Numerical Modelling of Braiding Processes in Gravel-Bed Rivers

Gravel-bed braided rivers are distinctive natural environments that provid a wide range of key environmental, economic and recreational services. There is, however,a growing concern that over the twentieth century, an increasing number of braided rivers have metamorphosed into wandering or single thread channels, representing a loss of key habitats, geodiversity and amenity. While in some situations, shifts in channel pattern may be unambiguously linked to abrupt changes in flow or sediment supply, the lack of a theoretical basis underpinning the development and maintenance of braiding makes identification of the cause and effect of channel metamorphosis hazardous. A growing body of research has suggested that the transition between channelpatterns may depend on the poorly understood interaction between the flow regime,sediment supply and vegetation colonisation. Such interactions are governed by critical thresholds, due to changes in flow resistance and bank strength associated with the distribution, form and intensity of vegetation colonisation. Subtle changes in flow or sediment supply that promote vegetation growth or indeed remove itthrough inundation or attrition. This can lead to complex non-linear shifts in the balance of forces that govern sediment transport and bedform morphodynamics, ultimately resulting in one-way changes in channel morphology. There is, therefore, a critical need to develop a quantitative understanding of these feedbacks in orderto design sustainable river management programmes that seek to optimize the ecological and socio-economic benefits these rivers offer. In summary, this thesis aims to advance our understanding of the morphodynamics of braided rivers and the role numerical models may have in helping to interrogate their behavior and governing controls.

Grantor dc:publisher

Università degli studi di Trento

Year dc:date

2018

Author dc:creator

• Baral, Bishnu Raj

Contributors dc:contributor

• Bertoldi, Walter

• Settore ICAR/01 - Idraulica
• Settore MAT/08 - Analisi Numerica
• Settore GEO/04 - Geografia Fisica e Geomorfologia

Statement dc:rights

• info:eu-repo/semantics/openAccess
• license:Tutti i diritti riservati (All rights reserved)
• license uri:iris.PRI01

Language dc:language

eng

Identifier

http://dx.doi.org/10.15168/11572_367755
10.15168/11572_367755

OAI identifier oai:identifier

oai:iris.unitn.it:11572/367755