HR: 13:40h
AN: H43H-01 INVITED    [Abstracts]
TI: Of Magic Carpets, Rolling Snowballs, and Sleeping Dragons: an Energetics-based Classification for Hillslope/channel Interactions
AU: * Grant, G
EM: gordon.grant@oregonstate.edu
AF: USDA Forest Service, Pacific Northwest Research Station, Corvallis, OR 97331, United States
AU: Cashman, K
EM: cashman@uoregon.edu
AF: University of Oregon, Department of Geological Sciences, Eugene, OR 97403, United States
AU: O'Connor, J
EM: oconnor@usgs.gov
AF: US Geological Survey, Oregon Water Science Center, Portland, OR 97201, United States
AB: Interactions between hillslopes and channels can include a diverse range of geophysical processes, including debris flows, landslides, water floods, and volcanic flows. Each has its own characteristic time-energy trajectory. In some cases the energy of an event increases as it propagates through a landscape, primarily through the addition of mass and momentum; examples of these"rolling snowball" include the initiation and runout phases of volcanic lahars, avalanches, and debris flows. In other cases, loss of both mass and momentum from a moving body or fluid causes the energy of an event to dissipate with distance, similar to the unwinding of a rug; examples of these "magic carpets" include the depositional phases of lahars, pyroclastic flows, lava flows, and debris flows. Both snowballs and carpets leave distinctive imprints or tracks on the landscape that reflect the resultant mass flux from hill slope to channel. The efficiency of this mass transfer depends on the width and slope of the receiving channel and the rheological properties of the transported material. At one extreme, the channel easily accommodates mass flux from the slope, sometimes accompanied by fractionation into constituent phases. At the other extreme, mass from the hill slope can inundate and block the channel; these "sleeping dragons" modulate subsequent mass transfer down channel by changing the channel profile and bed properties. They also have the potential to "wake up" suddenly as mass failure and/or outbreak floods. Hazard prediction requires that the time-energy trajectory of each type of event be assessed; here we suggest some first order controls.
DE: 1810 Debris flow and landslides
DE: 1826 Geomorphology: hillslope (1625)
SC: Hydrology [H]
MN: 2007 Fall Meeting