The importance of secondary processes on alluvial fan morphology, channel behaviour, and flood hazards
department or school: Arts, Faculty of
department or school: Geography, Department of
data provider: DSpace
degree campus: UBCV
creator: Vincent, Lauren
issued: 2020-12-18T19:16:16Z
issued: 2020
related degree: Master of Science - MSc
degree grantor: University of British Columbia
description: Alluvial fans form through primary and secondary processes. Primary processes act to transport sediment from the drainage basin to the fan and secondary processes re-mobilize and rework sediment previously deposited on the fan. There is still a poor understanding of how primary and secondary processes interact on alluvial fans. The primary objective of this research is to isolate the role of secondary processes in determining alluvial fan behaviour and morphology. Four experiments were conducted, in which alluvial fans were created under different durations of secondary processes. In these experiments secondary processes were run between each primary process, or flood period. The duration of secondary process periods ranged from 5 to 40 minutes across the four experiments. Here primary processes reflect inputs of Q = 100 ml/s and Qb = 10 g/s, and secondary processes reflect inputs of Q = 50 ml/s and Qb = 0 g/s, wherein Q refers to water discharge and Qb refers to sediment feed rate. For each experiment, alternating primary and secondary processes were run until a total of 72 kg of sediment had been added to the fan. Following this, a sequence of nine flood events was run over the fan surface to evaluate fan response to flooding. Experiments with longer durations of secondary processes generated fans with larger areas and gentler gradients. In addition, longer secondary process durations led to increased flow channelization and channel incision between flood periods. The dominant channel pattern throughout the experiments was the formation of a single, centralized channel during secondary process periods, and the bifurcation of flow following the onset of primary processes. The increased incision and flow confinement during prolonged periods of secondary processes resulted in a decreased avulsion frequency during subsequent flood periods. In addition, the onset of avulsion was delayed for experiments with longer secondary process duration. These results indicate that…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/76853
note: The Importance of SecondaryProcesses on Alluvial Fan Morphology,Channel Behaviour, and FloodHazardsbyLauren VincentB.Sc.E., Queen’s University, 2010A THESIS SUBMITTED IN PARTIAL FULFILLMENT OFTHE REQUIREMENTS FOR THE DEGREE OFMASTER OF SCIENCEinThe Faculty of Graduate and Postdoctoral Studies(Geography)THE UNIVERSITY OF BRITISH COLUMBIA(Vancouver)December 2020c© Lauren Vincent 2020The following individuals certify that they have read, and recommend tothe Faculty of Graduate and Postdoctoral Studies for acceptance, a thesisentitled:The Importance of Secondary Processes on Alluvial Fan Morphology, ChannelBehaviour, and Flood Hazardssubmitted by: Lauren Vincent in partial fulfillment of the requirementsfor the degree of Master of Sciencein GeographyExamining Committee:Brett Eaton, Professor, Geography, UBCCo-supervisorMatthias Jakob, BGC Engineering Inc.Co-supervisorSarah Davidson, BGC Engineering Inc.Supervisory Committee MemberDan Moore, Professor, Geography, UBCAdditional ExamineriiAbstractAlluvial fans form through primary and secondary processes. Primary pro-cesses act to transport sediment from the drainage basin to the fan andsecondary processes re-mobilize and rework sediment previously depositedon the fan. There is still a poor understanding of how primary and sec-ondary processes interact on alluvial fans. The primary objective of thisresearch is to isolate the role of secondary processes in determining alluvialfan behaviour and morphology. Four experiments were conducted, in whichalluvial fans were created under different durations of secondary processes.In these experiments secondary processes were run between each primaryprocess, or flood period. The duration of secondary process periods rangedfrom 5 to 40 minutes across the four experiments. Here primary processesreflect inputs of Q = 100 ml/s and Qb = 10 g/s, and secondary processesreflect inputs of Q = 50 ml/s and Qb = 0 g/s, wherein Q refers to waterdischarge and Qb refers to sediment feed rate. For ea…
has type: Thesis/Dissertation
date issued: 2021-05
is shown at: 10.14288/1.0395354
language: eng
degree discipline: Geography
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/76853