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Mississippi Valley Division Engineer Research and Development Center
Pictorial Account and Landscape Evolution of the Crevasses near
Fort St. Philip, Louisiana MRG&P Report No. 2 • January 2014
Mississippi River Geomorphology and Potamology Program
MRG&P Report No. 2 January 2014
Pictorial Account and Landscape Evolution of the Crevasses near Fort St. Philip, Louisiana
Glenn M. Suir Environmental Laboratory U.S. Army Engineer Research and Development Center Wetlands and Environmental Technologies Research Facility Louisiana State University - Wetland Resources Building Baton Rouge, LA 70803
William R. Jones U.S. Geological Survey (USGS) National Wetlands Research Center 700 Cajundome Boulevard Lafayette, LA 70506
Adrienne L. Garber Five Rivers Services, LLC National Wetlands Research Center 700 Cajundome Boulevard Lafayette, LA 70506
John A. Barras U.S. Geological Survey (USGS) Coastal and Marine Science Center 600 Fourth Street South St. Petersburg, FL 33701
Final report Approved for public release; distribution is unlimited.
MRG&P Report No. 2 ii
Abstract
Quantifying the effects of active natural and constructed crevasses is critical to the planning and success of future ecosystem restoration activities. This document provides a historical overview of landscape changes within the vicinity of the natural crevasses near Fort St. Philip, Louisiana. A significant event influencing landscape change within the Fort St. Philip study area was the breaching of the eastern levee of the Mississippi River. Initially, the river water that was diverted through these crevasse channels physically removed significant marsh areas within the study area. These initial direct impacts were succeeded by several decades of larger regional loss patterns driven by subsidence and other episodic events (e.g, hurricanes and floods), and recent localized land gains. These increases in land area are potentially the long-term results of the Fort St. Philip crevasses, and the short-term impacts of delta management activities. However, for the majority of the 1956-2008 period of analysis, the crevassing of the eastern bank of the Mississippi River levee was a loss accelerant in the Fort St. Philip area.
DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents. DESTROY THIS REPORT WHEN NO LONGER NEEDED. DO NOT RETURN IT TO THE ORIGINATOR.
MRG&P Report No. 2 iii
Contents Abstract .......................................................................................................................................................... ii
Figures and Tables ........................................................................................................................................ iv
Summary ......................................................................................................................................................... vi
Preface ...........................................................................................................................................................vii
Unit Conversion Factors ........................................................................................................................... viii
1 Introduction ............................................................................................................................................ 1 1.1 Background .................................................................................................................... 1 1.2 Purpose .......................................................................................................................... 1 1.3 Project area .................................................................................................................... 3
2 Methods .................................................................................................................................................. 4 2.1 Data acquisition and processing .................................................................................. 4 2.2 High-resolution data ...................................................................................................... 6 2.3 Moderate-resolution data ............................................................................................. 7
3 Results .................................................................................................................................................... 8 3.1 Aerial photography ......................................................................................................... 8 3.2 Landscape area and change – High-resolution analyses ......................................... 10 3.3 Landscape area and change – Moderate-resolution analyses ................................. 31
4 Conclusions .......................................................................................................................................... 34
References ................................................................................................................................................... 35
Report Documentation Page
MRG&P Report No. 2 iv
Figures and Tables
Figures
Figure 1. Fort St. Philip Crevasses study location map. ............................................................................ 2 Figure 2. Daily Mississippi River stage data (water level, in feet) at Empire gage (blue) and Venice gage (green), Louisiana. Flood stage peak identified with red circle. ........................................ 8 Figure 3. Aerial photography showing pre- (left pane), active- (middle pane), and post-breaching (right pane) of the Mississippi River levee near Fort St. Philip, Louisiana in 1970, 1973 (moderate-resolution photography experiencing Moiré effect), and 1974, respectively. Breach site identified with red ovals. .................................................................................... 9 Figure 4. Fort St. Philip study area - 1956 high-resolution photomosaic map. ................................... 11 Figure 5. Fort St. Philip study area with access canals (#1) - 1970 high-resolution photomosaic map (Table 2). ....................................................................................................................... 12 Figure 6. Fort St. Philip study area with crevasse locations (#2), areas with major land-to-water conversion (#3), and formation of crevasse channels (#4) - 1978 high-resolution photomosaic map (Table 2). ....................................................................................................................... 13 Figure 7. Fort St. Philip study area with areas of land-to-water conversion (#3), crevasse channel development (#4), and large impoundment area (#5) - 1989 high-resolution photomosaic map (Table 2). ....................................................................................................................... 14 Figure 8. Fort St. Philip study area with areas of land-to-water conversion (#3), crevasse channel development (#4), and large impoundment area (#5) - 1998 high-resolution photomosaic map (Table 2). ....................................................................................................................... 15 Figure 9. Fort St. Philip study area constructed Coastal Wetlands Planning, Protection, and Restoration Act BS-11 project terraces (#6) - 2008 high-resolution photomosaic map (Table 2). ........................................................................................................................................................ 16 Figure 10. Delta Management at Fort St. Philip project area - 2011 high-resolution photomosaic map (USFWS 2013b). .......................................................................................................... 17 Figure 11. Fort St. Philip study area - 1956 high-resolution land-water classification map. ............. 19 Figure 12. Fort St. Philip study area - 1970 high-resolution land-water classification map. ............. 20 Figure 13. Fort St. Philip study area - 1956-1970 high-resolution land change analysis map. ............ 21 Figure 14. Fort St. Philip study area - 1978 high-resolution land-water classification map. .................. 22 Figure 15. Fort St. Philip study area - 1970-1978 high-resolution land change analysis map. ............. 23 Figure 16. Fort St. Philip study area - 1988 high-resolution land-water classification map. .................. 24 Figure 17. Fort St. Philip study area - 1978-1988 high-resolution land change analysis map. ............. 25 Figure 18. Fort St. Philip study area - 1998 high-resolution land-water classification map. .................. 26 Figure 19. Fort St. Philip study area - 1988-1998 high-resolution land change analysis map. ............ 27 Figure 20. Fort St. Philip study area - 2008 high-resolution land-water classification map. .................. 28 Figure 21. Fort St. Philip study area - 1998-2008 high-resolution land change analysis map............. 29 Figure 22. Fort St. Philip study and reference area zonal boundaries and the 1956-2008 moderate-resolution land change analysis map. .................................................................................... 32
MRG&P Report No. 2 v
Tables
Table 1. Status of available photography, imagery, and classified land and water data within the Fort St. Philip study area. ............................................................................................................ 5 Table 2. Dominant landscape feature changes identified using visual observation of high-resolution aerial photography and digital imagery. Corresponding feature numbers are represented in Figures 5-9 for location identification. ................................................................... 18 Table 3. Summary of Fort St. Philip study area acreages, and percentages of area change, for select time periods - from high-resolution analyses. The color-ramp illustrates the type and magnitude of land change, where the darkest red represents the loss maxima and darkest green represents gain maxima. ................................................................................................... 30 Table 4. Summary of Fort St. Philip study area zonal statistics, and percentages of area change, for select time periods - from moderate-resolution analyses. The color-ramp illustrates the type and magnitude of land change, where the darkest red represents the loss maxima and the darkest green represents gain maxima. ............................................................. 33
MRG&P Report No. 2 vi
Summary
Quantifying the effects of active natural and constructed crevasses is critical to the planning and success of future ecosystem restoration activities. However, program stakeholders often lack the comprehensive assessments and tools necessary to quantify those short- and long-term effects. Therefore, this document has been prepared to provide a historical overview of landscape changes within the vicinity of the natural crevasses near Fort St. Philip, Louisiana.
This study utilized aerial photography, satellite imagery, and existing and newly generated land and water classifications to: (1) identify the time at which the Fort St. Philip crevasses were formed; (2) provide a pictorial account of the evolution of the Fort St. Philip crevasses and impacted wetlands; (3) evaluate land-water ratios and landscape change within the study area; (4) detect change relative to reference wetland areas; and (5) develop descriptive figures and summary statistics. These assessments, which cover decadal or greater time periods, include historical and modern landscape analyses that are based on previous methodologies developed by this study’s principal investigators.
A significant event influencing landscape change within the Fort St. Philip study area during the study period was the breaching of the eastern levee of the Mississippi River and subsequent development of the Fort St. Philip crevasse channels. Initially, the river water that was diverted through these crevasse channels physically removed significant marsh areas within the study area. These initial direct impacts were succeeded by several decades of larger regional loss patterns driven by subsidence and other episodic events (e.g, hurricanes and floods), and recent localized land gains. These increases in land area are potentially the long-term results of the Fort St. Philip crevasses, and the short-term impacts of the Coastal Wetlands Planning, Protection, and Restoration Act (CWPPRA) BS-11 delta management activities. However, for the majority of the 1956-2008 period of analysis, the crevassing of the eastern bank of the Mississippi River levee was a loss accelerant in the Fort St. Philip area.
