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Wave‐ and current‐supported gravity flows (WCSGFs) represent a primary mechanism responsible for the transport of sediment along gentle coastal and continental slopes. However, due to limited in situ measurements, the dynamic processes involved in the downslope movement of WCSGFs along such slopes remain poorly understood. Here, tripods were strategically deployed on a muddy coastal slope in central Jiangsu, China. We found that WCSGFs occurred following a wave event, particularly during tidal slack periods. In instances where WCSGF events coincide with low slack water, the observed time lags between break and toe sites align with expectations based on gravity‐driven velocities and distances, thereby corroborating the gravitationally induced sediment transport across the gently sloping coast. Comparatively, WCSGF events during high slack water were suggested to originate from the upper tidal flat of the cross‐shore profile and were unable to reach the toe site. Waves are crucial in supporting the downslope transport of WCSGFs. In addition to sustaining the cross‐shore movement of WCSGFs, currents suspend sediments from the high‐concentration layer, dispersing them into the overlying water column. This suspension helps extinguishing WCSGFs. The local slope at the toe site lacks the necessary gravitational force to propel high‐concentration layers further offshore, as evidenced by the abnormally low drag coefficient (CD) derived from the theoretical WCSGF model. Despite their short‐lived nature and limited travel distance, the WCSGFs examined in this study make a significant contribution to cross‐shore sediment transport. This study contributes to a better understanding of WCSGF dynamics and their importance in coastal sediment transport. [ABSTRACT FROM AUTHOR]

[Display omitted] • Strong interannual variability of the sediment dynamics in the Gulf of Lion. • Massive sediment accumulation near the Rhone River mouth (∼56 % of the river inputs) • Sediment deficit on the inner shelf due to the long-term reduction of the Rhone inputs. • Storm-induced sediment accumulation in the southwestern Gulf of Lion. • Cold winters mainly impact the southwestern and outer shelf and the submarine canyons. A simulation based on a hydro-sedimentary model was conducted for the period between summer 2010 and spring 2012 in the Gulf of Lion (northwestern Mediterranean Sea) to understand the spatial and temporal variability of sediment transport, erosion and deposition on the continental shelf and slope. Datasets of both simulated and observed current, temperature and suspended matter from the shelf and the Cap de Creus Canyon which is the main export route towards the continental slope, were first compared to assess the reliability of the simulation. The simulation shows the massive sediment accumulation near the Rhone River mouth (∼56 % of the inputs), the accretion along the mid-shelf mud belt, and the impact of dense shelf water cascading on sediment resuspension and erosion inside the Cap de Creus Canyon. The two studied autumn–winter periods were strongly contrasted in terms of meteorological conditions and subsequent impacts on the sediment dynamics. During the first period (2010–2011) dominated by marine storms, the shelf sediment underwent strong changes, the Rhone River sediment load accumulated in a relatively small area, stock of littoral sands moved to the inner shelf (20–40 m) while inner shelf fine particles fed the mid-shelf mud belt and the upper Cap de Creus Canyon. During the second period (2011–2012) with very little marine wind and a particularly cold winter, sediment on the shelf underwent little change except for a southwestward growth of the Rhone River prodeltaic deposit. Sediment from the southwestern end of the shelf as well as from the upper Cap de Creus Canyon was flushed toward deeper reaches by dense shelf water cascading. Cascading also had a more moderate impact in the various canyons incising the continental shelf. Our work supports the view of an unbalanced sedimentary system, with a deficit mainly over the inner shelf, whose main driver is probably the strong and fast reduction of particulate matter inputs from the Rhone River (by a factor of 4 in less than one century). [ABSTRACT FROM AUTHOR]