Faculty Mentor
Chad Pritchard
Presentation Type
Poster
Primary Discipline of Presentation
Geosciences
Abstract
Located in Omak, Washington atop what is observed to be a gravel point bar are giant current ripples associated with outburst floods that took place during the Pleistocene (O’Connor et al. 2020 and Minard 1985). Thorough breakdown of these giant current ripples was conducted using their geomorphologies associated with stream flow mechanisms for gravel bedforms such as hydraulic radius of cross- sectional area and velocity using Manning’s equation to determine Froude’s Number (USDA 2007). Ripple index associated with ripple wavelength and height was then compared to additional megaripples located throughout Scablands of Washington that have been correlated to the Great Missoula Outburst Floods (Lee 2009, Rudoy 2001, and Baker 1978). Froude’s Number can be used to then understand the relationship to flow regimes, upper or lower, that water velocity has at a specific depth (Baker 1978). Within the channeled scablands of Washington, Froude’s Number for numerous megaripples ranges from 0.5-0.9, associated with the upper end of the lower flow regime (Baker 1978). It is important to note the lack of comprehensive research and thorough understanding pertaining to depositional macroforms and mesoforms, specifically gravel comprising megaripples associated with glacial outburst floods. Calculations and numbers for megaripples were obtained using LIDAR within Google Earth Pro.
Recommended Citation
Lawrence, Jessica M., "Paleohydraulic Analysis of Megaripples from Outburst Floods in Omak, Washington" (2024). 2024 Symposium. 11.
https://dc.ewu.edu/srcw_2024/works_2024/works_2024/11
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.
Included in
Geology Commons, Other Earth Sciences Commons, Other Physical Sciences and Mathematics Commons, Sedimentology Commons
Paleohydraulic Analysis of Megaripples from Outburst Floods in Omak, Washington
Located in Omak, Washington atop what is observed to be a gravel point bar are giant current ripples associated with outburst floods that took place during the Pleistocene (O’Connor et al. 2020 and Minard 1985). Thorough breakdown of these giant current ripples was conducted using their geomorphologies associated with stream flow mechanisms for gravel bedforms such as hydraulic radius of cross- sectional area and velocity using Manning’s equation to determine Froude’s Number (USDA 2007). Ripple index associated with ripple wavelength and height was then compared to additional megaripples located throughout Scablands of Washington that have been correlated to the Great Missoula Outburst Floods (Lee 2009, Rudoy 2001, and Baker 1978). Froude’s Number can be used to then understand the relationship to flow regimes, upper or lower, that water velocity has at a specific depth (Baker 1978). Within the channeled scablands of Washington, Froude’s Number for numerous megaripples ranges from 0.5-0.9, associated with the upper end of the lower flow regime (Baker 1978). It is important to note the lack of comprehensive research and thorough understanding pertaining to depositional macroforms and mesoforms, specifically gravel comprising megaripples associated with glacial outburst floods. Calculations and numbers for megaripples were obtained using LIDAR within Google Earth Pro.
