Catchment-based classification of Australia's continental slope canyons

Abstract

This study presents an approach to the classification of submarine canyons on the Australian continental slope. There are many canyons around the Australian continental margin it provides an opportunity to undertake a characterisation and inventory of these potentially important assets. By establishing a shelf, break and foot of slope based on gradient, submarine catchments are defined based on a drainage network derived from across the continental shelf and slope. On completion of this classification, metrics are extracted for both the drainage network representing submarine canyons and the catchment morphology.The rationale for this research is to demonstrate the application of algorithms developed for drainage analysis. These algorithms have traditionally been applied in terrestrial environments for the automatic extraction of drainage networks and catchments from digital elevation models. This work is made possible by recent advances in deep-sea multibeam technology, so that the seafloor morphology can be mapped in higher definition. With the recent advances in data quality, these algorithms can be applied to an integrated and combined model of both elevation and bathymetric datasets to provide better insight into geomorphological features, including the relationships between subaqueous sedimentary canyons, channels and drainage system morphology. Drainage analysis provides a rapid automatic procedure to derive networks on the continental shelf and slope.Results show that by establishing a shelf break and foot of slope based on gradient, submarine catchments can be derived on the continental slope based on the drainage analysis. The Australian continental slope contains 257 shelf-incised catchments based on analysis of a bathymetric model mapped at a resolution of 250m. The drainage analysis demonstrates the capabilities of correctly predicting the layout of dendritic patterns leading to a better geological understanding.