Optimizing the management of riparian zones to improve the health of the Great Barrier Reef
Led by: Dr Keryn Paul, CSIRO
This study uses evaluation of past investments to demonstrate effectiveness, and enable improved targeting, of riparian remediation works for reducing streambank erosion to achieve improved water quality outcomes within the Great Barrier Reef. By re-visiting previous riparian erosion-control investments we will identify what factors result in generating a functional riparian zone, including the conditions under which the investment occurred (rainfall zone, fencing arrangements, soil type, etc.), and the type of remediation revegetation (width of revegetation, connectivity of riparian area, species mix established, etc.). With stakeholder input, we will develop an initial framework to guide future investment in riparian remediation works.
Sediment tracing suggests that streambank erosion contributes ~30-40% to end of catchment sediment yields in the Great Barrier Reef (GBR) catchments1. Researchers have made considerable progress into understanding the source areas and processes delivering sediment to the GBR2-7. Although there is still room for their improvement, tools are available (e.g. SourceCatchments model, which using empirical relationship of meander migration rate to estimate bank erosion) for informing decisions about where to invest in riparian zone management for improved water quality outcomes. But despite having tools to estimate which catchments to target for riparian management, knowledge gaps remain on what sort of management activities have the greatest success in minimizing bank erosion.
How Research Addresses Problem
It is timely to develop a reliable framework to guide investment in riparian remediation works as there is growing interest in using trees and vegetation to reduce the rates of erosion from stream banks through the utilization of carbon markets. As restoration of riparian zones (e.g. fencing and associated offsite watering points) is expensive, with an estimated cost about $16,000 per kilometre, accessing the carbon market may subsidize this costs through carbon payments made for carbon sequestration in biomass (e.g. regulated markets such as the Emissions Reduction Fund projects, or the voluntary market). Previous work has shown that carbon sequestration potential is particularly high in riparian regions and that there are associated biodiversity benefits, particularly when establishing blocks of environmental plantings comprised of a mixture of species (i.e. mix of over- and under-story species). Further, previous work on erosion control has indicated that priority should be given to connecting in-tact riparian zones. Such landscape connectivity of vegetation will have additional co-benefits to biodiversity outcomes.
Focusing on two contrasting catchments, one from the Wet Tropics (Tully or Johnstone) and one from the Dry Tropics (Fitzroy Basin), a combination of remote sensing and on-ground assessments will be used evaluate the specific conditions under which past riparian restoration and revegetation projects have been successful. This will include an assessment of the conditions under which the project occurred (rainfall zone, fencing arrangements, soil type, etc.), and the type of revegetation (width and connectivity of riparian area, species mix established, etc.). The aim is to work with our partners (Terrain, FBA) and next users or stakeholders (DoEE, QDEHP, QDSITI and QNRM) to provide evidence-based recommendations for targeted remediation activities that have the greatest chance of success in terms of reduced erosion and improved water quality, and which have added potential to be at least partially funded through access to carbon markets, while also providing biodiversity benefits.
Alignment with NESP Research Priorities
This project will primarily support NESP priorities under theme 1, Water Quality Improvement. Specifically, it will support Priority 1b: Provide science that demonstrates effectiveness and enables improved targeting of streambank erosion and on-ground remediation works to achieve improved water quality outcomes. This should enable better understanding of cause and effect (where and how investments should be targeted) and may include evaluating past investments.
Water Quality; Sediment; Bank Erosion; Riparian Zone; Great Barrier Reef.
This project is jointly funded through CSIRO, Terrain, FBA and the Australian Government’s National Environmental Science Programme.
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