Towards a guideline document on dredge plume modelling in the context of environmental impact assessment in Western Australia

C. Sun, P. Branson

Research output: Chapter in Book/Conference paperConference paper


Major dredging projects in Western Australia require detailed environmental impact assessment (EIA) before they are approved. The EIA is mainly based on the results of far-field numerical modelling of dredged sediments, which predict the extent, intensity and duration of impacts associated with the dredging proposal. However, a robust prediction is challenging due to a lack of baseline data, unknown dredging plan and method, natural variability in large-scale meteorology and oceanic forcing, and inherently complex sediment transport processes. In addition, models are often developed in the northern hemisphere context and not well calibrated and validated for the tropical and subtropical Australian marine environment. Further uncertainty is introduced by a lack of knowledge in the response and thresholds of the benthic ecosystem to the pressures induced by dredging. The main goals of the Western Australia Marine Science Institution (WAMSI) Dredging Science Node (DSN), a large multi-institutional research program, are to improve the planning and regulation of major dredging operations, and enhance the capacity within government and private sector to predict and manage the environmental impact of dredging. The numerical modelling project of the WAMSI DSN is undertaking an extensive case study to model dredge plume dispersal and its fate. This case study is based on an actual dredging campaign (the Chevron Wheatstone Project), whose dredge and monitoring datasets during and after the dredging were made available to the WAMSI DSN researchers for the purpose of improving EIA modelling and impact predictions. The focus of the modelling work is on determining the probability distribution of critical model parameters in hydrodynamic and sediment transport models relevant to the Australian marine environment, quantifying model uncertainty associated with source terms of sediments released by dredging and sediment transport processes, and interpretation of physical model results that are useful for ecological prediction. At the end of the project, a guideline document on dredge plume modelling will be developed in the context of EIA in the Western Australian marine environment, with the aim to improve the confidence in modelling and increase the efficiency in the assessment and interpretation of model results. In this paper, we describe our approach towards the development of this guideline document, which is a combination of a literature review of current practice in EIA plume modelling, expert advice and stakeholder input through consultation and workshops, and an extensive modelling case study. It is noted that some significant part of the guidelines could be applicable to the other parts of Australia or internationally even though they have been developed from case studies in the Western Australia region. To ensure the uptake of the guideline document by regulators and practitioners, the structure and governance of the WAMSI DSN is set up in such a way as to provide a clear and direct 'pathway to adoption'. The Node Science Plan was developed to address gaps in knowledge as they relate to the EIA process in WA through a thorough process of gap analysis involving regulators, industry, consultants and researchers. The final plan was set by the regulators. Key aspects are the dual node leaders Science and Policy, and a Dredging Science Advisory Committee comprised of end users. All information is made publically available as it comes to light. © Australasian Coasts and Ports 2017 Conference. All rights reserved.
Original languageEnglish
Title of host publicationAustralasian Coasts & Ports 2017: Working with Nature
Place of PublicationBarton, ACT
PublisherEngineers Australia
Number of pages6
ISBN (Print)9781922107916
Publication statusPublished - 2017
EventCoasts & Ports 2017 Conference - Cairns, Australia
Duration: 21 Jun 201723 Jun 2017


ConferenceCoasts & Ports 2017 Conference
Internet address

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