Since 2004, WRL has been working in collaboration with the NSW National Parks and Wildlife Services (NPWS) and the Department of Primary Industries (NSW Fisheries) to transform the Tomago Wetlands site from a large acidic landscape into a restored productive tidal wetland. The wetland is being created to compensate for migratory wading bird habitat destroyed elsewhere in the lower Hunter River estuary.
The project has been joint-funded by NSW Fisheries, National Parks and Wildlife Service (NPWS) and the Hunter Region Local Land Services (formerly Hunter River Catchment Management Authority) with in-kind support provided by WRL. Advice and assistance from the Hunter Bird Observers Club (HBOC) has been provided throughout the project.
Nature is complex. Endangered ecological communities embody this complexity, existing in a fine balance, though influenced by numerous factors including topography, geology and hydrology. Restoring this balance, to foster the genesis of an endangered ecological community, is a multi-disciplinary challenge.
The specific challenge faced by the Tomago Wetland Restoration Project was to design and build a system that would naturally encourage salt marsh regeneration, an ecological community in serious decline in NSW. Salt marsh requires very specific hydrological and water quality conditions. The engineering challenge was to deliver the right volume of water, to the right place, at the right depth, at the right time and at the right salinity to allow nature to flourish and generate salt marsh.
Previous projects have taken a trial and error “shot gun” approach to restoration with limited success. The engineering design and assessment approach applied to research, planning and on-ground solutions at Tomago Wetland sets a new standard in engineering practice and has been highly successful.
Key features of the project include:
- Design and application of a staged restoration approach:
- Detailed hydrodynamic modelling to test and fine-tune tidal inundation extent and hydraulic controls across the wetland during design;
- Design, construction and application of innovative on-ground engineering works including remotely controlled SmartGates and buoyancy controlled swing gates;
- Monitoring of changes in vegetation, fisheries and birds throughout the site;
- Effective adaptive management of habitat type and extent through remote and onground monitoring; and
- Enhanced ecosystem services to the wider community through increased fisheries and bird populations.
Environment and Heritage
This project utilised innovative engineering practice to create > 400 hectares of thriving wetlands attracting thousands of migratory birds. The methods and on-ground practices developed from this project are now being used at other sites including large restoration projects on the Manning, Clarence, Shoalhaven and Macleay Rivers in NSW. The site is also used as a demonstration site to train practitioners in “Wetland Hydrology and Restoration”.
Two aspects that showcase leading practice are:
- Eco-hydraulic modelling. Hydrology underpins our approach to restoration. This project linked ecosystem hydrology modelling with various on-ground design scenarios. This practice is now being adopted at similar sites across NSW.
- Adaptive Management (via Photo Monitoring and Hydraulic Controls). To promote adaptive management principles elevated cameras were installed across the site to provide hourly images of tidal inundation. These images detail inundation regimes, onsite geomorphic change, vegetation dynamics and security/vandalism. The analysis is then used to adaptively manage onsite tidal flushing via the Smart and Swing Gates infrastructure. This environmental practice is now being employed at other sites across Australia.
A primary aspect of this project is avoiding the ‘trial by error’ approach common to most environmental restoration projects. As such, all planning for the project focused on sustainable, environmentally mature outcomes. This is unique in environmental projects and limits long-term maintenance costs.
Environmental sustainability was delivered by:
- Reviewing practice worldwide and developing new methods where necessary.
- Ensuring on-ground designs were engineered using techniques and products suitable for the harsh environment.
- A ranger has been assigned to ensure the long-term monitoring directly links to the adaptive management of the site.
- Engineering hardware was designed to ensure easy access, high OHS standards, ease of serviceability and long lasting materials (including marine grade stainless steel). 15 year maintenance programs were incorporated into all major infrastructure plans.
The community is the obvious beneficiary in this project with:
- The addition of >400 hectares of publicly accessible migratory bird habitat and tidal wetlands.
- Public groups such as the Hunter Bird Observers Club and recreational fishing groups advocating for the project.
- Direct alignment with the regional Plan of Management’s objectives.
Leading Engineering Practice
Bringing sound engineering principles to ecosystem restoration practice is a key strength of any environmental engineering project. Until now most large restoration projects have not incorporated principles of hydraulics, hydrodynamics and hydrology to concepts such as wetland channel design, shallow overland inundation, fish movement and wetland geomorphology.
Our application of these principles, such as the innovative use of automated SmartGates onsite to control broad acre wetland design, highlights why this project is an example of leading engineering practice.
Prior to this study, the project leader Dr William Glamore undertook a global exploration of similar projects as part of a Churchill Fellowship. This background provided a benchmark for the project.
The significance of this work is the use of sound engineering principles and innovative engineering practice to ensure environmental restoration outcomes. As noted in Dr Glamore’s Churchill Fellowship report, the outcomes at Tomago were desperately needed to integrate the unique aspects of the Australian environment (including hydrology and ecology) with engineering practice. The findings are now applicable at thousands of similar sites across Australia.
Various challenges were overcome with innovative solutions. Examples include:
- SmartGates and SwingGates were engineered to provide hydrologic control over a broad acre wetland.
- Eco-hydrodynamic modelling was developed to guide on-ground practice and ensure the health of fish and vegetation.
- Innovative monitoring, using elevated remote photography, assisted in adaptively managing the large site.
Budget and Program
The recent sighting of thousands of migratory shorebirds is the best demonstration that the project achieved what it set out to accomplish.
- The project program was defined in the ‘Review of Environmental Factors’, a public document with detailed public scrutiny. Between 2012 and 2014 all of the major program objectives have been reached for Stages 1 and 2.
- This project has provided excellent value for the funds obtained and highlights the collaborative partnership. Funded via multiple grants ($15,000-$80,000) obtained by each project partner, the team works collaboratively to reduce overheads and leverage in-kind support. Each project budget was externally reviewed (on a line item basis) upon completion.