Numerical Modelling of Braiding Processes in Gravel-Bed Rivers

Baral, Bishnu Raj (2018) Numerical Modelling of Braiding Processes in Gravel-Bed Rivers. PhD thesis, Queen Mary University of London, University of Trento.

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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.

Item Type:Doctoral Thesis (PhD)
Doctoral School:Civil, Environmental and Mechanical Engineering
PhD Cycle:29
Subjects:Area 08 - Ingegneria civile e Architettura > ICAR/01 IDRAULICA
Area 01 - Scienze matematiche e informatiche > MAT/08 ANALISI NUMERICA
Area 04 - Scienze della terra > GEO/04 GEOGRAFIA FISICA E GEOMORFOLOGIA
Uncontrolled Keywords:Braided Rivers, Numerical Modelling, BASEMENT, Unsteady Flow, Vegetation
Funders:ERASMUS MUNDUS action (EU)
Repository Staff approval on:05 Sep 2018 09:46

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