Wildfires may profoundly affect forested catchments by altering hydrological processes, soil properties, and sediment dynamics. While post-fire increases in water quality constituents are well documented, the underlying divers for such changes remain poorly understood. This study examines how fire and short-term hydrologic conditions interact to shape sediment dynamics using a novel Bayesian Hierarchical modelling framework. The analysis is at event-scale based on multi-year, high-frequency turbidity and streamflow data collected from 14 forested catchments in eastern Australia, which were burned to varying severities during the 2019/2020 Black Summer fires and affected by subsequent floods. Further, we explored how these effects vary across catchments with the extent of burning and other catchment characteristics.</p> <p>Model results show that severe burning had a clear steepening effect on the slopes of event concentration-discharge (C-Q) in 5 out of the 10 severely burnt catchments studied, indicating enhanced sediment mobilization following extreme burning. The influence of short-term hydrologic conditions on C-Q slopes was comparatively minor, suggesting that fire effects dominated post-disturbance sediment responses. The magnitude of fire effects (as post-fire changes in the C-Q slopes) did not always scale directly with the proportion of catchment burnt, which also seems to be driven by the location of extreme burning and forest types. These findings provide a large-scale, multi-catchment understanding of post-fire sediment mobilization mechanisms, which can inform future improvement of modelling and management of sediment in fire-affected forested landscapes.