MRG&P Report No. 2 vii
Preface
The research documented in this report was conducted as part of the Mississippi River Geomorphology and Potamology (MRG&P) Program. The MRG&P is part of the Mississippi River and Tributaries Program and is managed by the US Army Corps of Engineers (USACE) Mississippi Valley Division (MVD) and Districts. The MRG&P Program Manager was Freddie Pinkard and the Technical Leader was Dr. Barbara Kleiss.
The MVD Commander was BG Peter A. DeLuca. The MVD Director of Programs was Edward Belk.
Providing Mississippi River engineering direction and policy advice was the Mississippi River Commission. The Commission members were BG DeLuca, USACE; the Honorable Sam E. Angel; the Honorable R. D. James; the Honorable Norma Jean Mattei, Ph.D.; RDML Gerd F. Glang, National Oceanic and Atmospheric Administration; BG Margaret W. Burcham, USACE; and BG John S. Kem, USACE.
The US Army Engineer Research and Development Center (ERDC) conducted this research supporting the MRG&P under the purview of the Environmental Laboratory (EL), Vicksburg, Mississippi.
This report was prepared by Glenn Suir, Environmental Systems Branch (EE-C), ERDC-EL; Bill Jones, U.S. Geological Survey, National Wetlands Research Center; Adrienne Garber, Five Rivers Services, LLC, National Wetlands Research Center; and John Barras, U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center–Baton Rouge Colocation Office. The report was prepared under the general supervision of Mark Graves, Chief, EE-C; Dr. Edmond J. Russo, Jr., P.E., Chief, Ecosystem Evaluation and Engineering Division, EL; Dr. Jack Davis, Deputy Director, EL; and Dr. Beth Fleming, Director, EL.
COL Jeffrey R. Eckstein was Commander of ERDC. Dr. Jeffery P. Holland was the ERDC Director.
MRG&P Report No. 2 viii
Unit Conversion Factors
Multiply By To Obtain
acres 4,046.873 square meters
cubic feet 0.02831685 cubic meters
feet 0.3048 meters
miles (U.S. statute) 1,609.347 meters
square miles 2.589998 E+06 square meters
MRG&P Report No. 2 1
1 Introduction
1.1 Background
Crevassing of the Mississippi River has significantly contributed to delta lobe formation adjacent to the river. Crevasses, which occur as large breaches or breaks in river levees, promote infilling of shallow inter-distributary ponds with sediment-laden river water, ultimately resulting in vegetated deltaic splays (Rodrigue 2003). From 1773 to 1927, the total number of Mississippi River crevasses (principally in Louisiana) reported in the literature was 1,062 (Davis 2000). During that same period, as many as 20 natural crevasse splays were active in the modern Mississippi River Delta, accounting for more than 80% of its subaerial land (Davis 2000). However, human alterations to the Mississippi River system (e.g. channel training and flood protection measures) have eliminated the majority of crevasses above river mile 42 (corresponds to the southern terminus of the east bank flood protection levee, Figure 1), thereby reducing the supply of nutrient- and sediment-rich water that is vital for the subsistence of deltaic wetlands (National Research Council 2006).
For the last half-century, Louisiana’s coastal wetlands have experienced rapid degradation (Suir et al. 2013). However, with past successes of delta progradation through natural crevassing, artificial crevasse cuts and freshwater diversions could be viable engineering techniques for utilizing nutrient- and sediment-laden water for marsh management and ecosystem restoration. With numerous artificial crevasses and freshwater diversions currently constructed or proposed, quantifying the long-term landscape changes and trends that are associated with active crevasses is critical to the planning and success of future projects.
1.2 Purpose
The primary goals of this study were to identify and quantify recent and historical land change trends from the mid-1950s through 2008 for the area surrounding the active Mississippi River levee breach near Fort St. Philip, Louisiana, and to compare the magnitude and sequencing of those changes to reference areas along the eastern bank of the Mississippi River (Breton Sound Basin).
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epor
t No.
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2
Figure 1. Fort St. Philip Crevasses study location map.
MR
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epor
t No.
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3
To a
chie
ve th
ese
goal
s, th
e au
thor
s pr
opos
ed th
at g
eosp
atia
l dat
a be
ac
quir
ed, p
roce
ssed
, and
/or
gene
rate
d in
ord
er to
: (1)
iden
tify
the
even
t(s)
an
d ti
min
g at
whi
ch th
e M
issi
ssip
pi R
iver
leve
e w
as b
reac
hed,
res
ulti
ng in
th
e Fo
rt S
t. Ph
ilip
crev
asse
s; (2
) pro
vide
a p
icto
rial
acc
ount
of t
he
evol
utio
n of
the
Fort
St.
Phili
p cr
evas
ses;
(3) a
naly
ze c
hang
es in
pro
ject
ar
ea w
etla
nd la
ndsc
apes
ove
r ti
me
usin
g la
nd a
nd w
ater
cla
ssifi
cati
ons;
(4
) ana
lyze
cha
nges
to c
ompa
re th
e pr
ojec
t are
a to
ref
eren
ce a
rea
land
scap
es; a
nd (5
) dev
elop
des
crip
tive
figu
res
and
sum
mar
y st
atis
tics
.
1.3
Proj
ect a
rea
The
7,39
1-ac
re s
tudy
sit
e is
loca
ted
in s
outh
east
ern
Bre
ton
Soun
d B
asin
, w
hich
ext
ends
from
the
Mis
siss
ippi
Riv
er e
ast t
o th
e M
issi
ssip
pi R
iver
Gul
f O
utle
t, an
d so
uth
from
Bay
ou T
erre
aux
Boe
ufs
to B
apti
ste
Col
lett
e B
ayou
(F
igur
e 1)
. The
983
-mi2
bas
in, a
rem
nant
of t
he S
t. B
erna
rd D
elta
, als
o co
ntai
ns s
ever
al a
band
oned
dis
trib
utar
y ch
anne
ls in
clud
ing
Bay
ou L
a Lo
utre
, Riv
er a
ux C
hene
s, a
nd B
ayou
Lam
oque
(US
Fish
and
Wild
life
Serv
ice
(USF
WS)
200
3). I
n ad
diti
on to
thes
e ch
anne
ls, f
low
s al
so e
scap
e th
e ri
ver
thro
ugh
seve
ral n
atur
al a
nd m
an-m
ade
open
ings
in th
e ba
nk
(Fig
ure
1). T
he s
tudy
are
a is
gen
eral
ly im
pact
ed b
y ri
veri
ne o
verb
ank
flood
ing/
crev
assi
ng, t
idal
and
met
rolo
gica
l con
diti
ons,
and
rap
id s
ubsi
-de
nce.
Thi
s st
udy
will
focu
s on
the
open
ings
(cre
vass
es) a
nd th
e ar
ea o
f in
fluen
ce lo
cate
d ne
ar F
ort S
t. Ph
ilip.
Ass
essi
ng th
e sh
ort-
and
long
-ter
m la
ndsc
ape
chan
ges
that
hav
e oc
curr
ed
pre-
and
pos
t-cr
evas
sing
, and
com
pari
ng th
ose
chan
ges
to r
efer
ence
are
as,
prov
ides
val
uabl
e in
form
atio
n re
late
d to
nat
ural
cre
vass
e fo
rmat
ion
and
evol
utio
n. A
lso,
at 1
00,0
00 ft
3 /se
c (m
easu
red
duri
ng h
igh
rive
r st
age)
, the
flo
w th
roug
h th
ese
crev
asse
cha
nnel
s pr
ovid
es a
n an
alog
by
whi
ch to
as
sess
land
scap
e-le
vel i
mpa
cts
from
larg
e fr
eshw
ater
div
ersi
ons.
MR
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epor
t No.
2
4
2 M
etho
ds
Thre
e pr
imar
y ta
sks
wer
e as
soci
ated
with
this
stu
dy. T
hose
task
s w
ere:
(1
) dat
a ac
quis
ition
and
pro
cess
ing,
(2) l
ands
cape
ana
lyse
s w
ithin
the
stud
y ar
ea u
sing
hig
h-re
solu
tion
phot
ogra
phy
and
imag
ery,
and
(3) c
ompa
riso
n of
pr
ojec
t and
ref
eren
ce a
rea
land
scap
es u
sing
mod
erat
e-re
solu
tion
imag
ery.
