Context and Rationale
Unsealed forest roads are a major source of fine sediment to waterways, yet road managers still lack a standardised way to predict where sediment delivery risk is highest or which mitigation actions will work best. This project was developed to close that gap by translating established road-to-stream connectivity science into a practical decision-support toolbox for road design, drainage, maintenance and regulatory communication.
Method and Approach
The toolbox was developed through collaboration between Alluvium, University of Newcastle, state agencies, FWPA, and private forestry partners. It combines stakeholder-informed design, GIS-based geoprocessing, field verification and scenario testing. The tool assesses sediment delivery from individual road segments, drain outlets, crossings, and catchments. Modules include culvert sizing, identifying road embankments that obstruct diffuse drainage, and testing how drainage spacing, road crowning and related treatments change sediment delivery risk.
Results and Outputs
The main output is a fully accessible ArcGIS Pro toolbox, supported by documentation, case-study application and a field collection framework. It generates spatial risk maps, summary statistics and scenario comparisons that show where fine sediment is most likely to reach waterways and where mitigation effort will be most effective.
Outcomes and Impact
This matters because it shifts road erosion management from generic compliance to targeted investment. It helps managers reduce sediment risk, optimise maintenance, improve crossing and culvert design, and communicate the basis for action clearly to regulators, industry and communities. The framework is also transferable to other forested road networks facing similar erosion and climate pressures.