C/Doc/Let.04/L8890 Lawson and Treloar Pty Ltd ACN001882873 ABN55001882873 Page 1 Offices in Sydney, Melbourne and Brisbane Directors N.V. Lawson BE(Hons), MEngSc, FIEAust, CPEng P.D. Treloar BE(Hons), ME, PhD, FIEAust, CPEng, MASCE R.A. Rice BE(Hons), BSc, MEngSc, FIEAust, CPEng N.I. Collins BE(Civil), MEngSc, MIEAust, CPEng 16 February, 2004 Level 2, 27 Merriwa Street Gordon NSW 2072 PO Box 852, Pymble NSW 2073 Australia Phone: +61-2-9499 3000 Fax: +61-2-9499 3033 Email: [email protected] «FirstName» «LastName» «Company» «Address1» «City» «State» «PostCode» Our Ref: J2255/L8890 Dear Sir/Madam, Re: Brisbane Water Estuary Processes Study Lawson and Treloar, in association with Bio-Analysis, KBR, GHD Longmac and HLA Envirosciences have been commissioned by Gosford City Council to undertake an estuary processes study for the Brisbane Water Estuary. The Gosford Council Coastline Management, Lagoon Management and Coastline Planning Committee (CLP) has resolved to prepare an Estuary Management Plan for the Brisbane Water Estuary. The Estuary Processes Study is an integral step leading towards the preparation of such a plan. The intent of the Study is to provide an analysis of estuary processes, and to clearly identify any ongoing studies that are necessary to facilitate sound decisions about sustainable estuary management. This study builds on the findings of the Brisbane Water Data Compilation Study commissioned by Council and completed in 2002. An important part of this process is to inform key stakeholders who have an interest in the management of the Brisbane Water catchment, of the nature and findings of the Study. The study is broad in its coverage and will include assessments of:- catchment processes flora and fauna (including field studies of aquatic ecology) hydrodynamic processes (water movement) water quality processes geomorphological processes (such as sand shoal movement, mud siltation and foreshore erosion) recreational use cultural heritage the interactions amongst all of the above processes. This work is being undertaken under the direction of Gosford City Council’s CLP Committee. Discussions are underway between the Study Team, Gosford City Council, State agencies and other community groups in order to identify key issues for the Study. Due to the extensive nature of the investigations, the study will be conducted over a three-year period. During this time, periodic updates on the progress of the study will be posted on Gosford City Council’s website:- www.gosford.nsw.gov.au/information/environment/index.htm. Your input to the Study as a valued stakeholder of the Brisbane Water Estuary is greatly appreciated. If you have any questions or have information that you think is relevant to the study, please do not hesitate to forward your query or information to [email protected] or contact the undersigned. Yours faithfully, Louise Howells Associate, Senior Project Engineer
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
C/Doc/Let.04/L8890 Lawson and Treloar Pty Ltd ACN001882873 ABN55001882873 Page 1 Offices in Sydney, Melbourne and Brisbane
Directors N.V. Lawson BE(Hons), MEngSc, FIEAust, CPEng P.D. Treloar BE(Hons), ME, PhD, FIEAust, CPEng, MASCE R.A. Rice BE(Hons), BSc, MEngSc, FIEAust, CPEng N.I. Collins BE(Civil), MEngSc, MIEAust, CPEng 16 February, 2004
Level 2, 27 Merriwa Street Gordon NSW 2072 PO Box 852, Pymble NSW 2073 Australia Phone: +61-2-9499 3000 Fax: +61-2-9499 3033 Email: [email protected]
«FirstName» «LastName» «Company» «Address1» «City» «State» «PostCode» Our Ref: J2255/L8890 Dear Sir/Madam,
Re: Brisbane Water Estuary Processes Study Lawson and Treloar, in association with Bio-Analysis, KBR, GHD Longmac and HLA Envirosciences have been commissioned by Gosford City Council to undertake an estuary processes study for the Brisbane Water Estuary. The Gosford Council Coastline Management, Lagoon Management and Coastline Planning Committee (CLP) has resolved to prepare an Estuary Management Plan for the Brisbane Water Estuary. The Estuary Processes Study is an integral step leading towards the preparation of such a plan. The intent of the Study is to provide an analysis of estuary processes, and to clearly identify any ongoing studies that are necessary to facilitate sound decisions about sustainable estuary management. This study builds on the