Managing sediment export from large, evolving mining landscapes remains a key challenge for downstream waterway protection. Mine catchments are inherently dynamic making it essential to understand sediment sources and fate in order to deliver focused, timely management interventions. As part of a broader mine management project, Hydrobiology undertook a catchment-scale sediment runoff assessment to quantify erosion risk and prioritise mitigation across multiple disturbed catchments.
The study applied a hybrid modelling framework combining the physically based erosion model GeoWEPP with a stochastic SedNet-RUSLE–based Sediment Source Dynamics Model (SSDM). GeoWEPP simulates spatial patterns of runoff, soil detachment, transport and deposition based on terrain, soil, climate and vegetation inputs. The SSDM uses a Monte Carlo framework to estimate sediment yield from multiple sources hillslopes, gullies, channel beds and banks, representing uncertainty in erosion processes probabilistically.
Results revealed substantial variability in sediment export across catchments, with high yields consistently associated with steep terrain, sparse vegetation and concentrated flow paths. While both models aligned well in identifying sediment source hotspots, predicted export magnitudes differed. GeoWEPP captured greater spatial variability and episodic high-magnitude erosion, while the SSDM produced higher, more spatially uniform estimates.
The comparison highlights the value of integrating deterministic and stochastic approaches when assessing sediment risk in landscapes that are simultaneously degraded and recovering. The framework supports adaptive catchment management by identifying priority intervention areas and testing mitigation scenarios as rehabilitation and mine closure continues to place itself at the forefront of sustainable mine futures.