Global Abundance and Morphology of Rivers and Streams Public Deposited

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Last Modified
  • March 20, 2019
Creator
  • Allen, George
    • Affiliation: College of Arts and Sciences, Department of Geological Sciences
Abstract
  • The abundance and morphology of rivers control the rates of hydraulic and biogeochemical exchange between rivers, groundwater and the atmosphere. However, current knowledge of the abundance and morphology of Earth’s rivers and streams is based on a series of highly unconstrained hydrologic, geomorphic, climatic, and fractal river network scaling extrapolations. These extrapolations are the source of significant uncertainty in many large-scale hydrologic, geomorphic, and biogeochemical applications. In this dissertation, I characterize the global abundance and morphology of rivers and streams using fieldwork and global-scale satellite remote sensing observations. In Chapter 1, I use field surveys to characterize the distribution of stream widths in thirteen small headwater stream networks across North American and New Zealand. I show a strikingly consistent lognormal statistical distribution of stream width in all surveys, including a characteristic most abundant stream width of 32±7 cm independent of physiographic or hydrologic conditions. I propose a framework showing that, as stream networks expand and contract within the geomorphic channel network in response to changes in streamflow, the most abundant stream width remains approximately static. In Chapter 2, I present the Landsat-derived North American River Width (NARWidth) dataset, the first fine-resolution, continental-scale river centerline and width database. NARWidth contains measurements of >240,000 km of rivers wider than 30 m at mean annual discharge. I find that conventional digital elevation model-derived river width datasets underestimate the abundance of wide rivers. In Chapter 3, I present the Global River Widths from Landsat (GRWL) Database, the first global survey of river planform geometry at mean discharge. GRWL contains measurements of river geometry of >2.1 x 106 km of rivers. GRWL is being used by other researchers to improve the representation of river water resources, hazards, and hydrological processes at large scale. I use GRWL, and the results presented in Chapter 1, to estimate the global distribution of rivers and streams. Using geographic information science and a novel statistical method, I constrain the total surface area of all rivers and streams to 745,000 km2, or 0.55% of Earth’s unglaciated land surface.
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  • In Copyright
Advisor
  • Band, Lawrence
  • Lees, Jonathan
  • Pavelsky, Tamlin
  • Moore, Laura
  • Wegmann, Karl
Degree
  • Doctor of Philosophy
Degree granting institution
  • University of North Carolina at Chapel Hill Graduate School
Graduation year
  • 2017
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