Quantifying the Variability in Flow Competence and Streambed Mobility with Water Discharge in a Gravel-Bed Channel: River Esva, NW Spain

Abstract

Streambed mobility in gravel-bed rivers is largely controlled by the rate at which particles with different grain sizes are recruited from the riverbed into the bed load. In this paper, we present a study case in which we explored this question, based on combining field observations using painted plots and the grain size analysis of a large flood sediment deposit in the River Esva, northwest Spain, and the generalized threshold model (GTM) competence model developed by Recking. The main aim was to accomplish a complete characterization of streambed mobility in this river. The obtained results suggest the large potential of the GTM model compared to previous competence models when searching for the quantitative description of particle entrainment and streambed mobility in the River Esva. We observed how the grain size of the bed load in the River Esva tended to be closer to that of the sub-armour bed material during large floods, while moderate magnitude flows tended to carry a relatively fine bed load. Additionally, we compared our results with previously published field observations on flow competence. This comparison outlined the large degree of site specificity in the links between grain size of the bed load and that of the bed material.

Channel changes over the last 200 years: A meta data analysis on European rivers

“…To achieve knowledge as comprehensive as possible, additional data have to be considered as a time series of hydrological (discharges and stages) and piezometric data that can be used conjointly to estimate changes in channel depth and conveyance (Biedenharn & Watson, 1997; Pinter & Heine, 2005; Ruiz‐Villanueva et al, 2023). Measures of sediment transport in relation to hydrological data are important to demonstrate the link between sediment regimes, alterations in sediment flux and sediment connectivity and morphological changes (Casserly et al, 2021; Dépret et al, 2023, 2019; Liébault & Piégay, 2001; Scorpio et al, 2024; Vázquez‐Tarrío et al, 2019). Quantification of sediments extracted for gravel mining or trapped at retention works and dams can allow for estimating the volumes subtracted from rivers (De Vincenzo et al, 2017; Scorpio et al, 2024).…”

“…Reach scale changes and drivers must always be considered within an integrated catchment perspective, bearing in mind that there is a time lag between causes and effects and that each anthropogenic action will cause effects propagating both upstream and downstream. This is a scientific and practical challenge because the most appropri- between sediment regimes, alterations in sediment flux and sediment connectivity and morphological changes (Casserly et al, 2021;Dépret et al, 2023Dépret et al, , 2019Liébault & Piégay, 2001;Scorpio et al, 2024;Vázquez-Tarrío et al, 2019). Quantification of sediments extracted for gravel mining or trapped at retention works and dams can allow for estimating the volumes subtracted from rivers (De Vincenzo et al, 2017;Scorpio et al, 2024).…”

Bedload entrainment dynamics in a partially channelized river with mixed bedload: A case study of the Drava River, Hungary

“…Entrainment thresholds of individual grains have been studied by numerous researchers after Einstein (1950). Bed material mobilization is largely controlled by the rate at which particles of different grain sizes are entrained from the riverbed and incorporated into the bedload (Vázquez-Tarrío, Fernández-Iglesias, Fernández García, & Marquínez, 2019). Charru, Mouilleron, and Eiff (2004) claim that the rate of entrainment depends on the Shields number.…”