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iiiii
Thi
s ha
ndbo
ok is
ded
icat
ed to
the
mem
ory
of
Dit
i Hen
gcha
ovan
ich
Geo
tech
nica
l Eng
inee
r
of
Tha
iland
.
He
pion
eere
d th
e us
e of
vet
iver
on
a la
rge
scal
e fo
r h
ighw
ay
stab
iliza
tion,
and
for
man
y ye
ars
was
a v
ery
valu
able
con
trib
utor
to
The
Vet
iver
Net
wor
k In
tern
atio
nal.
Diti
will
be
rem
embe
red
with
gr
atef
ulne
ss b
y m
any.
1st E
diti
on 2
008
Pub
lish
ed b
y T
he V
etiv
er N
etw
ork
Inte
rnat
iona
l
Cov
er b
y L
ily
Gri
msh
aw
ivi
PR
EF
AC
E
TH
E V
ET
IVE
R S
YST
EM
F
OR
SL
OP
E S
TAB
ILIZ
AT
ION
AN
EN
GIN
EE
R'S
HA
ND
BO
OK
The
Vet
iver
Sys
tem
(V
S) i
s de
pend
ent
on t
he u
se o
f a
very
uni
que
trop
ical
pl
ant,
vetiv
er
gras
s,
Veti
veri
a zi
zani
oide
s –
rece
ntly
re
clas
sifie
d as
Chr
ysop
ogon
ziz
anio
ides
. T
he p
lant
can
be
grow
n ov
er a
ver
y w
ide
rang
e of
clim
atic
and
soi
l con
ditio
ns, a
nd if
pla
nted
co
rrec
tly c
an b
e us
ed v
irtu
ally
any
whe
re u
nder
trop
ical
, sem
i-tr
opic
al,
and
Med
iterr
anea
n cl
imat
es.
It h
as c
hara
cter
istic
s th
at i
n to
talit
y ar
e un
ique
to a
sin
gle
spec
ies.
Whe
n ve
tiver
gra
ss is
gro
wn
in th
e fo
rm o
f a
narr
ow s
elf-
sust
aini
ng h
edge
row
it
exhi
bits
spe
cial
cha
ract
eris
tics
that
are
ess
entia
l to
man
y of
the
dif
fere
nt a
pplic
atio
ns t
hat
com
pris
e th
e V
etiv
er S
yste
m.
Vet
iver
gra
ss c
an b
e us
ed f
or a
pplic
atio
ns th
at w
ill p
rote
ct r
iver
bas
ins
and
wat
ersh
eds
agai
nst e
nvir
onm
enta
l dam
age,
par
ticul
arly
from
poi
nt
sour
ce f
acto
rs r
elat
ing
to:
1. s
edim
ent
flow
s (o
ften
ass
ocia
ted
with
ag
ricu
lture
and
inf
rast
ruct
ure)
, an
d 2.
tox
ic c
hem
ical
flow
s re
sulti
ng
from
exc
ess
nutr
ient
s, h
eavy
met
als
and
pest
icid
es i
n le
acha
te f
rom
ag
ricu
lture
and
oth
er in
dust
ries
. Bot
h ar
e cl
osel
y lin
ked.
Thi
s ha
ndbo
ok
is
a m
odifi
ed
extr
actio
n fr
om
Vetiv
er
Syst
ems
App
licat
ions
- A
Tec
hnic
al R
efer
ence
Man
ual (
2008
) by
Paul
Tru
ong,
T
ran
Tan
Van
, an
d E
lise
Pinn
ers,
and
foc
uses
on
the
prot
ectio
n of
in
fras
truc
ture
and
for
dis
aste
r m
itiga
tion
by a
pply
ing
the
Vet
iver
Sy
stem
to
slop
e st
abili
zatio
n. I
t dr
aws
on o
ngoi
ng v
etiv
er w
ork
in
Vie
tnam
and
els
ewhe
re i
n th
e w
orld
. It
s te
chni
cal
reco
mm
enda
tions
an
d ob
serv
atio
ns a
re b
ased
on
real
lif
e si
tuat
ions
, pr
oble
ms
and
solu
tions
. The
han
dboo
k is
pri
mar
ily f
or e
ngin
eers
and
oth
ers
with
res
po
nsib
ility
for
the
cons
truc
tion
and
prot
ectio
n of
infr
astr
uctu
re.
Dic
k G
rim
shaw
Fou
nder
and
Cha
irm
an o
f T
he V
etiv
er N
etw
ork
Inte
rnat
iona
l.
ii
FO
RW
AR
D
Bas
ed o
n th
e re
view
of
the
huge
vol
ume
of V
etiv
er S
yste
m r
esea
rch
and
appl
icat
ion,
the
aut
hors
con
side
red
that
it
was
tim
e to
com
pile
a
new
pub
licat
ion
to r
epla
ce t
he fi
rst
Wor
ld B
ank
publ
ishe
d ha
ndbo
ok
(198
7), V
etiv
er G
rass
- A
Hed
ge A
gain
st E
rosi
on (c
omm
only
kno
wn
as
the
Gre
en B
ook)
, pre
pare
d by
Joh
n G
reen
field
. Thi
s ha
ndbo
ok is
one
of
thre
e, a
nd fo
cuse
s on
the
use
of th
e V
etiv
er S
yste
m fo
r inf
rast
ruct
ure
prot
ectio
n th
roug
h its
app
licat
ion
for
slop
e st
abili
zatio
n.
The
han
dboo
k in
clud
es th
e m
ost u
p to
dat
e R
&D
resu
lts a
nd n
umer
ous
exam
ples
of
high
ly s
ucce
ssfu
l re
sults
fro
m a
roun
d th
e w
orld
and
pa
rtic
ular
ly f
rom
Vie
tnam
, w
here
an
inte
nsiv
e co
untr
y w
ide
vetiv
er
prog
ram
has
bee
n in
trod
uced
sin
ce 2
000.
The
mai
n ai
m o
f th
is
hand
book
is
to i
ntro
duce
VS
to p
lann
ers,
des
ign
and
cons
truc
tion
engi
neer
s an
d ot
her
pote
ntia
l us
ers
invo
lved
with
inf
rast
ruct
ure
at
all
leve
ls,
who
oft
en a
re u
naw
are
of t
he e
ffec
tiven
ess
of t
he V
etiv
er
Syst
em f
or b
io-e
ngin
eeri
ng a
pplic
atio
ns.
In a
dditi
on to
the
info
rmat
ion
in th
is h
andb
ook
ther
e ar
e m
any
artic
les
and
rese
arch
pap
ers
rela
ting
to th
e us
e of
the
Vet
iver
Sys
tem
for
slo
pe
stab
iliza
tion
on th
e V
etiv
er N
etw
ork'
s w
ebsi
te a
t: w
ww
.vet
iver
.org
.
Det
ails
ab
out
the
auth
ors,
an
d ac
know
ledg
men
ts
of
thos
e w
ho
cont
ribu
ted
to th
is h
andb
ook
can
be fo
und
in th
e m
aste
r man
ual V
etiv
er
Syst
ems
App
licat
ions
- A
Tec
hnic
al R
efer
ence
Man
ual
(200
8). I
t is
su
ffice
to
say
that
we
deep
ly a
ckno
wle
dge
and
appr
ecia
te a
ll th
ose
invo
lved
in th
is h
andb
ook
prod
uctio
n.
The
pri
ncip
le a
utho
r of
this
han
dboo
k is
Tra
n Ta
n V
an, V
ice-
Dir
ecto
r of
the
Vie
tnam
Ins
titut
e of
Geo
scie
nces
and
Min
eral
Res
ourc
es i
n V
ietn
am a
nd C
oord
inat
or o
f T
he V
ietn
am V
etiv
er N
etw
ork.
Pau
l Tru
ong,
Tra
n Ta
n Va
n an
d E
lise
Pin
ners
.T
he a
utho
rs.
iii
TH
E V
ET
IVE
R S
YST
EM
F
OR
SL
OP
E S
TAB
ILIZ
AT
ION
AN
EN
GIN
EE
R'S
HA
ND
BO
OK
PAR
T 1
- V
ET
IVE
R G
RA
SS -
TH
E P
LA
NT
1
PAR
T 2
- V
ET
IVE
R S
YST
EM
FO
R S
LO
PE
STA
BIL
IZA
TIO
N
16IN
DE
X -
87
iv1
PAR
T 1
V
ET
IVE
R G
RA
SS -
TH
E P
LA
NT
CO
NT
EN
TS
1.
INT
RO
DU
CT
ION
1
2.
SPE
CIA
L C
HA
RA
CT
ER
IST
ICS
OF
VE
TIV
ER
GR
ASS
2
2.1
Mor
phol
ogic
al c
hara
cter
istic
s 2
2.2
Phys
iolo
gica
l cha
ract
eris
tics
32.
3 E
colo
gica
l cha
ract
eris
tics
42.
4 C
old
wea
ther
tole
ranc
e of
vet
iver
gra
ss
62.
5 Su
mm
ary
adap
tabi
lity
rang
e 7
2.6
Gen
etic
cha
ract
eris
tics
92.
7 W
eed
pote
ntia
l 14
3.
CO
NC
LU
SIO
N
154.
R
EFE
RE
NC
ES
15
1. I
NT
RO
DU
CT
ION
The
Vet
iver
Sys
tem
(V
S), w
hich
is b
ased
on
the
appl
icat
ion
of v
etiv
er
gras
s (V
etiv
eria
ziz
anio
ides
L N
ash,
now
rec
lass
ified
as
Chr
ysop
ogon
zi
zani
oide
s L
Rob
erty
), w
as fi
rst
intr
oduc
ed b
y th
e W
orld
Ban
k fo
r so
il an
d w
ater
con
serv
atio
n in
Ind
ia i
n th
e m
id 1
980s
. W
hile
thi
s ap
plic
atio
n st
ill p
lays
a v
ital
role
in
agri
cultu
ral
land
man
agem
ent,
R&
D c
ondu
cted
in th
e la
st 2
0 ye
ars
has
clea
rly
dem
onst
rate
d th
at, d
ue
to v
etiv
er g
rass
’ ex
trao
rdin
ary
char
acte
rist
ics,
VS
also
has
im
port
ant
appl
icat
ion
as a
bio
engi
neer
ing
tech
niqu
e fo
r ste
ep s
lope
sta
biliz
atio
n,
was
tew
ater
dis
posa
l, ph
yto-
rem
edia
tion
of c
onta
min
ated
lan
d an
d w
ater
, and
oth
er e
nvir
onm
enta
l pro
tect
ion
purp
oses
.
Wha
t doe
s th
e Ve
tiver
Sys
tem
do
and
how
doe
s it
wor
k?
VS
is a
ver
y si
mpl
e, p
ract
ical
, in
expe
nsiv
e, l
ow m
aint
enan
ce a
nd
very
eff
ectiv
e m
eans
of s
oil a
nd w
ater
con
serv
atio
n, s
edim
ent c
ontr
ol,
land
sta
biliz
atio
ns a
nd r
ehab
ilita
tion,
and
phy
to-r
emed
iatio
n. B
eing
ve
geta
tive
it is
als
o en
viro
nmen
tal
frie
ndly
. W
hen
plan
ted
in s
ingl
e
2
row
s ve
tiver
pla
nts
will
form
a h
edge
whi
ch is
ver
y ef
fect
ive
in s
low
ing
and
spre
adin
g ru
n of
f w
ater
, re
duci
ng s
oil
eros
ion,
con
serv
ing
soil
moi
stur
e an
d tr
appi
ng s
edim
ent a
nd f
arm
che
mic
als
on s
ite. A
lthou
gh
man
y he
dges
can
do
this
, ve
tiver
gra
ss,
due
to i
ts e
xtra
ordi
nary
and
un
ique
m
orph
olog
ical
an
d ph
ysio
logi
cal
char
acte
rist
ics
desc
ribe
d be
low
can
do
it be
tter
than
all
othe
r sy
stem
s te
sted
. In
add
ition
, th
e ex
trem
ely
deep
and
mas
sive
ly t
hick
roo
t sy
stem
of
vetiv
er b
inds
the
so
il an
d at
the
sam
e tim
e m
akes
it v
ery
diffi
cult
for
it to
be
disl
odge
d un
der
high
vel
ocity
wat
er fl
ows.
Thi
s ve
ry d
eep
and
fast
gro
win
g ro
ot
syst
em a
lso
mak
es v
etiv
er v
ery
drou
ght
tole
rant
and
hig
hly
suita
ble
for
stee
p sl
ope
stab
iliza
tion.
The
Ext
ensi
on W
orke
rs M
anua
l, or
the
Lit
tle
Gre
en B
ook
Com
plem
entin
g th
is h
andb
ook
is t
he s
lim g
reen
ext
ensi
on w
orke
rs
pock
et b
ook
first
pub
lishe
d be
the
Wor
ld B
ank
in 1
987
and
refe
rred
to
on
page
ii
as V
etiv
er G
rass
- A
Hed
ge A
gain
st E
rosi
on,
or m
ore
com
mon
ly k
now
n th
e “l
ittle
gre
en b
ook”
by
John
Gre
enfie
ld.
Thi
s ha
ndbo
ok is
far m
ore
tech
nica
l in
its d
escr
iptio
n of
the
Vet
iver
Sys
tem
an
d is
aim
ed a
t en
gine
ers,
tec
hnic
ians
, ac
adem
ics,
pla
nner
s an
d G
over
nmen
t offi
cial
s an
d la
nd d
evel
oper
s.
2. S
PE
CIA
L C
HA
RA
CT
ER
IST
ICS
OF
VE
TIV
ER
GR
ASS
2.1
Mor
phol
ogic
al c
hara
cter
istic
s:•
Vet
iver
gra
ss d
oes
not
have
sto
lons
or
rhiz
omes
. It
s m
assi
ve
finel
y st
ruct
ured
roo
t sys
tem
that
can
gro
w v
ery
fast
, in
som
e ap
plic
atio
ns r
ootin
g de
pth
can
reac
h 3-
4m i
n th
e fir
st y
ear.
Thi
s de
ep r
oot s
yste
m m
akes
vet
iver
pla
nt e
xtre
mel
y dr
ough
t to
lera
nt a
nd d
iffic
ult t
o di
slod
ge b
y st
rong
cur
rent
. •
Stif
f an
d er
ect
stem
s, w
hich
can
sta
nd u
p to
rel
ativ
ely
deep
w
ater
flow
- p
hoto
1.
• H
ighl
y re
sist
ance
to p
ests
, dis
ease
s an
d fir
e -
phot
o 2.
• A
den
se h
edge
is fo
rmed
whe
n pl
ante
d cl
ose
toge
ther
act
ing
as
a ve
ry e
ffec
tive
sedi
men
t filte
r an
d w
ater
spr
eade
r. •
New
sho
ots
deve
lop
from
the
und
ergr
ound
cro
wn
mak
ing
vetiv
er
resi
stan
t to
fir
e,
fros
ts,
traf
fic
and
heav
y gr
azin
g pr
essu
re.
• N
ew
root
s gr
ow
from
no
des
whe
n bu
ried
by
tr
appe
d
3
sedi
men
t. V
etiv
er w
ill c
ontin
ue to
gro
w u
p w
ith th
e de
posi
ted
silt
even
tual
ly f
orm
ing
terr
aces
, if
tra
pped
sed
imen
t is
not
re
mov
ed.
Ph
oto
1:
Ere
ct a
nd
sti
ff s
tem
s fo
rm a
den
se h
edg
e w
hen
pla
nte
d c
lose
to
get
her
.
2.2
Phy
siol
ogic
al c
hara
cter
istic
s •
Tole
ranc
e to
ext
rem
e cl
imat
ic v
aria
tion
such
as
prol
onge
d dr
ough
t, flo
od,
subm
erge
nce
and
extr
eme
tem
pera
ture
fro
m
-15º
C to
+55
ºC.
• A
bilit
y to
regr
ow v
ery
quic
kly
afte
r bei
ng a
ffec
ted
by d
roug
ht,
fros
ts,
salin
ity
and
adve
rse
cond
ition
s af
ter
the
wea
ther
im
prov
es o
r so
il am
elio
rant
s ad
ded.
•
Tole
ranc
e to
wid
e ra
nge
of s
oil
pH f
rom
3.3
to
12.5
with
out
soil
amen
dmen
t. •
Hig
h le
vel o
f to
lera
nce
to h
erbi
cide
s an
d pe
stic
ides
. •
Hig
hly
effic
ient
in
abso
rbin
g di
ssol
ved
nutr
ient
s su
ch a
s N
an
d P
and
heav
y m
etal
s in
pol
lute
d w
ater
. •
Hig
hly
tole
rant
to g
row
ing
med
ium
hig
h in
aci
dity
, alk
alin
ity,
salin
ity, s
odic
ity a
nd m
agne
sium
. •
Hig
hly
tole
rant
to
Al,
Mn
and
heav
y m
etal
s su
ch a
s A
s, C
d,
Cr,
Ni,
Pb, H
g, S
e an
d Z
n in
the
soils
.
4
2.3
Eco
logi
cal c
hara
cter
istic
s A
lthou
gh v
etiv
er i
s ve
ry t
oler
ant
to s
ome
extr
eme
soil
and
clim
atic
co
nditi
ons
men
tione
d ab
ove,
as
typi
cal
trop
ical
gra
ss,
it is
int
oler
ant
to s
hadi
ng. S
hadi
ng w
ill r
educ
e its
gro
wth
and
in e
xtre
me
case
s, m
ay
even
elim
inat
e ve
tiver
in th
e lo
ng te
rm. T
here
fore
vet
iver
gro
ws
best
Ph
oto
2: U
pp
er: V
etiv
er g
rass
su
rviv
ing
fore
st fi
re;
low
er: t
wo
mo
nth
s af
ter
the
fire
.
in t
he o
pen
and
wee
d fr
ee e
nvir
onm
ent,
wee
d co
ntro
l m
ay b
e ne
eded
du
ring
est
ablis
hmen
t ph
ase.
On
erod
ible
or
unst
able
gro
und
vetiv
er
first
red
uces
ero
sion
, sta
biliz
es th
e er
odib
le g
roun
d (p
artic
ular
ly s
teep
sl
opes
), th
en b
ecau
se o
f nu
trie
nt a
nd m
oist
ure
cons
erva
tion,
impr
oves
its
mic
ro-e
nvir
onm
ent s
o ot
her v
olun
teer
ed o
r sow
n pl
ants
can
est
ablis
h la
ter.
Bec
ause
of
thes
e ch
arac
teri
stic
s ve
tiver
can
be
cons
ider
ed a
s a
nurs
e pl
ant o
n di
stur
bed
land
s.
5
Ph
oto
3: O
n c
oas
tal s
and
du
nes
in Q
uan
g B
ình
(u
pp
er)
and
sal
ine
soil
in G
ò C
ôn
g P
rovi
nce
(lo
wer
).
6
Ph
oto
4: O
n e
xtre
me
acid
su
lfat
e so
il in
Tân
An
(u
pp
er)
and
alk
alin
e an
d s
od
ic s
oil
in N
inh
Th
un
(lo
wer
).
2.4
Col
d w
eath
er to
lera
nce
of v
etiv
er g
rass
A
lthou
gh v
etiv
er i
s a
trop
ical
gra
ss,
it ca
n su
rviv
e an
d th
rive
und
er
extr
emel
y co
ld c
ondi
tions
. U
nder
fro
sty
wea
ther
its
top
gro
wth
die
s ba
ck o
r bec
omes
dor
man
t and
‘pur
ple’
in c
olou
r und
er fr
ost c
ondi
tions
bu
t its
und
ergr
ound
gro
win
g po
ints
sur
vive
d. I
n A
ustr
alia
, ve
tiver
gr
owth
was
not
aff
ecte
d by
sev
ere
fros
t at
–14
ºC a
nd i
t su
rviv
ed f
or
a sh
ort
peri
od a
t –2
2ºC
(-8
ºF)
in n
orth
ern
Chi
na.
In G
eorg
ia (
USA
),
vetiv
er s
urvi
ved
in s
oil t
empe
ratu
re o
f -1
0ºC
but
not
at –
15ºC
. Rec
ent
rese
arch
show
ed th
at 2
5ºC
was
opt
imal
soil
tem
pera
ture
for r
oot g
row
th,
but v
etiv
er r
oots
con
tinue
d to
gro
w a
t 13º
C. A
lthou
gh v
ery
little
sho
ot
grow
th o
ccur
red
at th
e so
il te
mpe
ratu
re r
ange
of
15ºC
(da
y) a
nd 1
3ºC
ro
ot g
row
th c
ontin
ued
at th
e ra
te o
f 12.
6cm
/day
, ind
icat
ing
that
vet
iver
gr
ass
was
not
dor
man
t at t
his
tem
pera
ture
and
ext
rapo
latio
n su
gges
ted
7
that
roo
t dor
man
cy o
ccur
red
at a
bout
5ºC
(Fi
g.1)
.
Fig
ure
1: T
he e
ffec
t of s
oil t
empe
ratu
re o
n th
e ro
ot g
row
th o
f vet
iver
.
2.5
Sum
mar
y ad
apta
bilit
y ra
nge
Tabl
e 1:
Ada
ptab
ility
ran
ge o
f ve
tive
r gr
ass
in A
ustr
alia
and
ot
her
coun
trie
s.
cont
inue
d on
nex
t pag
e ...
.
Con
diti
on
char
acte
rist
icA
ustr
alia
Oth
er C
ount
ries
Adv
erse
Soi
l C
ondi
tion
s
Aci
dity
(pH
)3.
3-9.
54.
2-12
.5 (
high
leve
l so
lubl
e A
l)
Salin
ity (
50%
yie
ld
redu
ctio
n)17
.5 m
Scm
-1
Salin
ity (
surv
ived
)47
.5 m
Scm
-1
Alu
min
ium
leve
l (A
l Sa
t. %
)B
etw
een
68%
- 8
7%
Man
gane
se le
vel
> 5
78 m
gkg-1
Sodi
city
48%
(ex
chan
ge N
a)
Mag
nesi
city
2400
mgk
g-1 (
Mg)
8
Con
diti
on
char
acte
rist
icA
ustr
alia
Oth
er C
ount
ries
Fer
tiliz
er
vetiv
er c
an b
e es
tabl
ishe
d on
ver
y in
fert
ile s
oil d
ue to
its
str
ong
asso
ciat
ion
with
myc
orrh
iza
N a
nd P
(3
00 k
g/ha
DA
P)N
and
P, f
arm
man
ure
Hea
vy M
etal
s
Ars
enic
(A
s)
100
- 25
0 m
gkg-1
Cad
miu
m (
Cd)
20 m
gkg-1
Cop
per
(Cu)
35 -
50
mgk
g-1
Chr
omiu
m (
Cr)
200
- 60
0 m
gkg-1
Nic
kel
(Ni)
50 -
100
mgk
g-1
Mer
cury
(H
g)>
6 m
gkg-1
Lea
d (P
b)>
150
0 m
gkg-1
Sel
eniu
m (
Se)
> 7
4 m
gkg-1
Zin
c (Z
n)>
750
mgk
g-1
Loc
atio
n15
0 S to
370 S
410 N
- 3
80 S
Clim
ate
Ann
ual R
ainf
all (
mm
)45
0 -
4000
250
- 50
00
Fro
st (
grou
nd te
mp.
)-1
10 C-2
20 C
Hea
t wav
e45
0 C55
0 C
Dro
ught
(no
eff
ectiv
e
rain
)15
mon
ths
Pal
atab
ility
Dai
ry c
ows,
cat
tle, h
orse
, ra
bbits
, she
ep, k
anga
roo
Cow
s, c
attle
, goa
ts,
shee
p, p
igs,
car
p
Nut
riti
onal
Val
ueN
= 1
.1 %
Cru
de p
rote
in 3
.3%
P =
0.1
7%C
rude
fat
0.4
%
K =
2.2
%
Cru
de fi
bre
7.1%
Gen
otyp
es:
VV
Z00
8-18
, Ohi
to, a
nd T
aiw
an, t
he l
atte
r tw
o ar
e ba
sica
lly t
he
sam
e as
Sun
shin
e. T
empe
ratu
re t
reat
men
ts:
day
15ºC
/ni
ght
13ºC
(PC
: YW
W
ang)
.
9
2.6
Gen
etic
cha
ract
eris
tics
Thr
ee v
etiv
er s
peci
es a
re u
sed
for
envi
ronm
enta
l pro
tect
ion
purp
oses
.
2.6.
1 Ve
tiver
ia z
izan
ioid
es r
ecla
ssifi
ed a
s C
hrys
opog
on z
izan
ioid
es
The
re a
re tw
o sp
ecie
s of
vet
iver
ori
gina
ting
in th
e In
dian
sub
cont
inen
t: C
hrys
opog
on z
izan
ioid
es a
nd C
hrys
opog
on l
awso
nii.
Chr
ysop
ogon
zi
zani
oide
s ha
s m
any
diff
eren
t acc
essi
ons.
Gen
eral
ly th
ose
from
sou
th
Indi
a ha
ve b
een
culti
vate
d an
d ha
ve l
arge
and
str
ong
root
sys
tem
s.
The
se a
cces
sion
s te
nd t
owar
ds p
olyp
loid
y an
d sh
ow h
igh
leve
ls o
f st
erili
ty a
nd a
re n
ot c
onsi
dere
d in
vasi
ve. T
he n
orth
Ind
ian
acce
ssio
ns,
com
mon
to th
e G
ange
tic a
nd I
ndus
bas
ins,
are
wild
and
hav
e w
eake
r ro
ot sy
stem
s. T
hese
acc
essi
ons a
re d
iplo
ids a
nd a
re k
now
n to
be
wee
dy,
thou
gh n
ot n
eces
sari
ly i
nvas
ive.
