ft.
---Oct.
12-13
,
1971
survey
Feb.
21-23,
1972
survey
30
20
10
0
-5
-200
300
400
500
C\
5
-
100
1
M
1
)ID
VHI
Th
S
VU
11
10
1.
4
10
0
distance
in
ft.
FIGURE
6
BEACH
PROFILES
Range
No.
72
overtopping
SBL
20
yr.
freq.
MHW
=1
CO
2
20
10
0
0
0
7,,
0
5
30
1VISVOD
distance
in
ft.
100
indicates
unsurveyed
trend
Nov.
2-4,1971
survey
---
Jon.
11,
1972
survey
Feb.
2
-23,
1972
survey
200
Range
Na.
73
SBL
overtopping
20
yr.
freq.
MHW
-
100
0
30
CO
2
20
10
O
0
711
0
-5
-
100
0
distance
in
ft.
100
200
FIGURE
7
BEACH
PROFILES
Range
Na.
123
\prush
SBL
20
yr.
freq.
MHW
L
30
Range
Na.
122
uprush
e
le
va
tion
in
20
yr.
freq.
MHW
0
100
200
distance
in
ft.
mow.
indicates
unsurveyed
trend
Feb.
21-23,
1972
survey
—•—
Nov.
2-4,
1971
survey
30
20
10
0
-5
-100
0
100
200
20
10
0
0
SBL
5
-
100
al\I
I
IN
DVaia
S
VCI
D1013
distance
in
ft.
FIGURE
8
BEACH
PROFILES