Th
ese
asse
ssm
ents
con
sist
ed o
f his
tori
cal a
nd m
oder
n la
ndsc
ape
anal
yses
ba
sed
on m
etho
dolo
gies
and
dat
a de
velo
ped
for
prio
r co
asta
l tre
nd s
tudi
es
(Bar
ras
2009
, Bar
ras
et a
l. 20
08, L
ouis
iana
Dep
artm
ent o
f Nat
ural
R
esou
rces
(LD
NR
) 199
5, S
altu
s et
al.
2012
, Sui
r et
al.
2011
).
2.1
Dat
a ac
quis
ition
and
pro
cess
ing
Dec
adal
or
grea
ter
peri
ods
of a
naly
ses
wer
e pr
opos
ed fo
r th
is s
tudy
. H
owev
er, t
hose
per
iods
wer
e ul
timat
ely
base
d on
the
tim
e of
cre
vass
e fo
rmat
ion,
ava
ilabl
e ae
rial
pho
togr
aphy
and
cla
ssifi
ed im
ager
y, a
nd ti
me
requ
irem
ents
for
perf
orm
ing
addi
tiona
l lan
d an
d w
ater
cla
ssifi
catio
ns.
Hig
her
reso
lutio
n (<
1:65
,000
sca
le) h
isto
rica
l and
rec
ent a
eria
l pho
to-
grap
hy a
nd d
igit
al im
ager
y w
ere
acqu
ired
for
the
year
s 19
56, 1
970,
197
3,1
1974
,1 19
78, 1
989,
1 199
8, a
nd 2
008
(Tab
le 1
). T
houg
h th
e 19
98 a
nd 2
008
data
exi
st in
geo
-rec
tifie
d an
d m
osai
cked
dig
ital
form
ats,
the
1956
, 197
0,
1973
, 197
4, 1
978,
and
198
9 da
ta w
ere
only
ava
ilabl
e in
un-
rect
ified
Tag
ged
Imag
e Fi
le (T
IF) f
orm
at. T
here
fore
, all
un-r
ectif
ied
fram
es w
ere
rect
ified
us
ing
the
2008
dig
ital i
mag
ery
as th
e co
ntro
l, an
d su
bset
to th
e st
udy
area
bo
unda
ry.
The
land
cha
nge
asse
ssm
ents
(bot
h hi
gh- a
nd m
oder
ate-
reso
lutio
n)
disc
usse
d w
ithin
this
rep
ort w
ere
calc
ulat
ed u
sing
land
and
wat
er d
ata
sets
an
d m
etho
ds d
evel
oped
for
prio
r co
asta
l lan
d ar
ea c
hang
e as
sess
men
ts
(Bar
ras
2006
, 200
9; B
arra
s et
al.
1994
, 200
3, 2
008;
Cah
oon
and
Gro
at
1990
; Sal
tus
et a
l. 20
12; U
S G
eolo
gica
l Sur
vey
(USG
S) 1
980,
198
8a, 1
988b
, 20
09),
as
wel
l as
land
and
wat
er d
ata
sets
cre
ated
as
part
of t
his
stud
y (1
970
and
1998
). E
xist
ing
and
new
ly c
reat
ed la
nd a
nd w
ater
dat
a se
ts w
ere
deri
ved
from
mul
tiple
sou
rce
data
. Exi
stin
g da
ta s
ourc
es in
clud
e La
ndsa
t
1 The
se p
hoto
grap
hs w
ere
conv
erte
d to
a d
igita
l for
mat
by
the
US G
eolo
gica
l Sur
vey,
Eart
h Re
sour
ces
Obse
rvat
ion
and
Scie
nce
(ERO
S) C
ente
r usi
ng c
harg
e-co
uple
d de
vice
(CCD
) cap
ture
rath
er th
an a
fla
tbed
sca
nner
and
are
con
side
red
med
ium
-reso
lutio
n da
ta. H
owev
er, c
ompa
red
to m
oder
ate-
reso
lutio
n La
ndsa
t im
ager
y, an
d fo
r sim
plify
ing
asse
ssm
ent t
asks
, the
se p
hoto
s w
ill b
e co
nsid
ered
hi
gh-re
solu
tion
data
for t
his
stud
y.
MR
G&
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epor
t No.
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5
Them
atic
Map
per
(TM
) sat
ellit
e im
ager
y ob
tain
ed fr
om th
e U
SGS
Cen
ter
for
Ear
th R
esou
rces
Obs
erva
tion
and
Sci
ence
(mod
erat
e-re
solu
tion
data
fr
om 1
988,
200
1, a
nd 2
008;
Tab
le 1
). T
hose
land
and
wat
er d
ata
sets
that
w
ere
mod
ified
from
pho
to-i
nter
pret
ed N
atio
nal W
etla
nds
Inve
ntor
y (N
WI)
ha
bita
t dat
a co
nsis
t of h
igh-
reso
lutio
n da
ta fr
om 1
956,
197
8, 1
988,
and
20
08 (T
able
1).
Add
itio
nally
, the
land
and
wat
er d
ata
sets
that
wer
e de
rive
d sp
ecifi
cally
for
this
stu
dy c
onsi
st o
f pho
to-i
nter
pret
ed, h
igh-
reso
lutio
n pa
nchr
omat
ic a
nd c
olor
infr
ared
(CIR
) aer
ial p
hoto
grap
hy fr
om 1
970
and
1998
, res
pect
ivel
y (T
able
1).
Sin
ce th
ese
data
wer
e pr
oces
sed
by v
ario
us
anal
ysts
and
cla
ssifi
ed u
sing
diff
erin
g m
etho
ds, m
easu
res
wer
e ta
ken
to
ensu
re c
ompa
tibili
ty b
etw
een
data
set
s (s
ee b
elow
).
Tabl
e 1.
Sta
tus
of a
vaila
ble
phot
ogra
phy,
imag
ery,
and
clas
sifie
d la
nd a
nd w
ater
dat
a wi
thin
the
Fort
St. P
hilip
stu
dy a
rea.
Asse
ssm
ent
Date
Da
ta T
ype
Data
Sou
rce
Scal
e Pr
oces
s/Ap
plic
atio
n
Fort St. Philip Project Area Higher Resolution (1-m resampled)
24 M
arch
19
56
Panc
hrom
atic
Ph
otog
raph
y Ar
my
Map
Ser
vice
1:
24,0
00
Aggr
egat
ed N
WI H
abita
t
8 M
arch
19
701
Panc
hrom
atic
Ph
otog
raph
y U.
S. G
eolo
gica
l Sur
vey
1:54
,800
La
nd a
nd W
ater
D
elin
eatio
n
11 A
pril
1973
Pa
nchr
omat
ic
Phot
ogra
phy3
N
ASA
- AM
ES
1:12
7,00
0 Vi
sual
Inte
rpre
tatio
n
17 O
ctob
er
1974
Pa
nchr
omat
ic
Phot
ogra
phy3
N
ASA
- JSC
1:
119,
000
Visu
al In
terp
reta
tion
15 O
ctob
er
1978
CI
R Ph
otog
raph
y4
NAS
A - A
MES
1:
65,0
00
Aggr
egat
ed N
WI H
abita
t
1 Ja
nuar
y 19
88
CIR
Phot
ogra
phy4
N
ASA
1:65
,000
Ag
greg
ated
NW
I Hab
itat
30 O
ctob
er
1989
2 CI
R Ph
otog
raph
y4
U.S.
Geo
logi
cal S
urve
y - N
APP
1:40
,000
Vi
sual
Inte
rpre
tatio
n
4 Fe
brua
ry
1998
1 D
OQQ4
La
. Oil
Spill
Coo
rdin
ator
's O
ffice
1:
40,0
00
Land
and
Wat
er
Del
inea
tion
30 O
ctob
er
2008
D
igita
l Im
ager
y4
U.S.
Geo
logi
cal S
urve
y -
Aggr
egat
ed N
WI H
abita
t
Breton Reference Area Moderate Resolution (25-m resampled)
24 M
arch
19
56
Panc
hrom
atic
Ph
otog
raph
y Ar
my
Map
Ser
vice
1:
20,0
00
Prev
ious
ly Ag
greg
ated
and
Re
sam
pled
NW
I
15 O
ctob
er
1978
CI
R Ph
otog
raph
y N
ASA
- AM
ES
1:65
,000
Pr
evio
usly
Aggr
egat
ed a
nd
Resa
mpl
ed N
WI
28 Ja
nuar
y 19
88
Land
sat 5
Im
ager
y N
ASA
- La
nd a
nd W
ater
D
elin
eatio
n
30 O
ctob
er
2001
La
ndsa
t 5
Imag
ery
NAS
A -
Land
and
Wat
er
Del
inea
tion
1 Oc
tobe
r 20
08
Land
sat 5
Im
ager
y N
ASA
- La
nd a
nd W
ater
D
elin
eatio
n 1 1
970
and
1998
land
and
wat
er d
ata
wer
e de
linea
ted
as p
art o
f thi
s st
udy.