The
se n
orth
Ind
ian
acce
ssio
ns a
re
NO
T r
ecom
men
ded
unde
r th
e V
etiv
er S
yste
m. I
t sho
uld
also
be
note
d th
at m
ost
of t
he r
esea
rch
into
dif
fere
nt v
etiv
er a
pplic
atio
ns a
nd fi
eld
expe
rien
ce h
ave
invo
lved
the
sou
th I
ndia
n cu
ltiva
rs t
hat
are
clos
ely
rela
ted
(sam
e ge
noty
pe) a
s M
onto
and
Sun
shin
e. D
NA
stu
dies
con
firm
th
at a
bout
60%
of
Chr
ysop
ogon
ziz
anio
ides
use
d fo
r bi
o-en
gine
erin
g an
d ph
ytor
emed
iatio
n in
tro
pica
l an
d su
btro
pica
l co
untr
ies
are
of t
he
Mon
to/S
unsh
ine
geno
type
.
2.6.
2 C
hrys
opog
on n
emor
alis
T
his n
ativ
e ve
tiver
spec
ies a
re w
ide
spre
ad in
the
high
land
s of T
haila
nd,
Lao
s, a
nd V
ietn
am a
nd m
ost
likel
y in
Cam
bodi
a an
d M
yanm
ar a
s w
ell.
It i
s be
ing
wid
ely
used
in
Tha
iland
for
tha
tchi
ng p
urpo
se. T
his
spec
ies
is n
ot s
teri
le, t
he m
ain
diff
eren
ces
betw
een
C. n
emor
alis
and
C
. ziz
anio
ides
, are
that
the
latte
r is
muc
h ta
ller a
nd h
as th
icke
r and
stif
f st
ems,
C. z
izan
ioid
es h
as a
muc
h th
icke
r an
d de
eper
roo
t sy
stem
and
its
leav
es a
re b
road
er a
nd h
as a
ligh
t gre
en a
rea
alon
g th
e m
id r
ibs,
as
show
n on
the
phot
os b
elow
- p
hoto
s 5-
8.
10
Ph
oto
5: V
etiv
er le
aves
, up
per
: C. z
izan
ioid
es, l
ow
er: C
. nem
ora
lis.
Ph
oto
6:
Dif
fere
nce
bet
wee
n C
. zi
zan
ioid
es (
up
per
) an
d C
. n
emo
ralis
ro
ots
(lo
wer
).
11
Ph
oto
7: V
etiv
er s
ho
ots
: up
per
- C
. nem
ora
lis, l
ow
er -
C. z
izan
ioid
es.
12
Ph
oto
8: V
etiv
er r
oo
ts a
fter
bei
ng
gro
wn
in
so
il (t
op
lef
t an
d r
igh
t), a
nd
af
ter
bei
ng
gro
wn
su
spen
ded
in w
ater
(lo
wer
).
13
Alth
ough
C. n
emor
alis
is n
ot a
s eff
ectiv
e as
C. z
izan
ioid
es, f
arm
ers h
ave
also
rec
ogni
zed
the
usef
ulne
ss o
f C
. ne
mor
alis
in
soil
cons
erva
tion;
th
ey h
ave
used
it i
n th
e C
entr
al H
ighl
ands
as
wel
l as
in s
ome
coas
tal
prov
ince
s of
Cen
tral
Vie
tnam
suc
h as
Qua
ng N
gai t
o st
abili
ze d
ikes
in
rice
fiel
ds, -
pho
to 9
.
Ph
oto
9:
C.
nem
ora
lis o
n a
ric
e fi
eld
bu
nd
in
Qu
ang
Ng
ai (
up
per
), an
d
wild
in C
entr
al H
igh
lan
ds
(lo
wer
).
2.6.
3 C
hrys
opog
on n
igri
tana
Thi
s sp
ecie
s is
nat
ive
to S
outh
ern
and
Wes
t Afr
ica,
its
app
licat
ion
is
mai
nly
rest
rict
ed to
the
sub
con
tinen
t, an
d as
it p
rodu
ces
viab
le s
eeds
its
app
licat
ion
shou
ld b
e re
stri
cted
to th
eir
hom
e la
nds
- ph
oto
10.
14
2.7
Wee
d po
tent
ial
Vet
iver
gra
ss c
ultiv
ars
deri
ved
from
sou
th I
ndia
n ac
cess
ions
are
non
-ag
gres
sive
; the
y pr
oduc
e ne
ither
sto
lons
nor
rhi
zom
es a
nd h
ave
to b
e es
tabl
ishe
d ve
geta
tivel
y by
roo
t (cr
own)
sub
divi
sion
s. I
t is
impe
rativ
e th
at a
ny p
lant
s us
ed f
or b
ioen
gine
erin
g pu
rpos
es w
ill n
ot b
ecom
e a
wee
d in
the
loca
l env
iron
men
t; th
eref
ore
ster
ile v
etiv
er c
ultiv
ars
Ph
oto
10:
Ch
ryso
po
go
n n
igri
tan
a in
Mal
i, W
est
Afr
ica.
(suc
h as
Mon
to, S
unsh
ine,
Kar
nata
ka, F
iji a
nd M
adup
atty
) fro
m s
outh
In
dian
acc
essi
ons
are
idea
l fo
r th
is a
pplic
atio
n. I
n Fi
ji, w
here
vet
iver
gr
ass
was
int
rodu
ced
for
that
chin
g m
ore
than
100
yea
rs a
go,
it ha
s be
en w
idel
y us
ed fo
r soi
l and
wat
er c
onse
rvat
ion
purp
oses
in th
e su
gar
indu
stry
for
ove
r 50
yea
rs w
ithou
t sho
win
g an
y si
gns
of in
vasi
vene
ss.
Vet
iver
gra
ss c
an b
e de
stro
yed
easi
ly e
ither
by
spra
ying
with
gly
phos
ate
15
(Rou
ndup
) or
by
cutti
ng o
ff th
e pl
ant b
elow
the
crow
n.
3. C
ON
CL
USI
ON
Due
to
C.
nem
oral
is l
ow g
row
th f
orm
s an
d m
ost
impo
rtan
tly v
ery
shor
t roo
t sys
tem
it is
not
sui
tabl
e fo
r st
eep
slop
e st
abili
zatio
n w
orks
. In
add
ition
, no
rese
arch
has
bee
n co
nduc
ted
on it
s w
aste
wat
er d
ispo
sal
and
trea
tmen
t, an
d ph
yto-
rem
edia
tion
capa
citie
s, i
t is
rec
omm
ende
d th
at o
nly
non
fert
ile c
ultiv
ars
of C
. ziz
anio
ides
be
used
for a
pplic
atio
ns
liste
d in
this
man
ual.
4. R
EF
ER
EN
CE
S
Ada
ms,
R.P
., D
affo
rn,
M.R
. (1
997)
. D
NA
fing
erpr
ints
(R
APD
s) o
f th
e pa
ntro
pica
l gr
ass,
Vet
iver
ia z
izan
ioid
es L
, re
veal
a s
ingl
e cl
one,
“Su
nshi
ne,”
is
wid
ely
utili
sed
for
eros
ion
cont
rol.
Spec
ial P
aper
, The
Vet
iver
Net
wor
k, L
eesb
urg
Va,
USA
.A
dam
s,
R.P
., M
. Z
hong
, Y
. T
urus
peko
v,
M.R
. D
affo
rn,
and
J.F.
Vel
dkam
p. 1
998.
DN
A fi
nger
prin
ting
reve
als
clon
al n
atur
e of
Vet
iver
ia z
izan
ioid
es (
L.)
Nas
h, G
ram
inea
e an
d so
urce
s of
po
tent
ial n
ew g
erm
plas
m. M
olec
ular
Eco
logy
7:8
13-8
18.
Gre
enfie
ld, J
.C. (
1989
). V
etiv
er G
rass
: T
he id
eal p
lant
for
veg
etat
ive
soil
and
moi
stur
e co
nser
vatio
n.
AST
AG
- T
he W
orld
Ban
k,
Was
hing
ton
DC
, USA
.N
atio
nal
Res
earc
h C
ounc
il. 1
993.
Vet
iver
Gra
ss: A
Thi
n G
reen
Lin
e A
gain
st E
rosi
on. W
ashi
ngto
n, D
.C.:
Nat
iona
l Aca
dem
y Pr
ess.
17
1 pp
.Pu
rseg
love
, J.
W.
1972
. T
ropi
cal
Cro
ps:
Mon
ocot
yled
ons
1. ,
New
Y
ork:
Joh
n W
iley
& S
ons.
Tru
ong,
P.N
. (19
99).
Vet
iver
Gra
ss T
echn
olog
y fo
r la
nd s
tabi
lisat
ion,
er
osio
n an
d se
dim
ent
cont
rol
in
the
Asi
a Pa
cific
re
gion
. Pr
oc.
Firs
t A
sia
Paci
fic C
onfe
renc
e on
Gro
und
and
Wat
er
Bio
engi
neer
ing
for
Ero
sion
Con
trol
and
Slo
pe S
tabi
lisat
ion.
M
anila
, Phi
lippi
nes,
Apr
il 19
99.
Vel
dkam
p. J
.F.
199
9. A
rev
isio
n of
Chr
ysop
ogon
Tri
n. i
nclu
ding
Ve
tive
ria
Bor
y (P
oace
ae)
in T
haila
nd a
nd M
elan
esia
with
no
tes
on
som
e ot
her
spec
ies
from
Afr
ica
and
Aus
tral
ia.
Aus
trob
aile
ya 5
: 503
-533
.
16
PAR
T -
2
TH
E V
ET
IVE
R S
YST
EM
F
OR
SL
OP
E S
TA
BIL
IZA
TIO
N
CO
NT
EN
TS
1. T
YPE
S O
F N
AT
UR
AL
DIS
AST
ER
S T
HA
T C
AN
BE
RE
DU
CE
D B
Y U
SIN
G T
HE
VE
TIV
ER
SY
STE
M (
VS)
17
2. G
EN
ER
AL
PR
INC
IPL
ES
OF
SLO
PE S
TAB
ILIT
Y A
ND
SLO
PE S
TAB
ILIS
AT
ION
19
2.1
Slop
e pr
ofile
19
2.2
Slop
e st
abili
ty
192.
3 Ty
pes
of s
lope
fai
lure
22
2.4
Hum
an im
pact
on
slop
e fa
ilure
22
2.5
Miti
gatio
n of
slo
pe f
ailu
re
252.
6 V
eget
ativ
e sl
ope
stab
ilisa
tion
263.
SL
OPE
STA
BIL
ISA
TIO
N U
SIN
G V
ET
IVE
R S
YST
EM
29
3.
1 C
hara
cter
istic
s of
vet
iver
sui
tabl
e fo
r sl
ope
stab
ilisa
tion
29
3.2
Spec
ial c
hara
cter
istic
s of
vet
iver
sui
tabl
e fo
r
w
ater
dis
aste
r m
itiga
tion
32
3.3
Tens
ile a
nd s
hear
str
engt
h of
vet
iver
roo
ts
33
3.4
Hyd
raul
ic c
hara
cter
istic
s 36
3.
5 Po
re w
ater
pre
ssur
e 37
3.
6 A
pplic
atio
ns o
f V
S in
nat
ural
dis
aste
r
m
itiga
tion
an in
fras
truc
ture
pro
tect
ion
37
3.7
Adv
anta
ges
and
disa
dvan
tage
s of
Vet
iver
Sys
tem
38
3.
8 C
ombi
natio
ns w
ith o
ther
type
s of
rem
edy
40
3.9
Com
pute
r m
odel
ling
404.
APP
RO
PRIA
TE
DE
SIG
NS
AN
D T
EC
HN
IQU
ES
41
4.1
Prec
autio
ns
41
4.2
Plan
ting
time
43
4.3
Nur
sery
44
4.
4 Pr
epar
atio
n fo
r ve
tiver
pla
ntin
g 45
17
4.
5 L
ayou
t spe
cific
atio
ns
45
4.6
Plan
ting
spec
ifica
tions
47
4.
7 M
aint
enan
ce
475.
VS
APP
LIC
AT
ION
S FO
R S
LO
PE S
TAB
ILIZ
AT
ION
RE
LA
STE
D T
O N
AT
UR
AL
DIS
AST
ER
RE
DU
CT
ION
A
ND
IN
FRA
-ST
RU
CT
UR
E P
RO
TE
CT
ION
IN
VIE
TN
AM
49
5.1
VS
appl
icat
ion
for
sand
dun
e pr
otec
tion
in
C
entr
al V
ietn
am
495.
2 V
S ap
plic
atio
n to
con
trol
riv
er b
ank
eros
ion
565.
3 V
S A
pplic
atio
n fo
r co
asta
l ero
sion
con
trol
73
5.4
VS
appl
icat
ion
to s
tabi
lize
road
bat
ters
80
6. C
ON
CL
USI
ON
S 84
7. R
EFE
RE
NC
ES
85
1. T
YP
ES
OF
NA
TU
RA
L D
ISA
STE
RS
TH
AT
CA
N B
E
RE
DU
CE
D B
Y U
SIN
G T
HE
VE
TIV
ER
SY
STE
M (
VS)
Bes
ides
soi
l er
osio
n, t
he V
etiv
er S
yste
m (
VS)
can
red
uce
or e
ven
elim
inat
e m
any
type
s of
na
tura
l di
sast
ers,
in
clud
ing
land
slid
es,
mud
slid
es,
road
bat
ter
inst
abili
ty,
and
eros
ion
(riv
er b
anks
, ca
nals
, co
astli
nes,
dik
es, a
nd e
arth
-dam
bat
ters
).
Whe
n he
avy
rain
s sa
tura
te ro
cks
and
soils
, lan
dslid
es a
nd d
ebri
s-flo
ws
occu
r in
man
y m
ount
aino
us a
reas
of V
ietn
am. R
epre
sent
ativ
e ex
ampl
es
are
the
cata
stro
phic
lan
dslid
es, d
ebri
s flo
ws
and
flash
floo
ding
in
the
Muo
ng L
ay d
istr
ict,
Die
n B
ien
prov
ince
(19
96),
and
the
lan
dslid
e on
th
e H
ai V
an P
ass (
1999
) tha
t dis
rupt
ed N
orth
-Sou
th tr
affic
for m
ore
than
tw
o w
eeks
and
cos
t mor
e th
an $
1 m
illio
n U
SD to
rem
edy.
Vie
tnam
’s
larg
est
land
slid
es, t
hose
lar
ger
than
one
mill
ion
cubi
c m
eter
s (a
mon
g th
em T
hiet
Din
h L
ake,
Hoa
i N
hon
dist
rict
, B
inh
Din
h pr
ovin
ce,
in
An
Ngh
iêp
and
An
Lin
h co
mm
unes
, T
uy A
n di
stri
ct,
and
Phu
Yen
pr
ovin
ce),
cau
sed
loss
of
life
as w
ell a
s pr
oper
ty d
amag
e.
Riv
er b
ank
and
coas
tal
eros
ion,
and
dik
e fa
ilure
s ha
ppen
con
tinua
lly
thro
ugho
ut V
ietn
am. T
ypic
al e
xam
ples
inc
lude
: ri
ver
bank
ero
sion
in
Phu
Tho
, Han
oi, a
nd i
n se
vera
l ce
ntra
l Vie
tnam
pro
vinc
es (
incl
udin
g T
hua
Thi
en H
ue,
Qua
ng N
am,
Qua
ng N
gai
and
Bin
h D
inh)
; co
asta
l
18
eros
ion
in H
ai H
au d
istr
ict,
Nam
Din
h pr
ovin
ce,
and;
riv
erba
nk
and
coas
tal
eros
ion
in t
he M
ekon
g D
elta
. A
lthou
gh t
hese
eve
nts
and
flood
ing/
stor
m d
isas
ters
usu
ally
occ
ur d
urin
g th
e ra
iny
seas
on,
som
etim
es r
iver
bank
ero
sion
take
s pl
ace
duri
ng th
e dr
y se
ason
, whe
n w
ater
dro
ps t
o its
low
est
leve
l. T
his
happ
ened
in
Hau
Vie
n vi
llage
, C
am L
o di
stri
ct, i
n Q
uang
Tri
pro
vinc
e.
Lan
dslid
es a
re m
ore
com
mon
in
area
s w
here
hum
an a
ctiv
ities
pla
y a
deci
sive
rol
e. A
lmos
t 20
perc
ent o
r 20
0 km
(12
4 m
iles)
of
mor
e th
an
1000
km
(62
1 m
iles)
of
the
Ha
Tin
h -
Kon
Tum
sec
tion
of th
e H
o C
hi
Min
h H
ighw
ay i
s hi
ghly
sus
cept
ible
to
land
slid
e or
slo
pe i
nsta
bilit
y,
mai
nly
beca
use
of p
oor
road
con
stru
ctio
n pr
actic
es a
nd a
n un
derl
ying
fa
ilure
to u
nder
stan
d th
e un
favo
urab
le g
eolo
gica
l con
ditio
ns.
Rec
ent
land
slid
es i
n th
e to
wns
of
Yen
Bai
, L
ao C
ai,
and
Bac
Kan
fol
low
ed
mun
icip
al d
ecis
ions
to e
xpan
d ho
usin
g by
allo
win
g cu
tting
at i
ncre
ased
sl
ope
grad
ient
s.
Maj
or e
arth
quak
es h
ave
also
gen
erat
ed la
ndsl
ides
in V
ietn
am, i
nclu
ding
th
e 19
83 s
lide
in T
uan
Gia
o di
stri
ct, a
nd th
e 20
01 s
lide
alon
g th
e ro
ute
from
Die
n B
ien
tow
n to
Lai
Cha
u di
stri
ct.
From
a s
tric
tly e
cono
mic
poi
nt o
f vi
ew, t
he c
ost o
f re
med
iatin
g th
ese
prob
lem
s is h
igh
and
the
Stat
e bu
dget
for s
uch
wor
ks is
nev
er su
ffici
ent.
For e
xam
ple,
rive
r ban
k re
vetm
ent u
sual
ly c
osts
bet
wee
n U
S $2
00,0
00-
300,
000
/km
, som
etim
es r
unni
ng a
s hi
gh a
s U
S $7
00,0
00-$
1 m
illio
n /k
m. T
he T
an C
hau
emba
nkm
ent
in t
he M
ekon
g D
elta
is
an e
xtre
me
case
tha
t co
st n
earl
y U
S $7
mill
ion
/km
. R
iver
ban
k pr
otec
tion
in
Qua
ng B
inh
prov
ince
alo
ne i
s es
timat
ed t
o re
quir
e an
exp
endi
ture
of
mor
e th
an U
S $2
0 m
illio
n ; t
he a
nnua
l bud
get i
s on
ly U
S $3
00,0
00 .
Con
stru
ctio
n of
sea
dik
es u
sual
ly c
osts
bet
wee
n U
S $7
00,0
00-$
1 m
illio
n /k
m, b
ut m
ore
expe
nsiv
e se
ctio
ns c
an c
ost u
pwar
ds o
f US
$2.5
m
illio
n /k
m, a
nd a
re n
ot u
ncom
mon
. Aft
er s
torm
No.
7 in
Sep
tem
ber
2005
was
hed
away
man
y im
prov
ed d
ike
sect
ions
, som
e di
ke m
anag
ers
conc
lude
d th
at e
ven
sect
ions
eng
inee
red
to w
ithst
and
stor
ms
up to
the
9th
leve
l ar
e to
o w
eak,
and
beg
an t
o se
riou
sly
cons
ider
con
stru
ctin
g se
a di
kes
capa
ble
of w
ithst
andi
ng s
torm
s of
up
to t
he 1
2th
leve
l th
at
wou
ld c
ost b
etw
een
US
$7-$
10 m
illio
n /k
m.
19
Bud
get
cons
trai
nts
alw
ays
exis
t, w
hich
co
nfine
s ri
gid
stru
ctur
al
prot
ectio
n m
easu
res
to th
e m
ost a
cute
sec
tions
, nev
er to
the
full
leng
th
of th
e ri
ver
bank
or
coas
tline
. T
his
band
aid
app
roac
h co
mpo
unds
the
prob
lem
s.
Eac
h of
thes
e ev
ents
repr
esen
ts a
type
of s
lope
failu
re o
r mas
s w
astin
g,
refle
ctin
g th
e do
wn
slop
e m
ovem
ent o
f roc
k de
bris
and
soi
l in
resp
onse
to
gra
vita
tiona
l st
ress
es.
Thi
s m
ovem
ent
can
be v
ery
slow
, al
mos
t im
perc
eptib
le,
or d
evas
tatin
gly
rapi
d an
d ap
pare
nt w
ithin
min
utes
. Si
nce
man
y fa
ctor
s in
fluen
ce w
heth
er n
atur
al d
isas
ters
will
occ
ur, w
e sh
ould
und
erst
and
the
caus
es a
s w
ell a
s so
me
basi
c pr
inci
ples
of
slop
e st
abili
satio
n. T
his
info
rmat
ion
will
allo
w u
s to
eff
ectiv
ely
empl
oy V
S bi
oeng
inee
ring
met
hods
to r
educ
e th
eir
impa
ct.
2. G
EN
ER
AL
PR
INC
IPL
ES
OF
SLO
PE
ST
AB
ILIT
Y A
ND
SL
OP
E S
TA
BIL
ISA
TIO
N
2.1
Slop
e pr
ofile
Som
e sl
opes
are
gra
dual
ly c
urve
d, a
nd o
ther
s ar
e ex
trem
ely
stee
p.
The
pro
file
of a
nat
ural
ly-e
rode
d sl
ope
depe
nds
prim
arily
on
its r
ock/
soil
type
, the
soi
l’s n
atur
al a
ngle
of
repo
se, a
nd t
he c
limat
e.
For
slip
re
sist
ant
rock
/soi
l, es
peci
ally
in
arid
reg
ions
, ch
emic
al w
eath
erin
g is
slo
w c
ompa
red
to p
hysi
cal
wea
ther
ing.
The
cre
st o
f th
e sl
ope
is
slig
htly
con
vex
to a
ngul
ar, t
he c
liff f
ace
is n
earl
y ve
rtic
al, a
nd a
deb
ris
slop
e is
pre
sent
at
a 30
-35°
ang
le o
f re
pose
, th
e m
axim
um a
ngle
at
whi
ch lo
ose
mat
eria
l of
a sp
ecifi
c so
il ty
pe is
sta
ble.
Non
-res
ista
nt r
ock/
soil,
esp
ecia
lly in
hum
id r
egio
ns, w
eath
ers
rapi
dly
and
erod
es e
asily
. The
res
ultin
g sl
ope
cont
ains
a t
hick
soi
l co
ver.
Its
cres
t is
conv
ex, a
nd it
s ba
se is
con
cave
.
2.2
Slop
e st
abili
ty2.
2.1
Upl
and
natu
ral s
lope
, cut
slo
pe, r
oad
batte
r et
c.T
he s
tabi
lity
of s
uch
slop
es i
s ba
sed
on t
he i
nter
play
bet
wee
n tw
o ty
pes
of f
orce
s, d
rivi
ng f
orce
s an
d re
sist
ing
forc
es.
Dri
ving
for
ces
prom
ote
dow
n sl
ope
mov
emen
t of
mat
eria
l, w
hile
res
istin
g fo
rces
de
ter m
ovem
ent.
Whe
n dr
ivin
g fo
rces
ove
rcom
e re
sist
ing
forc
es, t
hese
sl
opes
bec
ome
unst
able
.
20
2.2.
2 R
iver
ban
k, c
oast
al e
rosi
on a
nd in
stab
ility
of w
ater
reta
inin
g st
ruct
ures
Som
e hy
drau
lic e
ngin
eers
may
arg
ue th
at b
ank
eros
ion
and
unst
able
w
ater
ret
aini
ng s
truc
ture
s sh
ould
be
trea
ted
sepa
rate
ly f
rom
oth
er
type
s of
slo
pe f
ailu
re b
ecau
se t
heir
res
pect
ive
load
s ar
e di
ffer
ent.
In o
ur o
pini
on, h
owev
er, b
oth
are
subj
ect
to t
he s
ame
inte
ract
ion
betw
een
“dri
ving
for
ces”
and
“re
sist
ing
forc
es”.
Fai
lure
res
ults
w
hen
the
form
er o
verc
omes
the
latte
r.
How
ever
, er
osio
n of
ban
ks a
nd t
he i
nsta
bilit
y of
wat
er r
etai
ning
st
ruct
ures
ar
e sl
ight
ly
mor
e co
mpl
icat
ed;
they
re
sult
from
in
tera
ctio
ns b
etw
een
hydr
aulic
for
ces
actin
g at
the
bed
and
toe
an
d gr
avita
tiona
l for
ces
affe
ctin
g th
e in
-situ
ban
k m
ater
ial.
Failu
re
occu
rs w
hen
eros
ion
of th
e ba
nk to
e an
d th
e ch
anne
l bed
adj
acen
t to
the
ban
k ha
ve i
ncre
ased
the
hei
ght
and
angl
e of
the
ban
k to
th
e po
int t
hat g
ravi
tatio
nal f
orce
s ex
ceed
the
shea
r st
reng
th o
f th
e ba
nk m
ater
ial.
Aft
er fa
ilure
, fai
led
bank
mat
eria
l may
be
deliv
ered
di
rect
ly t
o th
e flo
w a
nd d
epos
ited
as b
ed m
ater
ial,
disp
erse
d as
w
ash
load
, or
depo
site
d al
ong
the
toe
of t
he b
ank
eith
er a
s in
tact
bl
ock,
or
as s
mal
ler,
disp
erse
d ag
greg
ates
.