findings of the Brisbane Water Data Compilation Study commissioned by Council and completed in 2002. An important part of this process is to inform key stakeholders who have an interest in the management of the Brisbane Water catchment, of the nature and findings of the Study. The study is broad in its coverage and will include assessments of:- � catchment processes � flora and fauna (including field studies of aquatic ecology) � hydrodynamic processes (water movement) � water quality processes � geomorphological processes (such as sand shoal movement, mud siltation and foreshore erosion) � recreational use � cultural heritage � the interactions amongst all of the above processes. This work is being undertaken under the direction of Gosford City Council’s CLP Committee. Discussions are underway between the Study Team, Gosford City Council, State agencies and other community groups in order to identify key issues for the Study. Due to the extensive nature of the investigations, the study will be conducted over a three-year period. During this time, periodic updates on the progress of the study will be posted on Gosford City Council’s website:-
www.gosford.nsw.gov.au/information/environment/index.htm. Your input to the Study as a valued stakeholder of the Brisbane Water Estuary is greatly appreciated. If you have any questions or have information that you think is relevant to the study, please do not hesitate to forward your query or information to [email protected] or contact the undersigned. Yours faithfully, Louise Howells Associate, Senior Project Engineer
BRISBANE WATER ESTUARY PROCESSES STUDY
February 2004 Project StatusAs part of the Estuary Management Process administered by theDepartment of Infrastructure, Planning and Natural Resources(DIPNR), the Brisbane Water Estuary Processes Study is inpreparation to determine key processes in the estuary.
A multi-disciplinary team led by Lawson and Treloar is preparing thisstudy for Gosford City Council and DIPNR.
Location: Central Coast, NSWClient: Gosford City CouncilServices:To identify and assess key
processes for the estuary.
(Photograph: DIPNR)
Status of Brisbane Water within theNSW Estuary Management
Process
Brisbane Water, located near themouth of the Hawkesbury NepeanRiver system connects to the northernside of Broken Bay, a major estuaryjunction that also drains Pittwater tothe south and the Hawkesbury-Nepean River and its tributaries to thewest.
Complex interactions occur within thewaterway. They are governed by theentrance and the estuary's capacityfor exchange with ocean water. Thewaterway is intensively used forrecreational purposes.
The Rip Bridge
The study will investigate thefollowing processes:
� catchment processes and runoff
� flora and fauna (including fieldstudies of aquatic ecology)
� hydrodynamic processes (watermovement, waves)
� water quality processes
� geomorphological processes(such as sand shoal movement,mud siltation and foreshoreerosion)
� recreational use
� cultural heritage
� the interactions amongst all of theabove processes
In terms of current project status, theproject commenced in January2004. At present, hydrographicsurvey of some of the bay areas isbeing undertaken by the Departmentof Infrastructure, Planning andNatural Resources. Following this, aDELFT3D model for estuarineprocesses will be prepared to aidthe assessment of thehydrodynamics of the estuaryincluding currents, waves andadvection-dispersion processes andsiltation.
The model will be used to considerboth day to day tidal conditions aswell as the effect of rainfall-runoffevents in the catchment.
Catchment modelling will beundertaken to provide inputs to theDELFT-3D model.
Other studies such as ecologicalinvestigations and recreationalstudies will commence shortly.
Waterfall Bay
If you would like to be added to thecontact database for the project, orhave information on the estuary thatmay be helpful, please forward yourdetails by email to:[email protected]
LAWSON AND TRELOAR
Implementation of the Plan
Estuary Management Plan
Estuary Management Study
Estuary Processes Study
Data Compilation/Collection
Formation of Committee
O
n T
hu
rsd
ay
1st
July
Go
sfo
rd C
ity
Co
un
cil
will
be
h
ost
ing
th
e B
risb
an
e W
ate
r E
stu
ary
Pro
ce
sse
s S
tud
y In
form
ati
on
Eve
nin
g in
th
e E
rin
a R
oo
m a
t th
e E
rin
a C
en
tre
, Eri
na
Fa
ir.
