Simulating unsteady flow and sediment transport in vegetated channel network

Yang Bai, Guohong Duan

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

This paper presents a one-dimensional model for simulating flood routing and sediment transport over mobile alluvium in a vegetated channel network. The modified St. Venant equations together with the governing equations for suspended sediment and bed load transport were solved simultaneously to obtain flow properties and sediment transport rate. The Godunov-type finite volume method is employed to discretize the governing equations. Then, the Exner equation was solved for bed elevation change. Since sediment transport is non-equilibrium when bed is degrading or aggrading, a recovery coefficient for suspended sediment and an adaptation length for bed load transport were used to quantify the differences between equilibrium and non-equilibrium sediment transport rate. The influence of vegetation on floodplain and main channel was accounted for by adjusting resistance terms in the momentum equations for flow field. A procedure to separate the grain resistance from the total resistance was proposed and implemented to calculate sediment transport rate. The model was tested by a flume experiment case and an unprecedented flood event occurred in the Santa Cruz River, Tucson, Arizona, in July 2006. Simulated results of flow discharge and bed elevation changes showed satisfactory agreements with the measurements. The impacts of vegetation density on sediment transport and significance of non-equilibrium sediment transport model were discussed.

Original languageEnglish (US)
Pages (from-to)90-102
Number of pages13
JournalJournal of Hydrology
Volume515
DOIs
StatePublished - Jul 16 2014

Fingerprint

unsteady flow
sediment transport
bedload
suspended sediment
flood routing
flume experiment
finite volume method
vegetation
alluvial deposit
flow field
floodplain
momentum
river
rate

Keywords

  • Channel network
  • Numerical model
  • Sediment transport
  • Unsteady flow
  • Vegetation

ASJC Scopus subject areas

  • Water Science and Technology

Cite this

Simulating unsteady flow and sediment transport in vegetated channel network. / Bai, Yang; Duan, Guohong.

In: Journal of Hydrology, Vol. 515, 16.07.2014, p. 90-102.

Research output: Contribution to journalArticle

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AB - This paper presents a one-dimensional model for simulating flood routing and sediment transport over mobile alluvium in a vegetated channel network. The modified St. Venant equations together with the governing equations for suspended sediment and bed load transport were solved simultaneously to obtain flow properties and sediment transport rate. The Godunov-type finite volume method is employed to discretize the governing equations. Then, the Exner equation was solved for bed elevation change. Since sediment transport is non-equilibrium when bed is degrading or aggrading, a recovery coefficient for suspended sediment and an adaptation length for bed load transport were used to quantify the differences between equilibrium and non-equilibrium sediment transport rate. The influence of vegetation on floodplain and main channel was accounted for by adjusting resistance terms in the momentum equations for flow field. A procedure to separate the grain resistance from the total resistance was proposed and implemented to calculate sediment transport rate. The model was tested by a flume experiment case and an unprecedented flood event occurred in the Santa Cruz River, Tucson, Arizona, in July 2006. Simulated results of flow discharge and bed elevation changes showed satisfactory agreements with the measurements. The impacts of vegetation density on sediment transport and significance of non-equilibrium sediment transport model were discussed.

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