Fluv
ial c
ontr
olle
d pr
oces
ses
of b
ank
retr
eat a
re e
ssen
tially
twof
old.
Fl
uvia
l sh
ear
eros
ion
of b
ank
mat
eria
ls r
esul
ts i
n pr
ogre
ssiv
e in
crem
enta
l ba
nk r
etre
at. A
dditi
onal
ly,
a ri
se i
n ba
nk h
eigh
t du
e to
nea
r-ba
nk b
ed d
egra
datio
n or
an
incr
ease
in
bank
ste
epne
ss
due
to fl
uvia
l ero
sion
of
the
low
er b
ank
may
act
alo
ne o
r to
geth
er
to d
ecre
ase
the
stab
ility
of
the
bank
with
res
pect
to
mas
s fa
ilure
. D
epen
ding
on
the
cons
trai
nts
of i
ts m
ater
ial
prop
ertie
s an
d th
e ge
omet
ry o
f its
pro
file,
a b
ank
may
fai
l as
the
res
ult
of a
ny o
ne
of s
ever
al p
ossi
ble
mec
hani
sms,
inc
ludi
ng p
lana
r, ro
tatio
nal,
and
cant
ileve
r ty
pe f
ailu
res.
Non
-fluv
ial
cont
rolle
d m
echa
nism
s of
ban
k re
trea
t in
clud
e th
e ef
fect
s of
wav
e w
ash,
tra
mpl
ing,
and
pip
ing
- an
d sa
ppin
g-ty
pe
failu
res,
ass
ocia
ted
with
str
atifi
ed b
anks
and
adv
erse
gro
undw
ater
co
nditi
ons.
21
2.2.
3 D
rivi
ng f
orce
sA
lthou
gh g
ravi
ty i
s th
e m
ain
driv
ing
forc
e, i
t ca
nnot
act
alo
ne.
Slop
e an
gle,
ang
le o
f re
pose
of
spec
ific
soil,
clim
ate,
slo
pe
mat
eria
l, an
d es
peci
ally
wat
er, c
ontr
ibut
e to
its
effe
ct:
• Fa
ilure
occ
urs
far m
ore
freq
uent
ly o
n st
eep
slop
es th
an o
n ge
ntle
slo
pes.
•
Wat
er p
lays
a k
ey ro
le in
pro
duci
ng s
lope
failu
re e
spec
ially
at
the
toe
of th
e sl
ope:
- In
the
for
m o
f ri
vers
and
wav
e ac
tion,
wat
er e
rode
s th
e ba
se o
f slo
pes,
rem
ovin
g su
ppor
t, w
hich
incr
ease
s dr
ivin
g fo
rces
.-
Wat
er a
lso
incr
ease
s th
e dr
ivin
g fo
rce
by lo
adin
g, th
at
is, fi
lling
pre
viou
sly
empt
y po
re s
pace
s an
d fr
actu
res,
w
hich
add
s to
the
tota
l mas
s su
bjec
ted
to g
ravi
tatio
nal
forc
e.-
The
pre
senc
e of
wat
er r
esul
ts i
n po
re w
ater
pre
ssur
e th
at r
educ
es t
he s
hear
str
engt
h of
the
slo
pe m
ater
ial.
Impo
rtan
tly,
abru
pt
chan
ges
(dra
mat
ic
incr
ease
s an
d de
crea
ses)
in
pore
wat
er p
ress
ure
may
pla
y th
e de
cisi
ve r
ole
in s
lope
fai
lure
.-
Wat
er’s
inte
ract
ion
with
surf
ace r
ock
and
soil
(che
mic
al
wea
ther
ing)
sl
owly
w
eake
ns
slop
e m
ater
ial,
and
redu
ces
its s
hear
str
engt
h.
Thi
s in
tera
ctio
n re
duce
s re
sist
ing
forc
es.
2.2.
4 R
esis
ting
forc
esT
he m
ain
resi
stin
g fo
rce
is th
e m
ater
ial's
she
ar s
tren
gth,
a fu
nctio
n of
coh
esio
n (t
he a
bilit
y of
par
ticle
s to
attr
act a
nd h
old
each
oth
er
toge
ther
) an
d in
tern
al f
rict
ion
(fri
ctio
n be
twee
n gr
ains
with
in a
m
ater
ial)
that
opp
oses
dri
ving
for
ces.
The
rat
io o
f re
sist
ing
forc
es
to d
rivi
ng f
orce
s is
the
saf
ety
fact
or (
SF).
If
SF >
1 th
e sl
ope
is s
tabl
e. O
ther
wis
e, i
t is
uns
tabl
e. U
sual
ly a
SF
of 1
.2-1
.3 i
s m
argi
nally
acc
epta
ble.
Dep
endi
ng o
n th
e im
port
ance
of
the
slop
e an
d th
e po
tent
ial
loss
es a
ssoc
iate
d w
ith i
ts f
ailu
re,
a hi
gher
SF
shou
ld b
e en
sure
d. I
n sh
ort,
slop
e st
abili
ty is
a f
unct
ion
of: r
ock/
soil
type
and
its
stre
ngth
, slo
pe g
eom
etry
(he
ight
, ang
le),
clim
ate,
ve
geta
tion
and
time.
Eac
h of
the
se f
acto
rs m
ay p
lay
a si
gnifi
cant
ro
le in
con
trol
ling
driv
ing
or r
esis
ting
forc
es.
22
2.3
Typ
es o
f sl
ope
failu
reD
epen
ding
on
the
type
of
mov
emen
t an
d th
e na
ture
of
the
mat
eria
l in
volv
ed, d
iffe
rent
type
s of
slo
pe f
ailu
re m
ay r
esul
t:
Tabl
e 1:
Typ
es o
f sl
ope
failu
re
In r
ock,
usu
ally
fal
ls a
nd t
rans
latio
nal
slid
es (
invo
lvin
g on
e or
mor
e pl
anes
of
wea
knes
s) w
ill o
ccur
. Si
nce
soil
is m
ore
hom
ogen
ous
and
lack
s a
visi
ble
plan
e of
wea
knes
s, r
otat
iona
l sl
ides
or
flow
s oc
cur.
In
gene
ral,
mas
s w
astin
g in
volv
es m
ore
than
one
type
of
mov
emen
t, fo
r ex
ampl
e, u
pper
slu
mp
and
low
er fl
ow,
or u
pper
soi
l sl
ide
and
low
er
rock
slid
e.
2.4
Hum
an im
pact
on
slop
e fa
ilure
Lan
dslid
es a
re n
atur
al o
ccur
ring
phe
nom
ena
know
n as
geo
logi
cal
eros
ion.
Lan
dslid
es o
r sl
ope
failu
res
occu
r w
heth
er p
eopl
e ar
e th
ere
or n
ot!
How
ever
, hu
man
lan
d us
e pr
actic
es p
lay
a m
ajor
rol
e in
sl
ope
proc
esse
s. T
he c
ombi
natio
n of
unc
ontr
olla
ble
natu
ral
even
ts
Typ
e of
mov
emen
tM
ater
ial i
nvol
ved
Roc
kSo
il
Fal
lsR
ock
fall
Soil
fall
Slid
esR
otat
iona
lR
ock
slum
p bl
ock
Soil
slum
p bl
ocks
Tra
nsla
tiona
lR
ock
slid
ede
bris
slid
e
Flo
ws
Slow
Roc
k cr
eep
Soil
cree
p
satu
rate
d &
un
cons
olid
ated
m
ater
ial
eart
h flo
w
mud
flow
(up
to
30%
wat
er)
Fast
debr
is fl
ow
debr
is a
vala
nche
Com
plex
Com
bina
tion
of tw
o or
mor
e ty
pes
of m
ovem
ent
23
(ear
thqu
akes
, hea
vy ra
inst
orm
s, e
tc.)
and
art
ifici
ally
alte
red
land
(slo
pe
exca
vatio
n, d
efor
esta
tion,
urb
anis
atio
n, e
tc.)
can
cre
ate
disa
stro
us
slop
e fa
ilure
s.
2.5
Miti
gatio
n of
slo
pe f
ailu
reM
inim
izin
g sl
ope
failu
re
requ
ires
th
ree
step
s:
iden
tifica
tion
of
pote
ntia
lly
unst
able
ar
eas;
pr
even
tion
of
slop
e fa
ilure
, an
d;
impl
emen
tatio
n of
cor
rect
ive
mea
sure
s fo
llow
ing
slop
e fa
ilure
. A
th
orou
gh u
nder
stan
ding
of g
eolo
gica
l con
ditio
ns is
cri
tical
ly im
port
ant
to d
ecid
e th
e be
st m
itiga
tion
prac
tice.
2.5.
1 Id
entifi
catio
nT
rain
ed t
echn
icia
ns i
dent
ify
pros
pect
ive
slop
e fa
ilure
by
stud
ying
ae
rial
pho
togr
aphs
to
loca
te p
revi
ous
land
slid
e or
slo
pe f
ailu
re s
ites,
an
d co
nduc
ting
field
inv
estig
atio
ns o
f po
tent
ially
uns
tabl
e sl
opes
. Po
tent
ial
mas
s-w
astin
g ar
eas
can
be
iden
tified
by
st
eep
slop
es,
bedd
ing
plan
es i
nclin
ed t
owar
d va
lley
floor
s, h
umm
ocky
top
ogra
phy
(irr
egul
ar,
lum
py-l
ooki
ng s
urfa
ces
cove
red
by y
oung
er t
rees
), w
ater
se
epag
e, a
nd a
reas
whe
re l
ands
lides
hav
e pr
evio
usly
occ
urre
d. T
his
info
rmat
ion
is u
sed
to g
ener
ate
a ha
zard
map
sho
win
g th
e la
ndsl
ide-
pron
e un
stab
le a
reas
.
2.5.
2 P
reve
ntio
nPr
even
ting
land
slid
es a
nd s
lope
inst
abili
ty is
muc
h m
ore
cost
eff
ectiv
e th
an c
orre
ctio
n. P
reve
ntio
n m
etho
ds i
nclu
de c
ontr
ollin
g dr
aina
ge,
redu
cing
slo
pe a
ngle
and
slo
pe h
eigh
t, an
d in
stal
ling
vege
tativ
e co
ver,
reta
inin
g w
all,
rock
bol
t, or
sho
tcre
te (fi
nely
-agg
rega
ted
conc
rete
, with
ad
mix
ture
for
fas
t so
lidif
ying
, ap
plie
d by
a p
ower
ful
pum
p).
The
se
supp
ortiv
e m
etho
ds m
ust
be c
orre
ctly
and
app
ropr
iate
ly a
pplie
d by
fir
st e
nsur
ing
that
the
slo
pe i
s in
tern
ally
and
str
uctu
rally
sta
ble.
Thi
s re
quir
es a
goo
d un
ders
tand
ing
of lo
cal g
eolo
gica
l con
ditio
ns.
2.5.
3 C
orre
ctio
nSo
me
land
slid
es c
an b
e co
rrec
ted
by i
nsta
lling
a d
rain
age
syst
em t
o re
duce
wat
er p
ress
ure
in t
he s
lope
, an
d pr
even
t fu
rthe
r m
ovem
ent.
Slop
e in
stab
ility
pro
blem
s bo
rder
ing
road
s or
oth
er i
mpo
rtan
t pl
aces
ty
pica
lly r
equi
re c
ostly
tre
atm
ent.
Don
e tim
ely
and
prop
erly
, sur
face
an
d su
bsur
face
dra
inag
e w
ould
be
very
eff
ectiv
e.
How
ever
, si
nce
24
such
mai
nten
ance
is u
sual
ly d
efer
red
or n
egle
cted
ent
irel
y, m
uch
mor
e ri
goro
us a
nd e
xpen
sive
cor
rect
ive
mea
sure
s be
com
e ne
cess
ary.
In V
ietn
am,
rigi
d st
ruct
ural
pro
tect
ion
met
hods
(co
ncre
te o
r ro
ck
ripr
ap b
ank
reve
tmen
t, gr
oins
, re
tain
ing
wal
ls,
etc.
) ar
e co
mm
only
us
ed to
sta
biliz
e sl
opes
and
riv
erba
nks
and
to c
ontr
ol c
oast
al e
rosi
on.
Nev
erth
eles
s, d
espi
te th
eir c
ontin
uous
use
for d
ecad
es, s
lope
s co
ntin
ue
to f
ail,
eros
ion
wor
sens
, mai
nten
ance
cos
ts i
ncre
ase.
So
wha
t ar
e th
e m
ain
wea
knes
ses
of th
ese
mea
sure
s? F
rom
a s
tric
tly e
cono
mic
poi
nt o
f vi
ew, r
igid
mea
sure
s are
ver
y ex
pens
ive,
and
stat
e or
mun
icip
al b
udge
ts
for
such
pro
ject
s ar
e ne
ver
suffi
cien
t. A
tec
hnic
al a
nd e
nvir
onm
enta
l an
alys
is r
aise
s th
e fo
llow
ing
conc
erns
: •
Min
ing
of
the
rock
/con
cret
e oc
curs
el
sew
here
, w
here
it
undo
ubte
dly
wre
aks
envi
ronm
enta
l hav
oc.
• L
ocal
ized
rig
id s
truc
tura
l de
vice
s do
not
abs
orb
flow
/wav
e en
ergy
. Sin
ce ri
gid
stru
ctur
es c
anno
t fol
low
the
loca
l set
tlem
ent,
they
ca
use
stro
ng
grad
ient
s.
Stro
ng
grad
ient
s ge
nera
te
addi
tiona
l tur
bule
nce,
whi
ch c
reat
es m
ore
eros
ion.
Mor
eove
r, si
nce
the
devi
ces
are
loca
lized
, the
y fr
eque
ntly
end
abr
uptly
; th
ey d
o no
t tra
nsit
grad
ually
and
sm
ooth
ly to
the
natu
ral b
ank.
T
hus,
the
y si
mpl
y tr
ansf
er e
rosi
on t
o an
othe
r pl
ace,
to
the
oppo
site
sid
e or
dow
nstr
eam
, w
hich
agg
rava
tes
the
disa
ster
, ra
ther
tha
n re
duci
ng i
t fo
r th
e ri
ver
as a
who
le.
Exa
mpl
es o
f th
ese
abou
nd in
sev
eral
Cen
tral
Vie
tnam
pro
vinc
es.
• St
ruct
ural
, ri
gid
mea
sure
s in
trod
uce
cons
ider
able
am
ount
s of
sto
ne,
sand
, ce
men
t in
to t
he r
iver
sys
tem
, di
spla
cing
and
di
spos
ing
larg
e vo
lum
es o
f ba
nk s
oil
into
the
riv
er.
As
the
rive
r be
com
es s
ilted
up,
its
dyn
amic
s ch
ange
, its
bed
ris
es,
and
flood
and
ban
k er
osio
n pr
oble
ms
incr
ease
. Thi
s pr
oble
m
is p
artic
ular
ly g
rave
in
Vie
tnam
whe
re w
orke
rs t
hrow
was
te
soil
dire
ctly
int
o th
e ri
ver
as t
hey
re-s
hape
the
ban
k. O
ften
th
ey d
ump
ston
e di
rect
ly i
nto
the
rive
r to
sta
biliz
e th
e to
e of
uns
tabl
e ba
nk,
or t
ry t
o la
y ro
ck p
iece
s on
the
riv
erbe
d,
whi
ch r
educ
es t
he fl
ow d
epth
(ch
anne
l) c
onsi
dera
bly.
W
hen
the
emba
nkm
ents
ul
timat
ely
fail,
sc
raps
of
ro
ck
bask
ets,
gr
oins
, et
c. r
emai
n sc
atte
red
in t
he w
ater
cau
sing
man
-mad
e ag
grad
atio
n of
the
rive
r be
d.•
Rig
id s
truc
ture
s ar
e un
natu
ral
and
are
inco
mpa
tible
with
25
the
soft
gro
und
of e
rodi
ng o
r er
odib
le s
oils
. A
s th
e gr
ound
is
con
solid
ated
and
/or
erod
ed a
nd w
ashe
d aw
ay, i
t un
derc
uts
and
unde
rmin
es t
he u
pper
rig
id l
ayer
. E
xam
ples
inc
lude
the
ri
ght b
ank
imm
edia
tely
dow
nstr
eam
of
the
Tha
ch N
ham
Wei
r (Q
uang
Nga
i pro
vinc
e) th
at c
rack
ed a
nd c
olla
psed
. Eng
inee
rs
who
rep
lace
con
cret
e pl
ates
with
roc
k ri
prap
with
or
with
out
conc
rete
fra
mes
lea
ve u
nsol
ved
the
prob
lem
of
subs
urfa
ce
eros
ion.
Alo
ng th
e H
ai H
au s
ea d
ike,
the
who
le s
ectio
n of
rock
ri
prap
col
laps
ed a
s th
e fo
unda
tion
soil
unde
rnea
th w
as w
ashe
d aw
ay.
• R
igid
str
uctu
res
only
tem
pora
rily
redu
ce e
rosi
on.
The
y ca
nnot
he
lp s
tabi
lize
the
bank
whe
n bi
g la
ndsl
ides
with
dee
p fa
ilure
su
rfac
e.
• C
oncr
ete
or ro
ck re
tain
ing
wal
ls a
re p
roba
bly
the
mos
t com
mon
en
gine
erin
g m
etho
d em
ploy
ed t
o st
abili
ze r
oad
batte
rs i
n V
ietn
am. M
ost
of t
hese
wal
ls a
re p
assi
ve, s
impl
y w
aitin
g fo
r th
e sl
opes
to f
ail.
Whe
n th
e sl
opes
do
fail,
the
wal
ls a
lso
fail,
as
see
n in
man
y ar
eas
alon
g th
e H
o C
hi M
inh
Hig
hway
. The
se
stru
ctur
es a
re a
lso
dest
roye
d by
ear
thqu
akes
.
Alth
ough
ri
gid
stru
ctur
es
like
rock
em
bank
men
ts
are
obvi
ousl
y un
suita
ble
for
cert
ain
appl
icat
ions
, su
ch a
s sa
nd d
une
stab
ilisa
tion,
th
ey a
re s
till
bein
g bu
ilt,
as c
an b
e ob
serv
ed a
long
the
new
roa
d in
ce
ntra
l Vie
tnam
.
2.6
Vege
tativ
e sl
ope
stab
ilisa
tion
Veg
etat
ion
has
been
us
ed
as
a na
tura
l bi
oeng
inee
ring
to
ol
to
recl
aim
lan
d, c
ontr
ol e
rosi
on a
nd s
tabi
lize
slop
es f
or c
entu
ries
, an
d its
pop
ular
ity h
as i
ncre
ased
mar
kedl
y in
the
las
t de
cade
s. T
his
is
part
ly d
ue t
o th
e fa
ct t
hat
mor
e in
form
atio
n ab
out
vege
tatio
n is
now
av
aila
ble
to e
ngin
eers
, an
d al
so p
artly
due
to
the
cost
-eff
ectiv
enes
s an
d en
viro
nmen
t-fr
iend
lines
s of
this
“so
ft”
engi
neer
ing
appr
oach
.
Und
er t
he i
mpa
ct o
f th
e se
vera
l fa
ctor
s pr
esen
ted
abov
e a
slop
e w
ill
beco
me
unst
able
due
to:
(a)
sur
face
ero
sion
or
‘she
et e
rosi
on’;
and
(b
) in
tern
al s
truc
tura
l wea
knes
ses.
She
et e
rosi
on w
hen
not c
ontr
olle
d of
ten
lead
s to
rill
and
gul
ly e
rosi
on th
at, o
ver
time,
will
des
tabi
lize
the
slop
e; s
truc
tura
l w
eakn
ess
will
ulti
mat
ely
caus
e m
ass
mov
emen
t or
26
land
slip
. Sin
ce s
heet
ero
sion
can
als
o ca
use
slop
e fa
ilure
, slo
pe su
rfac
e pr
otec
tion
shou
ld b
e co
nsid
ered
as i
mpo
rtan
t as o
ther
stru
ctur
al
rein
forc
emen
ts b
ut it
s im
port
ance
is o
ften
ove
r lo
oked
. Pro
tect
ing
the
slop
e su
rfac
e is
an
effe
ctiv
e, e
cono
mic
al,
and
esse
ntia
l pr
even
tive
mea
sure
. I
n m
any
case
s, a
pply
ing
som
e pr
even
tive
mea
sure
s w
ill
ensu
re c
ontin
ued
slop
e st
abili
ty,
and
alw
ays
cost
muc
h le
ss t
han
corr
ectiv
e m
easu
res.
The
veg
etat
ive
cove
r pr
ovid
ed b
y gr
ass
seed
ing,
hyd
ro-s
eedi
ng o
r hy
dro-
mul
chin
g no
rmal
ly i
s qu
ite e
ffec
tive
agai
nst
shee
t er
osio
n an
d sm
all
rill
eros
ion,
and
dee
p-ro
oted
pla
nts
such
as
tree
s an
d sh
rubs
ca
n pr
ovid
e so
me
stru
ctur
al r
einf
orce
men
t fo
r th
e gr
ound
. H
owev
er,
on n
ewly
-con
stru
cted
slo
pes,
the
sur
face
lay
er i
s of
ten
not
wel
l co
nsol
idat
ed,
so e
ven
wel
l-ve
geta
ted
slop
es c
anno
t pr
even
t ri
ll an
d gu
lly e
rosi
on. D
eep-
root
ed tr
ees
grow
slo
wly
and
are
oft
en d
iffic
ult t
o es
tabl
ish
in su
ch h
ostil
e te
rrito
ry.
In th
ese
case
s, e
ngin
eers
oft
en ru
e th
e in
effic
ienc
y of
the
vege
tativ
e co
ver a
nd in
stal
l str
uctu
ral r
einf
orce
men
t so
on a
fter
con
stru
ctio
n. I
n sh
ort,
trad
ition
al s
lope
sur
face
pro
tect
ion
prov
ided
by
loca
l gra
sses
and
tree
s ca
nnot
, in
man
y ca
ses,
ens
ure
the
need
ed s
tabi
lity.
2.6.
1 P
ros,
con
s an
d lim
itatio
ns o
f pl
antin
g ve
geta
tion
on s
lope
.Ta
ble
2: G
ener
al p
hysi
cal e
ffec
ts o
f ve
geta
tion
on
slop
e st
abili
zati
on.
Eff
ect
Phy
sica
l Cha
ract
eris
tics
Ben
efici
al
Roo
t rei
nfor
cem
ent,
soil
arch
ing,
bu
ttres
sing
, anc
hora
ge, a
rres
ting
the
roll
of lo
ose
boul
ders
by
tree
s
Roo
t aer
atio
n, d
istr
ibut
ion
and
mor
phol
ogy;
Ten
sile
st
reng
th o
f ro
ots;
Spa
cing
, di
amet
er a
nd e
mbe
dmen
t of
tree
s, th
ickn
ess
and
incl
inat
ion
of y
ield
ing
stra
ta;
Shea
r st
reng
th p
rope
rtie
s of
so
ils
Dep
letio
n of
soi
l moi
stur
e an
d
incr
ease
of
soil
suct
ion
by r
oot
upta
ke a
nd tr
ansp
irat
ion
Moi
stur
e co
nten
t of
soil;
L
evel
of
grou
nd w
ater
; Por
e pr
essu
re/s
oil s
uctio
n
27
Tabl
e 3:
Slo
pe a
ngle
lim
itat
ions
on
esta
blis
hmen
t of
veg
etat
ion.
Slop
e an
gle
(deg
rees
)V
eget
atio
n ty
peG
rass
Shru
bs/T
rees
0 -
30
Low
in d
iffic
ulty
; ro
utin
e pl
antin
g te
chni
ques
may
be
used
Low
in d
iffic
ulty
; rou
tine
plan
ting
tech
niqu
es m
ay b
e us
ed
30 -
45
Incr
easi
ngly
dif
ficul
t fo
r sp
rigg
ing
or
turfi
ng; r
outin
e ap
plic
atio
n fo
r hy
dro
seed
ing
Incr
easi
ngly
dif
ficul
t to
plan
t
> 45
Spec
ial c
onsi
dera
tion
requ
ired
Plan
ting
mus
t gen
eral
ly b
e on
be
nche
s
Inte
rcep
tion
of r
ainf
all b
y fo
liage
, in
clud
ing
evap
orat
ive
loss
es.
Net
rai
nfal
l on
slop
e
Incr
ease
in th
e hy
drau
lic r
esis
tanc
e in
irri
gatio
n an
d dr
aina
ge c
anal
s.M
anni
ng’s
coe
ffici
ent
Adv
erse
Roo
t wed
ging
of
near
-sur
face
roc
ks
and
boul
ders
and
upr
ootin
g in
ty
phoo
ns.
Roo
t are
a ra
tion,
dis
trib
utio
n an
d m
orph
olog
y
Surc
harg
ing
the
slop
e by
larg
e(h
eavy
) tr
ees
(som
etim
es b
enefi
cial
de
pend
ing
on a
ctua
l situ
atio
ns).
Mea
n w
eigh
t of
vege
tatio
n
Win
d lo
adin
g.D
esig
n w
ind
spee
d fo
r re
quir
ed r
etur
n pe
riod
; m
ean
mat
ure
tree
hei
ght f
or
grou
ps o
f tr
ees
Mai
ntai
ning
infil
trat
ion
capa
city
Var
iatio
n of
moi
stur
e co
nten
t of
soil
with
dep
th
28
2.6.
