![Page 1: Quantification of sediment concentrations and fluxes A comparison between optical and acoustic measurements Utrecht, 11 June 2013 – Emile Lemey](https://reader038.vdocuments.us/reader038/viewer/2022102808/56649c7b5503460f9492ef1f/html5/thumbnails/1.jpg)
Quantification of sediment concentrations and fluxes
A comparison between optical and acoustic measurements
Utrecht, 11 June 2013 – Emile Lemey
![Page 2: Quantification of sediment concentrations and fluxes A comparison between optical and acoustic measurements Utrecht, 11 June 2013 – Emile Lemey](https://reader038.vdocuments.us/reader038/viewer/2022102808/56649c7b5503460f9492ef1f/html5/thumbnails/2.jpg)
ManagementJDN
Departments
DREDGING
Marine Environmental Department
MARINE ENVIRONMENTAL DEPARTMENT
SEDIMENTS SOIL
GROUNDWATERSPECIAL WASTE
Envisan
WHO?
ENVIRONMENTAL
QUALITY HEALTHSAFETY
SECURITY ENVIRONMENT
QHSSE
![Page 3: Quantification of sediment concentrations and fluxes A comparison between optical and acoustic measurements Utrecht, 11 June 2013 – Emile Lemey](https://reader038.vdocuments.us/reader038/viewer/2022102808/56649c7b5503460f9492ef1f/html5/thumbnails/3.jpg)
ManagementJDN
Departments
DREDGING
Marine Environmental Department
MARINE ENVIRONMENTAL DEPARTMENT
SEDIMENTS SOIL
GROUNDWATERSPECIAL WASTE
Envisan
WHO?
ENVIRONMENTAL
QUALITY HEALTHSAFETY
SECURITY ENVIRONMENT
QHSSE
![Page 4: Quantification of sediment concentrations and fluxes A comparison between optical and acoustic measurements Utrecht, 11 June 2013 – Emile Lemey](https://reader038.vdocuments.us/reader038/viewer/2022102808/56649c7b5503460f9492ef1f/html5/thumbnails/4.jpg)
WHEATSTONE Secondary Stabilisation Project
WHAT?
Dredging near sensitive marine habitats Intensive dredge plume monitoring Hind cast hydrodynamic modelling
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WHEATSTONE Secondary Stabilisation Project
WHAT?
Dredge plume monitoring
- Daily transects around CSD- Perpendicular to current direction- Downstream of turbidity source
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MONITORING METHODS
1) Optical measurements
- YSI 6920 V2 multi-parameter probe
- Davit with an electrical winch
- Undulating motion
- Turbidity, depth, temperature, conductivity and salinity
- Turbidity SSC with conversion coefficient
2) Acoustic measurements
- Acoustic Doppler Current Profiler (ADCP) Workhorse Mariner (Teledyne RD Instruments)
- VISea Plume Detection Toolbox (PDT) software (Aqua Vision)
- Mounted in moon pool of vessel, fixed depth
- Current speed and direction
- Backscatter data SSC
HOW?
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MONITORING METHODS
3) Integration positioning system / loggings
- Through software (QINSy and Visea PDT)
- GPS/DGPS data absolute flow velocity and direction
HOW?
![Page 8: Quantification of sediment concentrations and fluxes A comparison between optical and acoustic measurements Utrecht, 11 June 2013 – Emile Lemey](https://reader038.vdocuments.us/reader038/viewer/2022102808/56649c7b5503460f9492ef1f/html5/thumbnails/8.jpg)
POST PROCESSING
1) Acoustic method
- Sediment flux calculation in Visea PDT
2) Optical method
- Data outlier removal
- Surfer surface modelling software (© Golden Software)
- Quantification of total flux (kg/s)
HOW?
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- Most transects: similar sediment profiles
RESULTS
Optical:
Acoustic:
![Page 10: Quantification of sediment concentrations and fluxes A comparison between optical and acoustic measurements Utrecht, 11 June 2013 – Emile Lemey](https://reader038.vdocuments.us/reader038/viewer/2022102808/56649c7b5503460f9492ef1f/html5/thumbnails/10.jpg)
- Some differences in profiles
RESULTS
Optical:
Acoustic:
![Page 11: Quantification of sediment concentrations and fluxes A comparison between optical and acoustic measurements Utrecht, 11 June 2013 – Emile Lemey](https://reader038.vdocuments.us/reader038/viewer/2022102808/56649c7b5503460f9492ef1f/html5/thumbnails/11.jpg)
- Some differences in profiles
RESULTS
Optical:
Acoustic:
![Page 12: Quantification of sediment concentrations and fluxes A comparison between optical and acoustic measurements Utrecht, 11 June 2013 – Emile Lemey](https://reader038.vdocuments.us/reader038/viewer/2022102808/56649c7b5503460f9492ef1f/html5/thumbnails/12.jpg)
RESULTS
- Quantification of fluxes
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RESULTS
- Quantification of fluxes
![Page 14: Quantification of sediment concentrations and fluxes A comparison between optical and acoustic measurements Utrecht, 11 June 2013 – Emile Lemey](https://reader038.vdocuments.us/reader038/viewer/2022102808/56649c7b5503460f9492ef1f/html5/thumbnails/14.jpg)
- Point measurement comparison
RESULTS
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• Both methods yield similar profiles
• Real-time vs. Intensive post processing
• Flux quantification results differ
• TSS concentrations by acoustic measurement overestimated?
Maybe due to Algorithm used in processing
• ADCP + PDT very useful as visualisation tool
• Not yet alternative for optical TSS quantification of complex dredge plumes
CONCLUSIONS
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