- Ocean, Coastal and Estuary Process Investigations
- Storm Surge and Coastal Inundation Modelling
- Integrated Coastal Zone Management
- Harbour and Coastal Structure Design
- Dredging Program Design and Impact Assessments
- Oceanographic Data Collection
- Coastal Hazard and Vulnerability Assessments
- Climate Change Risk Assessment and Adaption Assessments
Shoreline Erosion: Aligning management strategies with community aspirations
Main image: Rodney Wiley
Located on the north-west corner of North Stradbroke Island, the township of Amity Point enjoys a rich diversity of seascapes and landscapes – providing extensive recreational and lifestyle opportunities that are considerably enhanced by local cultural, heritage and environmental values.
The historical development of Amity Point has focused on the shoreline – as residents and visitors seek to enjoy the unique character of this coastal precinct. However, the dynamic nature of the coastal environment means that local foreshores are experiencing erosion which is threatening these values, as well as endangering essential infrastructure.
Water Technology was engaged by Redland City Council to develop the Amity Point Shoreline Erosion Management Plan which included a framework for the sustainable use, development and management of this vulnerable foreshore that was acceptable to both the residents and the relevant management authorities.
Previous recommended approaches to shoreline management at Amity Point (including an earlier SEMP completed by another consultant in 2014) did not allow for Council and the local Amity Point community to appropriately and proactively plan for suitable erosion management along the vulnerable foreshore.
This project therefore focused on developing an approach that was consistent with the community aspirations and the polices of the Commonwealth and State Governments, and Redland City Council. Technically, the Shoreline Erosion Management Plan considered various strategies in response to the erosion processes and associated risks at Amity Point and, importantly, it involved considerable engagement with the local community and other stakeholders, and has delivered a unique solution to the considerable erosion hazard at Amity Point.
Key Services Provided:
- Physical Process Analysis
- Erosion Threat Risk Assessment
- Shoreline Erosion Management Plan
- Stakeholder Consultation and Engagement
- Shoreline and Erosion Management Optioneering and Recommendations
Presentation by Paul O’Brien (Water Technology) and Tim Mitchell (Redland City Council)
at the 6th Queensland Coastal Conference 2017 (5-7 September 2017).
The Latrobe River estuary is located at the interface between the Latrobe catchment and the Gippsland Lakes. It is a part of the Gippsland Lakes complex, recognised as a wetland of international significance. Upstream freshwater reserves have been set aside for ecological flows, but the environmental flow requirements were unknown. The water resources are also shared between agricultural, industrial, and domestic use. Water Technology was engaged to address the gap developing environmental flow recommendations for the lower Latrobe River estuary.
1D and 3D models were developed to characterize the hydrodynamic regime of the estuary. The 1D model represented river and floodplain flows and was used to examine the interactions between the river and the floodplains. The 3D model was used to provide more detailed information about the hydrodynamic properties of in-stream flows, including interactions between flows, lake levels, and salt wedges.
Water Technology is partnering with the Australian Sailing Team (AST) to provide detailed hindcast and near-time forecasts of hydrodynamic conditions within Guanabara Bay, Rio de Janeiro in preparation for major sailing events occurring in Brazil between 2014 and 2016.
A detailed 3-D coupled spectral wave and hydrodynamic model of the Bay with a suite of input boundary conditions has been developed which covers the 350km2 Bay and offshore area, extending from the famous beach of Copacabana in the west to Itaipuaçu eastward and north through the Bay and past Sugar Loaf Mountain. Collaboration with the AST has seen the collection of current profiles and water levels within the Bay to establish calibration points and allow model refinement to allow surface currents to be modelled with confidence and allow sailors to reliably predict the race conditions.
We wish our friends at AST the highest levels of success in coming events in Brazil.
Ecological and water quality experts from Water Technology and Monash University joined forces to assess the water quality and ecological processes of the Gippsland Lakes.