2 Ve
geta
tive
slop
e st
abili
satio
n in
Vie
tnam
To
a le
sser
ex
tent
, so
fter
, ve
geta
tive
solu
tions
ha
ve
also
be
en
empl
oyed
in
Vie
tnam
. T
he m
ost
popu
lar
bioe
ngin
eeri
ng m
etho
d to
co
ntro
l ri
verb
ank
eros
ion
is p
roba
bly
the
plan
ting
of b
ambo
o (w
hich
is
the
wor
st m
easu
re y
ou c
an ta
ke.
Onc
e ba
mbo
o cl
umps
was
hout
in a
flo
od a
nd g
o do
wn
rive
r th
ey c
an ta
ke o
ut b
ridg
es o
r an
ythi
ng th
ey g
et
caug
ht u
p in
. The
y ha
ve s
uch
high
ten
sile
str
engt
h th
ey d
o no
t br
eak
up).
To
cont
rol c
oast
al e
rosi
on, m
angr
ove,
cas
uari
nas,
wild
pin
eapp
le,
and
nipa
pal
m a
re a
lso
empl
oyed
. H
owev
er,
thes
e pl
ants
hav
e so
me
maj
or d
efici
enci
es, f
or e
xam
ple:
•
Gro
win
g in
clu
mps
, bam
boo
whi
ch is
sha
llow
roo
ted
does
not
cl
ose
as a
hed
gero
w. T
here
fore
floo
dwat
er c
once
ntra
tes
at th
e ga
ps b
etw
een
clum
ps,
whi
ch i
ncre
ases
its
des
truc
tive
pow
er
and
caus
es m
ore
eros
ion.
•
Bam
boo
is t
op h
eavy
. It
s sh
allo
w (
1-1.
5 m
dee
p) b
unch
roo
t sy
stem
doe
s no
t bal
ance
the
high
, hea
vy c
anop
y. T
here
fore
,
clum
ps
of
bam
boo
add
stre
ss
to
a ri
ver
bank
, w
ithou
t co
ntri
butin
g to
its
stab
ility
.•
Freq
uent
ly t
he b
unch
roo
t sy
stem
of
bam
boo
dest
abili
zes
the
soil
bene
ath
it, e
ncou
ragi
ng e
rosi
on a
nd c
reat
ing
the
cond
ition
s fo
r la
rger
la
ndsl
ides
. Se
vera
l C
entr
al
Vie
tnam
pr
ovin
ces
disp
lay
exam
ples
of
bank
fai
lure
fol
low
ing
inst
alla
tion
of
exte
nsiv
e ba
mbo
o st
rips
.•
Man
grov
e tr
ees,
whe
re th
ey c
an g
row
, for
m a
sol
id b
uffe
r th
at
redu
ces
wav
e po
wer
, w
hich
, in
tur
n, r
educ
es c
oast
al e
rosi
on.
How
ever
, est
ablis
hing
man
grov
e is
dif
ficul
t and
slo
w a
s m
ice
eat i
ts s
eedl
ing.
Typ
ical
ly, o
f the
hun
dred
s of
hec
tare
s pl
ante
d,
only
a s
mal
l pe
rcen
tage
sur
vive
s to
bec
ome
fore
st.
Thi
s ha
s be
en r
epor
ted
rece
ntly
in H
a T
inh
prov
ince
.•
Cas
uari
nas
tree
s ha
ve l
ong
been
pla
nted
on
thou
sand
s of
he
ctar
es o
f sa
nd d
unes
in
Cen
tral
Vie
tnam
. Wild
pin
eapp
le i
s al
so p
lant
ed a
long
ban
ks o
f riv
ers,
str
eam
s an
d ot
her c
hann
els,
an
d al
ong
the
cont
our
lines
of
dune
slo
pes.
Alth
ough
the
y re
duce
win
d po
wer
and
min
imiz
e sa
nd s
torm
, th
ese
plan
ts
cann
ot
stem
sa
nd
flow
be
caus
e th
ey
have
sh
allo
w
root
sy
stem
s an
d do
not
for
m c
lose
d he
dger
ows.
Des
pite
pla
ntin
g ca
suar
inas
and
wild
pin
eapp
le tr
ees
atop
the
sand
dik
es a
long
29
flow
cha
nnel
s in
Qua
ng B
inh
prov
ince
, san
d fin
gers
con
tinue
to
inv
ade
arab
le l
and.
Mor
eove
r, bo
th p
lant
s ar
e se
nsiti
ve
to c
limat
e; c
asua
rina
s se
edlin
gs b
arel
y su
rviv
e sp
orad
ic b
ut
extr
eme
cold
win
ters
(les
s th
an -1
5ºC
/5ºF
), a
nd w
ild p
inea
pple
ca
nnot
sur
vive
Nor
th V
ietn
am’s
blis
teri
ng s
umm
ers.
Fort
unat
ely,
vet
iver
gro
ws
quic
kly,
bec
omes
est
ablis
hed
unde
r ho
stile
co
nditi
ons,
and
its
ver
y de
ep a
nd e
xten
sive
roo
t sy
stem
pro
vide
s st
ruct
ural
str
engt
h in
a r
elat
ivel
y sh
ort
peri
od o
f tim
e. T
hus,
vet
iver
ca
n be
a s
uita
ble
alte
rnat
ive
to tr
aditi
onal
veg
etat
ion,
pro
vide
d th
at th
e fo
llow
ing
appl
icat
ion
tech
niqu
es a
re le
arne
d an
d fo
llow
ed c
aref
ully
.
3. S
LO
PE
ST
AB
ILIS
AT
ION
USI
NG
VE
TIV
ER
SY
STE
M
3.1
Cha
ract
eris
tics
of v
etiv
er s
uita
ble
for
slop
e st
abili
satio
nV
etiv
er’s
uni
que
attr
ibut
es h
ave
been
rese
arch
ed, t
este
d, a
nd d
evel
oped
th
roug
hout
the
tro
pica
l w
orld
, th
us e
nsur
ing
that
vet
iver
is
real
ly a
ve
ry e
ffec
tive
bioe
ngin
eeri
ng to
ol:
• A
lthou
gh t
echn
ical
ly a
gra
ss,
vetiv
er p
lant
s us
ed i
n la
nd
stab
ilisa
tion
appl
icat
ions
beh
ave
mor
e lik
e fa
st-g
row
ing
tree
s or
shr
ubs.
Vet
iver
roo
ts a
re, p
er u
nit a
rea,
str
onge
r an
d de
eper
th
an tr
ee r
oots
.•
Vet
iver
’s e
xtre
mel
y de
ep a
nd m
assi
ve fi
nely
str
uctu
red
root
sy
stem
can
ext
end
dow
n to
tw
o to
thr
ee m
eter
s (s
ix t
o ni
ne
feet
) in
the
firs
t ye
ar.
On
fill
slop
e, m
any
expe
rim
ents
sho
w
that
thi
s gr
ass
can
reac
h 3.
6m (
12 f
eet)
in
12 m
onth
s. (
Not
e th
at
vetiv
er
cert
ainl
y do
es
not
pene
trat
e de
eply
in
to
the
grou
ndw
ater
tabl
e. T
here
fore
at s
ites
with
a h
igh
grou
ndw
ater
le
vel,
its r
oot s
yste
m m
ay n
ot e
xten
d as
long
as
in d
rier
soi
l).
Vet
iver
’s e
xten
sive
, and
thic
k ro
ot s
yste
m b
inds
the
soil
whi
ch
mak
es i
t ve
ry d
iffic
ult
to d
islo
dge,
and
ext
rem
ely
tole
rant
to
drou
ght.
• A
s st
rong
or
stro
nger
tha
n th
ose
of m
any
hard
woo
d sp
ecie
s,
vetiv
er r
oots
hav
e ve
ry h
igh
tens
ile s
tren
gth
that
has
bee
n pr
oven
pos
itive
for
roo
t rei
nfor
cem
ent i
n st
eep
slop
es.
• T
hese
roo
ts h
ave
a m
ean
test
ed t
ensi
le s
tren
gth
of a
bout
75
Meg
a Pa
scal
(M
Pa),
whi
ch i
s eq
uiva
lent
to
1/6
of m
ild s
teel
re
info
rcem
ent
and
a sh
ear
stre
ngth
inc
rem
ent
of 3
9% a
t a
30
dept
h of
0.5
m (
1.5
feet
).•
Vet
iver
roo
ts c
an p
enet
rate
a c
ompa
cted
soi
l pr
ofile
suc
h as
har
dpan
and
blo
cky
clay
pan
com
mon
in
trop
ical
soi
ls,
prov
idin
g a
good
anc
hor
for
fill a
nd to
psoi
l.•
Whe
n pl
ante
d cl
osel
y to
geth
er,
vetiv
er p
lant
s fo
rm d
ense
he
dges
tha
t re
duce
flow
vel
ocity
, sp
read
and
div
ert
runo
ff
wat
er,
and
crea
te a
ver
y ef
fect
ive
filte
r th
at c
ontr
ols
eros
ion.
T
he h
edge
s sl
ow d
own
the
flow
and
spr
eads
it
out,
allo
win
g m
ore
time
for
wat
er to
soa
k in
to th
e gr
ound
.•
Act
ing
as a
ver
y ef
fect
ive
filte
r, ve
tiver
hed
ges
help
red
uce
the
turb
idity
of
surf
ace
run-
off.
Sin
ce n
ew r
oots
dev
elop
fro
m
node
s w
hen
buri
ed b
y tr
appe
d se
dim
ent,
vetiv
er c
ontin
ues
to
rise
with
the
new
gro
und
leve
l. Te
rrac
es f
orm
at t
he f
ace
of
Ph
oto
1: V
etiv
er fo
rms
a th
ick
and
eff
ecti
ve b
io-fi
lter
bo
th a
bov
e (u
pp
er)
and
bel
ow
gro
un
d (
low
er).
31
the
hedg
es,
this
sed
imen
t sh
ould
nev
er b
e re
mov
ed.
The
fe
rtile
sed
imen
t typ
ical
ly c
onta
ins
seed
s of
loca
l pla
nts,
whi
ch
faci
litat
es th
eir
re-e
stab
lishm
ent.
• V
etiv
er to
lera
tes e
xtre
me
clim
atic
and
env
iron
men
tal v
aria
tion,
in
clud
ing
prol
onge
d dr
ough
t, flo
odin
g an
d su
bmer
genc
e, a
nd
tem
pera
ture
ext
rem
es r
angi
ng f
rom
-14
ºC t
o 55
ºC (
7º F
to
131º
F) (
Tru
ong
et a
l, 19
96).
• T
his
gras
s re
-gro
ws
very
qui
ckly
follo
win
g dr
ough
t, fr
ost,
salt
and
othe
r ad
vers
e so
il co
nditi
ons
whe
n th
e ad
vers
e ef
fect
s ar
e re
mov
ed.
Vet
iver
dis
play
s a
high
lev
el o
f to
lera
nce
to s
oil
acid
ity,
• sa
linity
, so
dici
ty a
nd a
cid
sulf
ate
cond
ition
s (L
e va
n D
u an
d T
ruon
g, 2
003)
.
Fig
ure
1: U
pper
: pr
inci
ples
of s
lope
sta
bili
sati
on b
y ve
tive
r;
low
er:
veti
ver
root
s re
info
rcin
g th
is d
am w
all k
ept i
t fr
om b
eing
was
hed
away
by
flood
.
32
Vet
iver
is v
ery
effe
ctiv
e w
hen
plan
ted
clos
ely
in ro
ws
on th
e co
ntou
r of
slop
es. C
onto
ur li
nes
of v
etiv
er c
an s
tabi
lize
natu
ral s
lope
s, c
ut s
lope
s an
d fil
led
emba
nkm
ents
. Its
dee
p, r
igor
ous
root
sys
tem
hel
ps s
tabi
lize
the
slop
es s
truc
tura
lly w
hile
its
shoo
ts d
ispe
rse
surf
ace
run-
off,
redu
ce
eros
ion,
and
trap
sed
imen
ts to
fac
ilita
te th
e gr
owth
of
nativ
e sp
ecie
s.
Hen
gcha
ovan
ich
(199
8) a
lso
obse
rved
that
vet
iver
can
gro
w v
ertic
ally
on
slo
pes
stee
per
than
150
% (
~56º
). I
ts f
ast
grow
th a
nd r
emar
kabl
e re
info
rcem
ent
mak
e it
a be
tter
cand
idat
e fo
r sl
ope
stab
ilisa
tion
than
ot
her
plan
ts. A
noth
er le
ss o
bvio
us c
hara
cter
istic
that
set
s it
apar
t fro
m
othe
r tr
ee r
oots
is
its p
ower
of
pene
trat
ion.
It
s st
reng
th a
nd v
igou
r en
able
it to
pen
etra
te d
iffic
ult s
oil,
hard
pan,
and
rock
y la
yers
with
wea
k sp
ots.
It c
an e
ven
punc
h th
roug
h as
phal
t con
cret
e pa
vem
ent.
The
sam
e au
thor
cha
ract
eriz
es v
etiv
er ro
ots
as li
ving
soi
l nai
ls o
r 2-3
m (6
-9 fe
et)
dow
els
com
mon
ly u
sed
in ‘
hard
app
roac
h’ s
lope
sta
bilis
atio
n w
ork.
C
ombi
ned
with
its
abi
lity
to b
ecom
e qu
ickl
y es
tabl
ishe
d in
dif
ficul
t so
il co
nditi
ons,
the
se c
hara
cter
istic
s m
ake
vetiv
er m
ore
suita
ble
for
slop
e st
abili
satio
n th
an o
ther
pla
nts.
3.2
Spec
ial c
hara
cter
istic
s of
vet
iver
sui
tabl
e fo
r w
ater
dis
aste
r m
itiga
tion
To r
educ
e th
e im
pact
of
wat
er r
elat
ed d
isas
ters
suc
h as
floo
d, r
iver
ba
nk a
nd c
oast
al e
rosi
on, d
am a
nd d
ike
inst
abili
ty, v
etiv
er i
s pl
ante
d in
row
s ei
ther
par
alle
l to
or a
cros
s th
e w
ater
flow
or w
ave
dire
ctio
n. It
s ad
ditio
nal u
niqu
e ch
arac
teri
stic
s ar
e ve
ry u
sefu
l:•
Giv
en it
s ex
trao
rdin
ary
root
dep
th a
nd s
tren
gth,
mat
ure
vetiv
er
is e
xtre
mel
y re
sist
ant
to w
asho
uts
from
hig
h ve
loci
ty fl
ow.
Vet
iver
pla
nted
in n
orth
Que
ensl
and
(Aus
tral
ia)
has
with
stoo
d flo
w v
eloc
ity h
ighe
r th
an 3
.5m
/sec
(10
’/se
c) i
n ri
ver
unde
r flo
od c
ondi
tions
and
, in
sou
ther
n Q
ueen
slan
d, u
p to
5m
/sec
(1
5’/s
ec)
in a
floo
ded
drai
nage
cha
nnel
.•
Und
er s
hallo
w o
r low
vel
ocity
flow
, the
ere
ct a
nd s
tiff s
tem
s of
ve
tiver
act
as
a ba
rrie
r th
at r
educ
es fl
ow v
eloc
ity (
i.e. i
ncre
ase
hydr
aulic
res
ista
nce)
and
trap
s er
oded
sed
imen
t. In
fac
t, it
can
mai
ntai
n its
ere
ct s
tanc
e in
a fl
ow a
s de
ep a
s 0.
6-0.
8m (
24-
31”)
.•
Vet
iver
lea
ves
will
bow
und
er d
eep
and
high
vel
ocity
flow
, pr
ovid
ing
extr
a pr
otec
tion
to s
urfa
ce s
oil w
hile
red
ucin
g flo
w
velo
city
.
33
• W
hen
plan
ted
on w
ater
-ret
aini
ng s
truc
ture
s su
ch a
s da
ms
or
dike
s, v
etiv
er h
edge
row
s hel
p re
duce
the
flow
vel
ocity
, dec
reas
e w
ave
run-
up (
lap-
eros
ion)
, ov
er-t
oppi
ng,
and
ultim
atel
y th
e vo
lum
e of
wat
er t
hat
flow
s in
to t
he a
rea
prot
ecte
d by
the
se
stru
ctur
es.
The
se
hedg
erow
s al
so
help
re
duce
so
-cal
led
retr
ogre
ssiv
e er
osio
n th
at o
ften
occ
urs
whe
n th
e w
ater
flow
or
wav
e re
trea
ts a
fter
it r
ises
ove
r w
ater
-ret
aini
ng s
truc
ture
s.•
As a
wet
land
pla
nt, v
etiv
er w
ithst
ands
pro
long
ed su
bmer
genc
e.
Chi
nese
res
earc
h sh
ows
that
vet
iver
can
sur
vive
lon
ger
than
tw
o m
onth
s un
der
clea
r w
ater
.
Fig
ure
2: R
oot d
iam
eter
dis
trib
utio
n
3.3
Tens
ile a
nd s
hear
str
engt
h of
vet
iver
roo
tsH
engc
haov
anic
h an
d N
ilaw
eera
(19
96)
show
that
the
tens
ile s
tren
gth
of v
etiv
er ro
ots
incr
ease
s w
ith th
e re
duct
ion
in ro
ot d
iam
eter
, im
plyi
ng
that
str
onge
r, fin
e ro
ots
prov
ide
grea
ter
resi
stan
ce t
han
thic
ker
root
s.
The
ten
sile
str
engt
h of
vet
iver
roo
ts v
arie
s be
twee
n 40
-180
MPa
in
the
ran
ge o
f ro
ot d
iam
eter
bet
wee
n 0.
2-2.
2 m
m (
.008
-.08
”).
The
m
ean
desi
gn t
ensi
le s
tren
gth
is a
bout
75
MPa
at
0.7-
0.8
mm
(.0
3”)
root
dia
met
er,
whi
ch i
s th
e m
ost
com
mon
siz
e of
vet
iver
roo
ts,
and
equi
vale
nt to
app
roxi
mat
ely
one
sixt
h of
mild
ste
el. T
here
fore
, vet
iver
ro
ots
are
as s
tron
g or
eve
n st
rong
er t
han
thos
e of
man
y ha
rdw
ood
34
spec
ies
that
hav
e be
en p
rove
n po
sitiv
e fo
r slo
pe re
info
rcem
ent -
figu
re
2 an
d ta
ble
4.
Tabl
e 4:
Ten
sile
str
engt
h of
som
e pl
ant
root
s.
Fig
ure
3: S
hear
str
engt
h of
vet
iver
roo
ts
Bot
anic
al n
ame
Com
mon
nam
eT
ensi
le s
tren
gth
(MP
a)Sa
lix s
ppW
illow
9-36
Pop
ulus
spp
Popl
ars
5-38
Aln
us s
ppA
lder
s4-
74
Pse
udot
suga
spp
Dou
glas
fir
19-6
1
Ace
r sa
char
inum
Silv
er m
aple
15-3
0
Tsug
a he
tero
phyl
iaW
este
rn h
emlo
ck27
Vacc
inum
spp
Huc
kleb
erry
16
Hor
deum
vul
gare
Bar
ley
15
-31
Gra
ss, F
orbs
2-
20
Mos
s2-
7kPa
Chr
ysop
ogon
zi
zani
oide
sV
etiv
er g
rass
40-1
20 (
aver
age
75)
35
In a
soi
l blo
ck s
hear
test
, Hen
gcha
ovan
ich
and
Nila
wee
ra (
1996
) al
so
foun
d th
at r
oot p
enet
ratio
n of
a tw
o-ye
ar-o
ld v
etiv
er h
edge
with
15c
m
(6”)
pla
nt s
paci
ng c
an in
crea
se.
In a
soi
l blo
ck s
hear
test
, Hen
gcha
ovan
ich
and
Nila
wee
ra (
1996
) al
so f
ound
that
roo
t pen
etra
tion
of a
two-
year
-old
Vet
iver
hed
ge w
ith
15cm
(6”
) pl
ant s
paci
ng c
an in
crea
se th
e sh
ear
stre
ngth
of
soil
in
adja
cent
50
cm (
20“)
wid
e st
rip
by 9
0% a
t 0.2
5 m
(10
”) d
epth
. The
in
crea
se w
as 3
9% a
t 0.5
0 m
(1.
5’)
dept
h an
d gr
adua
lly r
educ
ed
to 1
2.5%
at o
ne m
eter
(3’
) de
pth.
Mor
eove
r, ve
tiver
’s d
ense
and
m
assi
ve r
oot s
yste
m o
ffer
s be
tter
shea
r st
reng
th in
crea
se p
er u
nit
fibre
con
cent
ratio
n (6
-10
kPa/
kg o
f ro
ot p
er c
ubic
met
er o
f so
il)
com
pare
d to
3.2
-3.7
kPa
/kg
for
tree
roo
ts (
Fig.
3). T
he a
utho
rs
expl
aine
d th
at w
hen
a pl
ant r
oot p
enet
rate
s ac
ross
a p
oten
tial s
hear
su
rfac
e in
a s
oil p
rofil
e, th
e di
stor
tion
of th
e sh
ear
zone
dev
elop
s te
nsio
n in
the
root
; the
com
pone
nt o
f th
is te
nsio
n ta
ngen
tial t
o sh
ear
zone
dir
ectly
res
ists
she
ar, w
hile
the
norm
al c
ompo
nent
incr
ease
s th
e co
nfini
ng p
ress
ure
on th
e sh
ear
plan
e.
Tabl
e 5:
Dia
met
er a
nd t
ensi
le r
oot
stre
ngth
of
vari
ous
herb
s.
Che
ng e
t al (
2003
) sup
plem
ente
d D
iti H
engc
haov
anic
h’s
root
str
engt
h re
sear
ch b
y on
duct
ing
furt
her t
ests
on
othe
r gra
sses
. Tab
le 5
. Alth
ough
ve
tiver
has
the
sec
ond
fines
t ro
ots,
its
ten
sile
str
engt
h is
alm
ost
thre
e
Gra
ssM
ean
diam
eter
of
roo
ts (
mm
)M
ean
tens
ile
stre
ngth
(M
Pa)
Lat
e Ju
ncel
lus
0.38
±0.4
324
.50±
4.2
Dal
lis g
rass
0.92
±0.2
819
.74±
3.00
Whi
te C
love
r0.
91±0
.11
24.6
4±3.
36V
ET
IVE
R G
RA
SS0.
66±0
.32
85.1
0±31
.2
Com
mon
Cen
tiped
e gr
ass
0.66
±0.0
527
.30±
1.74
Bah
ia g
rass
0.73
±0.0
719
.23±
3.59
Man
ila g
rass
0.77
±0.6
717
.55±
2.85
Ber
mud
a gr
ass
0.99
±0.1
713
.45±
2.18
36
times
hig
her
than
all
pla
nts
test
ed.
3.4
Hyd
raul
ic c
hara
cter
istic
sW
hen
plan
ted
in r
ows,
vet
iver
pla
nts
form
thi
ck h
edge
s; t
heir
stif
f st
ems
allo
w th
ese
hedg
es to
sta
nd u
p at
leas
t 0.6
-0.8
m (2
-2.6
’), f
orm
ing
a liv
ing
barr
ier
to s
low
and
spr
ead
runo
ff w
ater
. Pr
oper
ly p
lann
ed,
thes
e he
dges
are
ver
y ef
fect
ive
stru
ctur
es th
at s
prea
d an
d di
vert
runo
ff
wat
er t
o st
able
are
as o
r pr
oper
dra
ins
for
safe
dis
posa
l. Fl
ume
test
s co
nduc
ted
at t
he U
nive
rsity
of
Sout
hern
Que
ensl
and
to s
tudy
the
de
sign
and
inc
orpo
ratio
n of
vet
iver
hed
ges
into
str
ip-c
ropp
ing
layo
ut
for
flood
miti
gatio
n co
nfirm
ed th
e hy
drau
lic c
hara
cter
istic
s of
vet
iver
he
dges
und
er d
eep
flow
s. F
igur
e 4.
The
hed
ges
succ
essf
ully
red
uced
flo
od v
eloc
ity a
nd l
imite
d so
il m
ovem
ent;
fallo
w s
trip
s su
ffer
ed v
ery
little
ero
sion
, an
d a
youn
g so
rghu
m c
rop
was
com
plet
ely
prot
ecte
d fr
om fl
ood
dam
age
(Dal
ton
et a
l, 19
96).
Fig
ure
4: H
ydra
ulic
mod
el o
f flo
odin
g th
roug
h ve
tiver
hed
ges
Whe
re:
q =
dis
char
ge p
er u
nit w
idth
y
= d
epth
of
flow
y
1 = d
epth
ups
trea
m
S
o =
lan
d sl
ope
S f =
ene
rgy
slop
e
N
F =
the
Frou
de n
umbe
r of
flow
37
3.5
Por
e w
ater
pre
ssur
eV
eget
atio
n co
ver
on
slop
ing
land
s in
crea
ses
wat
er
infil
trat
ion.
C
once
rns
have
bee
n ra
ised
tha
t th
e ex
tra
wat
er w
ill i
ncre
ase
pore
w
ater
pre
ssur
e in
the
soil
and
lead
to s
lope
inst
abili
ty. H
owev
er, fi
eld
obse
rvat
ions
act
ually
sho
w i
mpr
ovem
ents
. Fi
rst,
plan
ted
on c
onto
ur
lines
or
mod
ified
pat
tern
s of
lin
es t
hat
trap
and
spr
ead
runo
ff w
ater
on
the
slo
pe,
vetiv
er’s
ext
ensi
ve r
oot
syst
em a
nd fl
ow t
houg
h ef
fect
di
stri
bute
s su
rplu
s w
ater
mor
e ev
enly
and
gra
dual
ly a
nd h
elps
pre
vent
lo
caliz
ed a
ccum
ulat
ion.
