2 / 3 Synthesis: Characterising and predicting the pressure field

Description

The Dredging Science Node produced two cutting-edge reviews of available literature and monitoring reports on the process of sediment particle generation and release by different types of dredgers, and approaches to estimating dredge source terms.

The validity of a recently published empirical source term model approach was tested for over 22,000 separate dredge plumes across eight different operational modes used during the Wheatstone dredging campaign.

One of the key points emphasised in the Dredging Science Node was the significance of sediment deposition leading to smothering on adult and juvenile corals and hence defining zones of high impact

The theme consisted of numerical modelling, laboratory experiments, and a coordinated field program. Field measurements of sediment and plume characteristics were obtained from the near-field dynamic plume to the full extent of the passive plume. In addition, measurements of the smaller-scale sediment transport processes, which control the deposition and resuspension of dredge plumes over a range of benthic substrates and habitat types, were undertaken. These results have improved predictions of zones of impact and provided necessary datasets to map ecological responses (as defined by other themes).

Aims

• To develop protocols and guidelines for field, lab, remote sensing and numerical modelling procedures for predicting and monitoring dredge plume dispersal and the corresponding zones of impact.
• To achieve this objective the project aimed to improved understanding of the key physical processes that control the extent, intensity and duration of dredge generated sediment plumes from the actual dredge site and dredge spoil grounds and the deposition/resuspension processes across a range of habitats that may lead to further dispersal by currents and waves.

Outcomes

A practical dredge plume modelling guideline for practitioners and environmental regulators. The guideline focuses on establishing a consistent and sound approach to the modelling of dredge plumes for predicting the pressure fields of suspended sediments when seeking Environmental Impact Assessment approval.

Project News

• Best Practice Guideline for Dredge Plume Modelling
• Dredge Plume Modelling Guidelines
• Understanding the flow of suspended sediments across reefs
• New framework developed to assess coral resilience to dredging
• DSN Report 3.1.2: Sediment transport processes within coral reef and vegetated coastal ecosystems: a review
• DSN Report 2.1: Generation and release of sediments by hydraulic dredging: a review
• Better predictions for dredge plumes
• Groundbreaking research to build instruments to measure net sediment deposition
• Re-defining sediment transport models over coral reefs and seagrass meadows

Reports

Adams MP, Hovey RK, Hipsey MR, Bruce LC, Ghisalberti M, Lowe RJ, Gruber RK, Ruiz-Montoya L, Maxwell PS, Callaghan DP, Kendrick GA, O’Brien KR (2016), Feedback between sediment and light for seagrass: Where is it important?. Limnology and Oceanography., 61: 1937–1955. doi:10.1002/lno.10319

Cuttler MVW, Lowe RJ, Falter JL, Buscombe D (Dec 2016) Estimating the settling velocity of bioclastic sediment using common grain‐size analysis techniques Sedimentology 10.1111/sed.12338

Dorji P, Fearns P (2017) Impact of the spatial resolution of satellite remote sensing sensors in the quantification of total suspended sediment concentration: A case study in turbid waters of Northern Western Australia. PLoS ONE doi.org/10.1371/journal.pone.0175042

Dorji P, Fearns P. A. (2016) Quantitative Comparison of Total Suspended Sediment Algorithms: A Case Study of the Last Decade for MODIS and Landsat-Based Sensors. Remote Sensing. 2016; 8(10):810 doi:10.3390/rs8100810

Dorji P, Fearns P, Broomhall M (2016) A Semi-Analytic Model for Estimating Total Suspended Sediment Concentration in Turbid Coastal Waters of Northern Western Australia Using MODIS-Aqua 250 m Data. Remote Sensing. 2016; 8(7):556 doi:10.3390/rs8070556

Dufois F, Lowe R, Rayson M, Branson P. (2018) A numerical study of tropical cyclone-induced sediment dynamics on the Australian North West Shelf. Journal of Geophysical Research. doi:10.1029/2018JC013939

Dufois F, Lowe R, Branson P, Fearns P. (2017) Tropical cyclone-driven sediment dynamics over the Australian North West Shelf. Journal of Geophysical Research. doi:10.1002/2017JC013518

Lowe RJ and Falter JL (2015) Oceanic Forcing of Coral Reefs Annual Review of Marine Science DOI: 10.1146/annurev-marine-010814-015834

Pomeroy A, Lowe R, Ghisalberti M, Winter G, Storlazzi C, Cuttler M (2019) Spatial Variability of Sediment Transport Processes Over Intratidal and Subtidal Timescales Within a Fringing Coral Reef System. Journal of Geophysical Research  doi: 10.1002/2017JF004468

Pomeroy AW, Lowe RJ, Ghisalberti M, Storlazzi C, Symonds G, Roelvink D (2017), Sediment transport in the presence of large reef bottom roughness Journal of Geophysical Research 10.1002/2016JC011755

Pomeroy AWM, Lowe RJ, Ghisalberti M, Storlazzi CD, Cuttler M, Symonds G (2015) Mechanics of sediment suspension and transport within a fringing reef. Coastal Sediments 2015: DOI: http://dx.doi.org/10.1142/9789814689977_0086

 

Media

Presentations

Generation and Transport of Dredge Plumes – Synthesis of knowledge and considerations for management (2017 WAMSI Research Conference)

Remote Sensing of Dredge Plumes – how and how not. (2017 WAMSI Research Conference)

Sediment deposition over benthic habitats – corrections for sediment transport models (2017 WAMS Research Conference)

Measurement and modelling of key demographic processes in corals of the Dampier Archipelago. (2017 WAMSI Research Conference)