Beach Fill at Two Coasts of Different Configurations
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8/11/2019 Beach Fill at Two Coasts of Different Configurations
1/15
CHAPTER 7 7
Beach
fillattwocoastsofdifferentconfigurations
+
IchiroDeguchi
and
Toru
Sawaragi
ABSTRACT
Movements
f
orrow
and
eplenished
t
wo
oasts
f
ifferent
configurationsrenvestigatedynalyzingheopographic
ata
whichereurveyederiodicallyfterheeach
ill
lacements.
One
s
ong
traight
each
nd
orrow
andaslacedehind
submerged
reakwater.
nother
s
ocket
eachhichas
n
rc-
shoreline
with
groyne
at
one
end
and
aheadlandatanother.
It
s
ound
hat
he
mountf
orrow
andoved
n
he
ong-
shoreirection
urpasses
he
mountforrowandransportedn
theross-shoreirectionegardless
f
he
hapef
he
oast.
clearorrelations
lso
oundetweenisplacementsfhoreline
andhangesfectional
reas.
heseesultsmplyhathee-
formation
f
he
rtificiallyourished
each
nd
he
issipation
rate
ofborrow
sandcanbe
predicted
by
theso-calledne-line theory.
1. Introduction
Artificial
eachourishment
sommonly
tilized
pproach
for
reatment
f
horerotectionroblemsuchseachrosion,
wavever-toppingndon.
t
s
lso
heirect
ethod
o
maintainand
improve
recreational
benefits
in
thecoastal zone.
Inapan,herereanyoasts
here
eachillaveeen
already
eplenished.
theseoasts,tructuresuchsnff-
shore
ubmerged
reakwater,
etached
reakwater
nd
royne
haveeenonstructed
imultaneously
nrderorevent
each
ill
from
flowing
ut
from
he
replenished
field.
Howeverecausehe
ffective
eachillesignnvolveso
manyhysicalactors,hereciseegreefeachilltilization
to
stabilizea
shoreline is
notalwayspredictable.
The
bjective
fhis
tudy
s
o
nvestigate
ehaviors
f
beachilleplenishedtwooastsfifferentonfigulationsy
analyzing
uccessivelyeasured
each
rofiles
o
ffer
nformations
as
ohats
he
overning
actor
n
heeterminationfhe
effctiveness
of
beach
fill.
+Associate
rofessor
nd
+
Professor,
epartment
f
ivil
Engineering,
saka
niversity,amadaoka
-1,
uita-city,saka
565, Japan
1032
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BEACHFILL
AT
TWO
COASTS
1 0 3 3
2 .
Conf
igulations
of
Two
Coasts
and
Locationof
Beach
Fill
Locations
of
twocoastsareshown
i n
Fig.l.
Keino-Matsubara
Beach
S e t o
Inland
Sea
Osaka
Asakawaeach
Pacific
cean
Fig.l
Locations
of investigated
tw oeaches
One
s
e
ino-Matsubara-Beach
hich
s
n
he
ast
ide
f
he
Awaji
sland
acing
he
eto
nland
ea
nd
as
ong
traight
beachf
bout
kmongshownn
ig.
2 a).nhisoast,est
offshore
ubmerged
reakwaterf0mongnd0mideas
irst
constructedn983nd
orrow
and
fbout000m
3
aseplenished
behind
itabout
ne
yearafter
the
construction
of
the
breakwater.
Thepperurfacefheubmergedreakwatersbout.5m
below
.L..
.W.L.,.W.L.nd.W.L.orrespondo.L.+1.8m,
D.L.+1.2m
nd.L.+0.5m.
heater
epth
as
easured
pward
rom
D.L..
he
verage
eachlpoe
s
bout/7o/10n
he
hallow
water
eg
ion sha
lower
han
2m)
nd
bout
/30
n
he
eeper
resion.
ean
rain
ize
5
o
anges
rom
.2mm
o
mm
nd
here
s
no
orrelation
etween
5
o
nd
ater
epth.
ean
raion
izef
borrow
sand
is
1.5mm.