Seco
nd,
the
likel
y in
crea
se i
n in
filtr
atio
n is
off
set
by a
hig
her
and
grad
ual
rate
of
soil
wat
er d
eple
tion
by t
he g
rass
. R
esea
rch
in s
oil
moi
stur
e co
mpe
titio
n in
cro
ps in
Aus
tral
ia (
Dal
ton
et a
l, 19
96)
show
s th
at,
unde
r lo
w r
ainf
all
cond
ition
s, t
his
depl
etio
n w
ould
red
uce
soil
moi
stur
e up
to
1.5m
(4.
5’)
from
the
hed
ges.
T
his
incr
ease
s w
ater
in
filtr
atio
n in
tha
t zo
ne,
lead
ing
to t
he r
educ
tion
of r
unof
f w
ater
and
er
osio
n ra
te.
From
a g
eote
chni
cal
pers
pect
ive,
the
se c
ondi
tions
hel
p m
aint
ain
slop
e st
abili
ty. O
n st
eep
(30-
60º)
slo
pes,
the
spa
ce b
etw
een
row
s at 1
m (3
’) V
I (V
ertic
al In
terv
al) i
s ver
y cl
ose.
The
refo
re, m
oist
ure
depl
etio
n w
ould
be
grea
ter
and
furt
her
impr
ove
the
slop
e st
abili
satio
n pr
oces
s. H
owev
er, t
o re
duce
this
pot
entia
lly h
arm
ful e
ffec
t of
vetiv
er
on s
teep
slo
pes
in v
ery
high
rain
fall
area
s, a
s a
prec
autio
nary
mea
sure
, ve
tiver
hed
ges
coul
d be
pla
nted
on
a gr
adie
nt o
f ab
out
0.5%
as
in
grad
ed c
onto
ur t
erra
ces
to d
iver
t th
e ex
tra
wat
er t
o st
able
dra
inag
e ou
tlets
(H
engc
haov
anic
h, 1
998)
.
3.6
App
licat
ions
of V
S fo
r sl
ope
stab
iliza
tion
rela
ted
to n
atur
al
disa
ster
miti
gatio
n an
d in
fras
truc
ture
pro
tect
ion
Giv
en i
ts u
niqu
e ch
arac
teri
stic
s, v
etiv
er g
ener
ally
is
very
use
ful
in
cont
rolli
ng e
rosi
on o
n bo
th c
ut a
nd fi
ll ba
tters
and
on
othe
r sl
opes
as
soci
ated
with
roa
d co
nstr
uctio
n, a
nd p
artic
ular
ly e
ffec
tive
in h
ighl
y er
odib
le a
nd d
ispe
rsib
le s
oils
, suc
h as
sod
ic, a
lkal
ine,
aci
dic
and
acid
su
lfat
e so
ils.
Vet
iver
pl
antin
g ha
s be
en
very
ef
fect
ive
in
eros
ion
cont
rol
or
stab
ilisa
tion
in th
e fo
llow
ing
cond
ition
s:•
Slop
e st
abili
satio
n al
ong
high
way
s an
d ra
ilway
s.
Esp
ecia
lly
effe
ctiv
e al
ong
mou
ntai
nous
rura
l roa
ds, w
here
the
com
mun
ity
38
lack
s su
ffici
ent f
undi
ng f
or r
oad
slop
e st
abili
satio
n an
d w
here
it
ofte
n ta
kes
part
in r
oad
cons
truc
tion.
• D
ike
and
dam
bat
ter s
tabi
lisat
ion,
redu
ctio
n of
can
al, r
iver
bank
an
d co
asta
l ero
sion
, and
pro
tect
ion
of h
ard
stru
ctur
es th
emse
lves
(e
.g. r
ock
ripr
ap, c
oncr
ete
reta
inin
g w
alls
, gab
ions
, etc
.).
• Sl
ope
abov
e cu
lver
t inl
ets
and
outle
ts (
culv
erts
, abu
tmen
ts).
• In
terf
ace
betw
een
cem
ent a
nd ro
ck s
truc
ture
s an
d er
odib
le s
oil
surf
aces
.•
As
a fil
ter
stri
p to
trap
sed
imen
t at c
ulve
rt in
lets
.•
To r
educ
e en
ergy
at c
ulve
rt o
utle
ts.
• To
sta
biliz
e gu
lly h
ead
eros
ion,
whe
n ve
tiver
hed
ges
are
plan
ted
on c
onto
ur li
nes
abov
e gu
lly h
eads
. •
To e
limin
ate
eros
ion
caus
ed b
y w
ave
actio
n, b
y pl
antin
g a
few
ro
ws
of v
etiv
er o
n th
e ed
ge o
f the
hig
h w
ater
mar
k on
big
farm
da
m b
atte
rs o
r ri
ver
bank
s.•
In f
ores
t pla
ntat
ions
, to
stab
ilize
the
shou
lder
s of
acc
ess
road
s on
ver
y st
eep
slop
es a
s w
ell a
s th
e gu
llies
(log
ging
pat
hs/w
ays)
th
at d
evel
op f
ollo
win
g ha
rves
ts.
Giv
en i
ts u
niqu
e ch
arac
teri
stic
s, v
etiv
er e
ffec
tivel
y co
ntro
ls w
ater
di
sast
ers
such
as
flood
, co
asta
l an
d ri
verb
ank
eros
ion,
dam
and
dik
e er
osio
n, a
nd g
ener
al i
nsta
bilit
y.
It a
lso
prot
ects
bri
dges
, cu
lver
t ab
utm
ents
and
int
erfa
ces
betw
een
conc
rete
/roc
k st
ruct
ures
and
soi
l. V
etiv
er i
s pa
rtic
ular
ly e
ffec
tive
in a
reas
whe
re t
he e
mba
nkm
ent
fill
is h
ighl
y er
odib
le a
nd d
ispe
rsib
le, s
uch
as s
odic
, alk
alin
e, a
nd a
cidi
c (i
nclu
ding
aci
d su
lpha
te)
soils
.
3.7
Adv
anta
ges
and
disa
dvan
tage
s of
Vet
iver
Sys
tem
Adv
anta
ges:
• T
he m
ajor
adv
anta
ge o
f V
S ov
er c
onve
ntio
nal
engi
neer
ing
mea
sure
s is
its
low
cos
t and
long
evity
. For
slo
pe s
tabi
lisat
ion
in C
hina
, for
exa
mpl
e, s
avin
gs a
re in
the
orde
r of 8
5-90
% (X
ie,
1997
and
Xia
et a
l, 19
99).
In
Aus
tral
ia, t
he c
ost a
dvan
tage
of
VS
over
con
vent
iona
l eng
inee
ring
met
hods
ran
ges
from
64%
to
72%
, de
pend
ing
on t
he m
etho
d us
ed (
Bra
ken
and
Tru
ong
2001
). I
n su
mm
ary,
its
max
imum
cos
t is
onl
y 30
% o
f th
e co
st o
f tr
aditi
onal
mea
sure
s. I
n ad
ditio
n an
nual
mai
nten
ance
co
sts
are
sign
ifica
ntly
red
uced
onc
e ve
tiver
hed
gero
ws
are
esta
blis
hed
39
• A
s w
ith o
ther
bio
engi
neer
ing
tech
nolo
gies
, V
S is
a n
atur
al,
envi
ronm
enta
lly-f
rien
dly
way
to
cont
rol
eros
ion
cont
rol
and
stab
ilize
land
that
‘sof
tens
’ the
har
sh lo
ok o
f con
vent
iona
l rig
id
engi
neer
ing
mea
sure
s su
ch a
s co
ncre
te a
nd r
ock
stru
ctur
es.
Thi
s is
par
ticul
arly
im
port
ant
in u
rban
and
sem
i-ru
ral
area
s w
here
loc
al c
omm
uniti
es d
ecry
the
uns
ight
ly a
ppea
ranc
e of
in
fras
truc
ture
dev
elop
men
t. •
Lon
g-te
rm
mai
nten
ance
co
sts
are
low
. In
co
ntra
st
to
conv
entio
nal
engi
neer
ing
stru
ctur
es,
gree
n te
chno
logy
im
prov
es a
s th
e ve
geta
tive
cove
r m
atur
es.
VS
requ
ires
a
plan
ned
mai
nten
ance
pro
gram
in th
e fir
st tw
o ye
ars;
how
ever
, on
ce e
stab
lishe
d, i
t is
vir
tual
ly m
aint
enan
ce-f
ree.
The
refo
re,
the
use
of v
etiv
er i
s pa
rtic
ular
ly w
ell
suite
d to
rem
ote
area
s w
here
mai
nten
ance
is c
ostly
and
dif
ficul
t.•
Vet
iver
is
very
eff
ectiv
e in
poo
r an
d hi
ghly
ero
dibl
e an
d di
sper
sibl
e so
ils.
• V
S is
par
ticul
arly
wel
l su
ited
to a
reas
with
low
-cos
t la
bour
fo
rces
.•
Vet
iver
hed
ges
are
a na
tura
l, so
ft b
ioen
gine
erin
g te
chni
que,
an
eco-
frie
ndly
alte
rnat
ive
to r
igid
or
hard
str
uctu
res.
Dis
adva
ntag
es:
• T
he m
ain
disa
dvan
tage
of
VS
appl
icat
ions
is
the
vetiv
er’s
in
tole
ranc
e to
sha
ding
, pa
rtic
ular
ly w
ithin
the
est
ablis
hmen
t ph
ase.
Par
tial s
hadi
ng st
unts
its g
row
th; s
igni
fican
t sha
ding
can
el
imin
ate
it in
the
long
term
by
redu
cing
its
abili
ty to
com
pete
w
ith m
ore
shad
e-to
lera
nt s
peci
es.
How
ever
, th
is w
eakn
ess
coul
d be
des
irab
le i
n si
tuat
ions
whe
re i
nitia
l st
abili
satio
n re
quir
es
a pi
onee
r to
im
prov
e th
e ab
ility
of
th
e m
icro
-en
viro
nmen
t to
hos
t th
e vo
lunt
ary
or p
lann
ed i
ntro
duct
ion
of
nativ
e en
dem
ic s
peci
es.
• T
he V
etiv
er S
yste
m is
eff
ectiv
e on
ly w
hen
the
plan
ts a
re w
ell
esta
blis
hed.
Eff
ectiv
e pl
anni
ng re
quir
es a
n in
itial
est
ablis
hmen
t pe
riod
of
abou
t 2-3
mon
ths
in w
arm
wea
ther
and
4-6
mon
ths
in c
oole
r tim
es.
Thi
s de
lay
can
be a
ccom
mod
ated
by
plan
ting
earl
y, a
nd in
the
dry
seas
on.
• V
etiv
er h
edge
s ar
e fu
lly e
ffec
tive
only
whe
n pl
ants
for
m
clos
ed h
edge
row
s. G
aps
betw
een
clum
ps s
houl
d be
tim
ely
re-
plan
ted.
40
• It
is
diffi
cult
to p
lant
and
wat
er v
eget
atio
n on
ver
y hi
gh o
r st
eep
slop
es.
• V
etiv
er
requ
ires
pr
otec
tion
from
liv
esto
ck
duri
ng
its
esta
blis
hmen
t pha
se.
Bas
ed o
n th
ese
cons
ider
atio
ns,
the
adva
ntag
es o
f us
ing
VS
as a
bi
oeng
inee
ring
too
l ou
twei
gh i
ts d
isad
vant
ages
, pa
rtic
ular
ly w
hen
vetiv
er is
use
d as
a p
ione
er s
peci
es.
Wor
ldw
ide
evid
ence
sup
port
s th
e us
e of
VS
to s
tabi
lize
emba
nkm
ents
. V
etiv
er h
as b
een
used
suc
cess
fully
to
stab
ilize
roa
dsid
es,
amon
gst
othe
rs,
in A
ustr
alia
, B
razi
l, C
entr
al A
mer
ica,
Chi
na,
Eth
iopi
a, F
iji,
Indi
a, I
taly
, M
adag
asca
r, M
alay
sia,
Phi
lippi
nes,
Sou
th A
fric
a, S
ri
Lan
ka, V
enez
uela
, Vie
tnam
, and
the
Wes
t Ind
ies.
Use
d in
con
junc
tion
with
geo
tech
nica
l ap
plic
atio
ns,
vetiv
er h
as b
een
used
to
stab
ilize
em
bank
men
ts in
Nep
al a
nd S
outh
Afr
ica.
3.8
Com
bina
tion
with
oth
er ty
pes
of r
emed
yV
etiv
er is
eff
ectiv
e bo
th b
y its
elf
and
com
bine
d w
ith o
ther
trad
ition
al
met
hods
. Fo
r ex
ampl
e, o
n a
give
n se
ctio
n of
riv
erba
nk o
r di
ke,
rock
or
con
cret
e ri
prap
can
rei
nfor
ce t
he u
nder
wat
er p
art,
and
vetiv
er c
an
rein
forc
e th
e to
p pa
rt.
Thi
s ta
ndem
app
licat
ion
crea
tes
a fa
ctor
of
stab
ility
and
sec
urity
(w
hich
are
not
alw
ays
true
and
/or
nece
ssar
y).
Vet
iver
can
als
o be
pla
nted
with
bam
boo,
a p
lant
tra
ditio
nally
use
d to
pro
tect
riv
erba
nks.
Exp
erie
nce
show
s th
at u
sing
onl
y ba
mbo
o ha
s se
vera
l dr
awba
cks
that
can
be
over
com
e by
add
ing
vetiv
er. A
s no
ted
prev
ious
ly w
ashe
d ou
t bam
boo
can
crea
te s
erio
us p
robl
ems
on r
iver
s w
here
ther
e ar
e lo
w le
vel b
ridg
e cr
ossi
ng.
3.9
Com
pute
r m
odel
ling
Soft
war
e de
velo
ped
by P
rati
Am
ati,
Srl
(200
6) i
n co
llabo
ratio
n w
ith
the
Uni
vers
ity o
f M
ilan
dete
rmin
es th
e pe
rcen
tage
or
amou
nt o
f sh
ear
stre
ngth
that
vet
iver
root
s add
to v
ario
us so
ils u
nder
vet
iver
hed
gero
ws.
T
he s
oftw
are
help
s to
ass
ess
vetiv
er’s
con
trib
utio
n to
sta
biliz
e st
eep
batte
rs,
part
icul
arly
ear
then
lev
ees.
Und
er a
vera
ge s
oil
and
slop
e co
nditi
ons,
the
ins
talla
tion
of v
etiv
er w
ill i
ncre
ase
slop
e st
abili
ty b
y ab
out 4
0%.
Usi
ng
the
soft
war
e re
quir
es
the
oper
ator
to
en
ter
the
follo
win
g
41
geot
echn
ical
par
amet
ers
rela
ted
to a
par
ticul
ar s
lope
site
:•
Soil
type
.•
Slop
e gr
adie
nt.
• M
axim
um m
oist
ure
cont
ent.
• So
il co
hesi
on a
t a m
inim
um.
The
pro
gram
pro
vide
s th
e re
quir
ed n
umbe
r of
pla
nts
per
squa
re m
eter
an
d th
e di
stan
ce b
etw
een
row
s, c
onsi
deri
ng t
he s
lope
gra
dien
t. F
or
exam
ple:
• a
30°
slop
e re
quir
es s
ix p
lant
s pe
r sq
uare
met
er (
i.e.
7-10
pl
ants
per
line
al m
eter
) an
d a
dist
ance
bet
wee
n ro
ws
of a
bout
1.
7 m
(5.
7’).
• a
45°
slop
e re
quir
es 1
0 pl
ants
per
squ
are
met
er (
i.e.
7-10
pl
ants
per
line
al m
eter
) an
d a
dist
ance
bet
wee
n ro
ws
of a
bout
1
m (
3’).
4. A
PP
RO
PR
IAT
E D
ESI
GN
S A
ND
TE
CH
NIQ
UE
S
4.1
Pre
caut
ions
VS
is a
new
tec
hnol
ogy.
As
a ne
w t
echn
olog
y, i
ts p
rinc
iple
s m
ust
be
stud
ied
and
appl
ied
appr
opri
atel
y fo
r be
st r
esul
ts.
Failu
re t
o fo
llow
ba
sic
tene
ts w
ill re
sult
in d
isap
poin
tmen
t, or
wor
se, a
dver
se re
sults
. As
a so
il co
nser
vatio
n te
chni
que
and,
mor
e re
cent
ly, a
bio
engi
neer
ing
tool
, th
e ef
fect
ive
appl
icat
ion
of V
S re
quir
es a
n un
ders
tand
ing
of b
iolo
gy,
soil
scie
nce,
hy
drau
lics,
hy
drol
ogy,
an
d ge
otec
hnic
al
prin
cipl
es.
The
refo
re, f
or m
ediu
m t
o la
rge-
scal
e pr
ojec
ts t
hat
invo
lve
sign
ifica
nt
engi
neer
ing
desi
gn a
nd c
onst
ruct
ion,
VS
is b
est
impl
emen
ted
by
expe
rien
ced
spec
ialis
ts
rath
er
than
by
lo
cal
peop
le
them
selv
es.
How
ever
, kn
owle
dge
of p
artic
ipat
ory
appr
oach
es a
nd c
omm
unity
-ba
sed
man
agem
ent
are
also
ver
y im
port
ant.
Thu
s, t
he t
echn
olog
y sh
ould
be
desi
gned
and
impl
emen
ted
by e
xper
ts in
vet
iver
app
licat
ion,
as
soci
ated
with
an
agro
nom
ist
and
a ge
otec
hnic
al e
ngin
eer,
with
as
sist
ance
fro
m lo
cal f
arm
ers.
Add
ition
ally
, alth
ough
it is
a g
rass
, vet
iver
act
s m
ore
like
a tr
ee, g
iven
its
ext
ensi
ve a
nd d
eep
root
sys
tem
. To
add
to t
he c
onfu
sion
, VS
can
expl
oit
vetiv
er’s
dif
fere
nt c
hara
cter
istic
s fo
r di
ffer
ent
appl
icat
ions
. Fo
r exa
mpl
e, it
s de
ep ro
ots
stab
ilize
land
, its
thic
k le
aves
spr
ead
wat
er
42
and
trap
sed
imen
t, an
d its
ext
raor
dina
ry to
lera
nce
to h
ostil
e co
nditi
ons
allo
ws
it to
reh
abili
tate
soi
l and
wat
er c
onta
min
atio
n.
Failu
res
of V
S ca
n, i
n m
ost
case
s, b
e at
trib
uted
to
bad
appl
icat
ions
ra
ther
tha
n th
e gr
ass
itsel
f or
the
rec
omm
ende
d te
chno
logy
. Fo
r ex
ampl
e, i
n on
e ca
se, v
etiv
er w
as u
sed
in t
he P
hilip
pine
s to
sta
biliz
e ba
tters
on
a ne
w h
ighw
ay.
The
res
ults
wer
e ve
ry d
isap
poin
ting
and
failu
res
resu
lted.
It
late
r su
rfac
ed t
hat
the
engi
neer
s w
ho s
peci
fied
the
VS,
the
nur
sery
tha
t su
pplie
d th
e pl
antin
g m
ater
ial,
and
the
field
su
perv
isor
s an
d la
bour
ers
who
pla
nted
the
vet
iver
, la
cked
pre
viou
s ex
peri
ence
or
trai
ning
in th
e us
e of
VS
for
stee
p sl
opes
sta
bilis
atio
n.
Exp
erie
nce
in V
ietn
am s
how
s th
at v
etiv
er h
as b
een
very
suc
cess
ful
empl
oyed
whe
n it
is a
pplie
d co
rrec
tly.
Not
sur
pris
ingl
y, i
mpr
oper
ap
plic
atio
ns
may
fa
il. A
pplic
atio
ns
in
the
Cen
tral
H
ighl
ands
of
V
ietn
am sh
ow th
at v
etiv
er h
as e
ffec
tivel
y pr
otec
ted
road
em
bank
men
ts.
How
ever
, am
ong
mas
s ap
plic
atio
ns o
n ve
ry h
igh
and
stee
p sl
opes
w
ithou
t be
nche
s al
ong
the
Ho
Chi
Min
h H
ighw
ay,
failu
res
have
re
sulte
d. I
n sh
ort,
to e
nsur
e su
cces
s, d
ecis
ion
mak
ers,
des
igne
rs
and
engi
neer
s w
ho p
lan
to u
se t
he V
etiv
er S
yste
m f
or i
nfra
stru
ctur
e pr
otec
tion
shou
ld ta
ke th
e fo
llow
ing
prec
autio
ns:
Tech
nica
l pre
caut
ions
:•
To e
nsur
e su
cces
s, th
e de
sign
sho
uld
be c
reat
ed o
r ch
ecke
d
by
trai
ned
peop
le.
• A
t le
ast
for
the
first
few
mon
ths
whi
le t
he p
lant
is
beco
min
g es
tabl
ishe
d, th
e si
te sh
ould
be
inte
rnal
ly st
able
aga
inst
pos
sibl
e fa
ilure
. V
etiv
er m
anif
ests
its
ful
l ab
ilitie
s w
hen
mat
ure,
and
sl
opes
may
fai
l dur
ing
the
inte
rven
ing
peri
od.
• V
S is
app
licab
le o
nly
to e
arth
en s
lope
s w
ith g
radi
ents
tha
t sh
ould
nev
er e
xcee
d 45
-50º
• V
etiv
er g
row
s po
orly
in th
e sh
ade,
so
plan
ting
it di
rect
ly u
nder
a
brid
ge o
r ot
her
shel
ter
shou
ld b
e av
oide
d.
Pre
caut
ions
for
dec
isio
n-m
akin
g, p
lann
ing
and
orga
nisa
tion:
• T
imin
g: p
lann
ing
shou
ld c
onsi
der
the
seas
ons
and
the
time
it
take
s to
gro
w p
lant
ing
mat
eria
ls.
• M
aint
enan
ce a
nd r
epai
r: a
t an
ear
ly s
tage
, th
ere
is a
per
iod
43
duri
ng w
hich
vet
iver
is
not
yet
effe
ctiv
e. P
lann
ing
and
bud-
getin
g sh
ould
ant
icip
ate
repl
acem
ent o
f so
me.
• Pr
ocur
emen
t: A
ll in
puts
can
and
sho
uld
be p
rocu
red
loca
lly
(lab
our,
man
ure,
pla
ntin
g m
ater
ials
, m
aint
enan
ce c
ontr
acts
).
Em
ploy
men
t op
port
unity
pro
vide
s an
inc
entiv
e fo
r th
e lo
cal
com
mun
ity to
pro
tect
the
plan
ts d
urin
g th
eir
infa
ncy
and
ado-
lesc
ence
, and
to m
aint
ain
the
qual
ity a
nd s
usta
inab
ility
of
the
wor
ks.
• C
omm
unity
inv
olve
men
t: A
s m
uch
as p
ossi
ble,
loc
al c
om-
mun
ities
sho
uld
be in
clud
ed in
the
desi
gn, m
ater
ials
pro
cure
-m
ent,
and
mai
nten
ance
sta
ges.
Con
trac
ts w
ith l
ocal
peo
ple
shou
ld b
e dr
afte
d, g
over
ning
nur
seri
es, q
ualit
y/qu
antit
y sp
ec-
ifica
tions
, and
mai
nten
ance
/pro
tect
ion.
• T
imin
g: D
ecis
ion
mak
ers
shou
ld b
e re
ady
to in
nova
te a
nd to
co
nsid
er V
S in
the
ir p
lann
ing
and
budg
etin
g. F
or t
hat,
they
ne
ed i
ncen
tives
to
incl
ude
such
cos
t-ef
fect
ive
met
hods
in
thei
r pl
ans,
just
as
they
hav
e in
cent
ives
- j
ustifi
ed o
r no
t - to
ad
opt m
ore
expe
nsiv
e co
nven
tiona
l met
hods
.•
Inte
grat
ion:
Po
licy
mak
ers
shou
ld r
ecom
men
d V
etiv
er S
ys-
tem
as
part
of
a co
mpr
ehen
sive
app
roac
h to
inf
rast
ruct
ure
prot
ectio
n, a
pplie
d on
a s
cale
lar
ge e
noug
h to
ens
ure
a ta
n-gi
ble
incr
ease
in e
xper
tise
and
a gr
adua
l, sp
read
ing
effe
ct. V
S sh
ould
not
be
rega
rded
mer
ely
as a
fix
for
com
prom
ised
loca
l si
tes,
des
pite
its
abi
lity
to p
rovi
de a
con
cise
and
im
med
iate
ef
fect
.
4.2
Pla
ntin
g tim
eT
he i
nsta
llatio
n of
vet
iver
pla
nts
is c
ritic
al t
o th
e su
cces
s an
d th
e co
st o
f th
e pr
ojec
t. P
lant
ing
in d
ry s
easo
n w
ill r
equi
re e
xten
sive
and
ex
pens
ive
wat
erin
g. E
xper
ienc
e in
Cen
tral
Vie
tnam
sho
ws
that
dai
ly
or tw
ice
daily
wat
erin
g is
requ
ired
to e
stab
lish
vetiv
er in
the
extr
emel
y ha
rsh
cond
ition
s in
san
d du
nes.
Gro
wth
is
stun
ted
in t
he a
bsen
ce o
f w
ater
ing.
Sin
ce i
t is
dif
ficul
t to
sel
ect
the
best
tim
e to
pla
nt m
asse
s of
pla
nt m
ater
ial
on c
ut s
lope
s al
ong
the
Ho
Chi
Min
h H
ighw
ay,
for
exam
ple,
mec
hani
cal
wat
erin
g is
req
uire
d da
ily f
or t
he fi
rst
few
m
onth
s.
