Estimation of Fine Sediment Stocks in Alpine Rivers - INRAE - Institut national de recherche pour l’agriculture, l’alimentation et l’environnement Access content directly
Proceedings Year : 2022

Estimation of Fine Sediment Stocks in Alpine Rivers

Estimation des stocks de sédiments fins dans une rivière alpine

Abstract

In alpine rivers, a large amount of fine sediments travels over the gravel-bed system as suspension and interacts with the gravel matrix. Recent studies highlight that fine sediment stocks in river bed can be a significant source of suspended load at the event scale, and can affect sediment budget estimation. However, there barely exists any estimation of fine sediment stocks in gravel-bed rivers, especially for the sand fraction. One can also question the spatial and temporal variability of these stocks, which makes the estimation of such source of fine sediments challenging. In this study, we intend to quantify fine sediment stocks in an engineered Alpine river system (Arc-Isère in the French Alps) characterized by the presence of alternate bars. We estimate the potentially re-suspended fine stocks from the gravel bar matrix for different discharges by coupling field measurements, GIS spatial analysis and 1D modelling. The measured fine stocks show a significant amount of sand present in the river bed. The silt-clay part of the calculated re-suspended stocks from the bed for a 15year return period flood event is found equivalent to around 30% of annual Suspended Sediment Matter (SSM) flux, which appears consistent since such large event may yield up to 50% of the annual SSM flux. However, the silt-clay stocks represents around 20% of the total fine stocks only, 80% corresponding to sand. Therefore, a large amount of sand could be re-suspended from the gravel bar matrix and should not be neglected when estimating the downstream sediment budget.
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Dates and versions

hal-03948192 , version 1 (20-01-2023)

Identifiers

  • HAL Id : hal-03948192 , version 1

Cite

Junjian Deng, Téa Piednoir, Lionel Pénard, Benoît Camenen. Estimation of Fine Sediment Stocks in Alpine Rivers. 2022. ⟨hal-03948192⟩
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