The Lakes have suffered recurrent summer toxic blooms of cyanobacterium Nodularia spumigena since 1985. Diatoms and dinoflagellates also commonly form blooms in the Lakes. Nodularia has the ability fix free nitrogen and is typically found during periods of low freshwater inflows in brackish waters near the inflowing rivers. Growth of Nodularia is controlled by a combination of biological, chemical and physical drivers which are impossible to simultaneously assess through physical experiments.
Whilst the key drivers of the growth of Nodularia (intermediate salinity, stratification, bottom water hypoxia and sediment phosphorus release) are well understood, there was a lack of quantitative tools to predict bloom formation and assess management options to mitigate them.
A 3-D fully coupled hydrodynamic biological ecological model was used to explore the interaction between the physical and biogeochemical controls over Nodularia blooms. The hydrodynamic model included turbulent mixing within the water column, whilst the ecological component of the model contained over 40 state variables and 200+ processes, parameterised by 176 constants to describe the biological/ecological and chemical reactions occurring in the water column and sediment compartments.
The Corner Inlet Environmental Audit was undertaken by the CSIRO (2005) in response to growing concern from natural resource managers and the community about the health of Corner Inlet. One of the key recommendations from the audit was to undertake a catchment audit to identify pollutant sources and develop targeted amelioration strategies. This project responded to this call by developing a comprehensive sediment and nutrient model of the catchments of Corner Inlet. Water Technology and Melbourne University worked closely with the West Gippsland Catchment Management Authority and the Steering Committee for this project to ensure the final outcomes were user friendly and appropriate for the site.
The method pursued was to develop SOURCE (catchment) and receiving waters (estuary) models (MIKE 21), which were calibrated to both existing data and field measurements taken as part of the project. The simulations of these two calibrated models were then integrated within a single software framework so as to produce a Decision Support System (DSS). The DSS allows scenario testing to plan and prioritise future investments in the catchments, and make decisions on what comprises appropriate development with a view to protecting and enhancing the integrity of the Corner Inlet RAMSAR site.
In 2012 Water Technology and GeoLink were commissioned by the Coffs Harbour City Council to undertake an Estuary Management Plan and Hydraulic Assessment of the Coffs Creek estuary which runs along the boundary of the main centre of Coffs Harbour.
The estuary is a tranquil oasis on the edge of the city and is utilised by residents and visitors in increasing volumes. An Estuary Management Plan was undertaken to identify and assess management options for the estuary going forwards. In addition, the free passage of flood flows through the estuary was identified as a potential contributor to the severe flooding experienced in the city centre during flood events.
A hydraulic model of the estuary was established and calibrated to measured water levels at the upstream and downstream ends of the estuary. Modelling of a range of management options, including reduction in fringing mangrove density and spread, dredging of the flood tide shoals and tidal entrance channel were assessed.
The runoff from the urban and industrialised sections of the catchments had been studied previously and the information from these works were used to determine potential improvements in the water quality which could be made by strategic upgrade of drainage and water quality systems.
The results of the Hydraulics Assessment were used to help prioritise the management options and to provide the Council and local community of Coffs Harbour with a wealth of information on the drivers of estuary health in their town.
Water Technology carried out detailed numerical modelling of the potential release of an abalone aquaculture contaminant into the Southern Ocean off the coast of western Victoria.
As part of the process, Water Technology undertook verification of the numerical model using fluorecene dye tests, released from the facility outflow drains. EPA risk assessments and notification of the local catchment manager and EPA prior to the tests were completed. Overhead shots from a light plane were taken and the images rectified and time stamped.
Numerical modelling of the dispersion involved hydrodynamic and wave modelling of the Southern Ocean, extending from South Australia, south of Tasmania to the Victorian /New South Wales border to the east. The model of the Southern Ocean utilised inputs from global models and was calibrated to predicted and measured tidal stations and recorded wave data. The dispersion of the waterborne abalone virus was verified against the results of the fluoroscene dye test and showed good correlation between the actual and modelled wave setup of water (and contaminant) inshore of the fringing coastal reef.
