Using magnetic resonance imaging for experimental analysis of fine-sediment infiltration into gravel beds

Sedimentologists recognise that development of a fine resolution, truly three-dimensional analytical tool is essential if the internal structure of an opaque material is to be examined. This paper therefore seeks to: (i) test the viability of Magnetic Resonance Imaging (MRI) for sedimentological research; and (ii) investigate fine sediment infiltration into gravel beds. The results of six experiments are quantitatively analysed using ImageJ post-processing software. Data indicate that MRI-based measurements of particle axes and volumes are comparable to standard laboratory techniques. Also, the technique permits visualisation and analysis of differences in the pattern of fine sediment infiltration (median particle diameter d) into a framework of gravel (median particle diameter D). Data clearly illustrate a siltation process for samples of D/d = 34 and a sealing process for samples of D/d = 7 where the seal is restricted to a depth equal to 2D. This pore-scale visualisation is valuable to understanding hydraulic-sediment-habitat interactions.