Studies of soil-water transport by MRI.

Sequential spin-echo spin-warp MRI pulse sequences have been used to study soil-water transport processes including infiltration, redistribution, and drainage of water in soil columns. Those images provide a means for monitoring and quantifying spatial and temporal changes of soil-water distributions and the movement of wetting fronts. In addition, temporal-geometric changes of unstable wetting fronts during water redistribution were estimated from 2D images and the temporal development of the longest length of finger was described by a fractal relation t approximately L1.38. Bulk dispersion-time-dependent displacement and velocity spectra, as well as 2D maps of flow velocities and dispersion coefficients in soil macropores during saturated steady-state flow, were reconstructed from data obtained using the alternating-pulsed-field-gradient (APFG) pulse sequences.

Magnetic resonance imaging of soil-water phenomena.

2D and 3D images of static and dynamic water phenomena in packed clay soil columns were obtained by MRI. A spin-echo spin-warp Fourier imaging sequence, together with prefocused 90 degrees selective pulse for 2D imaging, was selected. The images demonstrate the potential of using MRI for studies of static and dynamic water phenomena in soil with modest iron content and adequate water content.