Pla
nkt
on
an
d t
he
ir u
se a
s in
dic
ato
rs
of
est
ua
rin
e h
ea
lth
(D
r A
nn
a
Re
dd
en
, Ne
wc
ast
le U
niv
ers
ity)
U
nd
ers
tan
din
g h
ow
est
ua
rie
s re
spo
nd
to
ra
infa
ll e
ven
ts,
ass
oc
iate
d
nu
trie
nt
an
d
sed
ime
nt
inp
uts
a
nd
v
ari
ou
s p
hy
sic
al
an
d
bio
ge
oc
he
mic
al
pro
ce
ss
es
is
c
riti
ca
l fo
r th
eir
su
cc
ess
ful
ma
na
ge
me
nt.
It
req
uir
es
a
co
mp
reh
en
sive
a
sse
ssm
en
t o
f th
e
hyd
rod
yna
mic
s,
ho
w
wa
ter
qu
alit
y va
rie
s sp
ati
ally
an
d t
em
po
rally
an
d h
ow
th
es
e
va
ria
ble
s
imp
ac
t o
n
the
d
istr
ibu
tio
n
an
d
ab
un
da
nc
e
of
pla
nkt
on
ic
form
s (p
hyt
op
lan
kto
n
ce
lls
an
d z
oo
pla
nkt
on
gra
zers
). T
he
pla
nkt
on
c
om
mu
nit
y n
ot
on
ly r
efl
ec
ts t
he
nu
trie
nt
sta
tus
an
d w
ate
r q
ua
lity
of
the
sys
tem
, it
als
o r
ep
rese
nts
a c
riti
ca
l fo
od
so
urc
e
for
larv
al
an
d j
uve
nile
fis
he
s a
nd
filt
er
fee
din
g s
he
llfis
h (
e.g
. oys
ters
).
Se
ag
rass
es
(Te
nie
lle B
oyl
an
d a
nd
M
an
dy
Co
x -
Ne
wc
ast
le U
niv
ers
ity)
Q
ua
nti
tati
ve
da
ta
on
se
ag
rass
es
is
be
ing
co
llec
ted
at
a n
um
be
r o
f sp
ati
al
sca
les
wit
hin
th
e
est
ua
ry
to
ass
ess
a
spe
cts
su
ch
as
de
nsi
ty,
co
ver,
sh
oo
t le
ng
th
an
d
the
c
ove
r o
f e
pip
hyt
es
att
ac
he
d t
o t
he
le
ave
s. T
he
se
ag
rass
d
ata
w
ill
a
lso
b
e
use
d
to
sele
ct
ap
pro
pri
ate
lo
ca
tio
ns
to
s
am
ple
a
sse
mb
lag
es
of
fish
wit
hin
th
e e
stu
ary
.
Th
e in
form
ati
on
eve
nin
g c
om
me
nc
es
at
7.3
0p
m
7:3
0
We
lco
me
an
d in
tro
du
cti
on
(L
ou
ise
G
ee
, D
ire
cto
r E
nv
iro
nm
en
tal
Pla
nn
ing
, GC
C)
7:3
5
Ba
ckg
rou
nd
to
B
risb
an
e
Wa
ter
Est
ua
ry
Pro
ce
sse
s S
tud
y (D
r P
ete
r F
ree
wa
ter,
N
atu
ral
Re
sou
rce
s O
ffic
er,
GC
C)
7:4
5
Ove
rvie
w o
f th
e B
risb
an
e W
ate
r E
stu
ary
Pro
ce
sse
s S
tud
y (L
ou
ise
H
ow
ells
, La
wso
n &
Tre
loa
r)
8:0
0
Re
cre
ati
on
al
as
pe
cts
(T
om
H
old
en
, Ke
llog
Bro
wn
& R
oo
t)
8:1
5
Ov
er
vie
w
of
ec
olo
gic
al
inve
stig
ati
on
s (D
r D
an
ny
Ro
be
rts,
B
io-A
na
lysi
s)
8:3
0
Sa
ltm
ars
he
s (G
eo
ff S
ain
ty,
Sa
inty
&
Ass
oc
iate
s)
8:4
5
Be
nth
ic i
nve
rte
bra
tes
(Dr
Will
iam
G
lad
sto
ne
, Ne
wc
ast
le U
niv
ers
ity)
9:0
0
Pla
nk
ton
(D
r A
nn
a
Re
dd
en
, N
ew
ca
stle
Un
ive
rsit
y)
9:1
5
Se
ag
rass
es
(Te
nie
lle B
oyl
an
d a
nd
M
an
dy
C
ox
-
Ne
wc
as
tle
U
niv
ers
ity)
9:3
0
Co
nc
lus
ion
(L
ou
ise
H
ow
ell
s,
La
wso
n &
Tre
loa
r)
This
bro
chur
e ha
s bee
n pr
epar
ed b
y G
osfo
rd C
ity C
ounc
il.
