HR: 1340h
AN: H43F-1690    [Abstracts]
TI: Overlandflow and Rainsplash Erosion Rates of Scoria Cone Hillslopes Affected and Unaffected by Wildlandfire
AU: * Martinez-Hackert, B
EM: martinb@buffalostate.edu
AF: SUNY College at Buffalo, Dept. of Earth Sciences and Science Education 1300 Elmwood Ave., Buffalo, NY 14222, United States
AU: Bursik, M I
EM: mib@buffalo.edu
AF: SUNY at Buffalo, Dept. of Geology 876 Natural Sciences Complex, Buffalo, NY 14260, United States
AB: Data on linear diffusion-type degradation by rainsplash and on non-linear, non-diffusion type degradation by overland flow were collected during summer monsoon season in Arizona from 1996 to 2000. Splashboards, erosion pins, rain gauges, GPS, and cross-sections were major instrumentation used in this field based study conducted on natural, undisturbed slope and rainfall conditions. Effective diffusion coefficients, erosion rates due to raindrop detachment and overlandflow estimated empirically were investigated with this data set. The rainsplash data are consistent with a long-term diffusion model of slope degradation. However, the data are in harmony with model results of more arid climate than with the semiarid climate of the San Francisco Volcanic Field. This indicates that previous diffusion-type modeling of scoria cones may have overestimated the contribution of quantity of rainsplash erosion and underestimated the contribution of overland flow processes to overall erosion. The short-term slope modification by overlandflow compares well with results from a cellular aautomaton, smooth particle hdrodynamics model (CASPH). Detailed measurements of horizontal and longitudianl profiles on the slopes give in depth insight to the processes shaping these landforms. A wildland fire damaged the vegetation (Ponderosa Pine) of one of the two hillslope observation sites in 1996. This event resulted in a great opportunity to observe the post-fire geomorphological response on rainsplash and overlandflow processes on a weathered scoria cone slope surface. The rate of degradation of the burned cone was orders of magnitude larger than of the unburned cone. Both diffusive and non-diffusive erosion measurements proofed that the first post-fire rainy season in areas affected by wildlandfires are severe.
DE: 1810 Debris flow and landslides
DE: 1815 Erosion
DE: 1826 Geomorphology: hillslope (1625)
DE: 1838 Infiltration
DE: 1850 Overland flow
SC: Hydrology [H]
MN: 2007 Fall Meeting