Vet
iver
gen
eral
ly n
eeds
3-4
mon
ths
to b
ecom
e es
tabl
ishe
d, s
omet
imes
44
up t
o 5-
6 m
onth
s un
der
adve
rse
cond
ition
s. S
ince
vet
iver
is
fully
ef
fect
ive
at t
he a
ge o
f 9-
10 m
onth
s, m
ass
plan
tings
sho
uld
occu
r at
the
beg
inni
ng o
f th
e ra
iny
seas
on (
i.e.
nurs
ery
deve
lopm
ent
and
prod
uctio
n of
pla
nt m
ater
ial
shou
ld b
e pl
anne
d to
mee
t th
at m
ass
plan
ting
sche
dule
).
Part
icul
arly
in N
orth
Vie
tnam
, it i
s po
ssib
le to
pla
nt d
urin
g th
e w
inte
r-sp
ring
per
iod.
Whe
n te
mpe
ratu
res
desc
end
low
er th
an 1
0ºC
(50
ºF)
in
Nor
th V
ietn
am, t
he g
rass
doe
s no
t gr
ow. H
owev
er, i
t ca
n su
rviv
e th
e co
ld w
eath
er a
nd r
esum
es g
row
ing
imm
edia
tely
whe
n th
e w
inte
r ra
in
star
ts a
nd th
e w
eath
er w
arm
s.
In c
entr
al V
ietn
am,
whe
re a
ir t
empe
ratu
re u
sual
ly s
tays
abo
ve 1
5ºC
(5
9ºF)
, mas
s pl
antin
g oc
curs
at t
he b
egin
ning
of s
prin
g. N
urse
ries
will
re
quir
e m
ore
care
to
ensu
re g
ood
grow
th a
nd m
ultip
licat
ion
of t
he
slip
s.
4.3
Nur
sery
The
suc
cess
of
any
proj
ect
depe
nds
on g
ood
qual
ity a
nd s
uffic
ient
nu
mbe
rs o
f ve
tiver
slip
s. L
arge
nur
seri
es g
ener
ally
are
not
req
uire
d to
pr
ovid
e su
ffici
ent p
lant
mat
eria
l. In
stea
d, in
divi
dual
farm
er h
ouse
hold
s ca
n se
t up
and
supe
rvis
e sm
all n
urse
ries
(a
few
hun
dred
squ
are
met
ers
each
). T
hey
will
be
cont
ract
ed a
nd p
aid
by th
e pr
ojec
t acc
ordi
ng to
the
num
ber
of s
lips
they
can
pro
vide
upo
n re
ques
t.
4.4
Pre
para
tion
for
vetiv
er p
lant
ing
In c
ases
whe
re m
ass
plan
ting
of v
etiv
er i
nvol
ves
the
part
icip
atio
n of
loc
al p
eopl
e, a
n ef
fect
ive
plan
ting
cam
paig
n sh
ould
inc
lude
the
fo
llow
ing
step
s:
Step
1:
Exp
erts
vis
it th
e si
tes,
and
con
duct
a s
urve
y to
ide
n-tif
y pr
oble
ms
and
desi
gn t
he a
pplic
atio
n of
the
tec
h-no
logy
;St
ep 2
: D
iscu
ss th
e pr
oble
ms
and
alte
rnat
ive
solu
tions
w
ith lo
cal p
eopl
e;
Step
3:
Use
wor
ksho
ps a
nd tr
aini
ng c
ours
es to
intr
oduc
e
th
e ne
w te
chno
logy
;St
ep 4
: O
rgan
ize
the
tria
l im
plem
enta
tion,
by
esta
blis
hing
45
nurs
erie
s,
cont
ract
ing
to
purc
hase
pl
ant
mat
eria
l, m
aint
enan
ce, e
tc.;
Step
5:
Mon
itor
the
impl
emen
tatio
n;St
ep 6
: D
iscu
ss re
sults
of t
he p
ilot,
follo
win
g w
orks
hop,
fiel
d ex
chan
ge v
isit,
etc
.;St
ep 7
: O
rgan
ize
mas
s pl
antin
g.
In c
ases
whe
re s
peci
aliz
ed c
ompa
nies
und
erta
ke t
he m
ass
plan
ting,
st
eps
1, 4
, 5
are
reco
mm
ende
d.
How
ever
, lo
cal
part
icip
atio
n is
stil
l ad
visa
ble
to r
aise
aw
aren
ess,
avo
id v
anda
lism
, an
d en
sure
tha
t th
e sl
ips
are
prot
ecte
d fr
om a
nim
als.
4.5
Lay
out s
peci
ficat
ions
4.5.
1 ‘U
plan
d’ n
atur
al s
lope
, cut
slo
pe, r
oad
batte
r, e
tc.
To s
tabi
lize
upla
nd n
atur
al s
lope
s, c
ut s
lope
s, a
nd r
oad
batte
rs,
the
follo
win
g sp
ecifi
catio
ns m
ay a
pply
:•
Ban
k sl
ope
shou
ld n
ot e
xcee
d 1(
H)
[hor
izon
tal]
:1(V
) [v
er-
tical
] or
45º
, gr
adie
nt o
f 1.
5:1
is r
ecom
men
ded.
Sha
llow
er
grad
ient
s ar
e re
com
men
ded
whe
reve
r po
ssib
le, e
spec
ially
on
erod
ible
soi
ls a
nd/o
r in
hig
h ra
infa
ll ar
eas.
• V
etiv
er s
houl
d be
pla
nted
acr
oss
the
slop
e on
app
roxi
mat
e co
ntou
r lin
es w
ith a
Ver
tical
Int
erva
l (V
I) b
etw
een
1.0-
2.0m
(3
-6’)
apa
rt, m
easu
red
dow
n th
e sl
ope.
Spa
cing
of
1.0m
(3’
) sh
ould
be
used
on
high
ly e
rodi
ble
soil,
whi
ch c
an in
crea
se u
p to
1.5
-2.0
m (
4.5-
6’)
on m
ore
sta b
le s
oil.
• T
he fi
rst r
ow s
houl
d be
pla
nted
on
the
top
edge
of
the
batte
r. T
his
row
sha
ll be
pla
nted
on
all
batte
rs t
hat
are
talle
r th
an
1.5m
(4.
5’).
• T
he b
otto
m r
ow s
houl
d be
pla
nted
at t
he b
otto
m o
f th
e ba
tter
at th
e to
e of
the
slop
e a
nd o
n cu
t bat
ter a
long
the
edge
of t
able
dr
ain.
• B
etw
een
thes
e ro
ws,
vet
iver
sho
uld
be p
lant
ed a
s sp
ecifi
ed
abov
e.•
Ben
chin
g or
ter
raci
ng 1
-3 m
(3-
9’)
in w
idth
for
eve
ry 5
-8 m
(1
5-24
’) V
I is
rec
omm
ende
d fo
r sl
opes
that
are
talle
r th
an 1
0 m
(30
’).
46
4.5.
2 R
iver
bank
s, c
oast
al e
rosi
on,
and
unst
able
wat
er r
etai
ning
st
ruct
ures
For fl
ood
miti
gatio
n an
d co
asta
l, ri
verb
ank
and
dike
/em
bank
men
t pro
-te
ctio
n, th
e fo
llow
ing
layo
ut s
peci
ficat
ions
are
rec
omm
ende
d:•
Max
imum
ban
k sl
ope
shou
ld n
ot e
xcee
d 1.
5(H
):1(
V).
Rec
-om
men
ded
bank
slo
pe is
2.5
:1.
Not
e: th
e se
a di
ke s
yste
m in
H
ai H
au (
Nam
Din
h) is
bui
lt w
ith b
ank
slop
e of
3:1
to 4
:1.
• V
etiv
er s
houl
d be
pla
nted
in tw
o di
rect
ions
:-
For
bank
sta
bilis
atio
n, v
etiv
er s
houl
d be
pla
nted
in
row
s pa
ralle
l to
flow
dir
ectio
n (h
oriz
onta
l),
on a
ppro
xim
ate
cont
our
lines
0.8
-1.0
m (
2.5-
3’)
apar
t (m
easu
red
dow
n sl
ope)
. A re
cent
layo
ut s
peci
ficat
ion
to p
rote
ct th
e se
a di
ke
syst
em in
Hai
Hau
(N
am D
inh)
incl
uded
spa
cing
bet
wee
n ro
ws
low
ered
to 0
.25
m. (
.8’)
.-
To r
educ
e flo
w v
eloc
ity, v
etiv
er s
houl
d be
pla
nted
in r
ows
norm
al (
righ
t an
gle)
to
the
flow
at
spac
ing
betw
een
row
s of
2.0
m (
6’)
for
erod
ible
soi
l an
d 4.
0m (
12’)
for
sta
ble
soil.
As
adde
d pr
otec
tion,
nor
mal
row
s ar
e pl
ante
d 1.
0m
(3’)
apa
rt o
n th
e ri
ver
dike
in Q
uang
Nga
i. •
The
firs
t ho
rizo
ntal
row
sho
uld
be p
lant
ed a
t th
e cr
est
of t
he
bank
and
the
last
row
sho
uld
be p
lant
ed a
t the
low
wat
er m
ark
of t
he b
ank.
N
ote:
sin
ce t
he w
ater
lev
el a
t so
me
loca
tions
ch
ange
s se
ason
ally
, vet
iver
can
be
plan
ted
muc
h fu
rthe
r dow
n th
e ba
nk w
hen
the
time
is r
ight
.•
Vet
iver
sho
uld
be p
lant
ed o
n th
e co
ntou
r al
ong
the
leng
th
of t
he b
ank
betw
een
the
top
and
botto
m r
ows
at t
he s
paci
ng
spec
ified
abo
ve.
• D
ue t
o hi
gh w
ater
lev
els,
bot
tom
row
s m
ay e
stab
lish
mor
e sl
owly
than
upp
er r
ows.
In
such
cas
es, t
he lo
wer
row
s sh
ould
be
pla
nted
whe
n th
e so
il is
dri
est.
Som
e V
S ap
plic
atio
ns p
ro-
tect
ant
i-sa
linity
dik
es; i
n th
ose
case
s, th
e w
ater
may
bec
ome
mor
e sa
line
at c
erta
in t
imes
of
the
year
, w
hich
may
aff
ect
the
grow
th o
f ve
tiver
. Exp
erie
nces
in
Qua
ng N
gai
show
tha
t ve
tiver
can
be
repl
aced
by
som
e lo
cal
salt-
tole
rant
var
ietie
s,
incl
udin
g th
e m
angr
ove
fern
.•
For
all a
pplic
atio
ns, V
S ca
n be
use
d in
com
bina
tion
with
oth
-er
tra
ditio
nal,
stru
ctur
al m
easu
res
such
as
rock
or
conc
rete
ri
prap
, and
ret
aini
ng w
alls
. For
exa
mpl
e, th
e lo
wer
par
t of
the
47
dike
/em
bank
men
t can
be
cove
red
by th
e co
mbi
natio
n of
roc
k ri
prap
and
geo
-tex
tile
whi
le t
he u
pper
hal
f is
pro
tect
ed w
ith
vetiv
er h
edge
row
s.
4.6
Pla
ntin
g sp
ecifi
catio
ns D
ig tr
ench
es th
at a
re a
bout
15-
20cm
(6-
8”)
deep
and
wid
e.• •
Plac
e w
ell-
root
ed p
lant
s (w
ith 2
-3 ti
llers
api
ece)
in th
e ce
ntre
of
eac
h ro
w a
t 100
-120
mm
(4-
5”)
inte
rval
s fo
r er
odib
le s
oils
, an
d at
150
mm
(6”
) fo
r no
rmal
soi
ls.
• Si
nce
soil
on s
lope
s, r
oad
batte
rs a
nd fi
lled
dike
/em
bank
men
t is
not
fer
tile,
it
is r
ecom
men
ded
that
pot
ted
or t
ube
stoc
k be
us
ed f
or l
arge
sca
le m
ass
plan
ting
and
rapi
d es
tabl
ishm
ent.
Add
ing
a bi
t of
goo
d so
il-m
anur
e m
ixtu
re (
slur
ry)
is e
ven
bette
r. To
pro
tect
nat
ural
riv
er b
anks
whe
re th
e so
il is
usu
ally
fe
rtile
and
ini
tial
wat
erin
g ca
n be
ens
ured
with
out
extr
a ef
-fo
rt, b
are
root
pla
ntin
g is
suf
ficie
nt.
• C
over
roo
ts w
ith 2
00-3
00m
m (
8-12
”) o
f so
il an
d co
mpa
ct
firm
ly.
• Fe
rtili
ze w
ith N
itrog
en a
nd P
hosp
horu
s suc
h as
DA
P (D
i -A
m-
mon
ium
Pho
spha
te)
or N
PK (
note
fro
m e
xper
ienc
e ve
tiver
do
es n
ot r
espo
nd s
igni
fican
tly f
rom
pot
ash
appl
icat
ions
) at
10
0g (3
.5oz
) per
line
ar m
eter
(row
). T
he s
ame
amou
nt o
f lim
e m
ay b
e ne
cess
ary
whe
n pl
antin
g in
aci
d an
d su
lfat
e so
il.•
Wat
er w
ithin
the
day
of p
lant
ing.
• To
redu
ce w
eed
grow
th d
urin
g th
e es
tabl
ishm
ent p
hase
, a p
re-
emer
gent
her
bici
de s
uch
as A
traz
ine
may
be
used
.4.
7 M
aint
enan
ceW
ater
ing
• In
dry
wea
ther
, w
ater
eve
ry d
ay d
urin
g th
e fir
st t
wo
wee
ks
afte
r pl
antin
g an
d th
en e
very
sec
ond
day.
• W
ater
twic
e w
eekl
y un
til th
e pl
ants
are
wel
l est
ablis
hed.
• M
atur
e pl
ants
req
uire
no
furt
her
wat
erin
g.R
epla
ntin
g•
Dur
ing
the
first
mon
th a
fter
pla
ntin
g, r
epla
ce a
ll pl
ants
tha
t fa
il to
est
ablis
h or
was
h aw
ay.
• C
ontin
ue
insp
ectio
ns
until
th
e pl
ants
ar
e su
itabl
y es
tab-
lishe
d.W
eed
cont
rol
48
• C
ontr
ol w
eeds
, esp
ecia
lly v
ines
, dur
ing
the
first
yea
r.•
DO
NO
T U
SE R
ound
Up
(gly
phos
ate)
her
bici
de.
Vet
iver
is
very
sen
sitiv
e to
gly
phos
ate,
so
it sh
ould
not
be
used
to
con-
trol
wee
ds b
etw
een
row
s.
Fer
tiliz
ing
On
infe
rtile
soi
l, D
AP
or N
PK f
ertil
izer
sho
uld
be a
pplie
d at
the
be
ginn
ing
of th
e se
cond
wet
sea
son.
Cut
ting
Aft
er fi
ve m
onth
s, r
egul
ar c
uttin
g (t
rim
min
g) i
s al
so v
ery
impo
rtan
t. H
edge
row
s sh
ould
be
cut d
own
to 1
5-20
cm
(6-
8”)
abov
e th
e gr
ound
. T
his
sim
ple
tech
niqu
e pr
omot
es th
e gr
owth
of n
ew ti
llers
from
the
base
an
d re
duce
s th
e vo
lum
e of
dry
lea
ves
that
oth
erw
ise
can
over
shad
ow
youn
g sl
ips.
Tri
mm
ing
also
impr
oves
the
appe
aran
ce o
f dry
hed
gero
ws
and
may
min
imiz
e th
e da
nger
of
fire.
Fres
h cu
t le
aves
can
als
o be
use
d as
cat
tle f
odde
r, fo
r ha
ndic
raft
, and
ev
en r
oof
that
ch.
Ple
ase
note
tha
t ve
tiver
pla
nted
for
the
pur
pose
of
red
ucin
g na
tura
l di
sast
ers
shou
ld n
ot b
e ov
erus
ed f
or s
econ
dary
pu
rpos
es.
Subs
eque
nt c
uttin
gs c
an b
e do
ne tw
o or
thre
e tim
es a
yea
r. C
are
shou
ld
be ta
ken
to e
nsur
e th
e gr
ass
has
long
leav
es d
urin
g th
e ty
phoo
n se
ason
. V
etiv
er c
an b
e cu
t im
med
iate
ly a
fter
the
typh
oon
seas
on e
nds.
Ano
ther
su
itabl
e cu
tting
tim
e co
uld
be a
roun
d 3
mon
ths
befo
re t
he t
ypho
on
seas
on b
egin
s.
Fen
cing
and
car
ing
Dur
ing
the
seve
ral-
mon
th e
stab
lishm
ent
peri
od,
fenc
ing
and
care
m
ay b
e re
quir
ed to
pro
tect
vet
iver
fro
m v
anda
lism
and
cat
tle. T
he o
ld
stem
s of
mat
ure
vetiv
er a
re to
ugh
enou
gh to
dis
cour
age
cattl
e. W
here
ne
cess
ary,
it
is a
dvis
able
to
fenc
e th
e ar
ea t
o pr
otec
t th
e gr
ass
duri
ng
the
first
few
mon
ths
afte
r pl
antin
g.
49
5. V
ET
IVE
R S
YST
EM
S A
PP
LIC
AT
ION
S F
OR
NA
TU
RA
L
DIS
AST
ER
RE
DU
CT
ION
AN
D I
NF
RA
STR
UC
TU
RE
P
RO
TE
CT
ION
IN
VIE
TN
AM
5.1
VS
appl
icat
ion
for
sand
dun
e pr
otec
tion
in C
entr
al
V
ietn
amA
vas
t are
a, m
ore
than
70,
000
ha (
175,
000
acre
s), a
long
the
coas
tline
of
Cen
tral
Vie
tnam
is
cove
red
by s
and
dune
s w
here
the
clim
atic
and
so
il co
nditi
ons
are
very
sev
ere.
San
d bl
ast o
ften
occ
urs
as s
and
dune
s m
igra
te u
nder
the
actio
n of
win
d. S
and
flow
als
o ta
kes
plac
e fr
eque
ntly
du
e to
the
act
ion
of n
umer
ous
perm
anen
t an
d te
mpo
rary
str
eam
s.
Blo
wn
sand
and
san
d flo
w tr
ansp
ort h
uge
amou
nts
of s
and
from
dun
es
land
war
d on
to t
he n
arro
w c
oast
al p
lain
. Alo
ng t
he C
entr
al V
ietn
am
coas
tline
, gi
ant
sand
“to
ngue
s” b
ite i
nto
the
plai
n da
y af
ter
day.
The
G
over
nmen
t ha
s lo
ng
impl
emen
ted
a fo
rest
atio
n pr
ogra
m
usin
g su
ch v
arie
ties
as C
asua
rina
s, w
ild p
inea
pple
, eu
caly
ptus
, an
d ac
acia
. H
owev
er, w
hen
fully
and
wel
l est
ablis
hed,
they
may
hel
p re
duce
onl
y bl
own
sand
. U
ntil
now
, th
ere
has
been
no
way
to
redu
ce s
and
flow
(t
rees
can
not
sta
biliz
e sa
nd d
unes
, esp
ecia
lly o
n th
eir
‘slip
-fac
e’, t
his
was
trie
d in
Nor
th A
fric
a by
FA
O a
t gre
at e
xpen
se a
nd f
aile
d).
In F
ebru
ary
2002
, w
ith fi
nanc
ial
supp
ort
from
the
Dut
ch E
mba
ssy
Smal
l Pr
ogra
m a
nd t
echn
ical
sup
port
fro
m E
lise
Pinn
ers
and
Pham
H
ong
Duc
Phu
oc, T
ran
Tan
Van
fro
m R
IGM
R in
itiat
ed a
n ex
peri
men
t to
sta
biliz
e sa
nd d
unes
alo
ng t
he C
entr
al V
ietn
am c
oast
line.
A s
and
dune
was
bad
ly e
rode
d by
a s
trea
m th
at s
erve
d as
a n
atur
al b
ound
ary
betw
een
farm
ers
and
a fo
rest
ry e
nter
pris
e. T
he e
rosi
on o
ccur
red
over
se
vera
l yea
rs, r
esul
ting
in a
mou
ntin
g co
nflic
t bet
wee
n th
e tw
o gr
oups
. V
etiv
er w
as p
lant
ed in
row
s al
ong
the
cont
our
lines
of
the
sand
dun
e.
Aft
er f
our
mon
ths
it fo
rmed
clo
sed
hedg
erow
s an
d st
abili
zed
the
sand
dun
e. T
he f
ores
try
ente
rpri
se w
as s
o im
pres
sed
that
it
deci
ded
to m
ass
plan
t th
e gr
ass
in o
ther
san
d du
nes
and
even
to
prot
ect
a br
idge
abu
tmen
t. V
etiv
er f
urth
er s
urpr
ised
loc
al p
eopl
e by
sur
vivi
ng
the
cold
est w
inte
r in
10
year
s, w
hen
the
tem
pera
ture
des
cend
ed lo
wer
10
ºC (
50ºF
), f
orci
ng th
e fa
rmer
s to
twic
e re
plan
t the
ir p
addy
ric
e an
d C
asua
rina
s. A
fter
tw
o ye
ars,
the
loc
al s
peci
es (
prim
arily
Cas
uari
nas
and
wild
pin
eapp
le)
beca
me
re-e
stab
lishe
d. T
he g
rass
its
elf
fade
d aw
ay u
nder
the
shad
e of
thes
e tr
ees,
hav
ing
acco
mpl
ishe
d its
mis
sion
.
50
The
pro
ject
pro
ved
agai
n th
at, w
ith p
rope
r ca
re, v
etiv
er c
ould
sur
vive
ve
ry h
ostil
e so
il an
d cl
imat
ic c
ondi
tions
- p
hoto
2.
Acc
ordi
ng to
Hen
k Ja
n V
erha
gen
from
Del
ft U
nive
rsity
of T
echn
olog
y (p
ers.
com
m.)
, ve
tiver
may
be
equa
lly e
ffec
tive
in r
educ
ing
blow
n sa
nd (
sand
dri
ft).
For
thi
s pu
rpos
e, t
he g
rass
cou
ld b
e pl
ante
d ac
ross
th
e w
ind
dire
ctio
n, e
spec
ially
at l
ow p
lace
s be
twee
n sa
nd d
unes
, whe
re
the
win
d ve
loci
ty ty
pica
lly in
crea
ses.
On
Chi
na’s
Pin
tang
Isl
and,
off
th
e co
ast o
f Fu
jian
Prov
ince
, vet
iver
hed
ges
effe
ctiv
ely
redu
ced
win
d ve
loci
ty a
nd b
low
san
d.
Follo
win
g th
e su
cces
s of
this
pilo
t pro
ject
, a w
orks
hop
was
org
aniz
ed
in e
arly
200
3. M
ore
than
40
repr
esen
tativ
es f
rom
loc
al g
over
nmen
t de
part
men
ts, d
iffe
rent
NG
Os,
the
Uni
vers
ity o
f C
entr
al V
ietn
am, a
nd
coas
tal p
rovi
nces
par
ticip
ated
. The
wor
ksho
p he
lped
the
auth
ors
of th
is
book
and
oth
er p
artic
ipan
ts to
com
pile
and
syn
thes
ize
loca
l pra
ctic
es,
part
icul
arly
re
gard
ing
plan
ting
times
, w
ater
ing,
an
d fe
rtili
zing
. Fo
llow
ing
the
even
t, W
orld
Vis
ion
Vie
tnam
dec
ided
in
2003
to
fund
an
othe
r pr
ojec
t in
the
Vin
h L
inh
and
Tri
eu P
hong
dis
tric
ts i
n Q
uang
T
ri p
rovi
nce
to e
mpl
oy v
etiv
er f
or s
and
dune
sta
bilis
atio
n -
phot
os
3-7.
51
5.1.
1 T
rial
app
licat
ion
and
prom
otio
n of
VS
for
sand
dun
e pr
otec
tion
in c
oast
al p
rovi
nce
of Q
uang
Bin
h
Ph
oto
2: S
and
flo
w in
Le
Th
uy
(Qu
ang
Bin
h)
in 1
999:
th
e fo
un
dat
ion
of
a p
um
pin
g s
tati
on
(u
pp
er);
th
is w
om
an’s
th
ree-
roo
m b
rick
ho
use
is
colla
psi
ng
bec
ause
san
d h
as b
een
blo
wn
fro
m fo
un
dat
ion
(lo
wer
).
52
Ph
oto
3: U
pp
er: s
ite
over
view
; lo
wer
: ear
ly A
pri
l 200
2,
on
e m
on
th a
fter
pla
nti
ng
.
53
Ph
oto
4: U
pp
er: e
arly
Ju
ly 2
002,
fou
r m
on
ths
afte
r p
lan
tin
g; l
ow
er:
Nov
emb
er 2
002,
den
se r
ow
s o
f g
rass
hav
e b
een
est
ablis
hed
.
54
Ph
oto
5: U
pp
er: V
etiv
er n
urs
ery;
low
er: N
ovem
ber
200
2, m
ass
pla
nti
ng
.
55
Ph
oto
6:
Up
per
: Vet
iver
pro
tect
s b
rid
ge
abu
tmen
t al
on
g N
atio
nal
Hig
h-
way
nr.
1; lo
wer
: Dec
emb
er 2
004,
loca
l sp
ecie
s h
ave
rep
lace
d v
etiv
er.
