Variable Shields number model for river bankfull geometry: Bankfull shear velocity is viscosity-dependent but grain size-independent

Chuan Li, Matthew J. Czapiga, Esther C. Eke, Enrica Viparelli, Gary Parker

Research output: Contribution to journalArticle

Abstract

The bankfull geometry of alluvial rivers is thought to be controlled by water and sediment supply, and characteristic sediment size. Here we demonstrate a novel finding: when bankfull shear velocity and bankfull depth are correlated against bed material grain size and bed slope, they are to first order independent of grain size and dependent on water viscosity. We demonstrate this using a similarity collapse for bankfull Shields number as a function of slope and grain size, obtained with data for 230 river reaches ranging from silt-bed to cobble-bed. Our analysis shows that bankfull Shields number increases with slope to about the half power. We show that the new relation for bankfull Shields number provides more realistic predictions for the downstream variation of bankfull characteristics of rivers than a previously used assumption of constant bankfull Shields number.

Original languageEnglish (US)
Pages (from-to)36-48
Number of pages13
JournalJournal of Hydraulic Research
Volume53
Issue number1
DOIs
StatePublished - Jan 2 2015

Fingerprint

shield
viscosity
grain size
Rivers
Viscosity
geometry
Geometry
Sediments
river
Silt
Water
sediment
silt
water
prediction

Keywords

  • River bankfull geometry
  • Shields number

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Water Science and Technology

Cite this

Variable Shields number model for river bankfull geometry : Bankfull shear velocity is viscosity-dependent but grain size-independent. / Li, Chuan; Czapiga, Matthew J.; Eke, Esther C.; Viparelli, Enrica; Parker, Gary.

In: Journal of Hydraulic Research, Vol. 53, No. 1, 02.01.2015, p. 36-48.

Research output: Contribution to journalArticle

@article{ab5c20873128446e817d0c4833efb623,
title = "Variable Shields number model for river bankfull geometry: Bankfull shear velocity is viscosity-dependent but grain size-independent",
abstract = "The bankfull geometry of alluvial rivers is thought to be controlled by water and sediment supply, and characteristic sediment size. Here we demonstrate a novel finding: when bankfull shear velocity and bankfull depth are correlated against bed material grain size and bed slope, they are to first order independent of grain size and dependent on water viscosity. We demonstrate this using a similarity collapse for bankfull Shields number as a function of slope and grain size, obtained with data for 230 river reaches ranging from silt-bed to cobble-bed. Our analysis shows that bankfull Shields number increases with slope to about the half power. We show that the new relation for bankfull Shields number provides more realistic predictions for the downstream variation of bankfull characteristics of rivers than a previously used assumption of constant bankfull Shields number.",
keywords = "River bankfull geometry, Shields number",
author = "Chuan Li and Czapiga, {Matthew J.} and Eke, {Esther C.} and Enrica Viparelli and Gary Parker",
year = "2015",
month = "1",
day = "2",
doi = "10.1080/00221686.2014.939113",
language = "English (US)",
volume = "53",
pages = "36--48",
journal = "Journal of Hydraulic Research",
issn = "0022-1686",
publisher = "International Association of Hydraulic Engineering Research",
number = "1",

}

TY - JOUR

T1 - Variable Shields number model for river bankfull geometry

T2 - Bankfull shear velocity is viscosity-dependent but grain size-independent

AU - Li, Chuan

AU - Czapiga, Matthew J.

AU - Eke, Esther C.

AU - Viparelli, Enrica

AU - Parker, Gary

PY - 2015/1/2

Y1 - 2015/1/2

N2 - The bankfull geometry of alluvial rivers is thought to be controlled by water and sediment supply, and characteristic sediment size. Here we demonstrate a novel finding: when bankfull shear velocity and bankfull depth are correlated against bed material grain size and bed slope, they are to first order independent of grain size and dependent on water viscosity. We demonstrate this using a similarity collapse for bankfull Shields number as a function of slope and grain size, obtained with data for 230 river reaches ranging from silt-bed to cobble-bed. Our analysis shows that bankfull Shields number increases with slope to about the half power. We show that the new relation for bankfull Shields number provides more realistic predictions for the downstream variation of bankfull characteristics of rivers than a previously used assumption of constant bankfull Shields number.

AB - The bankfull geometry of alluvial rivers is thought to be controlled by water and sediment supply, and characteristic sediment size. Here we demonstrate a novel finding: when bankfull shear velocity and bankfull depth are correlated against bed material grain size and bed slope, they are to first order independent of grain size and dependent on water viscosity. We demonstrate this using a similarity collapse for bankfull Shields number as a function of slope and grain size, obtained with data for 230 river reaches ranging from silt-bed to cobble-bed. Our analysis shows that bankfull Shields number increases with slope to about the half power. We show that the new relation for bankfull Shields number provides more realistic predictions for the downstream variation of bankfull characteristics of rivers than a previously used assumption of constant bankfull Shields number.

KW - River bankfull geometry

KW - Shields number

UR - http://www.scopus.com/inward/record.url?scp=84925801158&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84925801158&partnerID=8YFLogxK

U2 - 10.1080/00221686.2014.939113

DO - 10.1080/00221686.2014.939113

M3 - Article

AN - SCOPUS:84925801158

VL - 53

SP - 36

EP - 48

JO - Journal of Hydraulic Research

JF - Journal of Hydraulic Research

SN - 0022-1686

IS - 1

ER -