The model was used to determine the timing and concentration of the dispersion of the abalone virus along the western Victorian coast and through Bass Strait into Port Phillip Bay and Western Port. Scenario optioneering of different contaminant release points and concentrations were used to determine the likelihood of contamination originating at the subject site.
The results of the modelling were used in supporting arguments in the Supreme Court of Victoria and Water Technology was called upon by the court to provide an Expert Witness Statement and provide the presiding judge with additional comment during the hearing.
Nudgee landfill was formed adjacent to the Boondall Wetlands in 1976. The site was closed in 2002 with remediation completed in 2006. Water Technology staff were members of a team invited to undertake an ecological and water quality study to assess the influence of the Nudgee Landfill on the Boondall wetlands (now a RAMSAR listed site). The study included review of all existing monitoring and modelling data, as well as the design and implementation of targeted soil, water and biological monitoring program over a 2 year period. Automatic water quality and depth sensors (with data loggers) were used extensively. Manual sampling and laboratory analysis was also undertaken.
The Boondall Wetlands water quality monitoring sites were influenced by a number of interacting processes such as rainfall, tidal flushing, time of year and distance from Moreton Bay. Further, the impact of these processes on site water quality varies depending on the site and water quality parameter. Therefore, while the “raw” monitoring data may give a precise measure of water quality at the particular moment of sampling, the incomplete sampling coverage across all sites and times, along with the confounding effects of these various processes, meant that the raw data alone did not provide a complete description of water quality variation over time either at a site or between sites. Advanced statistical analysis was used to model and isolate the various physical, chemical and biological processes occurring within the study area.
The Boondall Wetlands have been subject to numerous historical changes apart from the construction of the landfill. These include, land clearing, drain construction, and waterway dredging. The study was able to isolate and identify the effect of natural and anthropogenic impacts on the wetlands.
Water Technology has worked with Tenax Energy to investigate and assess the potential for tidal power generation at a range of locations around Australia and the Pacific. We have used models to simulate tidal movements, and then extracted information of current speeds and directions to calculate the power generation potential for a site.
From this information, Tenax Energy is able to better understand the potential tidal power conditions at each location, and identify in more detail suitable locations for further more detailed investigation, which ultimately will lead to the installation of tidal power turbines. We aim to work with the renewable energy sector to harness the potential of green energy supplies in a cost-effective manner.
Water Technology was commissioned by Hatch SMEC JV on behalf of Adelaide Aqua to develop and validate the final design of the outfall diffuser of the Adelaide Desalination Project. The primary objectives of the analysis and modelling were to demonstrate initial dilution of the saline concentrate discharge equivalent to 50:1, and rapid dispersion of the saline concentrate into the surrounding seawater.
Full three-dimensional mid-field modelling was undertaken to simulate the performance of the outfall diffuser, it is considered that the mid-field model is capable of providing a realistic description of the water level variations and currents near the outfall diffuser. The three-dimensional midfield model was used to assess the outfall performance for a range of operating conditions and receiving water scenarios. Sensitivity tests were carried out to assess the effect of the loss of two duckbill valves on the outfall diffuser ports, assess the likely effects of modifying the outfall source description to include entrainment of water from lower layers and assess the dilution performance of the outfall with a different alignment.
Ecological and water quality experts from Water Technology and Monash University joined forces to assess the water quality and ecological processes of the Gippsland Lakes. The Lakes have suffered recurrent summer toxic blooms of cyanobacterium Nodularia spumigena since 1985. A 3-D fully coupled hydrodynamic biological ecological model was used to explore the interaction between the physical and biogeochemical controls over Nodularia blooms.
The hydrodynamic model included turbulent mixing within the water column, whilst the ecological component of the model contained over 40 state variables and 200+ processes, parameterised by 176 constants to describe the biological/ecological and chemical reactions occurring in the water column and sediment compartments
Water Technology has undertaken an examination of the potential application of geotextile offshore reefs to mitigate shoreline erosion and create an environment that enhances the recruitment success of mangroves (Avicennia marina subspecies australasica) in Western Port for the Department of Sustainability and Environment.
