Fitzroy – flood plumes. Transport

and processing of nutrients and

sediments in the GBR lagoon

Sampling in 2008Michelle Devlin, Zoe Bainbridge, Stephen Lewis

and Jon Brodie.

Why monitor Riverine plumes?

• Fifteen major river and many minor

catchments drain directly into the GBR

lagoon.

• These catchments are the main source

of terrestrial material and contaminants

into entering the GBR lagoon.

Why monitor riverine plumes?

Soil erosion from grazing lands increased suspended sediments

and particulate nutrients

Fertilized cropping Greatly increased nitrogen and phosphorus

losses

High nitrogen fertilizer use Greatly increased nitrate losses

Urban use Increased dissolved nutrient discharges

Loads of nitrogen and Phosphorus have increased significantly in

last 100 years.

Connectivity between land use and Great Barrier Reef lagoon.

Rivers – main source of pollutants

Landuse change affects the composition of runoff

MTSRF/GBRMPA marine monitoring

program – Flood plume monitoring

4 year program

To further our information on the extent,

duration of flood plumes

Transport and processing of pollutants

into GBR waters

Feedback into risk assessment, better

understanding of catchment land use and

GBR waters

Build into existing models (Mirjam et al.,

King et al., )

Flood plumes –story so far

• Often constrained to the coast;

• Flood plumes may extend out

to outer Reef;

• Contain environmentally

relevant concentrations of

sediment, nutrients and

pesticides;

• Different pathways for different

pollutants and

• Major route of contaminant

transfer to the GBR.

• Areas of research

2008-02-22 MODIS Aqua Fitzroy Zoom (Dekker)• Transport and

processing of

nutrients and

suspended sediment

• Extent and exposure

of flood plume related

to prevailing weather

and catchment

conditions

Primary

plume

Secondary plume

PN

DIP

SPM

DIN

PP

• Water quality

• Transport and Processing of water quality

parameters / pollutants

• Analysis of mixing curves

• Deviations from linearity indicate enrichment or

depletion of a particular water mass in excess of

that to be expected from the simple dilution

process

• A non-linear relationship between the water

quality parameter and salinity indicates some

form of addition or depletion of that parameter

through another process

Removal

Theoretical

dilution line

Co

ncen

tration o

f A

Addition

Co

ncen

tration o

f B Theoretical

dilution lineRemoval

Addition

• Flood plume act as a mechanism for transporting

and processing WQ constituents

• Dissolved nutrients tend to act conservatively,

that is they dilute linearly with dilution

• However biological uptake can and does occur

throughout the salinity range

• Suspended sediment drops out rapidly, close to

shore and in lower salinity range.

• Recent work suggests smaller particulate size

moves out much further than the larger clay

material (flocculation in the higher salinities)

• Similar processes in the particulate nutrients

• Chlorophyll typically measured as an indicator

of phytoplankton activity. Tends to be low in

lower salinities (light limiting conditions) and

increases in the middle stages with combination

of high nutrients and low turbidity.

• Exceptions to all these rules!

0

2

4

6

8

10

12

0 4 8 12 16 20 24 28 32 36Salinity

Nox

and

NH4 (

mM

)

0

0.2

0.4

0.6

0.8

1

1.2

DIP

(mM

)

DIN NH4 DIP

0

0

2

4

6

8

10

12

0 4 8 12 16 20 24 28 32 36Salinity

Nox

and

NH4 (

mM

)

0

0.2

0.4

0.6

0.8

1

1.2

DIP

(mM

)

DIN NH4 DIP

0

100

200

300

400

500

600

0 4 8 12 16 20 24 28 32 36Salinity

SPM

(mg/L

) Wet Tropics SPM Dry Tropics SPM

0

1

2

3

4

5

6

7

0 4 8 12 16 20 24 28 32 36Salinity

Chloro

phyll b

iomass

(mg/

L)

Chlorophyll a

0

5

10

15

20

25

30

0 4 8 12 16 20 24 28 32 36Salinity

PN (m

M)

0

1

2

3

4

5

100

200

300

400

500

600

0 4 8 12 16 20 24 28 32 36Salinity

SPM

(mg/L

) Wet Tropics SPM Dry Tropics SPM

0

1

2

3

4

5

6

7

0 4 8 12 16 20 24 28 32 36Salinity

Chloro

phyll b

iomass

(mg/

L)

