Repositorio
Institucional

Monsalve, A.

Yager, E. M.

Bed Surface Adjustments to Spatially Variable Flow in Low Relative Submergence Regimes

AMER GEOPHYSICAL UNION

WATER RESOURCES RESEARCH

en

In mountainous rivers, large relatively immobile grains partly control the local and reach-averaged flow hydraulics and sediment fluxes. When the flow depth is similar to the size of these grains (low relative submergence), heterogeneous flow structures and plunging flow cause spatial distributions of bed surface elevations, textures, and sedimentation rates. To explore how the bed surface responds to these flow variations we conducted a set of experiments in which we varied the relative submergence of staggered hemispheres (simulated large boulders) between runs. All experiments had the same average sediment transport capacity, upstream sediment supply, and initial bed thickness and grain size distribution. We combined our laboratory measurements with a 3-D flow model to obtain the detailed flow structure around the hemispheres. The local bed shear stress field displayed substantial variability and controlled the bed load transport rates and direction in which sediment moved. The divergence in bed shear stress caused by the hemispheres promoted size-selective bed load deposition, which formed patches of coarse sediment upstream of the hemisphere. Sediment deposition caused a decrease in local bed shear stress, which combined with the coarser grain size, enhanced the stability of this patch. The region downstream of the hemispheres was largely controlled by a recirculation zone and had little to no change in grain size, bed elevation, and bed shear stress. The formation, development, and stability of sediment patches in mountain streams is controlled by the bed shear stress divergence and magnitude and direction of the local bed shear stress field.

Artículo original

"Funding for this research was provided by a NSF Career award to E.M. Yager (0847799) and the Chilean Government-CONICYT ""Becas de Doctorado en el Extranjero-Becas Chile."" We thank Catalina Segura, Ali Khosronejad, and one anonymous reviewer for their constructive comments that helped to improve an earlier version of this manuscript. Invaluable laboratory assistance was provided by Bob Basham and Christina Beeson. Thoughtful discussions with Megan Kenworthy helped in the planning and execution of the laboratory experiments. Topographic, bed characteristics, and hydraulic data are available free of change at http://pangaea.de/."

"Esta investigación fue financiada por una beca de la NSF Career a E.M. Yager (0847799) y las ""Becas de Doctorado en el Extranjero-Becas Chile"" del Gobierno de Chile-CONICYT. Agradecemos a Catalina Segura, Ali Khosronejad y a un revisor anónimo sus comentarios constructivos, que contribuyeron a mejorar una versión anterior de este manuscrito. Bob Basham y Christina Beeson brindaron una invaluable asistencia de laboratorio. Las profundas conversaciones con Megan Kenworthy contribuyeron a la planificación y ejecución de los experimentos de laboratorio. Los datos topográficos, de las características del lecho y hidráulicos están disponibles gratuitamente en http://pangaea.de/.

Funding for this research was provided by a NSF Career award to E.M. Yager (0847799) and the Chilean Government-CONICYT ""Becas de Doctorado en el Extranjero-Becas Chile."" We thank Catalina Segura, Ali Khosronejad, and one anonymous reviewer for their constructive comments that helped to improve an earlier version of this manuscript. Invaluable laboratory assistance was provided by Bob Basham and Christina Beeson. Thoughtful discussions with Megan Kenworthy helped in the planning and execution of the laboratory experiments. Topographic, bed characteristics, and hydraulic data are available free of change at http://pangaea.de/."

10.1002/2017WR020845

pdf

sediment transport# fluvial geomorphology# sediment patches# low relative submergence regime# spatially variable flow# roughness

http://dx.doi.org/10.1002/2017WR020845

Environmental Sciences# Limnology# Water Resources

transporte de sedimentos# geomorfología fluvial# parches de sedimentos# régimen de sumergencia relativa baja# flujo espacialmente variable# aspereza

Oceanografía, Hidrología y Recursos del Agua

Geociencias

Otras Especialidades de Ciencias de la Tierra

WOS:000418736700038

Bed Surface Adjustments to Spatially Variable Flow in Low Relative Submergence Regimes

Artículo original

version publicada

AMER GEOPHYSICAL UNION

WATER RESOURCES RESEARCH

Ciencias Ambientales# Limnología# Recursos hídricos

0043-1397

en

ANID BECA-DOCTORADO

NSF 0847799

ANID Becas de Doctorado en el Extranjero-Becas Chile

Directorate For Geosciences

NSF Division Of Earth Sciences 0847799

"Funding for this research was provided by a NSF Career award to E.M. Yager (0847799) and the Chilean Government-CONICYT ""Becas de Doctorado en el Extranjero-Becas Chile."" We thank Catalina Segura, Ali Khosronejad, and one anonymous reviewer for their constructive comments that helped to improve an earlier version of this manuscript. Invaluable laboratory assistance was provided by Bob Basham and Christina Beeson. Thoughtful discussions with Megan Kenworthy helped in the planning and execution of the laboratory experiments. Topographic, bed characteristics, and hydraulic data are available free of change at http://pangaea.de/."

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