HR: 0800h
AN: H41C-0418    [Abstracts]
TI: Soil hydrophobicity and permeability after the Old Fire in the San Bernardino Mountains, California
AU: * Morrissey, S K
EM: skm@umail.ucsb.edu
AF: UC Santa Barbara, Department of Earth Science 552 University Rd - Bldg 526, Santa Barbara, CA 93106 United States
AU: Kong, H
EM: kongh@seas.ucla.edu
AF: UC Los Angeles, Department of Civil & Environmental Engineering 5731/5732 Boelter Hall, Los Angeles, CA 90095 United States
AU: Rademacher, L K
EM: lrademacher@pacific.edu
AF: University of the Pacific, Department of Geosciences 3601 Pacific Avenue, Stockton, CA 95211 United States
AU: Hogue, T
EM: thogue@seas.ucla.edu
AF: UC Los Angeles, Department of Civil & Environmental Engineering 5731/5732 Boelter Hall, Los Angeles, CA 90095 United States
AU: Meixner, T
EM: tmeixner@hwr.arizona.edu
AF: University of Arizona, Department of Hydrology and Water Resources 113 E. North Campus Drive, Tucson, AZ 85721 United States
AB: The fall 2003 Old Fire caused physical and chemical changes to mountain front watersheds in the San Bernardino Mountains, resulting in the formation of a hydrophobic layer, decreased transpiration, decreased infiltration, altered streamwater chemistry, and increased runoff. This study focused on soil hydrophobicity, permeability and their role in post-fire flooding. Hydrophobicity was measured in soils from a several burned chaparral environment at 7 and 19 months after the Old Fire. Water drop penetration tests were performed at 1-inch intervals from the soil surface to 5 inches depth. The maximum infiltration time was 120 seconds at 2 inches depth, 7 months after the wildfire compared with a maximum infiltration time of 18 seconds at soil surface, 19 months after the wildfire. The hydrophobic layer at depth disappeared by 19 months after the wildfire. Soil oxygen permeability was measured using a soil core air permeameter. Soil permeability decreased by an order of magnitude over the same time period 7 to 19 months after the Old Fire. End-member mixing analysis and runoff ratios indicate an increase in the precipitation and overland flow component following the wildfire, likely due to the hydrophobic layer in the soil. The hydrophobic layer played a greater role in hydrologic flowpath changes than the physical changes to soil permeability in this chaparral environment.
DE: 1000 GEOCHEMISTRY
DE: 1821 Floods
DE: 1830 Groundwater/surface water interaction
DE: 1879 Watershed
SC: Hydrology [H]
MN: Fall Meeting 2005