Electronic Thesis and Dissertation Repository


Master of Science




Peter Ashmore


Proglacial gravel-bed braided rivers have a dynamic planform composed of multiple unstable channels and ephemeral bars. The planform position is seen to change during high flows as the position of channels and bars is seen to change. These changes are produced as pulses of bedload transport are mobilized and transported downstream, causing an observable change in the river planform and morphology. While it is known that bedload transport, morphological change and planform change in a braided river are inter-related the relationships have not been quantified. The first component of this research was to build on previous results by re-analyzing daily areas of planform change on a proglacial reach of the Sunwapta River, Alberta. The second component was to extend the field data by replicating selected hydrographs from Sunwapta River in a small-scale physical model in which simultaneous measurements of bedload transport, morphological change and equivalent areas of planform change were measured. Planform change, morphological change and bedload transport were all found to increase in relation to an increase in peak discharge of the experimental hydrographs, with some variability among repeated hydrographs. Total bedload transport, area of planform change, and volumes of erosion and deposition, were significantly correlated. This result contributes to the overall understanding of braided river planform dynamics and provides a potential surrogate method for measuring rates of bedload transport in gravel-bed braided river systems using event-based area of planform change.

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