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Celebrating World Rivers Day at the International Riversymposium
Sunday 25 September is World Rivers Day, a global celebration of the world's waterways observed each year on the last Sunday in September. Established in 2005, it highlights the many values of rivers and strives to increase public awareness while encouraging the improved stewardship of rivers around the world.
Coinciding with World Rivers Day is the International Riversymposium in Brisbane. Attended by leading scientists, community groups, government agencies and corporate leaders from over 25 nations, the Riversymposium is the ultimate river and water management conference where the latest thinking and proven solutions are explored and debated.
At this year's symposium, the Hexham Swamp Rehabilitation Project will be featured in a presentation by Callaghan Cotter from the Hunter-Central Rivers Catchment Management Authority and project consultants Phil Haines from BMT WBM and John Paul-King from PEA Consulting. The following is a short summary of the presentation they will provide at the conference.
After 40 years of dreaming, 15 years of planning, and 2 years of implementation, the Hexham Swamp Rehabilitation Project has finally become a reality, with re-introduced saline tidal flows now starting to restore the former estuarine ecological characteristics of this iconic and internationally important wetland.
In the early 1970s Hexham Swamp was cut-off from regular tides by the installation of floodgates. The ensuing 40 years saw the dire transition from a complex mosaic of freshwater and saltwater habitats, to a monoculture of tall freshwater reeds.
As part of the Hexham Swamp Rehabilitation Project, some 300 hectares of the wetland are now periodically or permanently inundated with brackish water. Saltwater intolerant vegetation, such as Kikuyu and Typha, has died-back quickly, while more salt tolerant species such as Phragmites, are also starting to show some limited signs of retreat.
In more open areas, saltmarshes are beginning to return and spread, while the few remaining mangroves now have more vigour and have produced abundant propagules. Indeed early signs even indicate a shift in abundance and dominance of birdlife on the wetland. One of the expected future management challenges will now be to control the spread of propagules and juvenile mangroves to ensure adequate areas remain reserved for saltmarsh regeneration.