Chlorophyll a

0

5

10

15

20

25

30

0 4 8 12 16 20 24 28 32 36Salinity

PN (m

M)

0

1

2

3

4

5

6

PP (mM

)

Particulate N Particulate P

Biological uptake

Major sedimentation

Major sedimentation

Phytoplankton growth

phase

0

2

4

6

8

10

12

0 4 8 12 16 20 24 28 32 36Salinity

Nox

and

NH4 (

mM

)

0

0.2

0.4

0.6

0.8

1

1.2

DIP

(mM

)

DIN NH4 DIP

0

2

4

6

8

10

12

0 4 8 12 16 20 24 28 32 36Salinity

Nox

and

NH4 (

mM

)

0

0.2

0.4

0.6

0.8

1

1.2

DIP

(mM

)

DIN NH4 DIP

00

0

2

4

6

8

10

12

0 4 8 12 16 20 24 28 32 36Salinity

Nox

and

NH4 (

mM

)

0

0.2

0.4

0.6

0.8

1

1.2

DIP

(mM

)

DIN NH4 DIP

0

2

4

6

8

10

12

0 4 8 12 16 20 24 28 32 36Salinity

Nox

and

NH4 (

mM

)

0

0.2

0.4

0.6

0.8

1

1.2

DIP

(mM

)

DIN NH4 DIP

0

100

200

300

400

500

600

0 4 8 12 16 20 24 28 32 36Salinity

SPM

(mg/L

) Wet Tropics SPM Dry Tropics SPM

0

1

2

3

4

5

6

7

0 4 8 12 16 20 24 28 32 36Salinity

Chloro

phyll b

iomass

(mg/

L)

Chlorophyll a

0

100

200

300

400

500

600

0 4 8 12 16 20 24 28 32 36Salinity

SPM

(mg/L

) Wet Tropics SPM Dry Tropics SPM

0

1

2

3

4

5

6

7

0 4 8 12 16 20 24 28 32 36Salinity

Chloro

phyll b

iomass

(mg/

L)

Chlorophyll a

0

5

10

15

20

25

30

0 4 8 12 16 20 24 28 32 36Salinity

PN (m

M)

0

1

2

3

4

5

100

200

300

400

500

600

0 4 8 12 16 20 24 28 32 36Salinity

SPM

(mg/L

) Wet Tropics SPM Dry Tropics SPM

0

1

2

3

4

5

6

7

0 4 8 12 16 20 24 28 32 36Salinity

Chloro

phyll b

iomass

(mg/

L)

Chlorophyll a

0

5

10

15

20

25

30

0 4 8 12 16 20 24 28 32 36Salinity

PN (m

M)

0

1

2

3

4

5

100

200

300

400

500

600

0 4 8 12 16 20 24 28 32 36Salinity

SPM

(mg/L

) Wet Tropics SPM Dry Tropics SPM

0

1

2

3

4

5

6

7

0 4 8 12 16 20 24 28 32 36Salinity

Chloro

phyll b

iomass

(mg/

L)

Chlorophyll a

0

5

10

15

20

25

30

0 4 8 12 16 20 24 28 32 36Salinity

PN (m

M)

0

1

2

3

4

5

6

PP (mM

)

Particulate N Particulate P

Biological uptake

Major sedimentation

Major sedimentation

Phytoplankton growth

phase

Shape

of

mixing

Transport and

Processing

Extent

of

plumes

–

Change in dissolved and particulate nutrientsInitial

mixing

(salinity = 0)

Mixing processes

occurring in plume

(Salinity 0 to 35

Final reef exposure

concentration

Reliant on

catchment, timing

and flow

Variable 1 – River

concentrations //

landuse

Variable 2–

duration of flow

Variable 3– wind

direction and

strength

Variable 4–

distance of reef

(timing of plume)

PN

NOX

0 250 500 750 1000 1250Concentration (ug/L)

Tully River (n = 331)

PN

NOX

0 250 500 750 1000 12500 250 500 750 1000 1250Concentration (ug/L)

Tully River (n = 331)

PN

NOX

PN

NOX

0.2 km off Cairns Inshore from Green Is.

