The Great Barrier Reef, one of the planet’s richest and most complex natural ecosystems, is facing significant threats to its existence. Behind climate change, water quality is one of the Reef’s greatest risks, and declining water quality associated with run-off from adjacent catchments is a major contributor to the poor condition of many of the Reef’s coastal and marine ecosystems.
Fine sediments like those washed from unsealed roads and drains can contribute to higher algal growth, build up pollutants in sediments and marine species, and reduce light and smother corals. Conservative estimates indicate there is around 38,000km of unsealed roads – more than 50 percent of the entire road network within the Great Barrier Reef catchments.
Recognising the opportunity to leverage AECOM’s deep knowledge of road and highway engineering, water management and sustainability, our specialists are taking action with the Cleaner Road Run-off project. Working in partnership with the Local Government Association of Queensland and the Great Barrier Reef Foundation, the project seeks to understand the characteristics that drive unsealed road erosion and determine actions to reduce suspended sediments entering the Reef.
The project is a key initiative as part of AECOM’s three-year partnership with the Great Barrier Reef Foundation – an up to $1 million in-kind commitment to provide AECOM’s services to help build the resilience of the Reef.
Understanding the challenge
AECOM is delivering an evidence-based assessment to establish the relative impact of fine sediment from unsealed roads on water quality to identify high-risk road characteristics where improved infrastructure design or maintenance processes would benefit water quality.
Using these insights, the Cleaner Roads Run-off project will identify a suite of cost-effective and practical measures to improve sediment management from unsealed roads.
The Cleaner Roads Run-off project involves two main components. Firstly, an evidence-based assessment is being undertaken to estimate the amount of fine sediments produced annually by unsealed roads in the Reef catchment. Next, we will identify potential pathways for sediment migration and define high-risk road characteristics where improved infrastructure design or maintenance processes would benefit water quality.
Using data-led decision-making to create a better road network
AECOM specialists are building a bespoke model from first principles, capable of assessing the impact of various road management scenarios. The project requires a customisable software solution due to the scale of the catchments surrounding the Reef. The team are now progressing with a pilot catchment to validate the model before scaling it to include the broader Reef catchment.
The model will act as a decision support tool to run ‘what-if’ scenarios, testing the impact of elements like the road drain geometry, the number of drain turnout points, and rock-filled landscapes on diverting sediment from the Reef.
Insights from the technical assessment will inform existing guidelines for how operators maintain and upgrade unsealed roads and highlight where modification and changes to the guidelines could help reduce sediments. For example, we may consider the frequency of turnouts in drains, assessing the guidelines for turnout spacing, the location and the size of the turnouts and drains, and how changes may reduce fine sediments reaching the Reef.
In addition to the Local Government Association of Queensland’s communication and engagement processes, the Cleaner Road Run-off project will also use PlanEngageTM, AECOM’s digital platform, to share complex information with stakeholders, and enable collaboration and feedback. The project will also use digital solutions like drone surveys and photogrammetry to refine and inform aspects of the modelling. PlanEngageTM will be used as a repository for the project’s geographic information system (GIS) data, allowing stakeholders to view pilot catchment data and supporting information like drone surveys and site imagery.
AECOM has partnered with the Great Barrier Reef Foundation since 2018. Learn more about how our other projects, like the Resilient Reefs Initiative, are helping build the resilience of UNESCO World Heritage coral reef sites here.