2 198
9 ph
otog
raph
y pr
ovid
es h
ighe
r qua
lity
data
than
thos
e us
ed in
198
8 N
WI c
lass
ifica
tion.
3 Us
ed fo
r ass
essi
ng s
eque
ncin
g of
leve
e br
each
. 4 Th
e co
lor i
nfra
red
phot
ogra
phy u
sed
in th
is re
port
’s fi
gure
s ar
e di
spla
yed
in g
rays
cale
for e
ase
of c
ompa
rison
.
MR
G&
P R
epor
t No.
2
6
2.2
Hig
h-re
solu
tion
data
The
high
er r
esol
utio
n la
nd a
nd w
ater
dat
a th
at w
ere
used
in th
is s
tudy
wer
e de
rive
d fr
om p
hoto
grap
hy o
btai
ned
in 1
956
(1:2
4K),
197
0 (1
:58.
4K),
197
8 (1
:65K
), a
nd 1
988
(1:6
5K, m
agni
fied
to 1
:24k
for
zoom
tran
sfer
); fr
om 1
998
colo
r in
frar
ed (C
IR) p
hoto
grap
hy (1
:40K
/1 m
); a
nd fr
om 2
008
(1-m
) CIR
di
gita
l im
ager
y (T
able
1).
As
a pr
ecur
sor,
it s
houl
d be
not
ed th
at m
etho
ds
used
to d
eriv
e th
ese
land
and
wat
er d
ata
vari
ed c
onsi
dera
bly.
Lan
d an
d w
ater
dat
a fo
r th
e ye
ars
1956
, 197
8, a
nd 1
988
wer
e de
rive
d fr
om e
xist
ing
NW
I hab
itat d
ata
deve
lope
d fo
r pr
ior
coas
tal c
hara
cter
izat
ion
stud
ies
(Wic
ker
1980
, 198
1; U
SGS
1988
b; B
arra
s et
al.
1994
; Ful
ler
et a
l. 19
95).
Th
ese
habi
tat d
ata
wer
e cl
assi
fied
usin
g a
stan
dard
NW
I cla
ssifi
catio
n sc
hem
e (C
owar
din
et a
l. 19
79).
The
NW
I hab
itat
sch
eme
was
ada
pted
to
iden
tify
spec
ific
Loui
sian
a w
etla
nd h
abit
ats
usin
g co
de m
odifi
ers
(Wic
ker
1980
). T
o co
mpa
re c
hang
es in
land
and
wat
er a
rea,
the
clas
sifie
d ha
bita
t da
ta w
ere
aggr
egat
ed in
to la
nd a
nd w
ater
cat
egor
ies
usin
g a
stan
dard
cl
assi
ficat
ion
sche
me.
Lan
d fe
atur
es r
epre
sent
upl
ands
, em
erge
nt
vege
tatio
n, w
etla
nd fo
rest
, or
scru
b-sh
rub;
and
wat
er fe
atur
es r
epre
sent
any
op
en w
ater
, flo
atin
g or
sub
mer
ged
aqua
tics,
and
non
-veg
etat
ed m
ud fl
at.
For
tidal
ly-i
nflu
ence
d la
ndsc
apes
, as
with
the
Fort
St.
Phili
p st
udy
area
, de
linea
ting
land
and
wat
er fe
atur
e bo
unda
ries
from
NW
I hab
itat
dat
a is
of
ten
diff
icul
t. Fo
r th
is p
roje
ct, t
he d
elin
eatio
n w
as s
et b
etw
een
habi
tat
clas
ses
with
“R
egul
arly
Flo
oded
” an
d “I
rreg
ular
ly F
lood
ed”
wat
er r
egim
es.
Thes
e ti
dally
-inf
luen
ced
regi
mes
are
bas
ed o
n in
term
edia
te, b
rack
ish,
and
sa
line
mod
ifier
s. R
egul
arly
Flo
oded
feat
ures
rep
rese
nt a
reas
that
alte
rnat
ely
flood
and
exp
ose
the
land
sur
face
at l
east
onc
e da
ily; I
rreg
ular
ly F
lood
ed
feat
ures
are
thos
e w
here
wat
er fl
oods
the
land
sur
face
less
oft
en th
an d
aily
.
The
1970
and
199
8 la
nd a
nd w
ater
dat
a w
ere
deri
ved
from
unr
ecti
fied
panc
hrom
atic
pho
togr
aphy
and
ort
ho-r
ecti
fied
CIR
aer
ial p
hoto
grap
hy,
resp
ecti
vely
. The
197
0 ph
otos
wer
e sc
anne
d in
to a
dig
ital
form
at a
nd g
eo-
rect
ified
to a
Uni
vers
al T
rans
vers
e M
erca
tor
(UTM
) coo
rdin
ate
syst
em.
Man
ual l
and
and
wat
er c
lass
ifica
tion
s w
ere
perf
orm
ed u
sing
an
on-s
cree
n in
tera
ctiv
e "h
eads
-up"
tech
niqu
e th
at u
tiliz
es p
hoto
rad
ianc
e, c
ontr
ast,
text
ure,
and
pat
tern
rec
ogni
tion
by
whi
ch la
nd a
nd w
ater
feat
ures
wer
e de
linea
ted
dire
ctly
into
a d
igit
al G
IS (S
uir
et a
l. 20
11).
The
2008
hab
itat
dat
a w
ere
deri
ved
from
1-m
dig
ital
imag
ery
capt
ured
w
ith
the
ZI D
igit
al M
appi
ng C
amer
a. A
s pa
rt o
f ong
oing
eff
orts
by
the
USG
S to
map
Lou
isia
na’s
coa
stal
hab
itat
s, th
e 20
08 im
ager
y w
as c
lass
ified
MR
G&
P R
epor
t No.
2
7
usin
g th
e es
tabl
ishe
d N
WI
habi
tat c
lass
ifica
tion
sch
eme.
The
cla
ssifi
ed
habi
tat d
ata
wer
e th
en a
ggre
gate
d in
to la
nd a
nd w
ater
cat
egor
ies.
Due
to e
volv
ing
clas
sific
atio
n an
d re
ctifi
cati
on te
chni
ques
, it w
as e
ssen
tial t
o ev
alua
te in
cons
iste
ncie
s in
the
regi
stra
tion,
sca
le, a
nd m
appi
ng u
nit s
ize
of
sour
ce a
nd c
lass
ified
dat
a. T
he e
arlie
r ha
bita
t dat
a se
ts w
ere
tran
sfor
med
to
mat
ch th
e 19
98 a
nd 2
008
data
. Thi
s w
as a
chie
ved
by e
ither
re-
regi
ster
ing
the
hist
oric
line
-wor
k to
200
8 co
ntro
l poi
nts,
or
by r
aste
rizi
ng th
e hi
stor
ical
la
nd a
nd w
ater
line
-wor
k an
d ge
o-re
fere
ncin
g to
the
2008
imag
ery.
Co-
regi
ster
ing
the
data
pro
vide
s gr
eate
r co
nfid
ence
in th
e re
sults
. Add
ition
ally
, cl
assi
ficat
ion
accu
raci
es o
f tho
se la
nd a
nd w
ater
dat
a th
at w
ere
aggr
egat
ed
from
exi
stin
g N
WI d
ata
wer
e al
so a
sses
sed.
Any
mis
clas
sifie
d la
nd o
r w
ater
fe
atur
es w
ere
corr
ecte
d us
ing
the
“hea
ds-u
p” m
etho
d de
scri
bed
abov
e.
2.3
Mod
erat
e-re
solu
tion
data
The
mod
erat
e-re
solu
tion
dat
a us
ed in
this
stu
dy c
onsi
st o
f exi
stin
g La
ndsa
t 5 T
hem
atic
Map
per
(TM
) sat
ellit
e im
ager
y fr
om 1
988,
200
1, a
nd
2008
, pre
viou
sly
resa
mpl
ed to
25
m (B
arra
s 20
09; B
arra
s et
al.
