Laboratory experiments on alluvial cover in mixed bedrock-alluvial meandering channels and on the formation and evolution of supraglacial meltwater meandering streams

Rivers and other channels containing liquid flow develop meandering patterns over different media and across a broad range of scales. For example, alluvial rivers form and evolve by erosion and deposition of sediment, and by interactions with riparian vegetation. Meandering channels also form in bedrock where the driving processes include dissolution, abrasion by sediment particles, plucking of bedrock, and weathering. Rivulets on a plane can also meander due to an instability associated with surface tension, and channelized flows over ice surfaces also develop meandering patterns due to differential melting. In spite of the differences in size and underlying mechanisms, similarities in planform and channel morphology exist across media and scale, suggesting that there is a common underlying framework of river meandering. This dissertation focuses in two types of meandering channels, namely, mixed bedrock-alluvial meandering channels, and meltwater meandering channels. Experimental work was conducted to advance the current understanding of the processes and characteristics of these two types of meandering rivers. Specifically, this dissertation answers the following questions: 1. How does alluvial cover, as it relates to sediment supply and channel curvature, affect the zones of potential erosion in mixed bedrock-alluvial meandering rivers? 2. What is the role of alluvial cover fluctuations in erosion in mixed bedrock-alluvial meandering channels? 3. How does hydraulic roughness in a bedrock river change under different sediment supply scenarios and how do these changes relate to the ratio of areal alluvial cover to total bed area averaged over a reach? 4. How can the composite roughness, including the effect of bedrock and alluvium in a channel of complex shape, be better described and quantified so as to inform numerical models? 5. How do meltwater meandering channels form and evolve? 6. What are the characteristics of meltwater meandering channels and what is the degree of similarity between them and meandering channels in other media?

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Civil Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2018

Author dc:creator

• Fernandez Arrieta, Roberto

Contributors dc:contributor

• Parker, Gary
• Garcia, Marcelo H.
• Rhoads, Bruce
• Venditti, Jeremy

• meander
• bedrock
• alluvial
• cover
• supraglacial
• meltwater
• experiments

Statement dc:rights

• Copyright 2018 Roberto Fernandez Arrieta

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/101494

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/101494