Using X-ray micro-tomography and pore-scale modeling to quantify sediment mixing and fluid flow in a developing streambed

X-ray micro-tomography (XMT), image processing, and lattice Boltzmann (LB) methods were combined to observe sediment mixing, subsurface structure, and patterns of hydrogeological properties associated with bed sediment transport. Transport and mixing of sand and spherical glass beads were observed in a laboratory flume, beginning from a well-defined layered initial condition. Cores were obtained from the streambed at four different times, and each core was scanned by XMT in order to assess the evolution of spatial patterns within the bed. Image analysis clearly revealed the propagation of a sediment mixing front that began at the bed surface. The image data were used as boundary conditions in 3D LB simulation of pore fluid flow, showing that sediment sorting produced strong vertical gradients in permeability near the streambed surface. This new methodological approach offers potential for greatly improved characterization of mixing and transport of fine sediments in a wide variety of aquatic systems. Citation: Chen, C., A. I. Packman, and J.-F. Gaillard (2009), Using X-ray micro-tomography and pore-scale modeling to quantify sediment mixing and fluid flow in a developing streambed, Geophys. Res. Lett., 36, L08403, doi:10.1029/2009GL037157.