Constraints on the form and formation of branched channel networks
Abstract/Contents
- Abstract
- This thesis focuses on the form and formation of Branched Channel Networks (BCNs). These networks are among the most striking forms that define the surface of our planet, and are the primary means that transport rock and water from high to low elevations across Earth's surface. As such, they play a fundamental role in shaping the elevation structure of continents, the spatial distribution of vegetation, and the rates and routes by which rocks, nutrients, and water are transported across different terrestrial reservoirs. BCNs also exist in extraterrestrial environments, where, as on Earth, they may encapsulate information regarding the processes and physical conditions under which these environments are shaped. In studying these networks, I pose two main hypotheses: (a) the structure of BCNs is sensitive to the erosional mechanics of the processes that carve them, and (b) a common set of constraints rationalizes the ubiquity of BCNs across disparate physical conditions (e.g., subaerial, submarine, extraterrestrial). First, I evaluate the limitations of the numerical tools with which I test these hypotheses, and show that the flow-routing rules used for the downslope routing of water and sediment over gridded Digital Elevation Models (DEMs) have a statistically significant impact on the form of modeled topography and the spatial distribution of modeled geomorphic processes. Having these limitations in mind, I address the first hypothesis, and show that the structure of BCNs reflects two coupled constraints: (1) the characteristic along-flow channel profile shaped by the channel forming processes, and (2) the fact that two flows initiating at an infinitesimal distance apart on each side of a drainage divide must experience an identical elevation drop between the divide and the junction where these flows once again meet. I then use numerical Landscape Development Model (LDMs) and analysis tools to demonstrate that these constraints impact the plan-view structure of BCNs as well as their temporal evolution, and that the form of these networks is indeed sensitive to the erosional mechanics of the processes that shape them. To address the second hypotheses, I analytically show that a simple dependence between sediment transport rate and the frequency at which geophysical flows traverse landscapes rationalizes the formation of BCNs by a wide variety of process, regardless of the stochasticity or homogeneity in which these processes are generated in time and/or space. Thus, as long as this dependency exists, networks may form by a variety of processes across disparate physical conditions. I then use LDMs based on this analytical framework to demonstrate the conditions for network formation and the relationships between the physical characteristics of flows and the landscape features they form.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2014 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Shelef, Eitan |
|---|---|
| Associated with | Stanford University, Department of Geological and Environmental Sciences. |
| Primary advisor | Hilley, George E |
| Thesis advisor | Hilley, George E |
| Thesis advisor | Loague, Keith M. (Keith Michael), 1951- |
| Thesis advisor | McHargue, Timothy R, 1949- |
| Thesis advisor | Pollard, David D |
| Advisor | Loague, Keith M. (Keith Michael), 1951- |
| Advisor | McHargue, Timothy R, 1949- |
| Advisor | Pollard, David D |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Eitan Shelef. |
|---|---|
| Note | Submitted to the Department of Geological and Environmental Sciences. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2014. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2014 by Eitan Shelef
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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