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Water Science and Applications



  • Paleohydrology
  • Floods

Index Terms

  • 1821 Hydrology: Floods
  • 1824 Hydrology: Geomorphology
  • 1860 Hydrology: Runoff and streamflow



Modeled paleoflood hydraulics as a tool for interpreting bedrock channel morphology

Ellen Wohl

Dept. of Earth Resources, Colorado State University, Ft. Collins, Colorado

Reach-scale bedrock channel morphology is the product of adjustments between hydraulic driving forces and substrate resisting forces. Because the formative discharges along bedrock channels are likely to be infrequent, unpredictable, and difficult to measure directly, much of the information on hydraulic driving forces must be obtained indirectly using paleoflood records and flow modeling. The spatial distributions of hydraulic variables can then be compared to substrate characteristics and channel morphologies in order to detect consistent patterns that may provide insights into the controls on bedrock channel morphology. Four case studies from Japan, the United States, Israel and Australia illustrate the research approach. Field methods include channel surveys of geometry, PSIs, and sediment deposits, grain-size characterization, and use of the Selby rock-mass strength and a substrate heterogeneity index to characterize bedrock channel substrate. Modeling utilizes 1d and 2d flow simulations and flume experiments, and analyses utilize statistical methods to identify correlations between channel morphology and potential control variables. Stepwise discriminant analysis was employed to detect significant correlations between channel morphology and other variables for a dataset of forty bedrock channel reaches. The control variables substrate heterogeneity, channel gradient, and Selby rock-mass strength correlated significantly with channel morphology at p-values of less than 0.05. This suggests that bedrock channel morphology, like alluvial channel morphology, results from an adjustment between the controlling variables of substrate and hydraulics, and that the manner of this adjustment is predictable if the controlling variables can be quantified.

Citation: Wohl, E. (2002), Modeled paleoflood hydraulics as a tool for interpreting bedrock channel morphology, in Ancient Floods, Modern Hazards: Principles and Applications of Paleoflood Hydrology, Water Sci. Appl., vol. 5, edited by P. K. House et al., pp. 345–358, AGU, Washington, D. C., doi:10.1029/WS005p0345.


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