Characterizing water fingering phenomena in soils using magnetic resonance imaging and multifractal theory

Author(s)

Posadas, A. ^{[1, 2]} ; Quiroz, R. ^[2] ; Tannus, A. ^[3] ; Crestana, S. ^[1] ; Vaz, C. M. ^[1]

Affiliation

^[1] Embrapa Instrumentacao Agropecuaria, BR-13560970 Sao Carlos, SP - Brazil

^[2] Int Potato Ctr, CIP, Lima 12 - Peru

^[3] Univ Fed Sao Paulo, Dept Fis & Informat, Inst Fis Sao Carlos, BR-13560250 Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: Nonlinear Processes in Geophysics; v. 16, n. 1, p. 159-168, 2009.
• Web of Science Citations: 11

Abstract

The study of water movement in soils is of fundamental importance in hydrologic science. It is generally accepted that in most soils, water and solutes flow through unsaturated zones via preferential paths or fingers. This paper combines magnetic resonance imaging (MRI) with both fractal and multifractal theory to characterize preferential flow in three dimensions. A cubic double-layer column filled with fine and coarse textured sand was placed into a 500 gauss MRI system. Water infiltration through the column (0.15 x 0.15 x 0.15 m(3)) was recorded in steady state conditions. Twelve sections with a voxel volume of 0.1 x 0.1 x 10 mm(3) each were obtained and characterized using fractal and multifractal theory. The MRI system provided a detailed description of the preferential flow under steady state conditions and was also useful in understanding the dynamics of the formation of the fingers. The f (alpha) multifractal spectrum was very sensitive to the variation encountered at each horizontally-oriented slice of the column and provided a suitable characterization of the dynamics of the process identifying four spatial domains. In conclusion, MRI and fractal and multifractal analysis were able to characterize and describe the preferential flow process in soils. Used together, the two methods provide a good alternative to study flow transport phenomena in soils and in porous media. (AU)