2008
; Sa
ltus
et a
l. 20
12, T
able
1);
and
agg
rega
ted
1956
and
197
8 ha
bita
t dat
a (W
icke
r 19
80, 1
981)
that
wer
e ra
ster
ized
and
res
ampl
ed to
mat
ch T
M
spat
ial r
esol
utio
n (C
ahoo
n an
d G
roat
199
0). A
ll of
the
TM d
ata
that
wer
e us
ed in
this
stu
dy w
ere
clas
sifie
d us
ing
a st
anda
rd c
lass
ifica
tion
m
etho
dolo
gy to
ens
ure
repe
atab
ility
and
con
sist
ency
, as
wel
l as
to
min
imiz
e cl
assi
ficat
ion
inte
rpre
tati
on s
ubje
ctiv
ity
(Bar
ras
et a
l. 20
03).
Th
ese
met
hods
con
sist
ed o
f rad
iom
etri
c co
rrec
tion
, edg
e en
hanc
emen
t, an
d ba
nd 5
-lev
el s
licin
g of
the
TM d
ata.
Fin
al r
esam
plin
g an
d no
ise
filte
ring
wer
e pe
rfor
med
on
all d
ata
that
wer
e us
ed in
the
mod
erat
e-re
solu
tion
ass
essm
ents
(Bra
ud a
nd F
eng
1998
, Sui
r et
al.
2011
).
MR
G&
P R
epor
t No.
2
8
3 R
esul
ts
3.1
Aeria
l pho
togr
aphy
Exa
min
ing
hist
oric
al a
nd m
oder
n ae
rial
pho
togr
aphy
, acq
uire
d fr
om 1
956
thro
ugh
2008
, pro
vide
s a
mea
ns o
f ide
ntify
ing
and
empi
rica
lly d
ocu-
men
ting
the
land
scap
e ch
ange
s th
at h
ave
occu
rred
with
in th
e Fo
rt S
t. Ph
ilip
stud
y ar
ea. P
revi
ous
repo
rts
have
theo
rize
d th
at m
arsh
loss
in th
is a
rea
has
been
the
resu
lt of
sub
side
nce,
win
d an
d w
ave
eros
ion,
and
the
scou
ring
of
orga
nic
mar
sh s
oils
whe
n ri
ver
wat
er w
as in
trod
uced
thro
ugh
the
natu
ral
crev
asse
s ne
ar F
ort S
t. Ph
ilip
(USF
WS
2003
). T
houg
h th
e sp
ecifi
c tim
e of
br
each
ing
near
For
t St.
Phili
p ha
s ne
ver
been
doc
umen
ted,
it h
as b
een
assu
med
that
thes
e cr
evas
ses
wer
e cr
eate
d du
ring
the
maj
or M
issi
ssip
pi
Riv
er fl
ood
of 1
973
(USF
WS
2003
). F
igur
es 2
and
3 c
orre
late
bou
ndin
g ae
rial
pho
togr
aphy
and
his
tori
cal r
iver
sta
ge w
ith th
e se
quen
cing
of t
he
Mis
siss
ippi
Riv
er le
vee
brea
ch. T
he 7
Apr
il 19
73 fl
ood
stag
e pe
ak (+
7.7
ft) a
t th
e E
mpi
re g
age
(Fig
ure
2) c
orre
spon
ds to
the
pre-
, act
ive-
, and
pos
t-br
each
se
quen
ce th
at is
illu
stra
ted
in F
igur
e 3.
Figu
re 2
. Dai
ly M
issi
ssip
pi R
iver
sta
ge d
ata
(wat
er le
vel,
in fe
et) a
t Em
pire
gag
e (b
lue)
and
Ve
nice
gag
e (g
reen
), Lo
uisi
ana.
Flo
od s
tage
pea
k id
entif
ied
with
red
circ
le.
7 A
pril
1973
MR
G&
P R
epor
t No.
2
9
Figure 3. Aerial photography showing pre- (left pane), active- (middle pane), and post-breaching (right pane) of the Mississippi River levee near Fort St. Philip, Louisiana in 1970, 1973 (moderate-resolution photography experiencing Moiré effect), and 1974, respectively. Breach
site identified with red ovals.
MR
G&
P R
epor
t No.
2
10
Figu
res
4-10
pre
sent
a p
icto
rial
acc
ount
of t
he F
ort S
t. Ph
ilip
stud
y ar
ea
and
prov
ide
furt
her
evid
ence
that
the
crev
asse
s w
ere
a re
sult
of t
he 1
973
flood
(Fig
ure
6). T
hese
figu
res,
whi
ch c
onsi
st o
f pho
togr
aphy
from
195
6,
1970
, 197
8, 1
989,
199
8, a
nd 2
008
(and
the
2011
pho
tom
osai
c m
ap fr
om
the
Del
ta M
anag
emen
t at F
ort S
t. Ph
ilip
Coa
stal
Wet
land
s Pl
anni
ng,
Prot
ecti
on, a
nd R
esto
rati
on A
ct (C
WPP
RA
) pro
ject
), a
llow
for
visu
al
inte
rpre
tati
on a
nd c
ompa
riso
n of
land
scap
e fe
atur
e ex
tent
and
cha
nge.
N
otab
le la
ndsc
ape
feat
ure
chan
ges
wit
hin
the
Fort
St.
Phili
p st
udy
area
are
pr
ovid
ed in
Tab
le 2
and
iden
tifie
d in
Fig
ures
3-1
0.
3.2
Land
scap
e ar
ea a
nd c
hang
e –
Hig
h-re
solu
tion
anal
yses
Exi
stin
g an
d ne
wly
cla
ssifi
ed la
nd a
nd w
ater
dat
a pr
ovid
e vi
sual
and
co
mpu
tatio
nal a
ids
for
asse
ssin
g w
etla
nd a
rea
and
chan
ge. F
igur
es 1
1, 1
2, 1
4,
16, 1
8, a
nd 2
0 ill
ustr
ate
the
land
and
wat
er a
rea,
and
land
scap
e co
nfig
urat
ion
for t
he y
ears
195
6, 1
970,
197
8, 1
988,
199
8, a
nd 2
008.
Fig
ures
13,
15,
17,
19,
an
d 21
dep
ict l
and
and
wat
er c
hang
es fo
r seq
uent
ial p
erio
ds o
f ana
lysi
s.
Figu
re 1
1 sh
ows
a 19
56 la
ndsc
ape
that
con
sist
ed o
f 5,0
12 a
cres
of r
elat
ivel
y so
lid m
arsh
, and
2,3
79 a
cres
of w
ater
, com
pris
ed p
rim
arily
of t
he M
issi
ssip
pi
Riv
er, L
ittle
Coq
uille
Bay
, nat
ural
bay
ous,
and
min
imal
oil
and
gas
acce
ss
cana
ls. B
y 19
70 (F
igur
e 12
), th
e st
udy
area
con
sist
ed o
f 4,3
77 a
nd 3
,014
acr
es
of la
nd a
nd w
ater
, res
pect
ivel
y. T
his
amou
nts
to 6
35 a
cres
of n
et la
nd lo
ss
betw
een
1956
and
197
0 (T
able
3).
The
net c
hang
e be
twee
n 19
56 a
nd 1
970
was
ca
lcul
ated
by
subt
ract
ing
the
tota
l are
a of
land
loss
(832
acr
es) f
rom
the
tota
l ar
ea o
f lan
d ga
ins
(197
acr
es).
Thes
e m
oder
ate
land
loss
es (c
ompa
red
to
subs
eque
nt ti
me
peri
ods)
wer
e th
e pr
imar
y re
sults
of b
ay-s
ide
shor
elin
e er
osio
n (l
ikel
y ac
cele
rate
d by
Hur
rica
nes
Bet
sy a
nd C
amill
e), d
irec
t im
pact
s by
acc
ess
cana
ls, a
nd p
oten
tially
the
resu
lts o
f min
or u
nder
-cla
ssifi
catio
n of
w
ater
feat
ures
in th
e 19
56 d
ata
(Fig
ure
13; l
oss
depi
cted
in re
d). T
he g
ains
(d
epic
ted
in g
reen
) dur
ing
this
per
iod
wer
e pr
imar
ily d
ue to
the
arm
orin
g of
th
e ea
st b
ank
of th
e ri
ver.
By
1978
, the
For
t St.
