The importance of managing riparian zones for saving the Great Barrier Reef (11644)
Recent research into the sources of post-European settlement increases in sediment yield to the Great Barrier Reef World Heritage Area (GBRWHA) indicate that in most catchments the dominant erosion processes contributing elevated sediment are those associated with the sub-surface sources of bank, gully, and scald erosion. Alluvial gully erosion is the dominant form in the major sediment yielding catchments to the GBR like the Burdekin, Fitzroy, Normanby and Herbert catchments are of the alluvial form, where the erosion is occurring into floodplain deposits. By definition the initiation, and potential control of these alluvial gullies, are inherently linked to riparian zone land management. The riparian zone is hereby defined in the broadest terms, as per the definition by Malanson (1993), and refined by Brooks et al., (2008), which includes the channel and floodplain zone. Bank erosion is also clearly a process that is integrally associated with riparian zone processes, and in catchments such as the Normanby is as significant a source as alluvial gully erosion. New evidence from the Normanby also indicates that the deposition of suspended sediment within the macro-channel is far more significant than previously assumed; a sink that to date has not been accounted for in most catchment sediment budgets.
For various reasons, management strategies aimed at managing water quality delivered to the GBRWHA have not focused to the extent that they should on sediment sources derived from the riparian zone over the last decade, nor to the potential of this zone to mitigate sediment delivery through storage. In this paper we present a range of evidence for the critical role of riparian zone management to reducing sediment inputs to the GBRWHA, and suggest it is time to re-establish a program similar to the former Land and Water Australia Riparian Program, focused on the development of Riparian Management Strategies for the GBR. Given the dominance of sediment sourced from the riparian zone, significant reductions in sediment yield to the GBRWHA will not be achieved without a concerted focus on effectively managing these erosion processes.
- Malanson, G.P. (1993) Riparian Landscapes. Cambridge University Press, Cambridge, pp. 296.
- Brooks, A.P., L. Lymburner, J. Dowe, D. Burrows, I. Dixon, J. Spencer and J. Knight (2008) Development of a Riparian Condition Assessment Approach for Northern Gulf Rivers using Remote Sensing and Ground Survey, Final Report, Project No GRU38, August 2008, pp. 71.