Haskoning Australia Determining Circulation of the Great Barrier Reef Lagoon Using ADCP Data AiAiA – Gold Coast 2015 Heiko Loehr & Evan Watterson

OVERVIEW Intro: Great Barrier Reef (GBR) Lagoon ADCP Field Measurements Data Analysis Ocean Circulation in GBR Application of Results Excursion: Tropical Cyclones

GBR Lagoon 3

GBR Lagoon: Ocean Currents 4 South Equatorial Current

NCJ GBR Lagoon: Ocean Currents 5 Source: Andutta et al., 2013 South Equatorial Current NCJ – North Caledonia Jet NQC – North Queensland Current EAC – East Australian Current

GBR Lagoon: Study Site 6 Study Site Site 1 Site 2

GBR Lagoon: MetOcean 7

8 Semi-diurnal tides Spring range: ~2m Neap range: ~0.8m Waves:

Field Measurements Two sites 9 months: Dec 2013 to Oct Site 1 Lat: -19°41.692’ Lon: 148°07.255’ Site 2 Lat: -19°48.000’ Lon: 148°18.000’ Instrument 600 kHZ ADCP (TRDI workhorse) & Nortek AWAC 600 kHZ ADCP TRDI Sentinel V Depth (m) 37 m CD43m CD Vertical resolution (bin size) 2m Current measurement intervals 10 minutes

Data Analysis Decomposition of measured current signal: 10

Data Analysis Decomposition of measured current signal: 11 Near Surface Mid-Water Near Bottom

Data Analysis 12

Data Analysis 13

Data Analysis 14

Data Analysis 15 Northerly wind

ADCP residual peak ~2.5x model Data Analysis 16 Northerly wind

Data Analysis 17 Northerly wind ADCP residual peak ~2.5x model South-Eastward ADCP residual

Data Analysis 18 Northerly wind South-Easterly wind

Data Analysis 19 Northerly wind SEC EAC Geostrophic Velocity Sealevel Anomaly Source: Integrated Marine Observing System

Data Analysis 20 Geostrophic Velocity Sealevel Anomaly SEC NQC EAC South-Easterly wind Source: Integrated Marine Observing System

Data Analysis 21 December-February February-April April-May M2 Constituent S2 Constituent

Data Analysis 22 December-February February-April April-May M2 Constituent S2 Constituent Directional variability of tidal currents Evidence of other drivers?

Data Validation 23 Source: Integrated Marine Observing System Study area Year: 2011 & Further Offshore!

Application 24 Hydrodynamic/ Sediment Transport Modelling of GBR Lagoon Tide + Wind only boundary conditions Good fit! Bad fit! Current Speed (m/s) Current Direction (degN) Blue – ADCP data Red – Model data

Blue – ADCP data Red – Model data Application 25 Tide + Wind + Ocean Current boundary conditions Good fit!

Application 26 Tide + Ocean Current boundary conditions Suspended Sediment Modelling

Excursion: Tropical Cyclones 27 Source: BoM

Excursion: Tropical Cyclones 28 TC Dylan

Excursion: Tropical Cyclones 29 B C Current Residual Echo Intensity Current Speed

Excursion: Tropical Cyclones 30 B C Current Residual Acoustic Backscatter Current Speed Valuable data for future study!!!

WWF.org.au Thank you 31 Any questions? Any questions?

Literature Andutta, Fernando P., Ridd, Peter V. and Wolanski, E. (2013). The age and the flushing time of the great barrier reef waters, Continental Shelf Research, / /j.csr http://dx.doi.or CDM Smith (2013). Abbot Point Alternate Disposal Site Constraints Assessment. North Queensland Bulk Ports Corporation Choukroun, S., P. V. Ridd, R. Brinkman, and L. I. W. McKinna (2010). On the surface circulation in the western Coral Sea and residence times in the Great Barrier Reef, J. Geophys. Res., 115, C06013, doi: /2009JC Codiga, D.L. (2011). Unified Tidal Analysis and Prediction Using the UTide Matlab Functions. Technical Report Graduate School of Oceanography, University of Rhode Island, Narragansett, RI. 59pp. ftp:// RHDHV (2014). Abbot Point DSAP Assessment, Numerical Modelling Report. Royal HaskoningDHV Vianna, M. L., Menezes, V. V. (2004) Subtidal Modulation of Tidal Currents on the Northeast Brazilian Shelf. Simpósio Brasileiro de Oceanografia, São Paulo, Brasil. Available from RDI Watterson, E. (2014). Operations Report, ADCP Current and Wave Monitoring, Abbot Point Dredge Disposal. Royal HaskoningDHV 32

Field Deployments 33

Stats 34

Stats pt2 35

Waves 36