HR: 1330h
AN: H32A-0535    [PDF]
TI: SPATIAL VARIABILITY OF SOIL HYDRAULIC PARAMATERS IN RELATION TO SEDIMENTARY FACIES
AU: * Onsoy, Y
EM: yonsoy@ucdavis.edu
AF: University of California, Davis, One Shields Avenue, Davis, CA 95616
AU: Harter, T
EM: thharter@ucdavis.edu
AF: University of California, Davis, One Shields Avenue, Davis, CA 95616
AU: Ginn, T
EM: trginn@ucdavis.edu
AF: University of California, Davis, One Shields Avenue, Davis, CA 95616
AB: The objective of this study is to evaluate the hypothesis that spatial heterogeneity of soil hydraulic properties can vary significantly with major stratigraphic units identified based on a visual texture determination of soil samples collected at the Kearney Research Site in Fresno, California. We used the concept of facies to characterize the heterogeneity of soil hydraulic properties that are defined in the form of van Genuchten model. Undisturbed and disturbed cores were collected from 60 boreholes drilled to a depth of 16 m in a nectarine orchard subject to a long-term nitrate experiment and were used to give a detailed subsurface sedimentologic description by color, texture, and moisture. Visual inspection was used to identify laterally continuous major stratigraphic units, referred to as facies. Undisturbed samples were originally grouped according to their core scale characterization of soil texture prior to conducting a multistep outflow experiment in conjunction with inverse modeling for laboratory determination of van Genuchten parameters. Correlations between the facies and van Genuchten parameters were tested by analysis of variance (ANOVA). Subsequently, Post Hoc Turkey HSD comparison technique was used to elucidate significant differences for the van Genuchten parameters between the facies and the correlations between facies for a given soil hydraulic parameter. Both ANOVA and pairwise comparisons suggested that facies bounding surfaces tend to separate regions with different soil hydraulic properties. In this application a facies-based approach provides a good basis to conceptualize subsurface heterogeneity.
DE: 1875 Unsaturated zone
SC: Hydrology [H]
MN: 2003 Fall Meeting