0.01-1.66,

mean = 0.39 ug/L

0

1000

2000

3000

4000

500

0

1970 1975 1980 198 1990 1995 20000

1000

2000

3000

4000

500

0

1970 1975 1980 198 1990 1995 2000

Fe

rtilize

r nitro

gen

(ton

ne

s)

Sampling strategy 2008-2011

Catchment

Processes

Link with 3.7.2

River monitoring

programs

Freshwater and

Sediment exports

(NRW – AIMS)

Plume sampling

(JCU)

Aerial flyovers

Remote sensing

In situ logging data

(AIMS)

Receiving water

models

King et al

Mirjam et al

Other

Water quality

Dissolved and particulate nutrients

Suspended particulate matter

CDOM

Chlorophyll

Trace metals

Pesticides

Phytoplankton species

• Historic perspective on flood plumes in the

Fitzroy

• Plume sampling in 1991 (Brodie et al., )

• Cyclone Joy

Fitzroy River

0

200000

400000

600000

800000

1000000

1200000

1400000

1964

1965

1966

1967

1968

1969

1970

1971

1972

1973

1974

1975

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

1991

2008

• On the 26 December 1990, severe tropical

cyclone Joy crossed the eastern Australian coast

near Ayr.

• The 1991 Fitzroy flood, which resulted in more

than 18.5 million megalitres of flood waters, was

the third largest on record

• During the initial period of high discharge (30

December–13 January), the predominant winds over the

southern GBR were moderate SE (~12 knots).

• During this time, the plume was constrained relatively

close to the coast and moved north

• Winds became predominantly northerly and the plume

moved offshore eventually reaching the Capricorn

Island Group.

• The Fitzroy plume reached the Capricorn-Bunker reef

system at a distance of 200 km from the coastline in late

January 1991, with reductions in salinity levels to 27 at

the Capricorn reefs

• Very high chlorophyll concentrations measured in

offshore plume

• High concentrations of all nutrients found in salinities

30-35ppt (Cape Bunkers)

• Two different sampling events

Sampling strategy 2008 – 2001 – New techniques

Salinity gradient/distance from shoreRiver

mouth Offshore

Sediment tracing Measurements of phytoplankton

CASE 2 waters

SPM

Light limiting

0 – 5ppt

Mixture of case 1/case 2 waters

SPM ↓Light ↑

5- 15ppt 15 – 35ppt

Properties closer

to Case 1 waters

Potential for high nutrients /

high production

Use of RS algorithms

Load

Calc.

Flood sampling 2008

• 2 big events – Dry Tropics (Wet Tropics flooded but not sampled)

• 20 year event in Fitzroy

• Integrated approach to plume sampling

0

100000

200000

300000

400000

500000

600000

28/D

ec

31/D

ec

03/J

an

06/J

an

09/J

an

12/J

an

15/J

an

18/J

an

21/J

an

24/J

an

27/J

an

30/J

an

02/F

eb

05/F

eb

08/F

eb

11/F

eb

14/F

eb

17/F

eb

20/F

eb

23/F

eb

26/F

eb

29/F

eb

03/M

ar

06/M

ar

tota

l M

L / d

ay

.

Organisation catchment

Fitzroy

Timings

31/1 – 1/2

AIMS Fitzroy

CSIRO Fitzroy

23/2 – 26/2

5/2 – 6/2

JCU

CS

IRO

JCU

AIM

SFit

zroy

• Identification of primary, secondary and tertiary plume extents

22nd Feb 2008

Primary plume

– turbid plume

(processes

controlled by

sediment

• Using true colour images to map extents

26th Jan 2008

Secondary/

tertiary plumes

pollutants

transported

further. Uptake

and growth

zones

0

100000

200000

300000

400000

500000

600000

1-J

an

5-J

an

9-J

an

13-J

an

17-J

an

21-J

an

25-J

an

29-J

an

2-F

eb

6-F

eb

10-F

eb

14-F

eb

18-F

eb

22-F

eb

26-F

eb

1-M

ar

5-M

ar

9-M

ar

13-M

ar

date

flow

rate

(M

L)

• Applied confidence to the extent mapping.

• Identify turbid plumes and chlorophyll plumes. Less confidence in defining the chlorophyll plumes.