Prin
ted
on 1
00%
Rec
ycle
d pa
per b
y G
osfo
rd C
ity C
ounc
il 49
Man
n St
reet
Gos
ford
NSW
225
0 Ju
ne 2
004
– Pl
ease
recy
cle
Bri
sba
ne
Wa
ter
Est
ua
ry P
roc
ess
es
Stu
dy
INF
OR
MA
TIO
N E
VE
NIN
G
PR
OG
RA
M
Da
te:
1 J
uly
20
04
Ve
nu
e: E
rin
a R
oo
m,
Eri
na
Ce
ntr
e
Tim
e: 7
.30
pm
-9.3
0p
m
Info
rma
tio
n E
ven
ing
O
verv
iew
of
ec
olo
gic
al
inve
stig
ati
on
s (D
r D
an
ny
Ro
be
rts,
B
io-A
na
lysi
s)
Ge
ne
ral
intr
od
uc
tio
n
to
the
a
qu
ati
c
ec
olo
gy
of
Bri
sba
ne
W
ate
r e
stu
ary
, w
hic
h w
ill in
clu
de
a s
um
ma
ry o
f e
ac
h o
f th
e p
roje
cts
. In
ge
ne
ral
the
se w
ill b
e
salt
ma
rsh
es,
m
an
gro
ves,
se
ag
rass
es,
fi
sh
an
d
inve
rte
bra
tes.
P
relim
ina
ry
info
rma
tio
n o
n t
he
sa
ltm
ars
he
s w
ith
in
the
e
stu
ary
a
nd
th
e
me
tho
ds
be
ing
u
sed
to
q
ua
nti
fy
the
m
will
a
lso
b
e
pre
sen
ted
. S
alt
ma
rsh
es
(Ge
off
Sa
inty
, Sa
inty
&
Ass
oc
iate
s)
Th
e
Bri
sba
ne
W
ate
r e
stu
ary
h
as
ha
d
sig
nif
ica
nt
mo
dif
ica
tio
ns
to i
ts n
atu
ral
fore
sho
res
sin
ce
Eu
rop
ea
n c
olo
nis
ati
on
a
nd
th
e e
xte
nt
of
this
mo
dif
ica
tio
n h
as
no
t p
revi
ou
sly
be
en
qu
an
tifi
ed
. A
ra
pid
a
sse
ssm
en
t m
eth
od
wa
s d
eve
lop
ed
fo
r a
sse
ssin
g t
he
ec
olo
gic
al d
istu
rba
nc
e o
f th
e f
ore
sho
res.
Th
e a
im w
as
to o
bta
in
an
ass
ess
me
nt
of
the
ec
olo
gic
al
valu
e
of
sec
tio
ns
of
fore
sho
res
an
d
ob
tain
se
mi-
qu
an
tita
tive
da
ta o
n
the
fri
ng
ing
ve
ge
tati
on
.
Be
nth
ic in
vert
eb
rate
s (D
r W
illia
m
Gla
dst
on
e, N
ew
ca
stle
Un
ive
rsit
y)
Th
e g
oa
l o
f th
is p
roje
ct
is t
o d
esc
rib
e
the
va
ria
tio
n
tha
t o
cc
urs
a
mo
ng
in
vert
eb
rate
c
om
mu
nit
ies
of
Bri
sba
ne
W
ate
r e
stu
ary
a
nd
it
s re
lati
on
ship
to
e
nvi
ron
me
nta
l va
ria
ble
s (e
g.
wa
ter
an
d
sed
ime
nt
qu
alit
y).
