4 minute read
Tomago Wetlands
Tomago, New South Wales, Australia
Restoring a salt marsh’s hydrology regime with large-scale engineering. Hunter Wetlands National Park lies along the Hunter River estuary in southeastern New South Wales. Because it provides foraging habitat for migratory wading birds along the East Asian–Australasian Flyway, it is a designated wetland of international importance. However, due to sea level rise and an enhanced tidal range, the salt marsh ecosystem in the park has been under threat, experiencing ecosystem loss. To combat this loss and provide a nature-based solution, New South Wales National Parks and Wildlife Service, working with researchers from the University of New South Wales Sydney, restored a 450-hectare area of low-lying and drained land called the Tomago Wetlands. In 2007, the restoration began by installing novel tidal control gates and reintroducing tidal inundation to 250 hectares. In 2012, the project restored an additional 62 hectares; and in 2015, the team restored the final 138 hectares. This project, one of the first large-scale intertidal restoration projects in Australia, has successfully expanded the park’s salt marsh habitat and established significant foraging grounds for migratory avifauna—including over 5,000 birds in a single month. Additionally, the site remains an important test case for ongoing research linking hydrodynamics, geomorphology, and ecology in Australia.
Article cover: Tomago Wetlands is a thriving tidal wetland and part of the Ramsar-listed Hunter Wetlands National Park. (Photo by Will Glamore, PIANC)
Producing Efficiencies
Examining hydroperiods of salt marsh and mangrove systems across the estuary determined the optimal operational design to promote ecosystem recovery. The project team incorporated these variables into a detailed ecohydrodynamic model to provide on-theground site management options. To maximize salt marsh growth while also ensuring that adjoining landholders were not negatively affected, the team implemented an innovative SmartGate system at Tomago. The gates permit adaptive tidal inundation control across the large intertidal flats, protecting both the restored areas and the adjoining commercial properties from river-based floods.
Using Natural Processes
At Tomago, unlike at other shorelines, the project team wanted to limit mangrove expansion because the natural predators of migratory wading birds are often found in mangrove ecosystems. But the team also wanted to maximize the benefits of the local natural processes. The team achieved both by promoting the preferred hydrodynamic regime for salt marsh ecosystems while also installing sufficient water-level control to limit mangrove expansion. This hydrologic regime naturally optimizes carbon accumulation processes, enhancing the accretion rate of the wetland.
Broadening Benefits
The site is part of the lower Hunter River flood mitigation scheme, which ensures flood storage and retention for the nearby city of Newcastle. Open to the public and managed according to the local community’s needs, the restored wetlands now are not only an important habitat but also provide flood control to adjoining properties. By integrating a community approach and completing the project in stages, the New South Wales National Parks and Wildlife Service has made sure the restoration provides ecological, economic, and social benefits to the entire region.
Promoting Collaboration
The various collaborative partners on the Tomago project are still working to ensure the continued success of the plan. Researchers working on site have established long-term monitoring to assist with adaptive management plans, and the community has access to a live-streaming camera of the site—with over 15,000 images available since 2007—to ensure the site evolves as planned. Finally, the local bird watching club provides monthly monitoring of bird populations to track the project’s success. Together, these groups help to maintain the ongoing adaptive management of the site.