Phili
p st
udy
area
con
sist
ed o
f 2,7
60 a
nd 4
,631
acr
es
of la
nd a
nd w
ater
, res
pect
ivel
y (F
igur
e 14
). T
he 1
,617
acr
es o
f net
loss
(1
,932
acr
es o
f los
s an
d 31
5 ac
res
of g
ain)
are
pos
sibl
y du
e to
the
com
bine
d ef
fect
s of
mar
sh s
cour
ing,
as
a re
sult
of t
he n
ewly
form
ed c
reva
sses
(7.7
ft
rive
r st
age
on 7
Apr
il 19
73, E
mpi
re g
age;
Tab
le 3
and
Fig
ures
2 a
nd 1
5) a
nd
subs
iden
ce (G
aglia
no 1
999)
. Sub
sequ
ent m
ajor
floo
ding
eve
nts
(i.e
. 6.3
6 ft
ri
ver
stag
e on
14
Apr
il 19
75, E
mpi
re g
age)
may
hav
e ex
acer
bate
d th
e in
itia
l sc
ouri
ng. T
he n
omin
al la
nd g
ains
dur
ing
this
per
iod
are
pres
umab
ly d
ue to
in
fillin
g an
d de
posi
tion
al p
roce
sses
as
a re
sult
of s
edim
ent-
rich
riv
er w
ater
be
ing
dive
rted
thro
ugh
the
crev
asse
cha
nnel
s.
MR
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Figure 4. Fort St. Philip study area - 1956 high-resolution photomosaic map.
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Figure 5. Fort St. Philip study area with access canals (#1) - 1970 high-resolution photomosaic map (Table 2).
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Figure 6. Fort St. Philip study area with crevasse locations (#2), areas with major land-to-water conversion (#3), and formation of crevasse channels (#4) - 1978 high-resolution photomosaic map (Table 2).
MR
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Figure 7. Fort St. Philip study area with areas of land-to-water conversion (#3), crevasse channel development (#4), and large impoundment area (#5) - 1989 high-resolution photomosaic map (Table 2).
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Figure 8. Fort St. Philip study area with areas of land-to-water conversion (#3), crevasse channel development (#4), and large impoundment area (#5) - 1998 high-resolution photomosaic map (Table 2).
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Figure 9. Fort St. Philip study area constructed CWPPRA BS-11 project terraces (#6) - 2008 high-resolution photomosaic map (Table 2).
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Figure 10. Delta Management at Fort St. Philip project area - 2011 high-resolution photomosaic map (USFWS 2013b).
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Table 2. Dom
inant landscape feature changes identified using visual observation of high-resolution aerial photography and digital im
agery. Corresponding feature numbers are represented in Figures 5-10 for location
identification. N
o. Features
Period Reference
1 Construction of oil and gas access canals
1956-1978 Figures 5 &
6
2 Breaching of the M
ississippi River bank 1970-1978
Figures 3, 5 & 6
3 M
ajor conversion of land to water
1978-1998 Figures 6, 7 &
8
4 Form
ation of crevasse channels 1978-2008
Figures 6, 7 & 8
5 D
evelopment of large im
poundment feature
1978-2008 Figures 7 &
8
6 Construction of CW
PPRA BS-11 project terraces1
1998-2008 Figures 9 &
10 1 CW
PPRA’s Delta M
anagement at Fort St. Philip (BS-11) Sedim
ent and Nutrient Trapping, and Outfall Managem
ent project (USFW
S 2013a).
There were 2,444 acres of land and 4,947 acres of w
ater within the study
area in 1988 (Figure 16). This amounts to a net loss of 316 acres of land
between 1978 and 1988 (Table 3). Though this net loss is significantly
reduced from the previous period of analysis, the localized land losses
(1,054) and gains (738) remained relatively high. Figure 17 show
s the form
ation of additional crevasse channels, which resulted in increased
sediment deposition on m
ud flats and substrate, and potentially in direct localized scouring and flooding (during high river flow
). Additionally,
since the study area contains broad shallow flats, localized changes are
partially due to seasonality and fluctuations in river stage, tides, and w
inds, as well as recurring aquatic vegetation.
Land loss continued through 1998, when the study area accounted for
1,780 acres of land and 5,611 acres of water (Figure 18). Though this
period experienced loss (1,080 acres) similar to the previous period, there
were significantly few
er gains from 1988 to 1998 (Figure 19). The losses
experienced during this period appear to have occurred along the fringe of m
arsh and wetland landform
s, and are consistent with subsidence, and
wind- and w
ave-induced erosion.
The 1998 to 2008 time fram
e is the only period of analysis that experienced net land gains. B
y 2008, the study area contained 2,102 acres of land, a net land gain of 322 acres (Figure 22 and Table 3). These gains are presum
ably the effects of the crevasses (gains are in close proxim
ity to crevasse chan-nels) and the results of the C
WPPR
A B
S-11 restoration project. The BS-11
project authorized the construction of terraces in the large impounded area
to the west, and artificial crevasse cuts into tw
o BS-11 Project A
reas (both of w
hich are within the Fort St. Philip study area; Figure 10). A
reas that did experience erosion during this period w
ere primarily along the fringe m
arsh near Little C
oquille Bay and are therefore assum
ed losses due to wind and
wave energy (Figure 21).
MR
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Figure 11. Fort St. Philip study area - 1956 high-resolution land-water classification map.
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Figure 12. Fort St. Philip study area - 1970 high-resolution land-water classification map.
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Figure 13. Fort St. Philip study area - 1956-1970 high-resolution land change analysis map.
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Figure 14. Fort St. Philip study area - 1978 high-resolution land-water classification map.
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Figure 15. Fort St. Philip study area - 1970-1978 high-resolution land change analysis map.
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Figure 16. Fort St. Philip study area - 1988 high-resolution land-water classification map.
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Figure 17. Fort St. Philip study area - 1978-1988 high-resolution land change analysis map.
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Figure 18. Fort St. Philip study area - 1998 high-resolution land-water classification map.
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Figure 19. Fort St. Philip study area - 1988-1998 high-resolution land change analysis map.
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Figure 20. Fort St. Philip study area - 2008 high-resolution land-water classification map.
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Figure 21. Fort St. Philip study area - 1998-2008 high-resolution land change analysis map.
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Table 3. Summary of Fort St. Philip study area acreages, and percentages of area change, for select time periods - from high-resolution analyses. The color-ramp illustrates the type and magnitude of land
change, where the darkest red represents the loss maxima and darkest green represents gain maxima.
Period of Analysis Years
Land Area (initial)
Land Area (ending)
Area Change
Area Change1 (within period) Area Change2 f
Acres Percentage
1956 to 1970 14 5,012 4,377 -635 -13% -13%
1970 to 1978 8 4,377 2,760 -1,617 -37% -32%
1978 to 1988 10 2,760 2,444 -316 -11% -6%
1988 to 1998 10 2,444 1,780 -664 -27% -13%
1998 to 2008 10 1,780 2,102 322 18% 6%
1956 to 2008 52 5,012 2,102 -2,910 -58% -58% 1 Land change percentage is based on initial land area of the period of analysis. 2 Land change percentage is based on the 1956 land area.
The CWPPRA BS-11 restoration project provides useful ancillary informa-tion. The BS-11 project area experienced extensive loss of emergent wetlands from 1974 to 1990 (USFWS 2003). Data from the U.S. Army Corps of Engineers (Britsch and Dunbar 1993) indicate that the loss rates during that period were 4.1%/year for Project Area 1 and 1.6%/year for Project Area 2 (USFWS 2003, Figure 10). From 2002 to 2011, the amount of subaerial land within BS-11 Project Area 1 (artificial crevasse cuts and terraces) increased from 153 to 228 acres, while the land in Project Area 2 (artificial crevasse cuts) increased from 101 to 116 acres (Hymel and Breaux 2012, Figure 10). Visual comparisons between the photomosaics in Figure 9 (2008) and Figure 10 (2011) show large areas of sediment plumes and accretion in Project Areas 1 and 2. These features suggest that the sediments that are being transported through the natural Fort St. Philip crevasses (and possibly through other channelized cuts) are also being conveyed through the interior artificial crevasse cuts, and ultimately deposited within the BS-11 Project Areas.
Net land area changes for the Fort St. Philip study area are summarized in Table 3. This table contains the initial and ending acreages for each of the five sequential periods, and the overall period of analysis (1956 to 2008). The table also contains the percentage of land area change for each period, based both on that period’s initial land acreage and on the 1956 acreage. Color-ramping was assigned to the percentage of land change columns to classify the type (loss or gain) and magnitude of change. The time periods with the greatest land loss are represented with dark reds, and those with the greatest land gains are represented with dark greens. The 1956-1970 period, which contained a number of major episodic events (e.g Hurricanes
MRG&P Report No. 2 31
Betsy and Camille), accounted for 13% loss of land. Of the 58% of total land loss that occurred between 1956 and 2008, 32% occurred between 1970 and 1978. This period encompassed the major Mississippi River flood of 1973. Compared to the 1970-1978 time period, the 1978-1998 period experienced significantly reduced rates of loss. The 1978-1988 loss rates were similar to those experienced prior to 1970, while the 1988-1998 rates were higher, possibly as a result of additional floods (6.4-ft river stage on 23 May 1991, 6.33-ft river stage on 17 June 1995, and 6.2-ft river stage on 5 April 1997 at the Empire gage). The final period (1998-2008) was the only period with observed net land gain; an 18% increase in 1998 land acreages, and a 6% increase in 1956 land acreages.
