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UBC Theses and Dissertations
Landscape controls on the delivery of colluvial sediment to streams Abbey, Porter
Abstract
Many small mountainous watersheds are characterized by inefficient transfer of material within them, or disconnectivity. Understanding the relationship between landscape configuration and disconnectivity improves our ability to assess how sediment transfer processes, such as mass movements, and changes in their occurrence regime will travel through the landscape and alter its form and function. Published methods for quantitative assessment of disconnectivity measure either structural (the effect of landscape organization) or functional (direct measurement of material fluxes) indicators. Methods assessing the former are far more prevalent and work combining the two is rare. Additionally, metrics are infrequently developed based on the inefficiency of material transfer. We present a novel metric, the Disconnectedness Ratio, for quantitatively characterizing the influence of landforms on the sediment cascade which can be used to assess both structural and functional disconnectivity. We apply this methodology in a small, formerly glaciated watershed in British Columbia, Canada by utilizing an 84-year mass movement inventory to represent material fluxes. Our results highlight the importance of process-form relationships in disconnectivity dynamics. We find that most mass movements are intercepted, primarily by colluvial landforms, without reaching the valley bottom. The greater the contribution of colluvial processes to a landform's formation, the more effectively it buffers mass movements from the stream network. Additionally, we find that metrics for functional disconnectivity often disagree with those for structural disconnectivity and point to the importance of timescale in determining the relationship between the two. Finally, we present a conceptual framework for slope base systems to synthesize findings on the role of disconnectivity in process-form relationships. There is a need for future work to apply the Disconnectedness Ratio in more study sites at a variety of spatial and temporal scales to determine its utility and constrain its variance in a variety of watershed structures.
Item Metadata
Title |
Landscape controls on the delivery of colluvial sediment to streams
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Creator | |
Supervisor | |
Publisher |
University of British Columbia
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Date Issued |
2023
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Description |
Many small mountainous watersheds are characterized by inefficient transfer of material within them, or disconnectivity. Understanding the relationship between landscape configuration and disconnectivity improves our ability to assess how sediment transfer processes, such as mass movements, and changes in their occurrence regime will travel through the landscape and alter its form and function. Published methods for quantitative assessment of disconnectivity measure either structural (the effect of landscape organization) or functional (direct measurement of material fluxes) indicators. Methods assessing the former are far more prevalent and work combining the two is rare. Additionally, metrics are infrequently developed based on the inefficiency of material transfer. We present a novel metric, the Disconnectedness Ratio, for quantitatively characterizing the influence of landforms on the sediment cascade which can be used to assess both structural and functional disconnectivity. We apply this methodology in a small, formerly glaciated watershed in British Columbia, Canada by utilizing an 84-year mass movement inventory to represent material fluxes. Our results highlight the importance of process-form relationships in disconnectivity dynamics. We find that most mass movements are intercepted, primarily by colluvial landforms, without reaching the valley bottom. The greater the contribution of colluvial processes to a landform's formation, the more effectively it buffers mass movements from the stream network. Additionally, we find that metrics for functional disconnectivity often disagree with those for structural disconnectivity and point to the importance of timescale in determining the relationship between the two. Finally, we present a conceptual framework for slope base systems to synthesize findings on the role of disconnectivity in process-form relationships. There is a need for future work to apply the Disconnectedness Ratio in more study sites at a variety of spatial and temporal scales to determine its utility and constrain its variance in a variety of watershed structures.
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Genre | |
Type | |
Language |
eng
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Date Available |
2023-12-18
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Provider |
Vancouver : University of British Columbia Library
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Rights |
Attribution-NonCommercial-NoDerivatives 4.0 International
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DOI |
10.14288/1.0438301
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URI | |
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Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2024-05
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Campus | |
Scholarly Level |
Graduate
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Rights
Attribution-NonCommercial-NoDerivatives 4.0 International