HR: 0800h
AN: ED31B-1206    [Abstracts]
TI: The Relationship Between Soil Type, Water Repellency, and Permeability in the San Bernardino Mountains, California
AU: * Lopez, S R
EM: slopezon@ucla.edu
AF: University of California, Los Angeles, Department of Civil and Environmental Engineering, Los Angeles, CA 90024
AU: Hogue, T S
EM: thogue@seas.ucla.edu
AF: University of California, Los Angeles, Department of Civil and Environmental Engineering, Los Angeles, CA 90024
AU: Morrissey, S
EM: skmbruin@excite.com
AF: University of California, Santa Barbara, Department of Geological Sciences, Santa Barbara, CA 93106
AU: Rademacher, L
EM: lrademacher@pacific.edu
AF: University of the Pacific, Department of Geosciences, Stockton, CA 95211
AU: Nation, H
EM: liepzink@yahoo.com
AF: California State University, Los Angeles, Department of Geological Sciences, Los Angeles, CA 90032
AU: Curto, V
EM: toria@ucla.edu
AF: University of California, Los Angeles, Department of Civil and Environmental Engineering, Los Angeles, CA 90024
AU: Monterrosa, A
EM: atmonterrosa@yahoo.com
AF: California State University, Los Angeles, Department of Geological Sciences, Los Angeles, CA 90032
AU: Kong, H
EM: kongh@seas.ucla.edu
AF: University of California, Los Angeles, Department of Civil and Environmental Engineering, Los Angeles, CA 90024
AB: The San Bernardino Mountain region is a natural ecosystem that frequently suffers from sporadic fire occurrences. Promptly after the vegetation is burned, a hydrophobic layer is formed from the combustion of organic material and debris. This layer is typically found beneath the soil surface and can extend to various depths depending on pre-existing moisture content, vegetation and soil type. With an increase in hydrophobicity, there is an increase in the potential for hazardous post-fire flooding. The purpose of our research is to analyze the soils of two burned watersheds, Devil's Canyon and City Creek, conduct comparative analysis with an unburned (control) watershed, and establish a correlation between water repellency, soil type and runoff. Air and water permeability is measured at grids spread throughout both burned and unburned areas of the three watersheds. Each grid contains 25 sample points where air flow is measured at the surface and a water drop penetration test (WDPT) is performed at three depths. Soil sieve analysis is also conducted in the laboratory to determine the particle size distribution of the fine and coarse aggregates. An estimation of moisture content and porosity is established for each soil sample. Preliminary results show that a decrease in permeability is seen primarily at the surface of the soil; this suggests the hydrophobic layer remains relatively high in the burned soils. Sieving results at Devil's Canyon confirms that small aggregates from ash and settled organic material decreases permeability, thus increasing the potential for higher surface flows. This study provides a perspective of soil characteristics and will enhance our understanding of pre- and post-fire soil permeability. The data collected throughout the duration of this project will be used to improve the predictions of post-fire floods through the use of hydrologic models.
DE: 1821 Floods
DE: 1860 Streamflow
DE: 1865 Soils (0486)
DE: 1879 Watershed
SC: Education and Human Resources [ED]
MN: Fall Meeting 2005