Bundaberg Regional Council Stormwater Management Strategy - A New Path for Council's Longstanding Challenges

Abstract

Development of roughness and imperviousness data for flood modelling presents a tedious, time-consuming challenge. These inputs directly influence simulated flood behaviour and risk analysis. As such, their preparation must be given due care to avoid error and bias. Traditionally, practitioners have manually digitised landuse features with low detail and abundant inconsistency. Manual approaches also rely on the assumption that visually dense canopy correlates with dense understory. Moreton Bay Regional Council (MBRC) acquired new aerial imagery and LiDAR in 2019. Rather than manually update regional models, MBRC engaged with AECOM’s specialists to develop a data-driven, high value method for the definition of land use layers. The team made use of technological advances in GIS and Artificial Intelligence (AI) to automate preparation of these crucial layers. AI was used to delineate features such as building extents, roads and vegetation with high precision and minimal bias at a massive scale. Critically, the project team developed a new approach that uses x-ray vision (literally) and point cloud data science to calculate vegetation density below the canopy. This new approach was successfully ground-truthed and significantly improves Council’s understanding of hydraulic roughness where flood waters traverse. These new regional databases (landuse, fraction impervious, hydraulic roughness) boast a 1m resolution and span 2,500km2 of the LGA, promoting consistent model practice throughout the region. The project demonstrates that harnessing the full potential of GIS and AI in flood modelling is key to our industry’s future. It also highlighted the discrepancy between traditional and new approaches to fraction impervious estimation and the follow-on effect for hydrograph estimation. This paper will discuss the methods used for creating MBRC’s new regional databases, the positive impacts of the approach for Council, and the opportunities available for the broader industry.