Characteristic Scales of Drainage Reorganization in Cascadia

William T. Struble, Joshua J. Roering, Rebecca J. Dorsey, Rebecca Bendick

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Variations in uplift, erosion, climate, and bedrock are commonly invoked as key controls on drainage basin morphology, yet the scale of landforms that define changes in regional drainage networks has not been addressed, limiting our ability to predict their planform evolution. Here we use two-dimensional (2D) continuous wavelet transforms of topography in Cascadia to highlight dominant topographic features at different scales. Surprisingly, our wavelet analysis shows that for wavelengths >30 km, the Cascadia Forearc Lowland (CFL) spans the entire margin. Separately, we compare observed catchment boundaries with synthetic boundaries generated on topography filtered with 2D Gaussian functions. We observe reorganization of synthetic drainage networks from an arc-to-coast drainage system into arc-spanning, margin-parallel river systems, akin to the modern Willamette River and coincident with the CFL. In concert with field observations of stream capture and Willamette Valley expansion, we propose that the Cascadia forearc is actively transitioning to a predominately margin-parallel river system.

Original languageEnglish
Article numbere2020GL091413
JournalGeophysical Research Letters
Volume48
Issue number3
DOIs
StatePublished - Feb 16 2021

Funding

The author thanks N. Finnegan, D. O'Hara, J. O'Connor, R. Wells, L. Karlstrom, N. Klema, S. LaHusen, and T. Doane for helpful discussions. The authors are particularly grateful to Adam Booth, who provided several helpful conversations about wavelets, and whose Automated Landslide Mapping toolkit (ALMtools) served as the initial framework for the wavelet analysis done here ( http://web.pdx.edu/∼boothad/tools.html ). A. Moodie and an anonymous reviewer provided thoughtful comments that greatly improved the quality of this paper. W. T. Struble was supported by a Lokey Doctoral Fellowship through the University of Oregon.

FundersFunder number
University of Oregon

    Keywords

    • Cascadia
    • drainage reorganization
    • tectonics
    • topographic scaling
    • wavelets

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