Modelling flow, sediment transport and morphodynamics in rivers

• Published in: Tools in Fluvial Geomorphology pp. 412 - 441
• Main Authors: Nelson, Jonathan M, McDonald, Richard R, Shimizu, Yasuyuki, Kimura, Ichiro, Nabi, Mohamed, Asahi, Kazutake
• Format: Book Chapter
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 06.04.2016
• Subjects: bank evolution models; bed evolution; bedform models; flow conservation laws; modeling flow; morphodynamics; one‐dimensional model; sediment transport; two‐dimensional model
• ISBN: 0470684054; 9780470684054
• DOI: 10.1002/9781118648551.ch18

This chapter presents an overview of techniques for predicting flow, sediment transport and bed evolution, emphasizing the physical processes that are captured by various approaches. It first explains the flow conservation laws, such as the conservation of mass and momentum, and the Reynolds stresses. Then, the chapter discusses the sediment‐transport relations for bedload transport and suspended load transport. A one‐dimensional flow model solves for the cross‐sectionally averaged velocity, flow rate or discharge at each model cross‐section, but the flow model is generally of limited value for the prediction of morphodynamics. If the flow field of interest includes steering of the flow around islands or bars or if there is significant cross‐stream variability in the flow, at least a two‐dimensional model should be applied. The chapter also describes bank evolution models and bedform models, before presenting a note on the practical considerations in order to select an appropriate model.