• Application of various algorithms can help

WQ data from Fitzroy

2008 - SS data

0

100

200

300

400

500

0 5 10 15 20 25 30 35

salinity

SS

(u

g/L

)

JCU

AIMS

CSIRO

2008 - DIN data

0

2

4

6

8

10

12

0 5 10 15 20 25 30 35

salinity

DIN

(uM

)

JCU

AIMS

CSIRO

2008 - chl data

0

5

10

15

20

25

30

0 5 10 15 20 25 30 35

salinity

Ch

l (u

g/L

)

JCU

AIMS

CSIRO

2008 - DIP data

0

0.5

1

1.5

2

0 5 10 15 20 25 30 35

salinity

DIP

(uM

)

JCU

AIMS

CSIRO

SPM

0

100000

200000

300000

400000

500000

600000

1-J

an

5-J

an

9-J

an

13

-Ja

n

17

-Ja

n

21

-Ja

n

25

-Ja

n

29

-Ja

n

2-F

eb

6-F

eb

10

-Fe

b

14

-Fe

b

18

-Fe

b

22

-Fe

b

26

-Fe

b

1-M

ar

5-M

ar

9-M

ar

13

-Ma

r

date

flo

w r

ate

(M

L)

0

1

2

3

4

5

6

0 5 10 15 20 25 30 35

Salinity

PP

(uM

)

31/1/08 - 2/2/08

6/2/08 - 9/2/08

25/2/08 - 26/2/08

0

5

10

15

20

25

0 5 10 15 20 25 30 35

Salinity

PN

(uM

)

31/1/08 - 2/2/08

6/2/08 - 9/2/08

25/2/08 - 26/2/08

0

100

200

300

400

500

0 5 10 15 20 25 30 35Salinity

SS

(m

g/L

)

31/1/08 - 2/2/08

6/2/08 - 9/2/08

25/2/08 - 26/2/08

Particulate

Phosphorus

Particulate

Nitrogen

DIN

0

100000

200000

300000

400000

500000

600000

1-J

an

5-J

an

9-J

an

13

-Ja

n

17

-Ja

n

21

-Ja

n

25

-Ja

n

29

-Ja

n

2-F

eb

6-F

eb

10

-Fe

b

14

-Fe

b

18

-Fe

b

22

-Fe

b

26

-Fe

b

1-M

ar

5-M

ar

9-M

ar

13

-Ma

r

date

flo

w r

ate

(M

L)

0

2

4

6

8

10

12

0 5 10 15 20 25 30 35Salinity

DIN

(u

M)

31/1/08 - 2/2/08

6/2/08 - 9/2/08

25/2/08 - 26/2/08

0

0.5

1

1.5

2

0 5 10 15 20 25 30 35Salinity

DIP

(u

M)

31/1/08 - 2/2/08

6/2/08 - 9/2/08

25/2/08 - 26/2/08

DIP

Chlorophyll

0

5

10

15

20

25

0 5 10 15 20 25 30 35Salinity

Ch

loro

ph

yll (

ug

/L)

31/1/08 - 2/2/08

6/2/08 - 9/2/08

25/2/08 - 26/2/08

Comparison of WQ conditions

• Strong N signal in Wet Tropics plumes

• High chlorophyll in Fitzroy plume. 1991 value related to offshore production late in the

plume. 2008 value related to freshwater phytoplankton (in low salinities).

NOx between catchments

0

2

4

6

8

10

12

5 15 25 30Salinity

No

rma

lis

ed

NO

x (

uM

)

Barron

RM

tully

Burd

Fitz - 1991

Fitz 2008

NH4 between catchments

0

1

2

3

4

5

6

5 15 25 30Salinity

No

rma

lis

ed

NH

4 (

uM

)

Barron

RM

tully

Burd

Fitz - 1991

Fitz 2008

Chl between catchments

0

2

4

6

8

10

12

14

16

5 15 25 30Salinity

No

rma

lis

ed

Ch

l (u

g/L

)

Barron

RM

tully

Burd

Fitz - 1991

Fitz 2008

DIP

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

5 15 25 30Salinity

No

rma

lis

ed

DIP

(um

)

