Evaluation of the deposit dynamics on a gravel bar after different hydrologic events

Junjian Deng (1) , B. Camenen (1) , Lionel Pénard (1) , Thomas Drevet (1)

1 RiverLy - RiverLy - Fonctionnement des hydrosystèmes

Estimating the fine sediment budget in alpine rivers is an important challenge to better understand the morphodynamics of such rivers. In this paper, we describe the dynamics of fine-sediment deposits over a gravel bar before and after two flushing events in an alpine river based on pictures taken from the side of the river. These pictures are processed using a new image analysis method. It allows to estimate the spatial distribution of fine-sediment deposit on the gravel bar using photos taken at different dates. Photos before and after the flushing events in 2018 and 2019 were analysed. Comparison with the local in-situ measurement of surface grain size distribution has been carried out using the Wolman peddle count method. The image detection method presents a good agreement on the spatial distribution and variations of fine sediment deposits on the gravel bar with an acceptable bias. A discussion is provided on the limits and validation of the proposed method as well as on its applicability on medium term analysis.

Domaines: Géomorphologie; Hydrologie

Junjian Deng, B. Camenen, Lionel Pénard, Thomas Drevet. Evaluation of the deposit dynamics on a gravel bar after different hydrologic events. River Flow 2020, Jul 2020, Delft, Netherlands. ⟨hal-03118421⟩