Stream responses to urbanisation are commonly interpreted using space-for-time approaches that often overlook the influence of historical geomorphic legacy. This study investigates how past land-use disturbance and inherited channel conditions influence contemporary channel adjustment in Quinzeh Creek, Queensland Australia, a progressively urbanising catchment within the Logan River system.
A combination of field observations and LiDAR-derived Digital Elevation Model of Difference (DoD) analysis (2009–2023) was used to quantify geomorphic change across nine distinct reaches.
Results show that the most significant adjustment, including incision, lateral erosion, and headcut development, occurred in upstream reaches and was largely unrelated to recent urbanisation. Instead, these patterns reflect pre-existing instability associated with dispersive soils, vegetation clearance, and altered flow pathways. Downstream reaches exhibited lower rates of adjustment and greater sediment storage, indicating spatial variability in geomorphic response.
The results suggest that urbanisation mainly worsens pre-existing channel instability rather than independently causing all observed and/or inferred changes. This study highlights the importance of explicitly accounting for historical geomorphic legacy in interpreting urban stream behaviour and in developing effective, process-based management strategies