3.3 Landscape area and change – Moderate-resolution analyses
Landscape area change analyses, utilizing moderate-resolution imagery, were performed as a means of comparing the sequence and magnitude of land change within the Fort St. Philip study area with reference areas along the eastern bank of the Mississippi River. Reference and study area boundaries (zones) were established by adjusting (simplifying) 12-digit hydrologic unit boundaries (Figure 22). The total reference area was 658 mi2 (excluding the Fort St. Philip study area). The Fort St. Philip study area boundary coincides with zone 10, while the other zones constitute the reference areas. Zonal statistics were calculated for each zone using moderate resolution (25-m) land and water imagery that was generated using resampled 1956 and 1978 NWI data, and classified 1988, 2001, and 2008 Landsat 5 TM imagery (Barras et al. 2008). Figure 22 is an example of the land change analysis that was performed for all sequential periods within, and including, the 1956 to 2008 end points. The land change image in Figure 22 shows significant land loss in the northwestern zones (1-6; predominantly hurricane impacts; Barras et al. 2010; Barras 2006, 2009) and southeastern zones (subsidence and wind/wave impacts in zones 10-16; and significant hurricane impacts in 13-16; Barras 2006, 2007), and sparse land loss within the central zones (7-9; with minor regional scale impacts from Hurricane Katrina in zone 7). Gains that have resulted from ecosystem restoration activities are also identifiable in Figure 22, specifi-cally the CWPPRA MR-09 Delta Wide Crevasses project, which is in the bounds of zones 12, 13, 14, and 15.
Land area summaries by zone and date are included in Table 4. This table also includes percentages of land change by periods of analysis, which like Table 3, are color-ramped to illustrate the type and magnitude of land change. The time periods and zones with the greatest land loss are
MRG&P Report No. 2 32
Figure 22. Fort St. Philip study and reference area zonal boundaries and the 1956-2008 moderate-resolution land change analysis map.
represented with dark reds, and those with the greatest land gains are represented with dark greens. In 1956, zone 10 accounted for 5,228 acres of land (calculated using moderate-resolution data). By 2008, only 2,520 acres remained – a loss of 2,708 acres (51.8%, Table 4). The majority of that loss (46.7%) occurred during the period when the crevassing occurred near Fort St. Philip. Compared to zone 10, most of the reference zones experienced more gradual landscape changes over time, with the exceptions of zones 12, 13, and 14. However, those zones received significant restoration benefits from the MR-09 project (see land gains between 1998 and 2001). A more detailed investigation with finer temporal resolution, linked to known episodic events, would provide more confidence in landscape analyses using moderate-resolution data.
MRG&P Report No. 2 33
Table 4. Summary of Fort St. Philip study area zonal statistics, and percentages of area change, for select time periods - from moderate-resolution analyses. The color-ramp illustrates the type and magnitude of land change, where the
darkest red represents the loss maxima and the darkest green represents gain maxima.
Zone
Land Area (acres) Land Change (percentage)
1956 1978 1988 2001 2008 1956-1978 1978-19881 1988-20011 2001-20081 1956-2008
1 26,201 23,602 24,082 23,333 17,833 -9.9% 1.8% -2.9% -21.0% -31.9%
2 16,787 13,418 13,404 13,900 14,418 -20.1% -0.1% 3.0% 3.1% -14.1%
3 33,339 28,894 28,506 28,075 15,541 -13.3% -1.2% -1.3% -37.6% -53.4%
4 12,779 9,845 10,613 9,916 8,285 -23.0% 6.0% -5.5% -12.8% -35.2%
5 23,573 20,857 20,457 19,343 13,962 -11.5% -1.7% -4.7% -22.8% -40.8%
6 27,336 23,812 23,827 23,328 19,220 -12.9% 0.1% -1.8% -15.0% -29.7%
7 17,207 15,900 16,246 16,104 16,035 -7.6% 2.0% -0.8% -0.4% -6.8%
8 14,181 13,487 13,379 13,267 13,427 -4.9% -0.8% -0.8% 1.1% -5.3%
9 10,907 9,952 9,887 9,468 9,581 -8.8% -0.6% -3.8% 1.0% -12.2%
10 5,228 2,787 2,467 2,505 2,520 -46.7% -6.1% 0.7% 0.3% -51.8%
11 8,718 6,848 5,559 4,311 4,144 -21.5% -14.8% -14.3% -1.9% -52.5%
12 23,476 13,166 9,783 12,123 13,001 -43.9% -14.4% 10.0% 3.7% -44.6%
13 14,510 9,863 9,941 11,967 10,294 -32.0% 0.5% 14.0% -11.5% -29.1%
14 19,216 11,287 10,948 11,815 8,920 -41.3% -1.8% 4.5% -15.1% -53.6%
15 13,147 8,827 7,700 7,370 4,862 -32.9% -8.6% -2.5% -19.1% -63.0%
16 24,752 15,894 15,167 18,025 12,591 -35.8% -2.9% 11.5% -22.0% -49.1%
1 Land change percentage is based on 1956 land area.
MRG&P Report No. 2 34
4 Conclusions
This study identified and quantified land changes within the Fort St. Philip study area, and compared those changes to reference areas along the eastern bank of the lower Mississippi River. The assessments performed as part of this study were based on aerial photography and satellite imagery, as well as representative land and water data for the years 1956, 1970, 1978, 1988/89, 1998, 2001, and 2008. It should be noted that inconsistencies in area and percentage of change between the higher and moderate-resolution analyses are largely due to the reduction in precision with increasing grain (pixel) size.
A significant event influencing landscape change within the Fort St. Philip study area during the study period was the breaching of the eastern levee of the Mississippi River and subsequent development of the Fort St. Philip crevasse channels. Initially, the river water that was diverted through these crevasse channels physically removed significant marsh areas within the study area. These initial direct impacts were succeeded by several decades of larger regional loss patterns driven by subsidence (Gagliano 1999) and other episodic events (e.g, hurricanes and floods; Barras 2009), and recent localized land gains. These increases in land area are poten-tially the long-term results of the Fort St. Philip crevasses, and the short-term impacts of the CWPPRA BS-11 delta management activities. How-ever, for the majority of the 1956-2008 period of analysis, the crevassing of the eastern bank of the Mississippi River levee was a loss accelerant in the Fort St. Philip area.
The decadal comparison periods used in this study provide useful long-term trends, but they can potentially obscure short-term land and water variation. Additionally, variations in tidal and river regimes at the time of geospatial data acquisition may exacerbate or minimize actual loss trends. These can be considerable limitations, since Breton Sound contains multiple complex environmental conditions that may confound trend trajectories. Embedded within the decadal comparison periods are landscape changes that are typically caused by episodic events (e.g. hurricanes or major floods) that are super-imposed over subsidence-induced loss or losses caused by other processes (e.g. sea level rise, frontal passages, tidal variations, sediment deficiencies, etc.).
MRG&P Report No. 2 35
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Martucci, J. Porthouse, D. Reed, K. Roy, S. Sapkota, and J. Suhayda. 2003. Historical and projected coastal Louisiana land changes 1978–2050, Appendix B of Louisiana Coastal Area (LCA), Louisiana Ecosystem Restoration Study. U.S. Geological Survey Open-File Report 2003-334, available online at http://pubs.er.usgs.gov/usgspubs/ofr/ofr03334
Barras, J. A. 2006. Land area change in coastal Louisiana after the 2005 hurricanes—a series of three maps. U.S. Geological Survey Open-File Report 2006-1274, available online at http://pubs.usgs.gov/of/2006/1274/
Barras, J. A. 2007. Satellite images and aerial photographs of the effects of Hurricanes Katrina and Rita on coastal Louisiana. U.S. Geological Survey Data Series 281.
Barras, J. A. 2009. Land area change and overview of major hurricane impacts in coastal Louisiana, 2004-08. U.S. Geological Survey Scientific Investigations Map 3080, scale 1:250,000, available online at http://pubs.usgs.gov/sim/3080
Barras, J. A., J. C. Bernier, and R. A. Morton. 2008. Land area change in coastal Louisiana—A multidecadal perspective from 1956 to 2006. U.S. Geological Survey Scientific Investigations Map 3019, scale 1:250,000, available online at http://pubs.usgs.gov/sim/3019
Barras, J. A., J. C. Brock, R. A. Morton, and L. J. Travers. 2010. Remotely sensed imagery revealing the effects of Hurricanes Gustav and Ike on coastal Louisiana. US Geological Survey Data Series 566, 1 CD-ROM.
