https://ria.asturias.es/RIA/handle/123456789/2822 2025-12-12T11:13:59Z 2025-12-12T11:13:59Z Vázquez-Tarrío, Daniel Borgniet, Laurent Liébault, Frédéric Recking, Alain https://ria.asturias.es/RIA/handle/123456789/14604 2023-02-27T10:36:45Z 2017-05-15T00:00:00Z

Title: Using UAS optical imagery and SfM photogrammetry to characterize the surface grain size of gravel bars in a braided river (Vénéon River, French Alps) Authors: Vázquez-Tarrío, Daniel; Borgniet, Laurent; Liébault, Frédéric; Recking, Alain Abstract: This paper explores the potential of unmanned aerial system (UAS) optical aerial imagery to characterize grain roughness and size distribution in a braided, gravel-bed river (Vénéon River, French Alps). With this aim in view, a Wolman field campaign (19 samples) and five UAS surveys were conducted over the Vénéon braided channel during summer 2015. The UAS consisted of a small quadcopter carrying a GoPro camera. Structure-from-Motion (SfM) photogrammetry was used to extract dense and accurate three-dimensional point clouds. Roughness descriptors (roughness heights, standard deviation of elevation) were computed from the SfM point clouds and were correlated with the median grain size of the Wolman samples. A strong relationship was found between UAS-SfM-derived grain roughness and Wolman grain size. The procedure employed has potential for the rapid and continuous characterization of grain size distribution in exposed bars of gravel-bed rivers. The workflow described in this paper has been successfully used to produce spatially continuous grain size information on exposed gravel bars and to explore textural changes following flow events.

2017-05-15T00:00:00Z Daniel, Vázquez Tarrío Rosana, Menéndez Duarte https://ria.asturias.es/RIA/handle/123456789/14602 2023-02-27T10:35:57Z 2021-09-01T00:00:00Z

Title: The estimation of bedload in poorly-gauged mountain rivers Authors: Daniel, Vázquez Tarrío; Rosana, Menéndez Duarte Abstract: Bedload transport is one major driver of gravel-bed river morphodynamics, and its quantification is capital for many environmental issues and river engineering applications, as well as for landscape evolution studies. To this point, bedload transport rates and volumes have been classically computed by means of sediment transport formulae. The most used bedload transport equations compute the bulk bedload mass based on section-averaged hydraulic parameters. However, due to the non-linear behavior of sediment transport, bedload formulae are sensitive to the input parameters. Then, some doubts arise when applying bedload equations on poorly gauged river reaches, i.e. rivers where there are no hydrological records and rating curves. In this paper, we assess the application of bedload equations in the case of poorly gauged river reaches, and we test a workflow to follow in such situations. This workflow consists of three steps: (i) Reconstructing the flow duration curve, based on gauging records from neighboring river basins; (ii) Solving the hydraulic geometry relations of the study-case river-reach, based on a flow friction equation; and finally, (iii) Computing bedload with a sediment transport equation. We tested this approach against the bedload information available in the literature for Idaho streams and we found that it could potentially approximate annual bedload volumes in ungauged reaches under certain conditions. To illustrate the potential of this workflow, we also computed bedload volumes for two ungauged river reaches from the Cantabrian mountains (NW Spain).

2021-09-01T00:00:00Z Vázquez Tarrío, Daniel Menéndez Duarte, Rosana https://ria.asturias.es/RIA/handle/123456789/14601 2023-02-27T10:35:25Z 2021-02-01T00:00:00Z

Title: The active layer in gravel-bed rivers: An empirical appraisal Authors: Vázquez Tarrío, Daniel; Menéndez Duarte, Rosana Abstract: The vertical position of the streambed–water boundary fluctuates during the course of sediment transport episodes, due to particle entrainment/deposition and bedform migration, amongst other hydraulic and bedload mechanisms. These vertical oscillations define a topmost stratum of the streambed (i.e. the ‘active layer or active depth’), which usually represents the main source of particles entrained during long and high-magnitude bedload transport episodes. The vertical extent of this layer is hence a capital parameter for the quantification of bedload volumes and a major driver of stream ecology in gravel-bed rivers. However, knowledge on how the active depth scales to flow strength and the nature of the different controls on the relation between the flow strength and the active depth is still scarce. In this paper we present a meta-analysis over active depth data coming from ~130 transport episodes extracted from a series of published field studies. We also incorporate our own field data for the rivers Ebro and Muga (unpublished), both in the Iberian Peninsula. We explore the database searching for the influence of flow strength, grain size, streambed mobility and channel morphology on the vertical extent of the active layer. A multivariate statistical analysis (stepwise multiple regression) confirms that the set of selected variables explains a significant amount of variance in the compiled variables. The analysis shows a positive scaling between active depth and flow strength. We have also identified some links between the active depth and particle travel distances. However, these relations are also largely modulated by other fluvial drivers, such as the grain size of the bed surface and the dominant channel macro-bedforms, with remarkable differences between plane-bed, step-pool and riffle-pool channels.

2021-02-01T00:00:00Z Vázquez Tarrío, Daniel Piégay, Hervé Menéndez Duarte, Rosana https://ria.asturias.es/RIA/handle/123456789/14679 2024-02-01T06:52:21Z 2020-08-01T00:00:00Z

Title: Textural signatures of sediment supply in gravel-bed rivers: Revisiting the armour ratio Authors: Vázquez Tarrío, Daniel; Piégay, Hervé; Menéndez Duarte, Rosana Abstract: The surface of the streambed in gravel-bed rivers is commonly coarser than the underlying bed material. This surface coarsening, or ‘armouring’, is usually described by means of the ratio between surface and subsurface grain-size metrics (the ‘armour ratio’). Such surface coarsening is typical of river reaches that are degrading due to a deficit in sediment supply (e.g. gravel-bed reaches below dams or lakes), but non-degrading gravel-bed streams may also exhibit some degree of armouring in relation to specific hydrological patterns. For instance, selective transport during the recession limbs of long lasting floods may coarsen the bed more significantly than flash floods. Consequently, regional differences in bed coarsening should exist, reflecting in turn the variability in sediment and water regimes. In this paper, we explore the trends linking armour ratios to sediment supply, taking into account the differences in hydrological context. We based our analysis on a large data set of bedload and grain size measurements from 49 natural gravel-bed streams and four flume experiments compiled from the scientific literature. Our main outcome documents how the balances between sediment yields and transport capacities have a quantifiable reflection on the armour ratios measured in the field: we report statistically significant correlations between bedload fluxes and surface grain-size, and an asymptotic rise in armour ratios with the decline of sediment supply. Hydrological controls are also observed. Additionally, the trends observed in the field data are comparable to those previously documented in flume experiments with varying sediment feed. In this regard, different kinds of bedforms and particle arrangements have been commonly described with progressive reductions in sediment inputs and the subsequent coarsening of the streambed. Hence, armour ratios serve as a proxy for the general organization of the streambed of gravel-bed streams, and our results quantify this streambed adjustment to the dominant sediment regime.

2020-08-01T00:00:00Z