HR: 1340h
AN: H33D-1634    [Abstracts]
TI: Fractal and lacunarity analysis on soil structure and preferential flow using micro X-ray computing tomography
AU: * Luo, L
EM: lxl230@psu.edu
AF: Penn state Univ, 116 ASI Blg, University Park, PA 16802,
AU: Lin, H
EM: henrylin@psu.edu
AF: Penn state Univ, 116 ASI Blg, University Park, PA 16802,
AB: Quantification of soil structure and flow patterns is important to enhance our understanding of preferential flow phenomena in structured soil. Computing tomography (CT) provides a nondestructive means of observing soil pore structure and monitoring solute breakthrough in real-time. We investigated soil structure and solute transport dynamics in a large intact soil column. Five positions (at Ap1, Ap2, Bt, and two boundaries between the horizons) were scanned with a resolution of 78.1µm×78.1µm×86.7µm at three different stages of a leaching experiment: 1) saturated with water, 2) injection of 60 g/L potassium iodine (KI) solution after 6 min, and 3) injection of the solution after 78 min. Soil macropore structure and tracer distribution were reconstructed at the five positions. Pore volume, pore hydraulic radius, fractal dimensions, and lacunarity functions in both 2-D and 3- D were computed. The results showed distinct macropore and flow patterns at the five positions in the soil column. The continuous earthworm burrows and root channels were very active in solute transport because of its high continuity and low tortuosity. Positive logarithmic trends were found between fractal dimensions in both 2-D and 3-D and the fraction of interests. The lacunaritiy functions varied along the soil depth and among different features (e.g., macropore network and tracer distribution). Both macropore network and tracer distribution showed higher degree of cluster at the subsurface, which were associated with the biopores and preferential flow and transport. The nearly linear lacunaritiy function of tracer distribution, especially at 78 min, indicated the existence of a self-similarity. The 3-D and 2-D lacunarities were comparable for the data used in this study. Compared with fractal dimensions, lacunarity appears to be more sensitive to the structure difference and more effective in differentiating macropore and flow patterns.
DE: 0486 Soils/pedology (1865)
DE: 1865 Soils (0486)
SC: Hydrology [H]
MN: 2007 Fall Meeting