Impact of dumping operations at a canyon head on turbidity current geohazard: insights from a project development

In the framework of a liquified natural gas (LNG) project developmenti, 16 million m³ of sediment will be dumped at the head of a submarine canyon. We investigate the ability of spring tides an monsoon storms to resuspend the dumped sediment and trigger turbidity currents (TCs) along the canyon. An integrated modelling is developed and validated against in-situ measurements to describe the dispersion of the dumped sediment, its subsequent erosion due to macro-tidal and storm-induced currents, the triggering and down-canyon evolution of TCs. Our results show that TCs can ben triggered by both energetic spring tides and extreme storms after the dumping, indicating a pontential yearly frequency of these flows. However, the first TCs can erode most of the fine-grained sediments, cleaning the canyon of the fuel for successive events. If confirmed by surveys of tidal erosion, these findings imply a limited risk of damage for the planned subsea infrastructures.