Barras, J. A., P. E. Bourgeois, and L. R. Handley. 1994. Land loss in coastal Louisiana 1956-90: National Biological Survey. National Wetlands Research Center Open-File Report 94-01.
Braud, D. H., and W. Feng. 1998. Semi-automated construction of the Louisiana coastline digital land/water boundary using landsat thematic mapper satellite imagery. Department of Geography and Anthropology, Louisiana State University. Louisiana Oil Spill Research and Development Program, OSRADP Technical Report Series 97-002. http://www.osradp.lsu.edu/1997_Deliverables/Braud97/Braud97.htm.
Britsch, D. L., and J.B. Dunbar. 1993. Land Loss Rates: Louisiana Coastal Plain. Journal of Coastal Research 9(2):324-338.
Cahoon, D. R., and C. G. Groat, ed. 1990. A study of marsh management practice in coastal Louisiana, Volume II, Technical Description. Final report submitted to Minerals Management Service, New Orleans, LA. Contract No. 14-12-0001- 30410. OCS Study/MMS 90-0075.
MRG&P Report No. 2 36
Cowardin, L. M., V. Carter, F. Goblet, and E. T. LaRoe. 1979. Classification of wetlands and deepwater habitats of the United States. FWS/OBS-79/31. U.S. Fish and Wildlife Service, Biological Services Program. http://www.fws.gov/wetlands/Documents/Classification-of-Wetlands-and-Deepwater-Habitats-of-the-United-States.pdf
Davis, D.W. 2000. Historical perspective on crevasses, levees, and the Mississippi River. In Transforming New Orleans and its Environs: Centuries of Change, ed. C. E. Colten, 84-106. Pittsburgh, PA: University of Pittsburgh Press.
Fuller, D. A., J. G. Gosselink, J. Barras, and C. E. Sasser. 1995. Status and trends in vegetation and habitat modifications. Part 3 in Current Status and Historical Trends of Hydrologic Modification, Reduction in Sediment Availability and Habitat Loss/Modification in the Barataria and Terrebonne Estuarine Systems, ed. D. J. Reed. Baton Rouge, LA: Barataria-Terrebonne National Estuary Program.
Gagliano, S. M. 1999. Faulting, subsidence, and land loss in Coastal Louisiana. Dallas, TX: US Environmental Protection Agency, Region 6.
Hymel, M. K., and K. A. Breaux. 2012. 2012 Operations, Maintenance, and Monitoring Report for Delta Management at Fort St. Philip. New Orleans, LA: Coastal Protection and Restoration Authority of Louisiana.
Louisiana Department of Natural Resources (LDNR). 1995. Quality Management Plan for Coastal Wetlands Planning, Protection, and Restoration Act - Monitoring Program - Revised June 2002. Baton Rouge, LA: Louisiana Department of Natural Resources, Coastal Restoration Division.
National Research Council. 2006. Drawing Louisiana's New Map: Addressing Land Loss in Coastal Louisiana. Washington, DC: National Academy Press.
Rodrigue, D. 2003. MR-06 Channel Armor Gap Crevasse Summary Data and Graphics. Baton Rouge, LA: Louisiana Department of Natural Resources, Coastal Restoration Division.
Saltus, C. L., G. M. Suir, and J. A. Barras. 2012. Land Area Changes and Forest Area Changes in the vicinity of the Mississippi River Gulf Outlet - Central Wetlands Region - from 1935 to 2010. ERDC/EL TR 12-7. Vicksburg, MS: US Army Engineer Research and Development Center. http://el.erdc.usace.army.mil/elpubs/pdf/trel12-7.pdf
Suir, G. M., C. L. Saltus, and J. A. Barras. 2011. Development of Methodology to Classify Historical Aerial Photography to Analyze Land Area and Shoreline Change in Coastal Louisiana - Point Au Fer Island - from 1935 to 2010. ERDC/EL TR-11-17. Vicksburg, MS: US Army Engineer Research and Development Center. http://el.erdc.usace.army.mil/elpubs/pdf/trel11-17.pdf
Suir, G. M., D. E. Evers, G. D. Steyer, and C. E. Sasser. 2013. Development of a Reproducible Method for Determining Quantity of Water and its Configuration in a Marsh Landscape. Journal of Coastal Research: Special Issue 63 - Understanding and Predicting Change in the Coastal Ecosystems of the Northern Gulf of Mexico: 110–117.
MRG&P Report No. 2 37
US Fish and Wildlife Service (USFWS). 2003. Final Environmental Assessment - Delta Management at Fort St. Philip BS-11. Lafayette, LA.
US Fish and Wildlife Service (USFWS). 2013a. Delta Management at Fort St. Philip BS-11 – General Project Fact Sheet. Lafayette, LA.
US Fish and Wildlife Service (USFWS). 2013b. Delta Management at Fort St. Philip (BS-11) Coastal Wetlands Planning, Protection and Restoration Act 2011 Photomosaic. Lafayette, LA. https://lacoast.gov/products/sab_net_pub_products/map/original/2012-02-0064.pdf, 18 November 2013.
US Geological Survey (USGS). 1980. 1978 Coastal Louisiana Habitat Data. Lafayette, LA: National Wetlands Research Center, US Geological Survey.
US Geological Survey (USGS). 1988a. 1956 Coastal Louisiana Habitat Data. Lafayette, LA: National Wetlands Research Center, US Geological Survey.
US Geological Survey (USGS). 1988b. 1988 Gulf of Mexico Coastal Louisiana Habitat Data from NWRC. Lafayette, LA: National Wetlands Research Center, US Geological Survey.
US Geological Survey (USGS). 2009. 2008 Coastal Louisiana Habitat Data. Lafayette, LA: National Wetlands Research Center, US Geological Survey.
Wicker, K.M. 1980. Mississippi Deltaic Plain Region ecological characterization: A habitat mapping study, a user's guide to the habitat maps. FWS/OBS-79-07. U.S. Fish and Wildlife Service, Office of Biological Services.
Wicker, K.M., 1981. Chenier Plain Region ecological characterization: A habitat mapping study: A user's guide to the habitat maps: Louisiana Department of Natural Resources, Baton Rouge, La. 55 p. + appendices. Study and report funded through a contract with the National Oceanic and Atmospheric Administration.
REPORT DOCUMENTATION PAGE Form Approved
OMB No. 0704-0188 Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY)
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4. TITLE AND SUBTITLE
Pictorial Account and Landscape Evolution of the Crevasses Near Fort St. Philip, Louisiana
5a. CONTRACT NUMBER
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6. AUTHOR(S)
Glenn M. Suir, William R. Jones, Adrienne L. Garber, and John A. Barras
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U.S. Army Engineer Research and Development Center, Environmental Laboratory 3909 Halls Ferry Road, Vicksburg, MS 39180-6199;
US Geological Survey National Wetlands Research Center 700 Cajundome Boulevard, Lafayette, LA 70506;
Five Rivers Services, LLC National Wetlands Research Center 700 Cajundome Boulevard, Lafayette, LA 70506;
US Geological Survey, Coastal and Marine Science Center 600 Fourth Street South, St. Petersburg, FL 33701
MRG&P Report No. 2
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14. ABSTRACT Quantifying the effects of active natural and constructed crevasses is critical to the planning and success of future ecosystem restoration activities. This document provides a historical overview of landscape changes within the vicinity of the natural crevasses near Fort St. Philip, Louisiana. A significant event influencing landscape change within the Fort St. Philip study area was the breaching of the eastern levee of the Mississippi River. Initially, the river water that was diverted through these crevasse channels physically removed significant marsh areas within the study area. These initial direct impacts were succeeded by several decades of larger regional loss patterns driven by subsidence and other episodic events (e.g, hurricanes and floods), and recent localized land gains. These increases in land area are potentially the long-term results of the Fort St. Philip crevasses, and the short-term impacts of delta management activities. However, for the majority of the 1956-2008 period of analysis, the crevassing of the eastern bank of the Mississippi River levee was a loss accelerant in the Fort St. Philip area.
15. SUBJECT TERMS Crevasses Ecosystem restoration
Fort St. Philip, Louisiana Landscape change Wetlands
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Standard Form 298 (Rev. 8-98)
Prescribed by ANSI Std. 239.18