Riparian rehabilitation at a coal site
At the Bengalla coal operations in eastern Australia, Rio Tinto Coal Australia has established an ongoing partnership to restore a 10 kilometre section of the Hunter River, which has been degraded as a result of unsustainable land use practices since the time Europeans first settled within the region.
Bengalla and its neighbour, Mt. Arthur Coal (owned by BHP Billiton), manage approximately 30 kilometres of riverside (or riparian) land. The Upper Hunter River Rehabilitation Initiative (UHRRI) is working within the riparian margins of the river, on land shared by both mining operations. UHRRI is a showcase of successful partnerships between three tiers of government, three universities, four industry groups and the Upper Hunter community, who have come together for the first time to work towards a healthier Hunter River. Through this initiative, the aim is to create an ecologically self sustainable riparian forest - dominated by indigenous species on the margins of the Hunter River - so that river health is improved, a model is provided for future riparian efforts, and the river becomes a valued community resource.
UHRRI is much more than a revegetation project. At the forefront of an emerging international discipline known as integrative river science, UHRRI researchers are analysing relationships among geomorphological, hydrological and ecological (aquatic and terrestrial) processes. During the course of the five year project, five doctoral students working at the project site will examine:
- the relationship between weeds, landform and fluvial dynamics;
- the response of fish populations and communities to the installation of large engineered wooden structures;
- the effect of large wooden structures on nutrient transfer and processing instream;
- the response of flow patterns and processes to the installation of large wooden structures; and
- the geomorphic response of the riverbed to the installation of large wooden structures.
The removal of woody debris is one of the principal causes of channel instability and consequently instream habitat loss and homogenisation. Recent research has demonstrated that large, engineered, wooden structures introduced into the river are able to withstand flood flows and increase the complexity of channel morphology, which helps support a healthy, diverse aquatic ecosystem. Introducing such structures also increases the volume of sediment stored in the reach and contributes to bank stability. Preliminary results of fish monitoring are very encouraging, with the diversity and abundance of native fish species appearing to increase around the wood structures.
More than 45,000 trees and shrubs have been planted since the project commenced in 2002. UHRRI is using 18 tree and shrub species, up to 18 ground cover species and five littoral species, obtaining seeds from local stock wherever possible. Early plantings are already helping to reduce bank erosion and are expected to improve water quality and instream habitat quality for native aquatic species. This revegetation should also lead to further natural colonisation of native forests along the river.
Findings from the study will also be shared with researchers working in the field of riparian restoration, with the goal of contributing to academic knowledge and enhancing the success of future rehabilitation projects in this and other river basins.
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