Th
e
Bri
sb
an
e
Wa
ter
Es
tua
ry
Pro
ce
sse
s S
tud
y is
a c
utt
ing
ed
ge
re
sea
rch
pro
jec
t th
at
will
gu
ide
th
e
futu
re m
an
ag
em
en
t o
f th
e e
stu
ary
a
nd
it
s
ca
tch
me
nts
.
Th
e
Info
rma
tio
n E
ven
ing
will
pro
vid
e a
n
op
po
rtu
nit
y to
co
me
an
d le
arn
ab
ou
t B
risb
an
e W
ate
r a
nd
th
e f
asc
ina
tin
g
rese
arc
h
cu
rre
ntl
y u
nd
erw
ay.
A
tea
m
of
scie
nti
sts
an
d
oth
er
rese
arc
he
rs w
ill b
e p
rese
nti
ng
th
eir
w
ork
o
n
Bri
sba
ne
W
ate
r in
p
lain
E
ng
lish
fo
r th
e b
en
efi
t o
f a
ll. Y
ou
will
le
arn
a
bo
ut
the
d
iffe
ren
t fi
sh,
an
ima
ls a
nd
pla
nts
an
d h
ow
na
tura
l a
nd
h
um
an
p
roc
ess
es
infl
ue
nc
e
the
ir h
ea
lth
an
d s
urv
iva
l.
Th
e s
pe
ake
rs w
ill a
lso
an
swe
r yo
ur
qu
es
tio
ns
a
nd
p
rov
ide
a
n
op
po
rtu
nit
y fo
r yo
u t
o h
ave
yo
ur
say
ab
ou
t h
ow
Bri
sba
ne
Wa
ter
sho
uld
b
e m
an
ag
ed
. F
or
exa
mp
le,
ho
w d
o
we
b
ala
nc
e
co
mm
erc
ial
an
d
de
ve
lop
me
nt
inte
res
ts
wit
h
co
nse
rva
tio
n?
Ba
ckg
rou
nd
to
S
tud
y (D
r P
ete
r F
ree
wa
ter,
N
atu
ral
Re
so
urc
es
Off
ice
r, G
CC
)
Th
e
pro
ce
sse
s st
ud
y is
b
ase
d
on
a
h
olis
tic
fra
me
wo
rk i
nc
orp
ora
tin
g t
hre
e
dis
tin
ct
co
mp
on
en
ts:
1
la
nd
u
se
in
the
c
atc
hm
en
t a
nd
a
sso
cia
ted
imp
ac
t to
wa
terw
ays
2
lin
kin
g
lan
d-u
se
wit
h
ca
tch
me
nt
hyd
rolo
gy
3
lin
kin
g
ca
tch
me
nt
hyd
rolo
gy
wit
h
ec
olo
gic
al p
he
no
me
na
T
he
ove
rarc
hin
g o
bje
cti
ve is
to
ad
dre
ss
the
im
pa
ct
of
lan
d-u
se a
nd
wa
terw
ays
m
an
ag
em
en
t w
ith
e
stu
ari
ne
e
co
log
y a
nd
de
velo
p g
uid
elin
es
for
sust
ain
ab
le
ma
na
ge
me
nt.
O
verv
iew
o
f th
e
Bri
sba
ne
W
ate
r E
stu
ary
P
roc
ess
es
Stu
dy
(Lo
uis
e
Ho
we
lls, L
aw
son
& T
relo
ar)
: T
he
Bri
sba
ne
Wa
ter
Est
ua
ry P
roc
ess
es
Stu
dy
wa
s c
om
mis
sio
ne
d i
n D
ec
em
be
r 2
00
3 a
nd
is s
ch
ed
ule
d f
or
co
mp
leti
on
in
De
ce
mb
er
20
06
. T
he
ma
in o
bje
cti
ve i
s to
pro
vid
e a
co
mp
reh
en
sive
re
po
rt o
n
the
e
xist
ing
p
hys
ica
l,
ch
em
ica
l a
nd
b
iolo
gic
al
co
nd
itio
n o
f th
e E
stu
ary
an
d
tho
se p
roc
ess
es
an
d i
nte
rac
tio
ns
tha
t in
flu
en
ce
its
co
nd
itio
n.