56
Ph
oto
7: U
pp
er: m
id-F
ebru
ary
2003
, po
st-w
ork
sho
p fi
eld
trip
; No
te: V
etiv
-er
su
rviv
es e
ven
th
e co
ldes
t w
inte
r in
10
year
s; lo
wer
: Ju
ne
2003
, far
m-
ers
fro
m Q
uan
g T
ri p
rovi
nce
vis
it a
lo
cal
nu
rser
y d
uri
ng
a W
orl
d V
isio
n
Vie
tnam
-sp
on
sore
d fi
eld
tri
p.
5.2
VS
appl
icat
ion
to c
ontr
ol r
iver
ban
k er
osio
n
5.2.
1 V
S ap
plic
atio
n fo
r ri
ver
bank
ero
sion
con
trol
in
Cen
tral
V
ietn
amW
ithin
the
fram
ewor
k of
the
sam
e D
utch
Em
bass
y pr
ojec
t men
tione
d ab
ove,
vet
iver
was
pla
nted
to
halt
eros
ion
on a
riv
erba
nk,
on t
he
bank
of
a sh
rim
p po
nd, a
nd o
n a
road
em
bank
men
t in
Da
Nan
g C
ity.
In O
ctob
er 2
002,
the
loc
al D
ike
Dep
artm
ent
also
mas
s pl
ante
d th
e gr
ass
on b
ank
sect
ions
of
seve
ral r
iver
s. T
here
afte
r, th
e ci
ty a
utho
rity
de
cide
d to
fund
a p
roje
ct o
n cu
t slo
pe s
tabi
lisat
ion
by in
stal
ling
vetiv
er
57
alon
g th
e m
ount
aino
us ro
ad le
adin
g to
the
Ban
ana
proj
ect i
n D
a N
ang,
ill
ustr
atin
g th
e pa
ce o
f ad
optio
n -
phot
os 8
-10.
Ph
oto
8:
Up
per
: D
ecem
ber
200
4: V
etiv
er,
com
bin
ed w
ith
ro
ck r
ipra
p,
flo
uri
shes
aft
er t
wo
flo
od
sea
son
s (D
a N
ang
); l
ow
er:
pla
nte
d b
y lo
cal
farm
ers,
vet
iver
pro
tect
s th
eir
shri
mp
po
nd
s.
58
Ph
oto
9: U
pp
er: M
arch
200
2: V
S tr
ial a
t th
e ed
ge
of a
sh
rim
p p
on
d, w
her
e a
can
al d
rain
s fl
oo
d w
ater
to
Vin
h D
ien
Riv
er;
low
er:
Nov
emb
er 2
002:
m
ass
pla
nti
ng
co
mb
ined
wit
h r
ock
rip
rap
to
pro
tect
ban
k al
on
g V
inh
D
ien
riv
er.
59
Ph
oto
10:
Up
per
: Vet
iver
an
d r
ock
rip
rap
an
d c
on
cret
e fr
ame
pro
tect
an
em
ban
kmen
t; l
ow
er:
a b
end
on
Per
fum
e R
iver
ban
k in
Hu
e -
pro
tect
ed
wit
h v
etiv
er.
5.2.
2 V
S tr
ial
and
prom
otio
n fo
r ri
ver
bank
pro
tect
ion
in Q
uang
N
gai
As
anot
her
resu
lt of
thi
s pi
lot
proj
ect,
vetiv
er w
as r
ecom
men
ded
for
use
in a
noth
er n
atur
al d
isas
ter
redu
ctio
n pr
ojec
t in
Qua
ng N
gai
prov
ince
, fun
ded
by A
usA
id. W
ith te
chni
cal s
uppo
rt b
y T
ran
Tan
Van
in
Jul
y 20
03, V
o T
hanh
Thu
y an
d hi
s co
-wor
kers
fro
m t
he p
rovi
ncia
l A
gric
ultu
ral E
xten
sion
Cen
tre.
60
Ph
oto
11:
Vet
iver
gra
ss p
lan
ted
on
riv
er d
ike
alo
ng
Tra
Bo
ng
Riv
er
(up
per
) an
d li
nin
g t
he
sid
es o
f an
an
ti-s
alin
ity
estu
ary
dik
e al
on
g t
he
sam
e ri
ver
(lo
wer
).
61
Ph
oto
12:
Up
per
: sev
erel
y er
od
ed b
ank
of
the
Tra
Kh
uc
Riv
er,
at B
inh
Th
oi C
om
mu
ne;
low
er: p
rim
itiv
e sa
nd
bag
pro
tect
ion
.
62
Ph
oto
13:
Up
per
: Co
mm
un
ity
mem
ber
s p
lan
t ve
tive
r; lo
wer
: N
ovem
ber
200
5: b
ank
rem
ain
s in
tact
follo
win
g t
he
flo
od
sea
son
.
plan
ted
the
gras
s at
fou
r lo
catio
ns, i
rrig
atio
n ca
nals
in s
ever
al d
istr
icts
an
d a
seaw
ater
int
rusi
on p
rote
ctio
n di
kes.
Vet
iver
thr
ived
in
all
loca
tions
and
, des
pite
its
youn
g ag
e, s
urvi
ved
a flo
od in
the
sam
e ye
ar
- ph
otos
11-
13.
Follo
win
g th
ese
succ
essf
ul t
rial
s, t
he p
roje
ct d
ecid
ed t
o m
ass
plan
t ve
tiver
on
othe
r di
ke s
ectio
ns i
n th
ree
othe
r di
stri
cts,
in
com
bina
tion
with
roc
k ri
prap
. D
esig
n m
odifi
catio
ns i
ntro
duce
d to
bet
ter
adap
t
63
vetiv
er t
o lo
cal
cond
ition
s in
clud
e pl
antin
g m
angr
ove
fern
and
oth
er
salt-
tole
rant
gra
sses
on
the
low
est r
ow to
bet
ter w
ithst
and
high
sal
inity
an
d to
eff
ectiv
ely
prot
ect
the
emba
nkm
ent
toe.
Enc
oura
ging
ly,
loca
l co
mm
uniti
es a
re m
ore
read
ily u
sing
vet
iver
to
prot
ect
thei
r ow
n la
nds
5.2.
3 V
S ap
plic
atio
n to
con
trol
riv
er b
ank
eros
ion
in t
he M
ekon
g D
elta
With
Will
iam
Don
ner
Foun
datio
n fin
anci
al s
uppo
rt a
nd P
aul T
ruon
g’s
tech
nica
l hel
p, L
e V
iet D
ung
and
his
colle
ague
s at
Can
Tho
Uni
vers
ity
initi
ated
riv
erba
nk e
rosi
on c
ontr
ol p
roje
cts
in th
e M
ekon
g D
elta
. The
ar
ea e
xper
ienc
es lo
ng p
erio
ds o
f inu
ndat
ion
(up
to fi
ve m
onth
s) d
urin
g th
e flo
od s
easo
n, w
ith s
igni
fican
t dif
fere
nce
in w
ater
leve
ls, u
p to
5 m
(1
5’),
bet
wee
n dr
y an
d flo
od s
easo
ns, a
nd p
ower
ful w
ater
flow
dur
ing
flood
sea
son.
Fu
rthe
r, th
e ri
verb
anks
con
sist
of
soils
ran
ging
fro
m
allu
vial
silt
to
loam
, whi
ch a
re h
ighl
y er
odib
le w
hen
wet
. Due
to
the
impr
oved
eco
nom
y of
rec
ent
year
s, m
ost
boat
s tr
avel
ling
on r
iver
s an
d ca
nals
are
mot
oriz
ed, m
any
with
pow
erfu
l eng
ines
that
agg
rava
te
rive
rban
k er
osio
n by
gen
erat
ing
stro
ng w
aves
. N
ever
thel
ess,
vet
iver
st
ands
its
gro
und,
pro
tect
ing
larg
e ar
eas
of v
alua
ble
farm
lan
d fr
om
eros
ion
- ph
otos
14
and
15.
A c
ompr
ehen
sive
vet
iver
pro
gram
has
bee
n es
tabl
ishe
d in
An
Gia
ng
Prov
ince
, w
here
an
nual
flo
ods
reac
h de
pths
of
6
m
(18’
).
The
pr
ovin
ce’s
long
, 493
2 km
(30
65 m
iles)
, can
al s
yste
m r
equi
res
annu
al
mai
nten
ance
and
rep
air.
A n
etw
ork
of d
ikes
, 46
00 k
m l
ong,
pro
tect
s 20
9,95
7 ha
(52
5,00
0 ac
res)
of
prim
e fa
rmla
nd f
rom
floo
d. E
rosi
on
on t
hese
dik
es i
s ab
out
3.75
Mm
3/ye
ar a
nd r
equi
red
USD
1.3
M t
o re
pair.
The
are
a al
so i
nclu
des
181
rese
ttlem
ent
clus
ters
, co
mm
uniti
es b
uilt
on d
redg
ed m
ater
ials
tha
t al
so r
equi
re e
rosi
on c
ontr
ol a
nd p
rote
ctio
n fr
om fl
oodi
ng.
Dep
endi
ng o
n th
e lo
catio
ns a
nd fl
ood
dept
h, v
etiv
er
has
been
use
d su
cces
sful
ly a
lone
, and
tog
ethe
r w
ith o
ther
veg
etat
ion
to s
tabi
lize
thes
e ar
eas.
As
a re
sult,
vet
iver
now
line
s ri
goro
us s
ea a
nd
rive
r di
ke s
yste
ms
as w
ell
as r
iver
bank
s an
d ca
nals
in
the
Mek
ong
Del
ta. N
earl
y tw
o m
illio
n po
lyba
gs o
f ve
tiver
, a to
tal o
f 61
line
al k
m
(38
mile
s), w
ere
inst
alle
d to
pro
tect
the
dike
s be
twee
n 20
02 a
nd 2
005
64
- ph
otos
14
-15.
Bet
wee
n 20
06 a
nd 2
010,
the
11
dist
rict
s of
An
Gia
ng p
rovi
nce
are
expe
cted
to p
lant
202
5 km
(12
58 m
iles)
of
vetiv
er h
edge
s on
310
0 ha
(7
660
acre
s) o
f di
ke s
urfa
ce.
Lef
t un
prot
ecte
d, 3
750
Mm
3 of
soi
l lik
ely
will
be
erod
ed a
nd 5
Mm
3 w
ill h
ave
to b
e dr
edge
d fr
om t
he
cana
ls. B
ased
on
2006
cur
rent
cos
ts, t
otal
mai
nten
ance
cos
ts o
ver
this
pe
riod
wou
ld e
xcee
d U
S $
15.5
M in
this
pro
vinc
e al
one.
App
lyin
g th
e V
etiv
er S
yste
m in
this
rur
al a
rea
will
pro
vide
ext
ra in
com
e to
the
loca
l pe
ople
: men
to p
lant
, and
wom
en a
nd c
hild
ren
to p
repa
re p
olyb
ags.
Ph
oto
14:
In A
n G
ian
g v
etiv
er s
tab
ilize
s a
rive
r d
ike
(up
per
), an
d a
nat
ura
l ri
ver
ban
k (l
ow
er).
65
Ph
oto
15:
Up
per
: Vet
iver
bo
rder
s th
e ed
ge
of
flo
od
res
ettl
emen
t ce
ntr
es;
low
er:
the
red
mar
kers
del
inea
te a
bo
ut
5 m
(15
’) o
f d
ry l
and
sav
ed b
y ve
tive
r.
66
5.2.
4 Ve
tiver
Sys
tem
app
licat
ion
to c
ontr
ol s
ever
e ri
ver
bank
ero
sion
in
Cam
bodi
a
The
wat
er le
vel o
f th
e M
ekon
g ri
ver
sect
ion
in C
ambo
dian
fluc
tuat
es
wid
ely,
reac
hing
15m
and
mor
e du
ring
the
flood
sea
son
abov
e th
e le
vel
duri
ng th
e dr
y se
ason
. The
com
bina
tion
of v
ery
fast
cur
rent
and
wav
e ac
tion
duri
ng t
he a
nnua
l ra
iny
and
flood
sea
son
caus
es s
ever
e ba
nk
eros
ion,
ave
ragi
ng b
etw
een
5-10
m e
very
yea
r. G
ener
al s
oil e
rosi
on o
n th
e al
luvi
al p
lain
is
betw
een
10 a
nd 3
0cm
eac
h ye
ar. T
he l
oss
of t
his
fert
ile a
lluvi
al p
lain
sev
erel
y af
fect
s ag
ricu
lture
pro
duct
ion,
val
uabl
e ur
ban
land
and
inf
rast
ruct
ure
stab
ility
alo
ng t
he r
iver
. In
addi
tion
the
wat
er is
ver
y m
uddy
and
hig
h in
sed
imen
t loa
d.
A p
roje
ct w
as in
itiat
ed in
200
6 to
sta
bilis
e a
200m
long
str
etch
of
the
Mek
ong
bank
nor
th o
f Ph
nom
Pen
h, t
he c
apita
l of
Cam
bodi
a, w
hich
ha
s be
en s
ever
ely
erod
ed a
nd w
ill e
vent
ually
was
h aw
ay th
e na
tiona
l hi
ghw
ay to
nor
ther
n re
gion
s. O
n th
is s
ite, s
ever
e er
osio
n oc
curs
eve
ry
year
and
aft
er 1
0 ye
ars,
50m
hav
e di
sapp
eare
d th
at tr
ansl
ates
into
a lo
ss
of 5
0 m
x 2
00 m
(w
idth
) =
10,
000
m2
or 1
hec
tare
! Var
ious
sta
bilis
ing
optio
ns s
uch
as c
onve
ntio
nal
hard
str
uctu
res
incl
udin
g ga
bion
and
ro
ck w
all
and
loca
l ve
geta
tion,
bam
boo,
wer
e co
nsid
ered
, bu
t th
ese
mea
sure
s ar
e ei
ther
inef
fect
ive
and/
or to
o ex
pens
ive
to im
plem
ent.
As
a re
sult,
Vet
iver
Sys
tem
tech
nolo
gy w
as im
plem
ente
d as
a la
st r
esor
t.(T
uon
Van
, Coo
rdin
ator
Cam
bodi
an V
etiv
er N
etw
ork,
per
s.co
m.)
Res
ults
of r
iver
bank
stab
ilisa
tion
wor
ks in
Aus
tral
ia, C
hina
, Mad
agas
car
and
Vie
tnam
hav
e sh
own
that
the
stif
f ve
tiver
sho
ots
redu
ced
flow
ve
loci
ty, h
ence
ero
sive
pow
er, a
nd it
s de
ep a
nd e
xten
sive
roo
t sys
tem
re
info
rce
the
soil
and
hold
s it
firm
ly to
the
grou
nd, r
esul
ting
in a
ver
y ef
fect
ive
stab
ilisi
ng m
echa
nism
. It i
s ex
pect
ed th
at th
is m
echa
nism
is
also
eff
ectiv
e w
heth
er t
he v
etiv
er i
s al
ive
or d
ead
in t
he s
hort
ter
m.
The
refo
re w
hen
fully
est
ablis
hed
vetiv
er w
ould
con
trol
/red
uce
the
eros
ion
on th
e ba
nk o
f th
e M
ekon
g un
der
flood
.
Sout
h A
fric
an e
xper
ienc
e an
d C
hine
se r
esea
rch
show
ed t
hat
vetiv
er
coul
d su
rviv
e up
to
3 m
onth
s un
der
clea
n, c
lear
wat
er a
nd s
till
cond
ition
s. H
owev
er it
is n
ot k
now
n ho
w lo
ng v
etiv
er c
ould
sur
vive
67
Ph
oto
16:
Ero
ded
ban
k b
efo
re (
up
per
) an
d a
fter
ear
thw
ork
(lo
wer
).
unde
r m
uddy
, tu
rbul
ent
and
fast
flow
ing
cond
ition
s. I
t w
as e
xpec
ted
that
mud
dy r
iver
wat
er w
ould
aff
ect
vetiv
er g
row
th d
ue t
o lo
w l
ight
tr
ansm
issi
on.
The
ero
ded
bank
was
firs
t res
hape
d an
d fir
mly
pac
ked
to 3
00 g
radi
ent,
with
a v
ertic
al d
rop
of a
ppro
xim
atel
y 8m
- p
hoto
16.
To
prov
ide
max
imum
pro
tect
ion
vetiv
er w
as p
lant
ed in
a g
rid
patte
rn, b
oth
on th
e
68
cont
our
line
alon
g th
e ba
nk (
hori
zont
al r
ow)
to r
educ
e w
ave
eros
ion
and
up a
nd d
own
the
slop
e (v
ertic
al r
ow)
to r
educ
e flo
w v
eloc
ity. T
he
spac
ing
of t
he h
oriz
onta
l ro
ws
is 1
m a
part
with
pla
nt d
ensi
ty o
f 10
pl
ant/m
and
ver
tical
row
s ar
e sp
aced
at 2
m a
part
with
pla
nt d
ensi
ty o
f 5p
lant
/m. T
he p
lant
ing
was
fer
tiliz
ed w
ith b
oth
man
ure
and
chem
ical
fe
rtili
zers
to e
nsur
e m
axim
um g
row
th -
pho
to 1
7.
Ph
oto
17:
On
e m
on
th (
up
per
) an
d s
even
mo
nth
s af
ter
pla
nti
ng
(lo
wer
).
69
Seve
n m
onth
s af
ter
plan
ting,
with
int
ensi
ve m
aint
enan
ce (
fert
ilise
r, w
ater
ing
and
wee
d co
ntro
l), t
he v
etiv
er s
tand
was
1.5
m h
igh.
To
test
th
e su
rviv
al r
ate
of v
etiv
er u
nder
mud
dy c
ondi
tions
, som
e se
ctio
ns o
f th
e sl
ope
wer
e tr
imm
ed d
own
to 5
0cm
hig
h be
fore
floo
ding
.
Ph
oto
18:
Flo
od
wat
er s
tart
ed c
om
ing
up
(u
pp
er);
an
d d
ead
lo
oki
ng
vet
iver
on
low
er s
lop
e af
ter
wat
er r
etre
ats
(lo
wer
).
70
As
expe
cted
the
site
was
ful
ly fl
oode
d ni
ne m
onth
s af
ter
plan
ting,
co
veri
ng t
he w
hole
slo
pe a
nd h
ighe
r gr
ound
. A
lthou
gh v
etiv
er w
as
not f
ully
mat
ure
it su
cces
sful
ly s
topp
ed th
e er
osio
n. O
n th
e up
per
part
of
the
slop
e, w
here
sub
mer
genc
e tim
e w
as s
hort
er (
up to
two
mon
ths)
an
d sh
allo
wer
dep
th, v
etiv
er g
row
th w
as n
ot a
ffec
ted
and
cont
inue
d to
gr
ow u
nder
wat
er. I
t was
exp
ecte
d th
at p
lant
s on
the
botto
m p
art o
f the
sl
ope,
whi
ch w
as s
ubm
erge
d fo
r 6
mon
ths
and
unde
r 14
m o
f m
uddy
w
ater
, vet
iver
wou
ld b
e ba
dly
affe
cted
. But
sur
pris
ingl
y, a
lthou
gh th
ey
all l
ook
dead
onl
y a
few
wer
e ac
tual
ly d
ead
- ph
oto
18.
The
fol
low
ings
obs
erva
tions
and
con
clus
ion
wer
e re
cord
ed:
• th
e fir
st 3
row
s at
the
base
of t
he s
lope
all
surv
ived
! The
se ro
ws
wer
e su
bmer
ged
for
5-6
mon
ths
unde
r 14
m o
f m
uddy
wat
er.
The
y w
ere
not c
ut (
1.5m
tall)
bef
ore
the
wat
er s
tart
ed to
ris
e.•
the
next
5 r
ows
up,
the
vetiv
er w
as c
ut t
o 50
cm a
nd t
hey
all
died
bec
ause
they
wer
e al
l cov
ered
by
mud
.•
the
rest
of t
he s
lope
sta
rtin
g fr
om ro
ws
9, w
ere
also
cut
to 5
0cm
, bu
t all
surv
ived
bec
ause
the
mud
did
n't f
ully
cov
er th
em.
• pl
ants
from
upp
er s
ectio
n ac
tual
ly g
rew
und
er w
ater
dur
ing
the
flood
.•
Unc
ut p
lant
s su
rviv
ed b
ette
r -
phot
o 19
low
er.
• an
d th
e th
ick
mud
cov
er k
illed
them
- p
hoto
19
uppe
r.
But
mos
t im
port
antly
, ve
tiver
pla
ntin
g di
d no
t on
ly s
top
the
bank
er
osio
n, i
t al
so a
ccum
ulat
ed a
thi
ck c
over
of
allu
vial
silt
bet
wee
n th
e ro
ws
- ph
oto
20. O
n cl
oser
exa
min
atio
n, t
his
thic
k si
lt co
ver
was
the
ca
use
of v
etiv
er d
eath
in
som
e se
ctio
ns o
f th
e sl
ope.
Whe
re t
he m
ud
cove
r w
as n
ot to
o th
ick,
vet
iver
sho
ots
emer
ged
late
r -
phot
o 21
. The
de
ad p
lant
s ha
ve b
een
repl
aced
and
pla
ntin
g w
ill b
e ex
tend
ed to
eve
n lo
wer
are
a of
the
slop
e -
phot
o 21
.
The
abo
ve r
esul
ts s
how
that
:•
vetiv
er c
an s
urvi
ve u
p to
5-6
mon
ths
unde
r 14
m o
f m
uddy
w
ater
• un
cut s
hoot
s im
prov
e its
sur
viva
l und
er w
ater
• ve
tiver
is
kille
d w
hen
cove
red
with
or
buri
ed u
nder
thi
ck
allu
vial
mud
71
Ph
oto
19:
Dea
d v
etiv
er d
ue
to t
hic
k al
luvi
al s
ilt d
epo
sit
(up
per
); a
nd
re-
gro
wth
if t
he
mu
d w
as n
ot
too
th
ick
(lo
wer
).
It c
an b
e co
nclu
ded
that
whe
n co
rrec
tly d
esig
ned
and
impl
emen
ted,
ve
tiver
pla
ntin
g is
ver
y ef
fect
ive
in c
ontr
ollin
g er
osio
n on
the
bank
of
fast
flow
ing
rive
r eve
n un
der fl
ood
cond
ition
s an
d de
ep a
nd p
rolo
nged
su
bmer
genc
e in
mud
dy w
ater
. In
add
ition
it
enco
urag
es a
lluvi
al s
ilt
depo
sitio
n an
d ov
er ti
me
may
eve
ntua
lly r
ecla
im th
e er
oded
ban
ks.
72
Ph
oto
20:
Up
per
an
d lo
wer
: allu
vial
silt
dep
osi
t bet
wee
n v
etiv
er r
ow
s o
n
low
er p
art
of
the
slo
pe.
73
Ph
oto
21:
Fu
lly r
ecov
ered
aft
er th
e fl
oo
d (u
pp
er) a
nd
new
pla
nti
ng
on
the
bar
e lo
wer
sec
tio
n o
f sl
op
e (l
ow
er).
5.3
VS
appl
icat
ion
for
coas
tal e
rosi
on c
ontr
olH
uge
sea
dike
s w
ith re
vetm
ent p
rote
ctio
n bu
ilt fr
om tr
aditi
onal
“ha
rd”
mat
eria
l suc
h as
blo
ck c
oncr
etes
or
big
rock
hav
e gi
ven
good
res
ults
. T
he h
eigh
t of
the
se s
ea d
ikes
sho
uld
be s
uffic
ient
to
prot
ect
the
area
74
insi
de th
e co
asta
l floo
d de
fenc
e sy
stem
. How
ever
they
are
qui
te c
ostly
to
impl
emen
t and
mat
eria
ls a
re n
ot a
lway
s av
aila
ble.
In o
rder
to re
duce
to
tal
cost
, th
e tr
aditi
onal
rev
etm
ent
coul
d be
rep
lace
d by
che
aper
m
ater
ials
. A
com
bina
tion
of “
hard
” an
d “s
oft”
mat
eria
ls i
s a
good
al
tern
ativ
e so
lutio
n. V
etiv
er g
rass
is
wel
l-kn
own
as b
ioen
gine
erin
g sp
ecie
s in
sta
biliz
ing
inne
r slo
pes,
redu
cing
run-
off a
nd c
ontr
ollin
g so
il lo
ss. R
ecen
tly, i
t has
bee
n pl
ante
d on
out
er s
lope
as
sea
dike
pro
tect
ion
as w
ell
- ph
oto
22.
How
ever
the
und
erst
andi
ng o
f th
e pr
oces
ses
and
prop
ertie
s be
twee
n w
aves
and
Vet
iver
gra
ss is
stil
l lim
ited.
Ph
oto
22:
Vet
iver
pla
nte
d o
n t
he
insi
de
of
Hai
Hau
sea
dik
e (u
pp
er)
and
o
uts
ide
(lo
wer
).
75
Fig
ure
5: W
ave
run
up r
educ
tion
by
veti
ver
row
s (u
pper
) w
ave
run
up r
educ
tion
by
plan
t den
sity
(lo
wer
).
Rec
ently
the
Dep
artm
ent o
f H
ydra
ulic
Eng
inee
ring
at D
elft
Tec
hnic
al
Uni
vers
ity in
Hol
land
con
duct
ed re
sear
ch o
n th
e us
e of
vet
iver
gra
ss o
n th
e d
ike
oute
r sl
ope
to r
educ
e w
ave
run
up (
over
topp
ing
disc
harg
es)
76
Fig
ure
6: W
ave
run
on th
e ou
ter
wal
l (up
per)
and
con
stru
ctio
n co
st
savi
ng w
ith
and
wit
hout
vet
iver
(lo
wer
).
so th
at s
ea d
ike
cres
t can
be
redu
ced.
