Repositorio
Institucional

Smith, Heidi E. J.

Monsalve, Angel D. D.

Turowski, Jens M. M.

Rickenmann, Dieter

Yager, Elowyn M. M.

Controls of local grain size distribution, bed structure and flow conditions on sediment mobility

WILEY

EARTH SURFACE PROCESSES AND LANDFORMS

en

Steep, boulder bed streams often contain sediment patches, which are areas of the bed with relatively well-defined boundaries that are occupied by distinct grain size distributions (GSD). In sediment mixtures, the underlying GSD affects the critical Shields stress for a given grain size, which is commonly predicted using hiding functions. Hiding functions may vary with reach-wide bed GSD, but the effect of local GSD on relative sediment mobility between sediment patches is poorly understood. We explore the effects of patch-scale GSD on sediment mobility using tracer particles combined with local shear stresses to develop hiding functions for different patch classes within a steep stream. Hiding functions for all tested patch classes were similar, which indicates that the same hiding function can be used for different patches. However, the critical Shields stress for a given grain size generally decreased with lower patch median grain size (D-50) suggesting that patches control the relative mobility of each size through both the underlying GSD and local shear stresses. The effects of the underlying GSD partly depend on grain protrusion, which we measured for all grain sizes present on each patch class. Protrusion was generally greater for larger grains regardless of patch class, but for a given grain size, protrusion was increased with smaller patch D-50. For a given grain size, higher protrusion results in greater applied fluid forces and reduced resisting forces to partly explain our lower critical Shields stresses in finer patches. Patches therefore can importantly modulate relative sediment mobility through bed structure and may need to be included in reach-scale sediment transport and channel stability estimates.

2023

artículo original

10.1002/esp.5599

PDF

critical Shields stress

grain size distribution

hiding effects

local grain protrusion

relative grain size

spatial distribution of shear stresses

textural patches

Geografía Física

Geología

estrés crítico de los escudos

distribución granulométrica

efectos de ocultación

protrusión de grano local

tamaño relativo de grano

distribución espacial de tensiones cortantes

parches texturales

1990.0

2004

artículo original

versión publicada

metadata

https://onlinelibrary.wiley.com/doi/am-pdf/10.1002/esp.5599

metadata

WOS:001033204600001

0197-9337

Verde / hibrida

Geografía Física

Geología

NSF 847799