Fo
r fu
rth
er
de
tails
ab
ou
t th
e B
risb
an
e W
ate
r E
stu
ary
Pro
ce
sse
s S
tud
y, c
on
tac
t
Dr
Pe
ter
Fre
ew
ate
r o
n 4
32
5 8
93
5 o
r vi
sit
Co
un
cil’
s w
eb
site
go
sfo
rd@
nsw
.go
v.a
u
BRISBANE WATER ESTUARY PROCESSES STUDY
July 2004 Project Status As part of the Estuary Management Process administered by the Department of Infrastructure, Planning and Natural Resources (DIPNR), the Brisbane Water Estuary Processes Study is in preparation to determine key processes in the estuary. A multi-disciplinary team led by Cardno Lawson Treloar is preparing this study for Gosford City Council and DIPNR.
Location: Central Coast, NSW Client: Gosford City Council Services: To identify and assess key
processes for the estuary.
(Photograph: DIPNR)
Status of Brisbane Water within the
NSW Estuary Management Process
Project Partners:
Brisbane Water, located near the mouth of the Hawkesbury Nepean River system connects to the northern side of Broken Bay, a major estuary junction of Pittwater to the south and the Hawkesbury-Nepean River and its tributaries to the west. Complex interactions occur within the waterway. They are strongly influenced by the entrance and the estuary's capacity for exchange with ocean water. The waterway is intensively used for recreational purposes.
Looking toward the Estuary from President Hill The study will investigate the following processes: � catchment processes and runoff � flora and fauna � hydrodynamic processes � water quality processes � geomorphological processes � recreational use � cultural heritage � interactions amongst processes. In terms of status, the project commenced in January 2004. Additional hydrographic survey of some of the bay areas has been completed since this time by DIPNR. A DELFT3D computer model for estuarine processes is currently being prepared using this data to aid the assessment of currents, waves, siltation, and transport and mixing processes.
This model will be used to consider both day to day tidal conditions as well as the effect of rainfall-runoff events in the catchment. Computer modelling of the catchment is nearing completion and will provide inputs to the DELFT-3D model. Ecological investigations have commenced and include a range of field investigations within the estuary. Recreational studies have commenced and input from the community will be sought in the coming months for these aspects of the study. Concurrent studies are also being undertaken by the University of Newcastle, which will assist the overall management of the estuary.
Jetties at Woy Woy Inlet If you would like further details or to be added to the contact database please forward your details by email to: [email protected] or contact Dr Peter Freewater at Gosford City Council on 4325 8945 or Louise Howells at Cardno Lawson Treloar on 9499 3000.
Implementation of the Plan
Estuary Management Plan
Estuary Management Study
Estuary Processes Study
Data Compilation/Collection
Formation of Committee
1
���������������� �������������� ��
������������������ � ������
������� The Brisbane Water Estuary Processes Study is in its third year and is being undertaken by a
team of consultants led by Cardno Lawson Treloar. The key components of the study are
summarised below.
Ocean Processes - Extends to include Pittwater and Offshore areas as
required (eg for water quality and exchange studies)
Catchment Processes (considerations of effects of residential land use,
industrial land use, bushland areas)
River Processes (considerations of interactions with the Hawkesbury -
Nepean River)
In-Estuary Processes (considerations of tides, waves, winds, water quality, sediments, human usage and flora
fauna (eg seagrass, saltmarsh, mangroves, benthic fauna, fish)
Foreshore Processes (considerations of foreshore areas and interactions,
interface for recreational activities)
���!������� �The project is nearing completion and final reporting is underway. A summary of the key
components of the project is contained below.
Component Status
Aboriginal and Cultural
Heritage Complete
Recreational Foreshore Study Complete
Estuarine Ecology Reporting being Completed
Potential Acid Sulphate Soils Complete
Hydraulic and Wave
Processes Complete
Estuarine
Morphology/Siltation Scenarios being Completed
Water Quality Processes Scenarios being Completed
2
"���� #��$���##���%&�#'�(&)A 2D/3D Delft3D hydraulic model of Brisbane Water has been developed and achieved a
high level of calibration. The following figures illustrate the water level and discharge
calibration of the model at a number of sites.