These
data
aresummerized
in
Table 1.
Figure
b)
ndicates
ocation
f
he
ubmerged
reakwater
andhe
egion
here
each
ill
ouldelaced
ased
n
he
measuredeachrofile
ust
fter
heonstruction
f
he
ubmerged
breakwater.
Another
ssakawa-Beachhichso-calledocketeachnd
has
n
rc-shoreline
f
bout
00m
ong
nd
he
adius
f
hich
s
260m
s
hown
n
ig.3.
here
s
ockey
ead
and
t
he
outh
end
f
he
each
nd
royne
f50mong
as
onstructedn
974
athethernd.each
lope
nhallowegionshallowerhan
-3m)
isabout1/7 o1/10andabout1/30
in
thedeeperregion.
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1034
COASTAL
ENGINEERING-1986
SetoInland
Sea
1983.12
a)
v 3k m
SO '
Y(
25
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BEACH
FILL
AT
TWOCOASTS
1035
Table1haracteristics
of
twobeaches
Keino-Matsubara-Beach
[ d . 5 0 ]
native
sand
0.2mm 3mm
borrow
sand
. 5 m m
[Beachslope]
shallowregion 1/7-1/10
deepregion
/3 0
[waves]
winter-spring
pr ob ab i l i t y
of
appearance
ofwaveshigherthan
l m
is3 5 . ( f r o m
W-NW)
summer autumnlarge
part
ofwavesare
less
than
40cm
Asakawa-
Beach
0 . 5 m m - 3 m m
0.
4m m
and
0 .
8m m
1/7-1/10
1/30
large
partof
wavesare
less
than40cm
waveshigherthanl m
incidents
severalt i mes
ayear
in
a
typhoon
seasons.(from
SE-E)
Table
2
rogress
of
beach
fill
andtopographicsurvey
beach
f i l l
placement
o
a )
PQ
a
D
c t
s
5000m
topographic
survey
1983.12.21
1984.1.13
1984.1.30
1984.2.20
1984.3.6
1984.3.27
1984.4.27
1984.5.30
-1984.10.18
-1984.11.18
-1984.12.1
topographic
beachfill^.urvey
placement
14180m
o
a )
< U
t 16845m
v3
C O
M
.
it
.,
>:,}x
J
.
xi
r5x
0.00
0.00
o.00
ao.t
HO.
00
SOT.00
340.00 210.00 380.00 3*0.00 400.00
440.00
4(0.00
T
CM
X
wave
reaking
oint
a)
s
i-
,
t
t
,
f
_
,
ii
8
3
>W
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8/11/2019 Beach Fill at Two Coasts of Different Configurations
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BEACH
FILL
ATTWO
COASTS
1041
22
Southward
Y j )
1979
Xshoreline
Fig.8
hange
o f
water
depth
tookplace
during
Sept.,1979and
March,1980whenborrowsando f
16845m
wasplacedaround
shoreline
between
surveying
lines
No.7andNo.15
a t
Asakawa-Beach
22outhward
(
1980.3 980.9
X
shoreline
Q
vorthward
X(m )
0+
l
Fig.
9hannge
o f
waterdepth
took
placeduring6-monthafter
beach
f i l l
placement
a t
Asakawa-Beach
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1042
COASTAL
ENGINEERING-1986
From
hese twofigures,
it
is
easily
found
that
thereplenished
borrow
sand
moved
from
the
replenished
region mainly toward both
southward and
northward
along the shoreline. As is
the
case
of
K e
ino-Matsubara-Beach,
a
few
portion
of
borrow
sand
seemed
to
be
transported
in
onshore
and
ffshore
directions.
Figures0
nd
1
how
ross-shore
ndongshoreigen-
functionsi(i,t)
nd
i(j,t)hich
orrespond
o
he
argest
eigenvalues.
X ( i )
>f,-
J
3
-
'0
* - > .
