201250 willams, david coastal and estuarine dynamics in the arafura and timor seas
DESCRIPTION
Presentation from NT Spatial 2012: Northern Exposure "Science and Applications"TRANSCRIPT
Coastal and Estuarine Dynamics in the Arafura Timor Seas
David WilliamsCoastal Oceanography
Australian Institute of Marine ScienceArafura Timor Research Facility
Darwin
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Once upon a time …….. a long time ago …………
coastal
estuarine
Short term projects
NTC
Site Length of record
Centre Island 1973 - 1987
Melville Bay (Gove) 1964 – 2006
Aurari Bay 1979 - 1986
Snake Bay 1980 - 1986
Darwin Harbour 1959 – 2012*
Port Keats 1980 – 1986
Milner Bay (Groote-BOM) 1993 -2012*
Coastal Tide gauge network operated by NT Government
Several other sites with a few years of record
Dept Nat Resources, The Arts & Sport HYPLOT V133 Output 27/04/2011
Period 3 Year 00:00_01/01/1975 to 00:00_01/01/1978 1975-78
G9070122 Centre Island Tide G100.00 2 Day Max & Min Level (m)
G9070122 Centre Island Tide G100.00 1 Month Mean Level (m)
1
2
3
4
5
1975 1976 1977
Dept Nat Resources, The Arts & Sport HYPLOT V133 Output 28/04/2011
Period 3 Year 00:00_01/01/1995 to 00:00_01/01/1998 1995-98
G8260215 Melville Bay Tide Ga120.00 2 Day Max & Min Tide Level (m)
G8260215 Melville Bay Tide Ga120.00 1 Month Mean Tide Level (m)
0
1
2
3
4
5
1995 1996 1997
Dept Nat Resources, The Arts & Sport HYPLOT V133 Output 28/04/2011
Period 3 Year 00:00_01/01/1982 to 00:00_01/01/1985 1982-85
G8160007 Snake Bay Tide Gauge100.00 2 Day Max & Min Level (m)
G8160007 Snake Bay Tide Gauge100.00 1 Month Mean Level (m)
1
2
3
4
5
1982 1983 1984
Dept Nat Resources, The Arts & Sport HYPLOT V133 Output 28/04/2011
Period 3 Year 00:00_01/01/1974 to 00:00_01/01/1977 1974-77
G8150029 Darwin Harbour Tide120.00 2 Day Max & Min Tide Level (m)
G8150029 Darwin Harbour Tide120.00 1 Month Mean Tide Level (m)
-0.2
1.8
3.8
5.8
7.8
9.8
1974 1975 1976
Dept Nat Resources, The Arts & Sport HYPLOT V133 Output 28/04/2011
Period 3 Year 00:00_01/01/1981 to 00:00_01/01/1984 1981-84
G8130003 Port Keats Tide Gaug100.00 2 Day Max & Min Level (m)
G8130003 Port Keats Tide Gaug100.00 1 Month Mean Level (m)
-0.1
1.9
3.9
5.9
7.9
9.9
1981 1982 1983
Tide gauges
coastal
estuarine
Short term projects
NTC / AIMS
South Alligator River – Van Diemens Gulf
5 m tide range ~ 100 km inland from mouth (6 m range at mouth)
Dept Nat Resources, The Arts & Sport HYPLOT V132 Output 28/04/2010
Period 1 Year Plot Start00:00_01/02/2007 2007/08Interval12 Hour Plot End 00:00_01/02/2008
G8200041 South Alligator R. 100.00 Max & MinLevel (m)
-5
-0
5
10
Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan
Study Location
Location of tidal bores
What we hope to achieve
• No previous field studies on tidal bores.• Role of tidal bore on sediment transport not
understood.• Sediment transport / estuarine ecology unknown.• Environmental flow requirements.• Develop sediment transport /water quality models and
contribute to catchment management.
The Daly River
Level and ADCP
level & S4level & ADCP
level
Tide levels in the lower estuary. Green line: ocean tide levels, Blue line: inside the mouth near Palmerston Island, Pink line: 10km upstream. Due to the shoals the tidal amplitude reduces with distance upstream and the tides become more asymmetric
0
1
2
3
4
5
6
7
8
00:0006:00
12:0018:00
00:0006:00
12:0018:00
00:00
time (hrs)
tid
e l
eve
l (m
)
ocean
inside mouth
10km inside
Flood dominance
Tide dominance
We found that recent flood did not take sediment out to sea
1.8
2.3
2.8
3.3
3.8
4.3
4.8
5 6 7
Flood tide asymmetry
Qin = Qout therefore Vin > Vout
Field trip August 2003 Focus on tidal bore
1 day tidal bore experiment: July – August 2003And 1 month long estuarine study (August 2003)
1 site for bore
Safety awards
4 m/s
Passage of bore
Undular bore dynamics
Speed
Water level
SSC nephelometers
Turbulent eddies form after the passage of the bore
Up and down welling
Horizontal shear Backscatter in shear zone
Downstream of shoal
100
7
Downwelling occurs on the edge of shears and eddies. Upwelling toward the centre.
Is important for the re suspension of sediment and nutrient.
boat track 2003 on 1980 map
Boat track on latest satellite image
1885 chart
surveyed by Lt Carrington
HMS Palmerston
Historical evidence for siltation at the mouth.