The study team has reviewed the factors that affect the distribution and mortality of mangroves in Western Port and the impact of mangroves on sediment transport processes and in mitigating shoreline erosion in Western Port.
The physical processes that affect shoreline behaviour and erosion at two case study sites was investigated in detail including water level and wave data collection and numerical modelling of hydrodynamics, waves and sediment transport.
The physical process modelling has been used as a tool to inform, test and refine the design of offshore reef options for mitigating shoreline erosion problems occurring at the two study sites and to create a physical environment that assists in seedling survival, recruitment and colonisation in the lee of the structures.
Water Technology has been involved in the development of Wyndham Harbour since the early conceptual planning stages in 2003. The Harbour has evolved from the initial conceptual design through to final design and construction with the help of the Water Technology coastal and environment team. The key work items over the life of the project have included:
- Coastal processes and sediment transport studies
- Sampling and analysis of coastal sediments – Numerical modelling of harbour water quality, tidal and pump driven circulation and optimisation of harbour design and configuration
- Design and implementation of water quality testing and analysis programme
- Fate and transport of marine pollutants within the Harbour and the impact on Port Phillip Bay ecology – Breakwater design and optimisation through analysis of height, rock size, slope etc
- Management of verification of breakwater design through physical testing
- Assessment of dredging schedule and methodology
- Numerical modelling of impacts of dredging turbidity and optimisation of dredging and turbidity mitigation methods
- Application for Coastal Management Act Consent for Dredging
- Reporting to support the Environmental Effects Statement and presentations to the EES Panel hearing.
The work at Wyndham Harbour, combined with similar harbour and marine development projects at Martha Cove, Mornington Safe Harbour and Portarlington have provided Water Technology unparalleled experience and knowledge of the environment and coastal and oceanographic processes within Port Phillip Bay along with the procedure required to take a concept design to built product.
Water Technology was engaged by the Phillip Island Nature Parks to undertake the Phillip Island Nature Parks’ Coastal Processes Study. The objective of the project was to conduct an assessment of recent coastal evolution, future response of the coastline to coastal processes, and identify potential threats to natural and infrastructure assets as a result of coastal processes now and into the medium term future.
The overall outcome was to determine potential management strategies to protect natural assets such as Little Penguin and Hooded Plover habitat and the park’s critical infrastructure such as the viewing stands at Penguin Parade, the boardwalks at Smiths Beach, and the car park and Surf Lifesaving Club at Woolamai Beach.
Western Port Local Coastal Hazard Assessment
Western Port is one of four locations within Victoria where a Local Coastal Hazard Assessment (LCHA) has been undertaken as part of the Victorian Government’s Future Coasts Program. Led by the Department of Environment and Primary Industries (DEPI), the Future Coasts Program is designed to help Victorians understand and plan for climate risks along the coast by generating detailed coastal mapping and information. This information will assist in preparing Victorians for storm surges and possible sea level rise impacts into the future.
The Western Port Local Coastal Hazard Assessment (WPLCHA) involved detailed and comprehensive coastal hazard assessment, with a focus on inundation and erosion hazards around all shorelines of Western Port and French Island, as well as the northern shorelines of Phillip Island.
The information developed by the project will assist in better understanding, planning for, and managing coastal hazards. It will allow management agencies and other key stakeholders to identify and define triggers as the basis for short, medium and long term management responses.
Specifically, the information is intended to support decision-making about local infrastructure, natural asset management, emergency management planning, to inform land use planning and statutory planning decisions, and to provide information to support the development of adaptation plans.
Information from this project will also add to the suite of information available to help identify how and where State Government, Western Port Councils, the community, industry and other levels of government and governance agencies can work together to respond to or address the potential impacts of climate change.
Western Port Local Coastal Hazard Assessment: Documents via South East Councils Climate Change Alliance (SECCCA)