-
9J
,
*J
)
Fig.10 C r o s s - s h o r eempi ric a l
e i
genfunctionc o r r e s p o n d i n g
t o
thelargeste i genvalue .
10.0
f
l3
*3
**^?J.J.
i9
so.,
e,,;i9t
t
' ' ,
20
Y(j)
**>l
*, /J
J
.7
Fig.
11
Lo n g s h o r eempi ric a l
e i
genfunctionc o r r e s p on d i n g
to
thelargeste i g e nva l u e
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-
8/11/2019 Beach Fill at Two Coasts of Different Configurations
13/15
1044
COASTALENGINEERING-
1986
s
/
i
i
*xxxxxxxxietitfxiu*tx*r
t
x
r
>
*'*
K
'?'l'f *
. rf->
[
*'>fw*-x
,
B)
f>rir '
Jt
*
Jt
-
t-
S^\N _:tt'?:
0.5~/s
e-oo
o.eo ac.co
uo.co itc.oo
JM.OQ 49.00
stc.oo
:;o.w
Jtc.co
-
8/11/2019 Beach Fill at Two Coasts of Different Configurations
14/15
BEACH
FILLATTWO
COASTS 1 0 4 5
i V ( r a )
3000
2000
1000
0-8-16
J-10-14
100(t)
6 0
4 0
2 0
Fig.13 Remaining
ratefborrowsandandvolumetric
changeatKeino-Matsubara-Beach
AV(m')
4000
3000
2000
1 0 0 0
Volume
of
replenished
borrowsand
100(X)
6 0
2 0
Fig.
14
Remaining
rate
f
borrow
sand
and
volumetric
changeat
Asakawa-Beach
-
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1046
OASTAL
ENGINEERING-1986
Althoughorrowandf000m
3
as
lacedehindhe
ubmerged
breakwater,he
ncreasefheandolumeetweenheurveying
lines
o.8
nd
6
as
bout
300m
3
.
herefore,n
healculation
of
tn)
from
q. 4),
weused
3300m
3
for Vb.
It
s
ound
rom
his
igure
hat
he
and
olume
ust
ehind
the
ubmerged
reakwaterecreasedastndnly08 emainedwo
month
fter
heeach
ill
lacement.n
he
ther
and,
ore
han
30
f
he
orrowand
emained
etween
he
urveying
ines
o.8
nd
No.16.hiseanshatheigrationpeedforrowandsoto
fastndnly0 forrowandovedfforehan0mromhe
replenished
region.
Figure
4howsheolumetrichanges
nd
emainingatef
borrow
and
t
sakawa-Beach.t
his
each,
heolumef
and
n
the
hole
each
ncreased
t
very
each
ill
lacement.
owever,
the
emaining
ate
f
he
otal
orrow
and
eplenished
n
he
beach
rom
q. 4)
ecreasesraduallyrom0 ndinallyeaches
6 0 .hismplieshathere
s
ertainimito
eep
andithin
aocketeach
hich
illeetermined
y
he
eometrical
roperty
of thebeach,
wave
climate
andso
n.
6.
Conclusions
Movementsf
orrow
and
eplenished
t
ong
traight
each
and
ocket
each
hich
as
n
rc-shoreline
re
nvestigated
y
analyzing
he
eriodically
easured
ottom
opography
fter
he
beach
fillplacements.
It
s
ound
hat
he
mountforrow
and
oved
n
he
longshore
irection
urpasseshe
mount
forrow
andransported
inhe
ross-shore
irectionegardless
f
hehapesf
he
shorelines.learorrelationslso
ound
etweenhe
horeline
displacementsandthechangesof
sectional
areas.
References
S a w a r a g i ,
T. ,.
eguchi
nd
.S.
Lee
(1985),A
new
modelfora
p r e d i c t i o nof
beach
d e f o r m a t i o naroundarivermou t h,Proc.nt.
Sympo.Ocean
Space
Utilization'85,
2 ,
pp.229-237.