Paleohydraulic Analysis of Megaripples from Outburst Floods in Omak, Washington
Faculty Mentor
Chad Pritchard
Presentation Type
Poster
Start Date
5-8-2024 11:15 AM
End Date
5-8-2024 1:00 PM
Location
PUB NCR
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
This can go back to Shaw et al. (1999). Though the videos of Leseman and Zentner are great, it is good to cite the primary source. The video didn't discover these ripples as much as discuss them. There is even a new paper that describes these features with relation to paleohydraulics of megafloods by Gombiner and Leseman (2024) in Geology, titled: Okanogan lobe tunnel channels and subglacial floods into Moses Coulee, Channeled Scabland, northwestern United States.
Creative Commons License
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Paleohydraulic Analysis of Megaripples from Outburst Floods in Omak, Washington
PUB NCR
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.
Comments
The giant ripples may have been "described" by Leseman and Zentner, but this was not a "discovery". Please use primary sources.