Compare bathymetric surveys of Carrington (1885) with our surveys in 2004at the RAN tide gauge station
Distance
Depth (m)
634000 635000 636000 637000 638000 639000 640000 641000 642000
8518000
8519000
8520000
8521000
8522000
8523000
8524000
8525000
8526000
8527000
8528000
8529000
1885 D aly M outh Survey
637000 638000 639000 640000 641000 642000 643000
8519000
8520000
8521000
8522000
8523000
8524000
8525000
8526000
8527000
8528000
8529000
D aly M outh 2004 Survey
637000 638000 639000 640000 641000 642000 643000
8519000
8520000
8521000
8522000
8523000
8524000
8525000
8526000
8527000
8528000
8529000
D aly R iver EstuarySurvey M arch 2006
Comparison of bathymetric surveys 1885 - 2004 - 2007
Year Volume (m3)
Planar Area(m2)
Volume/Area~mean depth (m)
1885 111,465,813 17,153,758 6.50
2004 95,041,625 23,779,795 4.00
2006 93,030,645 21,731,400 4.28
Dodgy calculations
Need to know LAT derived in 1885
Need to recalculate using a bit more care.
cage
Area 1050 km2
Darwin Harbour
Charles Pt
Lee Pt
Gunn Pt
Area: 620 km2
50 km
Transects
Moorings
Location of measurement sites
-1
0
1
2
3
4
5
6
7
8
9
0:00 6:00 12:00 18:00 0:00
nth Abuoy
Darwin
Wickham
StormPt
Prawn
Rocks
Darwin Harbour Tide Levels
Outer boundary to upstream Middle Arm
3.85
3.90
3.95
4.00
4.05
4.10
4.15
4.20
1958 1968 1978 1988 1998 2008
Darwin Harbour
mean Annual
Linear (mean Annual)
1.7 mm / year
R² = 0.1547
y = 0.0051x + 4.0135R² = 0.2143
3.7
3.8
3.9
4
4.1
4.2
4.3
4.4
-40 -30 -20 -10 0 10 20 30 40
MM
SL
SOI
SOI v MMSL
Predicted versus recorded 1974
Effect of cyclonic winds on Christmas eve 1974 reaching >=220 km/hr
3.85
3.90
3.95
4.00
4.05
4.10
4.15
4.20
1958 1968 1978 1988 1998 2008
Darwin Harbour
mean Annual
Linear (mean Annual)
1.7 mm / year
R² = 0.1547
Measurements with ADCP
120,000 m3/s
Darwin Harbour
Model network
Darwin Harbour
Circulation around headlands and embayments
Darwin Harbour
Currents near islands
Sediment Plumes
Distinctive particle traces
Darwin Harbourdredging disposal proposal
Sediment concentration (mg/L)
Darwin Harbourdredging disposal proposal
Sediment concentration (mg/L)
0 1020
30
40
50
60
70
80
90
100
110
120
130
140
150
160170180190
200
210
220
230
240
250
260
270
280
290
300
310
320
330
340350
0%
4%
8%
12%
16%
<=0.2
>0.2 - 0 .4
>0.4 - 0 .6
>0.6 - 0 .8
>0.8 - 1
>1 - 1 .2
>1.2 - 1 .4
>1.4
D arw in N R S Septem ber 2009
Sediment import – 34t / m / month
0 1020
30
40
50
60
70
80
90
100
110
120
130
140
150
160170180190
200
210
220
230
240
250
260
270
280
290
300
310
320
330
340350
0% 4% 8% 12% 16%
>0 - 0 .2
>0.2 - 0 .4
>0.4 - 0 .6
>0.6 - 0 .8
>0.8
East A rm near B laydin P t
Sediment import – 9t / m / month
0 1020
30
40
50
60
70
80
90
100
110
120
130
140
150
160170180190
200
210
220
230
240
250
260
270
280
290
300
310
320
330
340350
0% 2% 4% 6% 8% 10%
>0 - 0 .2
>0.2 - 0 .4
>0.4 - 0 .6
>0.6 - 0 .8
>0.8 - 1
>1 - 1 .2
>1.2 - 1 .4
>1.4
H udson C k deploym ent 1
Sediment export– 17t / m /month
Year 2009 day 200 hour 0.0002000.
0.20
East Arm
Residual currents – 1 lunar tide cycle
Understanding Flushing Characteristics
69
IXSURVEY Darwin Projects
New Technology First Darwin Port Corporation Surveys using modern
multi-beam technology Requires a tightly integrated survey system
comprising: Multibeam Echosounder Motion and Heading Reference Unit GPS 1 PPS timing
70
IXSURVEY Darwin Projects
Changes in shallow sounding technology Leadline
2 soundings / minute Single Beam
20 soundings / second Multibeam
2000 soundings + / second
71
IXSURVEY Darwin Projects
Jan 2010 First Darwin Survey Charles Point Patches LNG Terminal East Arm
Charles Point Patches
72
IXSURVEY Darwin Projects
Jan 2012 Check Survey on
Charles Point Patches
required due to changes
Charles Point Patches
73
IXSURVEY Darwin Projects
Combined Master Surface
Included 3rd party data
Deconfliction Most recent Least depth
74
IXSURVEY Darwin Projects
Hydrographic Survey Products High resolution bathymetry
Navigation safety Object / wreck detection Modelling for large vessel movements Modelling currents and water movement Modelling sediment movement
Sonar Backscatter Sediment classification Benthic Habitat Mapping
75IXSURVEY Darwin Projects
High Resolution Bathymetry
USS Peary
76IXSURVEY Darwin Projects
Entrance to Middle Arm – Looking South
77IXSURVEY Darwin Projects
Sonar Backscatter
Elizabeth River
Northern Australian Observation System
Conclusion
There are a few basic requirements
•Tides
•Bathymetry
•Currents
•River flows
•Sediment properties
•Other physical, chemical and biological parameters