appendix two – tunnel erosion brochure - victorian...
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76
76
Appendix two – Tunnel Erosion brochure
Pote
nti
al
imp
act
s o
f tu
nn
el
ero
sio
n
reduce
d p
roduct
ivit
y
soil
and n
utr
ient
loss
fro
m p
roper
ty
inju
ry t
o liv
esto
ck
dam
age
to f
arm
equip
men
t
har
bor
for
rabbit
s an
d w
om
bat
s
sedim
enta
tion o
f dam
s an
d w
ater
way
s
the
pote
nti
al t
o t
urn
into
hig
hly
act
ive
gully
er
osi
on (
Figure
s 3
& 5
)
neg
ativ
e im
pac
t on t
he
Gip
psl
and L
akes
’ w
ater
qual
ity.
Publis
hed
by
the
Dep
artm
ent
of
Prim
ary
Indust
ries
.©
The
Stat
e of
Vic
tori
a, July
20
04
This
public
atio
n is
copyr
ight.
No p
art
may
be
repro
duce
d b
y an
y pro
cess
exce
pt
in a
ccord
ance
wit
h t
he
pro
visi
ons
of
the
Cop
yrig
ht
Act
19
68
.R
evis
ed July
20
09
.A
uth
ori
sed b
y th
e V
icto
rian
Gove
rnm
ent,
1 S
pri
ng S
tree
t, M
elbourn
e,
Vic
tori
a, 3
000.
ISBN
1
-74
10
6-6
50
-6
Dis
clai
mer
: T
his
pub
lica
tion m
ay b
e of
assi
stan
ce t
o y
ou b
ut
the
Stat
e of
Vic
tori
a an
d its
em
plo
yees
do n
ot
guar
ante
e th
at t
he
pub
lica
tion is
wit
hout
flaw
of
any
kin
d o
r is
wholly
app
rop
riat
e fo
r yo
ur
par
ticu
lar
purp
ose
s an
d t
her
efore
dis
clai
ms
all liab
ilit
y fo
r an
y er
ror, loss
or
oth
er c
onse
quen
ce w
hic
h m
ay a
rise
fro
m y
ou
rely
ing
on a
ny
info
rmat
ion in t
his
pub
lica
tion.
For
furt
her
info
rma
tion
ab
ou
t D
PI vis
it t
he w
eb
site
at
ww
w.
dp
i.vic
.gov.
au
or
con
tact
th
e D
PI
Cu
stom
er
Serv
ice C
en
tre
on
13
6 1
86
.
Kn
ow
n s
usce
pti
ble
are
as
Mit
chel
l R
iver
esc
arpm
ents
Gle
nal
adal
e
Mel
wood
Mount
Tayl
or
Clif
ton C
reek
Bruth
en
Kal
imna
Stra
tford
DEP
ART
MEN
T O
FPR
IMA
RY IN
DU
STR
IES
An
earl
y i
den
tifi
cati
on
g
uid
e f
or
East
Gip
psla
nd
Tunnel
Ero
sion
CC
09
/tl0
9_0
62
00
9
Figure
5:
Illust
rati
ng p
oten
tial dam
age
of t
unnel
ero
sion
.
77
Tunnel erosion in East Gippsland
77
Tunnel e
rosio
n is
....
....
. a n
atu
rally o
ccurr
ing pro
cess -
A p
roce
ss w
her
e th
e su
bso
il is
ero
ded
by
wat
er f
orm
ing u
nder
gro
und t
unnel
s.
It is
oft
en
asso
ciat
ed w
ith s
oils
that
hav
e a
har
d-s
etti
ng
top s
oil
ove
r a
subso
il (c
lay)
whic
h m
ay b
e st
able
when
dry
but
read
ily d
isper
ses
when
wet
(F
igure
4).
Iden
tify
ing t
unnel
ero
sion
in t
he
earl
y st
ages
is
difficu
lt a
s in
dic
atio
ns
are
smal
l are
as o
f cl
ay
dep
osits
and/o
r hol
es in
the
surf
ace
soil
on lo
wer
sl
opes
. As
mor
e su
bso
il is
was
hed
dow
n t
hro
ugh
the
‘tunnel
s’ f
an s
hap
ed c
lay
dep
osits
or fl
um
es
form
as
show
n in
Fig
ure
1.
As
mor
e su
bso
il is
was
hed
aw
ay, t
he
tunnel
s dee
pen
and w
iden
until t
he
roof
of
the
tunnel
ca
nnot
suppor
t its
own w
eight
and c
olla
pse
s fo
rmin
g h
oles
. At
this
sta
ge
the
ero
sion
is a
lrea
dy
w
ell a
dva
nce
d. E
ventu
ally
mor
e tu
nnel
s co
llapse
fo
rmin
g a
n a
ctiv
e gully
(Fi
gure
2, 3
and 4
).
Earl
y det
ection
of
tunnel
ero
sion
will
incr
ease
th
e ch
ance
s of
succ
essf
ul c
ontr
ol m
easu
res,
re
duci
ng t
he
repai
r co
sts
and li
mit t
he
dam
age
to
pro
duct
ive
farm
land a
nd t
he
Gip
psl
and L
akes
.Pro
duct
ivit
y a
nd w
hole
farm
assets
are
th
reate
ned b
y t
unnel ero
sio
n.
Earl
y s
ign
s o
f tu
nn
el
ero
sio
n
Smal
l hole
s an
d/o
r in
den
ts a
ppea
ring in
the
pas
ture
.
Wat
er ’s
pouti
ng’ f
rom
sm
all hole
s in
the
gro
und f
ollo
win
g h
eavy
rai
n.
Cla
y par
ticl
es d
eposi
ted in a
fan
shap
e on
the
pad
dock
surf
ace
(Fig
ure
1).
‘Dry
ing o
ff’ l
ines
in p
astu
re c
ause
d b
y sh
allo
w s
oil
dep
th (
Figure
2).
Colla
psi
ng s
urf
ace
soil
crea
ting e
longat
ed
dit
ches
, usu
ally
runnin
g d
ow
n a
slo
pe
(Fig
ure
3).
DEP
ART
MEN
T O
F PR
IMA
RY IN
DU
STR
IES
Figure
2:
Part
ial co
llapse
of
tunnel
wit
h d
ryin
g o
ff
lines
vis
ible
.
Figure
1:
Cla
y dep
osit
s ri
sing t
o th
e su
rface
thro
ugh a
n
outl
et,
crea
ting a
‘fan’ s
hape.
Figure
3:
Tunnel
col
lapse
and s
urf
ace
cla
y dep
osit
s.Fi
gure
4:
Start
of
gully
for
mati
on.