A p
hysi
cal m
odel
was
con
duct
ed
usin
g fu
lly g
row
n V
etiv
er g
rass
hed
ges
and
wav
e pa
ram
eter
s in
fro
nt
of th
e he
dges
. Exp
erim
enta
l res
ults
hav
e sh
own
that
:•
Res
ista
nce
to fl
ow b
y V
etiv
er h
edge
var
ies
with
gra
ss d
ensi
ty
77
- fig
ure
5.•
Res
ista
nce
(Man
ning
coe
ffici
ent)
var
ies
with
flow
dep
th a
nd
vetiv
er p
rovi
ded
2.5
times
gre
ater
res
ista
nce
than
bar
e sl
ope
• V
etiv
er g
rass
hed
ges
can
with
stan
d flo
w o
f ba
ckw
ater
up
to
near
ly 0
.4m
dep
th.
• T
he ro
ughn
ess
coef
ficie
nt o
f Vet
iver
gra
ss, d
epen
ding
on
gras
s de
nsity
var
ies
betw
een
0.33
and
0.4
1.
• T
he r
educ
tion
of w
ave
over
topp
ing
of m
ore
than
60%
- fi
gure
5.
Whe
n th
is m
odel
was
app
lied
on a
sea
dike
in V
ietn
am, r
esul
t sh
ows
that
a r
educ
tion
of 0
.5m
of
the
cres
t he
ight
is
feas
ible
fo
r up
grad
ing
the
pres
ent
sea
dike
in
Hai
Hau
, V
ietn
am.
In
dolla
r ter
m, t
he c
ost o
f con
stru
ctio
n pe
r met
er le
ngth
of $
147.
5 w
ithou
t vet
iver
, red
uces
to $
128.
96 w
hen
two
vetiv
er ro
ws
are
plan
ted
on th
e ou
ter
slop
e, a
red
uctio
n of
12.
6%.
Thi
s ca
se s
how
s th
at V
etiv
er g
rass
is
a go
od s
olut
ion
for
sea
dike
s in
or
der
to r
educ
e w
ave
run-
up o
n th
e ou
ter
slop
e an
d de
crea
ses
the
cost
fo
r s
ea d
ike
upgr
adin
g -
figur
e 6
(Vu
Min
h A
nh, 2
007)
.
With
sup
port
of
the
Will
iam
Don
ner
Foun
datio
n an
d w
ith t
echn
ical
su
ppor
t by
Pau
l T
ruon
g, L
e V
an D
u fr
om H
o C
hi M
inh
City
Agr
o-Fo
rest
ry U
nive
rsity
in
2001
ini
tiate
d w
ork
on a
cid
sulf
ate
soil
to
stab
ilize
can
al a
nd i
rrig
atio
n ch
anne
ls a
nd t
he s
ea d
ike
syst
em i
n G
o C
ong
prov
ince
. Vet
iver
gre
w v
igor
ousl
y on
the
em
bank
men
ts i
n ju
st
a fe
w m
onth
s, d
espi
te p
oor
soil.
It
is
now
pro
tect
ing
the
sea
dike
, pr
even
ting
surf
ace
eros
ion,
an
d fa
cilit
atin
g th
e es
tabl
ishm
ent
of
ende
mic
spe
cies
- p
hoto
23
and
24.
78
Ph
oto
23:
Pla
nte
d b
ehin
d n
atu
ral
man
gro
ve o
n a
n a
cid
su
lfat
e so
il se
a d
ike
in G
o C
on
g p
rovi
nce
, vet
iver
red
uce
s su
rfac
e er
osi
on
an
d f
ost
ers
the
re-e
stab
lish
men
t o
f lo
cal g
rass
es.
79
Ph
oto
24:
In
No
rth
Vie
tnam
; U
pp
er:
Vet
iver
pla
nte
d o
n o
ute
r si
de
of
a n
ewly
bu
ilt s
ea d
ike
in N
am D
inh
pro
vin
ce; l
ow
er: o
n th
e in
ner
sid
e o
f th
e d
ike,
pla
nte
d b
y th
e lo
cal D
ike
Dep
artm
ent.
80
5.4
VS
appl
icat
ion
to s
tabi
lize
road
bat
ter
Follo
win
g su
cces
sful
tria
ls b
y Ph
am H
ong
Duc
Phu
oc (
Ho
Chi
Min
h C
ity A
gro-
Fore
stry
Uni
vers
ity)
and
Thi
en S
inh
Co.
in
usin
g ve
tiver
to
sta
biliz
e cu
t sl
opes
in
Cen
tral
Vie
tnam
, in
200
3 th
e M
inis
try
of
Tra
nspo
rt a
utho
rize
d th
e w
ide
use
of v
etiv
er t
o st
abili
ze s
lope
s al
ong
hund
reds
of k
ilom
etre
s of t
he n
ewly
con
stru
cted
Ho
Chi
Min
h H
ighw
ay
and
othe
r na
tiona
l, pr
ovin
cial
roa
ds i
n Q
uang
Nin
h, D
a N
ang,
and
K
hanh
Hoa
pro
vinc
es -
pho
to 2
5.
Ph
oto
25:
Up
per
: V
etiv
er s
tab
ilize
s cu
t sl
op
es a
lon
g t
he
Ho
Ch
i M
inh
H
igh
way
; lo
wer
: b
oth
al
on
e an
d
in
com
bin
atio
n
wit
h
trad
itio
nal
m
easu
res.
Thi
s pr
ojec
t is
ce
rtai
nly
one
of
the
larg
est
VS
appl
icat
ions
in
in
fras
truc
ture
pr
otec
tion
in
the
wor
ld.
The
en
tire
Ho
Chi
M
inh
81
Hig
hway
is m
ore
than
300
0 km
(186
4 m
iles)
long
. It
is b
eing
and
will
be
pro
tect
ed b
y ve
tiver
pla
nted
und
er a
var
iety
of
soils
and
clim
ate
Ph
oto
26:
Up
per
- I
f n
ot
pro
per
ly p
rote
cted
ro
ck/s
oil
fro
m t
his
was
te
du
mp
will
was
h f
ar d
ow
nst
ream
. L
ow
er -
im
pac
tin
g a
do
wn
stre
am v
il-la
ge
in A
Lu
oi d
istr
ict,
Th
ua
Tie
n H
ue
pro
vin
ce.
from
ske
leta
l m
ount
aino
us s
oils
and
col
d w
inte
r in
the
Nor
th t
o ex
trem
ely
acid
ic a
cid
sulp
hate
soi
l an
d ho
t, hu
mid
clim
ate
in t
he
Sout
h. T
he e
xten
sive
use
of
vetiv
er t
o st
abili
ze c
ut s
lope
s w
orks
, for
ex
ampl
e:•
App
lied
prim
arily
as
a sl
ope
surf
ace
prot
ectio
n m
easu
re,
it gr
eatly
redu
ces
run-
off i
nduc
ed e
rosi
on, t
hat w
ould
oth
erw
ise
wre
ak h
avoc
dow
nstr
eam
- p
hoto
26.
• B
y pr
even
ting
shal
low
fai
lure
s, it
sta
biliz
es c
ut s
lope
s w
hich
gr
eatly
red
uces
the
num
ber
of d
eep
slop
e fa
ilure
s -
phot
o 27
.•
In s
ome
case
s w
here
dee
p sl
ope
failu
res
do o
ccur
, vet
iver
stil
l
82
does
a v
ery
good
job
in s
low
ing
dow
n th
e fa
ilure
s an
d re
duc-
ing
the
faile
d m
ass,
and
;•
It m
aint
ains
the
rur
al a
esth
etic
and
eco
-fri
endl
ines
s of
the
ro
ad.
Ph
oto
27:
Da
Deo
Pas
s, Q
uan
g B
inh
: U
pp
er:
Veg
etat
ion
cov
er i
s d
e-st
roye
d,
reve
alin
g u
gly
an
d c
on
tin
uo
us
failu
res
of
cut
slo
pes
; lo
wer
: V
etiv
er r
ow
s o
n to
p o
f th
e sl
op
e ve
ry s
low
ly s
qu
eeze
do
wn
, co
nsi
der
ably
re
du
cin
g t
he
faile
d m
ass.
On
a ro
ad l
eadi
ng t
o th
e H
o C
hi M
inh
Hig
hway
Pha
m H
ong
Duc
Ph
uoc
dem
onst
rate
d cl
earl
y ho
w V
S sh
ould
be
appl
ied,
as
wel
l as
its
ef
fect
iven
ess
and
sust
aina
bilit
y -
phot
o 28
.
He
care
fully
mon
itore
d th
e de
velo
pmen
t of
vet
iver
: its
est
ablis
hmen
t (6
5-10
0%),
togr
owth
(95
-160
cm
(37
-63”
) af
ter
six
mon
ths)
, till
erin
g ra
te (
18-3
0 til
lers
per
pla
nt),
and
roo
t de
pth
on t
he b
atte
r -
tabl
e 6.
83
Tabl
e 6:
Vet
iver
roo
t de
pth
on H
on B
a ro
ad b
atte
rs.
The
suc
cess
es a
nd fa
ilure
s us
ing
vetiv
er to
pro
tect
cut
slo
pes
alon
g th
e H
o C
hi M
inh
Hig
hway
are
inst
ruct
ive:
• Sl
opes
mus
t fir
st b
e in
tern
ally
sta
ble.
Sin
ce v
etiv
er i
s m
ost
help
ful
at m
atur
ity,
slop
es m
ay f
ail
in t
he i
nter
im.
Vet
iver
be
gins
to
stab
ilize
a s
lope
at
thre
e to
fou
r m
onth
s, a
t ea
rli-
est.
The
refo
re, t
he ti
min
g of
pla
ntin
g is
als
o ve
ry im
port
ant i
f sl
ope
failu
re d
urin
g th
e ra
iny
seas
on is
to b
e av
oide
d.
• A
ppro
pria
te s
lope
ang
le s
houl
d no
t exc
eed
45-5
0º.
• R
egul
ar t
rim
min
g w
ill e
nsur
e co
ntin
ued
grow
th a
nd t
iller
ing
of th
e gr
ass,
and
thus
ens
ure
dens
e, e
ffec
tive
hedg
erow
s.
Pos
itio
n on
th
e ba
tter
Roo
t de
pth
(cm
/inch
)6
mon
ths
12 m
onth
s1.
5 ye
ar2
year
s
Cut
Bat
ter
1B
otto
m
70/2
812
0/47
12
0/47
120/
47
2M
iddl
e 72
/28
110/
43
100/
3914
5/57
3To
p 72
/28
105/
41
105/
41
187/
74
Fill
Bat
ter
4B
otto
m
82/3
2 95
/37
95/3
7 18
0/71
5M
iddl
e 85
/33
115/
45
115/
45
180/
71
6To
p 68
/27
70/2
8 75
/30
130/
51
84
Ph
oto
28:
Ph
am H
on
g D
uc
Ph
uo
c, a
ro
ad p
rote
ctio
n p
roje
ct i
n K
han
h
Ho
a p
rovi
nce
, ro
ad t
o H
on
Ba)
: lef
t tw
o p
ho
tos:
sev
ere
ero
sio
n o
n n
ewly
bu
ilt b
atte
r o
ccu
rs a
fter
on
ly a
few
rai
ns;
rig
ht
two
ph
oto
s: e
igh
t m
on
ths
afte
r ve
tive
r p
lan
tin
g: V
etiv
er s
tab
ilize
d t
his
slo
pe,
to
tally
sto
pp
ing
an
d
pre
ven
tin
g f
urt
her
ero
sio
n d
uri
ng
th
e n
ext
wet
sea
son
.
6. C
ON
CL
USI
ON
S
Follo
win
g co
nsid
erab
le
rese
arch
an
d th
e su
cces
ses
of
the
man
y ap
plic
atio
ns p
rese
nted
in th
is h
andb
ook,
we
now
hav
e en
ough
evi
denc
e th
at v
etiv
er, w
ith it
s m
any
adva
ntag
es a
nd v
ery
few
dis
adva
ntag
es, i
s a
very
eff
ectiv
e, e
cono
mic
al, c
omm
unity
-bas
ed a
nd e
nvir
onm
enta
lly-
frie
ndly
sust
aina
ble
bioe
ngin
eeri
ng to
ol th
at p
rote
cts i
nfra
stru
ctur
e an
d m
itiga
tes
natu
ral d
isas
ters
, and
, onc
e es
tabl
ishe
d, th
e ve
tiver
pla
ntin
gs
will
last
for
dec
ades
with
littl
e, if
any
mai
nten
ance
. VS
has
been
use
d su
cces
sful
ly i
n m
any
coun
trie
s in
the
wor
ld,
incl
udin
g A
ustr
alia
, B
razi
l, C
entr
al A
mer
ica,
C
hina
, E
thio
pia,
In
dia,
It
aly,
M
alay
sia,
N
epal
, Phi
lippi
nes,
Sou
th A
fric
a, S
ri L
anka
, Tha
iland
, Ven
ezue
la, a
nd
85
Vie
tnam
. H
owev
er,
it m
ust
be s
tres
sed
that
the
mos
t im
port
ant
key
to s
ucce
ss a
re g
ood
qual
ity p
lant
ing
mat
eria
l, pr
oper
des
ign,
cor
rect
pl
antin
g te
chni
ques
.
7. R
EF
ER
EN
CE
S
Bra
cken
, N
. an
d T
ruon
g, P
.N.
(2 0
00).
App
licat
ion
of V
etiv
er G
rass
Te
chno
logy
in
the
stab
iliza
tion
of r
oad
infr
astr
uctu
re i
n th
e w
et t
ropi
cal
regi
on o
f A
ustr
alia
. Pr
oc.
Seco
nd I
nter
natio
nal
Vet
iver
Con
f. T
haila
nd, J
anua
ry 2
000.
Che
ng H
ong,
Xia
ojie
Yan
g, A
ipin
g L
iu,
Hen
gshe
ng F
u, M
ing
Wan
(2
003)
. A S
tudy
on
the
Perf
orm
ance
and
Mec
hani
sm o
f So
il-re
info
rcem
ent b
y H
erb
Roo
t Sys
tem
. Pro
c. T
hird
Int
erna
tiona
l V
etiv
er C
onf.
Chi
na, O
ctob
er 2
003.
Dal
ton,
P. A
., Sm
ith, R
. J. a
nd T
ruon
g, P
. N. V
. (1
996)
. Vet
iver
gra
ss
hedg
es f
or e
rosi
on c
ontr
ol o
n a
crop
ped
flood
plai
n, h
edge
hy
drau
lics.
Agr
ic. W
ater
Man
agem
ent:
31(1
, 2)
pp 9
1-10
4.H
engc
haov
anic
h, D
. (1
998)
. V
etiv
er g
rass
for
slo
pe s
tabi
lizat
ion
and
eros
ion
cont
rol,
with
par
ticul
ar r
efer
ence
to
engi
neer
ing
appl
icat
ions
. Te
chni
cal
Bul
letin
N
o.
1998
/2.
Paci
fic
Rim
V
etiv
er N
etw
ork.
Offi
ce o
f th
e R
oyal
Dev
elop
men
t Pr
ojec
t B
oard
, Ban
gkok
, Tha
iland
.H
engc
haov
anic
h, D
. an
d N
ilaw
eera
, N
. S.
(19
96).
An
asse
ssm
ent
of
stre
ngth
pro
pert
ies
of v
etiv
er g
rass
roo
ts i
n re
latio
n to
slo
pe
stab
ilisa
tion.
Pro
c. F
irst
Int
erna
tiona
l V
etiv
er C
onf.
Tha
iland
pp
. 153
-8.
Jasp
ers-
Fock
s, D
.J a
nd A
. Alg
era
(200
6). V
etiv
er G
rass
for R
iver
Ban
k Pr
otec
tion.
Pro
c. F
ourt
h V
etiv
er In
tern
atio
nal C
onf.
Ven
ezue
la,
Oct
ober
200
6.L
e V
an D
u, a
nd T
ruon
g, P
. (20
03).
Vet
iver
Sys
tem
for E
rosi
on C
ontr
ol
on D
rain
age
and
Irri
gatio
n C
hann
els
on S
ever
e A
cid
Sulp
hate
So
il in
Sou
ther
n V
ietn
am.
Proc
. T
hird
Int
erna
tiona
l V
etiv
er
Con
f. C
hina
, Oct
ober
200
3.Pr
ati A
mat
i, Sr
l (20
06).
She
ar s
tren
gth
mod
el. "
PRA
TI A
RM
AT
I Sr
l"
info
@pr
atia
rmat
i.it
. T
ruon
g, P
. N. (
1998
). V
etiv
er G
rass
Tec
hnol
ogy
as a
bio
-eng
inee
ring
to
ol f
or i
nfra
stru
ctur
e pr
otec
tion.
Pro
ceed
ings
Nor
th R
egio
n Sy
mpo
sium
. Q
ueen
slan
d D
epar
tmen
t of
Mai
n R
oads
, C
airn
s
86
Aug
ust,
1998
.T
ruon
g, P
., G
ordo
n, I
. an
d B
aker
, D
. (1
996)
. To
lera
nce
of v
etiv
er
gras
s to
som
e ad
vers
e so
il co
nditi
ons.
Pro
c. F
irst
Int
erna
tiona
l V
etiv
er C
onf.
Tha
iland
, Oct
ober
200
3.X
ia, H
. P. A
o, H
. X. L
iu, S
. Z. a
nd H
e, D
. Q. (
1999
). A
pplic
atio
n of
the
vetiv
er g
rass
bio
-eng
inee
ring
tec
hnol
ogy
for
the
prev
entio
n of
hig
hway
slip
page
in
sout
hern
Chi
na.
Inte
rnat
iona
l V
etiv
er
Wor
ksho
p, F
uzho
u, C
hina
, Oct
ober
199
7.X
ie,
F.X
. (1
997)
. V
etiv
er f
or h
ighw
ay s
tabi
lizat
ion
in J
ian
Yan
g C
ount
y: D
emon
stra
tion
and
Ext
ensi
on. P
roce
edin
gs a
bstr
acts
. In
tern
atio
nal
Vet
iver
W
orks
hop,
Fu
zhou
, C
hina
, O
ctob
er
1997
.
87
IND
EX
Chr
ysop
ogon
zi
zani
oide
s i,
9cl
imat
ic v
aria
tion
3C
. nem
oral
is 9
coas
tal e
rosi
on 1
7, 4
6co
asta
l ero
sion
con
trol
73
coas
tal e
rosi
on c
ontr
ol
- ap
plic
atio
ns
73co
asta
l san
d du
nes
5co
mm
unity
in
volv
emen
t 43
ompu
ter
mod
ellin
g 40
cons
and
lim
itatio
ns
of p
lant
ing
vege
tatio
n on
sl
op 2
6cu
lver
t abu
tmen
ts 3
8cu
lver
t inl
ets
38
culv
ert o
utle
ts 3
8cu
t and
fill
batte
rs 3
7cu
t slo
pe 1
9, 4
5C
. ziz
anio
ides
9
D debr
is fl
ows
17
deci
sion
-mak
ing:
pr
ecau
tions
42
Dep
artm
ent o
f H
ydra
ulic
E
ngin
eeri
ng a
t D
elft
Tec
hnic
al
Uni
vers
ity 7
5di
ke a
nd d
am b
atte
r st
abili
satio
n 3
8di
seas
es a
nd fi
re.
2di
ssol
ved
nutr
ient
s
such
as
N a
nd
P an
d he
avy
met
als
in
pollu
ted
wat
er.
3di
stur
bed
land
s. 4
driv
ing
forc
es 1
9dr
ough
t 3
E eart
hqua
kes
18
ecol
ogic
al
char
acte
rist
ics
4
Elis
e Pi
nner
s ii
extr
eme
acid
sul
phat
e
6ex
trem
e te
mpe
ratu
re 3
F farm
dam
bat
ters
38
fast
cur
rent
66
fenc
ing
and
cari
ng 4
8fe
rtili
zing
48
Fiji
-vet
iver
cul
tivar
14
fire
4fla
sh fl
oodi
ng 1
7flo
od 3
flood
miti
gatio
n 4
6fr
ost
3, 6
G grad
ed c
onto
ur te
rrac
es
37gr
avita
tiona
l for
ces
20
grav
itatio
nal s
tres
ses.
A acid
ity 3
adap
tabi
lity
rang
e 7
adva
ntag
es a
nd
disa
dvan
tage
s of
V
etiv
er S
yste
m
38al
kalin
ity 3
appl
icat
ions
of
VS
in
natu
ral d
isas
ter
miti
gatio
n an
d in
fras
truc
ture
pr
otec
tion
37
appl
icat
ion
to c
ontr
ol
rive
r ba
nk
eros
ion
63
B bam
boo
28
bioe
ngin
eeri
ng
tech
niqu
e 1
bio-
filte
r 3
0br
idge
s 3
8
C Can
Tho
Uni
vers
ity 6
3C
asua
rina
s tr
ees
28
char
acte
rist
ics
of
vetiv
er s
uita
ble
for
slop
e st
abili
satio
n 2
9C
hrys
opog
on la
wso
nii
9C
hrys
opog
on
nem
oral
is 9
Chr
ysop
ogon
nig
rita
na
13, 1
4
88
19gr
id p
atte
rn 6
7gu
llies
38
H hard
str
uctu
res:
pr
otec
tion
38
heav
y m
etal
s 3
hedg
erow
iH
engc
haov
anic
h 3
5H
engc
haov
anic
h, D
iti
iiihe
rbic
ides
3hi
ghw
ays
37
high
way
sta
biliz
atio
n
iiiH
o C
hi M
inh
Hig
hway
80
hydr
aulic
for
ces
20
hydr
aulic
mod
el o
f flo
odin
g 3
6
I infr
astr
uctu
re
prot
ectio
n 4
9in
terf
ace
- co
ncre
te a
nd
soil
38
iver
ban
k er
osio
n co
ntro
l 56
J John
Gre
enfie
ld 2
K Kar
nata
ka -
vet
iver
cu
ltiva
r 1
4
L land
slid
es 1
7, 1
8lo
ngev
ity.
38
M Mad
upat
ty -
vet
iver
cu
tivar
14
mag
nesi
um 3
mai
nten
ance
and
rep
air
42m
aint
enan
ce c
osts
39
man
grov
e tr
ees
28
Mek
ong
Del
ta 6
3M
ekon
g ri
ver
66
Mon
to -
vet
iver
cu
ltiva
r 9
, 14
N natu
ral d
isas
ters
17,
49
natu
ral m
angr
ove
78
nort
h In
dian
acc
essi
ons
9nu
rse
plan
t 4
Nur
sery
44
P Paul
Tru
ong
iipe
stic
ides
3pe
sts:
res
ista
nce
2ph
ysio
logi
cal
char
acte
rist
ics
3
plan
ning
and
or
gani
satio
n:
42pl
antin
g: p
repa
ratio
n
44pl
antin
g tim
e 4
3pl
ant s
hadi
ng 4
plan
t sho
ots
2pl
ant:
wat
erin
g ne
eds
47
poin
t sou
rce
ipo
re w
ater
pre
ssur
e
21, 3
7Pr
ati A
mat
i 40
proc
urem
ent
43
R railw
ays
37
resi
stin
g fo
rces
19,
21
rhiz
omes
2ri
gid
stru
ctur
e:
prot
ectio
n 2
4ri
ver
bank
ero
sion
17,
56
rive
r ba
nk p
rote
ctio
n
59ri
ver
bank
s 3
8ri
verb
ank
stab
ilisa
tion
66
road
bat
ter
19,
45,
65
Rob
erty
1ro
ot d
epth
83
root
dep
th o
n ro
ad
batte
r 8
3ro
ot d
iam
eter
di
stri
butio
n 3
3ro
ot g
row
th -
eff
ect o
f so
il te
mpe
ratu
re
7ro
ots
2, 1
2
S salin
ity 3
sand
dun
e pr
otec
tion
49
sea
dike
- a
cid
sulp
hate
so
ils 7
8se
a di
kes
18
sedi
men
t filte
r 2
slop
e an
gle
limita
tions
on
esta
blis
hmen
t of
vege
tatio
n 2
7
89
and
eros
ion
copn
trol
19
V Vet
iver
Gra
ss -
A
Hed
ge A
gain
st
Ero
sion
2V
ietn
am I
nstit
ute
of
Geo
scie
nces
an
d M
iner
al
Res
ourc
es i
i
W wat
er r
etai
ning
st
ruct
ures
in
stab
ility
46
wat
er s
prea
der
2w
ave
actio
n 3
8, 6
6w
ave
run
up r
educ
tion
75
Wes
t Afr
ica
13
Will
iam
Don
ner
Foun
datio
n
63,7
7W
orld
Ban
k 1
slop
e fa
ilure
22
slop
e pr
ofile
19
slop
e st
abili
ty 1
9sl
ope
stab
ility
- g
ener
al
phys
ical
eff
ects
of
veg
etat
ion
26
sodi
city
3so
il an
d w
ater
co
nser
vatio
n 1
soil
pH 3
sout
h In
dian
ac
cess
ions
14
stab
iliza
tion,
hig
hway
iii
stab
ilize
roa
d ba
tter
65
stol
ons
2su
bmer
genc
e 3
Suns
hine
- v
etiv
er
culti
var
9, 1
4
T tech
nica
l pre
caut
ions
42
tens
ile a
nd s
hear
st
reng
th o
f V
etiv
er r
oots
33
tens
ile s
tren
gth
of
vetiv
er r
oots
35
tens
ile s
tren
gth:
oth
er
plan
t roo
ts 3
4tim
ing
42
timin
g: p
lant
ing
43
Tra
n Ta
n V
an i
i
U unde
rgro
und
crow
n 2
Upl
and
natu
ral s
lope
st
abili
zatio
n