Barron

RM

tully

Burd

Fitz - 1991

Fitz 2008

SUSPENDED SOLIDS

0

20

40

60

80

100

120

5 15 25 30Salinity

No

rma

lis

ed

SS

(mg

/L)

Barron

RM

tully

Burd

Fitz - 1991

Fitz 2008

• Remote sensing images can provide greater detail in flood plume extent and concentration

• MODIS algorithms

• CSIRO developing algorithms for turbid inshore waters

• Chlorophyll concentrations calculated from RS images, used to support on ground water quality sampling

• Temporal sampling from RS images

Greater surveillance / Time series

High production extending Into Coral Sea. Nutrients moving great

distances (100’s km) in comparison to sediment (10’s km)

Caveats to using RS data

• Proximity to reefs

• Turbidity issues

• Apply flags to data

• Flags include atmospheric correction, land, high radiance, angle, cloud

contamination, algorithm failure, aerosol contamination, atmospheric correction,

turbid waters

• Chlorophyll may not be accurate, however still able to represent spatial and temporal

trends.

Step process

1. Identify match ups for insitu data. Compare adequacy of different algorithms to

identify most appropriate.

2. Apply algorithms to the most appropriate images over flood plume period

3. Integrate RS data with existing water quality data to add to information on extent

and concentrations and timings.

• Validation of data can be difficult

• Good match up with 2006/2007 flood data

• 2002 – 2007 ambient monitoring data

• Use this data to test the accuracy of the algorithms

• Applied flags to delete inappropriate data

• Existing work by CSIRO and AIMS already well advanced in this area.

• Unfortunately all the issues with application of RS algorithms happens in flood plumes (turbid, nearshore, complex)

• Difficult to get match ups in flood plume data

1. Match ups

• Data match ups (2002 – 2008),

including plume data (2006-2007)

2 – Testing appropriate algorithms

• Development by new algorithm by

CSIRO

All data

Flagged and

turbid pixels

omitted

1

3

5

7

9

11

13

15

17

19

21

0 50000 100000 150000 200000

distance from the river mouth (m)

Chlo

roph

yll

Turbid

TSM

flagged for QC

oc3

gsm

1

3

5

7

9

11

13

15

17

19

21

0 50000 100000 150000 200000 250000

distance from the river mouth(m)

Chlo

roph

yll

1

3

5

7

9

11

13

15

17

19

21

0 50000 100000 150000 200000 250000 300000

distance from the river mouth(m)

Ch

loro

ph

yll

22nd

February

• Comparison of algorithm outputs for 22nd

February 2008

• Spatial extent of chlorophyll plume

• Validation without match ups

• Apply flags and QC

• Low confidence in the exact amounts of

chlorophyll calculated

• Very useful to describe spatial extent

patterns of chlorophyll and TSM.

3. Integration of RS data into flood

Plume work

Site 1

Site 2

Site 3

0

1

2

3

4

5

6

24-12 3-1 13-1 23-1 2-2 12-2 22-2 3-3 13-3 23-3 2-4

Date

Chlo

rophyll

(ug/L

)

0

100000

200000

300000

400000

500000

600000

flow

rat

e

Excluded due to QC/flag

• Final assessment of images and algorithms

• Combination of extent confidence and algorithm validation.

• Useful to separate primary and secondary extent.

• Much further transport of nutrients and chlorophyll offshore

• Offshore and southwards movement. May be related to currents.

Remote sensing techniques

Useful to integrate with in situ data

Further understanding of extent and

Concentration

Need

Extent - Confidence +

validation +

Quality Control (flags, location)

+ expert judgement

Conclusions

• Water quality data identifies mixing profiles

• Large dry catchment events are extremely signficant in the transport of pollutants in GBR.

• Further work and data analysis currently underway

• Use of RS a valuable tool in the understanding of extent and prolonged exposure.

Further work

• Univariate analysis of individual events over individual catchments

• Already have reasonable idea of how prevailing weather conditions

and flow can influence extent and exposure

• Move to multivariate techniques, correlative analysis of flow,

catchment condition and water quality parameters in plume – better

information for water quality targets

Acknowledgements

• RRRC

• QPWS – Rosslyn Bay.

• Australian Institute of Marine Science and Britta.

• CSIRO

• Great Barrier Reef Marine Park Authority

• Regional bodies

• FBA