The emergence and evolution of channel networks are controlled by the competition between the hillslopes and fluvial processes on the landscape. Investigating the geomorphic and topologic properties of these networks is important for developing predictive models describing the network dynamics under changing environment as well as for quantifying the roles of processes in creating distinct patterns of channel networks. In this dissertation, the response of landscapes to changing climatic forcing via numerical-modeling and field observations was investigated. A new framework was proposed to evaluate the complexity of catchments using two different representations of channel networks. The structural complexity was studied using the width function, which characterizes the spatial arrangement of channels. Whereas, the functional complexity was explored using the incremental area function, capturing the patterns of transport of fluxes. Our analysis reveals stronger controls of topological connectivity on the functional complexity than on structural complexity, indicating that the unchannelized surface (hillslope) contributes to the increase of heterogeneity in transport processes. Furthermore, the channel network structure was investigated using a physically-based numerical landscape evolution model for varying hillslope and fluvial processes. Different magnitudes of soil transport (D) and fluvial incision (K) coefficients represent different magnitudes of hillslope and fluvial processes. We show that different combinations of D and K result in distinct branching structure in landscapes. For example, for smaller D and K combinations (mimicking dry climate), a higher number of branching channels was observed. Whereas, for larger D and K combinations (mimicking humid climate), a higher number of side-branching channels is obtained. These results are consistent with the field observations suggesting that varying climatic conditions imprint distinct signatures on the branching structure of channel networks.
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Doctor of Philosophy (Ph.D.)
College of Engineering and Computer Science
Civil, Environmental, and Construction Engineering
Length of Campus-only Access
Doctoral Dissertation (Open Access)
Ranjbar Moshfeghi, Sevil, "Climatic and Topologic Controls on the Complexity of River Networks" (2020). Electronic Theses and Dissertations, 2020-. 273.