Water Level Calibration Discharge Calibration
������������%��*)Detailed investigations into wave processes have been completed using the SWAN wave
model. Wave climate information for local sea and ocean swell conditions have been
prepared in a GIS format.
Local Sea Conditions Local Swell Conditions
3
����+���,��������-��� �����$���.�#���
Sediment transport and estuarine morphology have been investigated using the integrated
hydrodynamic, wave and sediment transport capabilities of Delft3D. A MUSIC catchment
model developed for in this study has been used to estimate sediment loads into the estuary.
The following figures detail areas where sand and / or mud will be subject to transport
(indicated by yellow regions) during the 1-Years ARI wind conditions (integrated over all
wind directions).
1-Years ARI Bed Shear Stress 1-Years ARI Bed Current Velocity
Estuarine morphology has been investigated at a number of sites where siltation has been
identified as a potential issue. The following plot indicates the potential siltation rate (mm/yr)
at the entrance to Mudflat Creek (Hardy’s Bay) for a scenario included in this study.
Example of Siltation Rate Investigations near the Entrance to Mudflat Creek
4
����/ �#������������
Water quality processes have been investigated using the integrated hydrodynamic and water
quality capabilities of Delft3D. The MUSIC catchment model has been used to estimate
nutrient loads into the estuary. Investigations have included ambient and episodic conditions.
Flushing times for various branches of the estuary have been calculated. The following plots
detail peak TP and TN concentrations during the 20-Years ARI event.
20-Years ARI Peak TP Concentrations 20-Years ARI Peak TN Concentrations
BRISBANE WATER ESTUARY PROCESSES STUDY December 2006 Project Status
As part of the Estuary Management Process administered by the Department of Natural Resources (DNR), the Brisbane Water Estuary Processes Study is in the final stages of preparation. The study’s key objective has been to determine the key processes in the estuary.
A multi-disciplinary team led by Cardno Lawson Treloar is preparing this study for Gosford City Council and DNR.
Brisbane Water, located near the mouth of the Hawkesbury Nepean River system connects to the northern side of Broken Bay, a major estuary junction of Pittwater to the south and the Hawkesbury-Nepean River and its tributaries to the west.
Depths of the Estuary (‘Bathymetry’)
Superimposed over an Aerial Photograph
The Brisbane Water Estuary Processes Study is currently being completed by Cardno Lawson Treloar for Gosford City Council in accordance with the NSW Estuary Management Manual (1992). The study is investigating the following processes: � Catchment processes and runoff � Flora and fauna � Hydrodynamic processes � Water quality processes � Geomorphological processes � Recreational use � Cultural heritage � Interactions amongst processes. This project commenced in January 2004 and the issue of draft reports is
scheduled for the end of 2006. The majority of the studies are nearing completion. Examples of some of the findings to be reported are outlined below. Hydrodynamic Processes Hydrodynamic processes were investigated in detail using computer modelling. Overall, the modelling completed provides a comprehensive assessment of currents, waves, siltation and transport and mixing of substances within the estuary and supports an analysis of the effects that these factors have on various environments such as seagrasses, the benthic environment and other estuarine ecosystems. Flora and fauna Flora and fauna studies for the study have been extensive. Examples of images from the studies are below.
Saltmarsh Investigations - Cockle Bay
Numb Fish Over Seagrass – Near Mouth
Recreational Usage Recreational user studies including foreshore usage mapping and water usage mapping have been completed. An example of foreshore usage is shown below for Koolewong.
Example of Foreshore Usage Mapping Specialist research investigations have been conducted concurrently with the Estuary Processes Study, including studies of: � Sediment Quality (University of
Sydney) � Larval dispersal from Saltmarsh
(UNSW) � Benthic macrofauna studies
(University of Newcastle). Where available, the findings of these complex research projects will be utilised to further understand the processes occurring in the estuary. If you would like further details or to be added to the contact database please forward your details to: [email protected] Or contact: � Gosford City Council - Dr Peter
Freewater on 4325 8945 � Cardno Lawson Treloar - Louise
Collier on 9499 3000.
Related Documents
