X-Ray Computed Tomography to Measure Bed Density in Sand Transport

This paper reports a new experimental method applying medical X-ray computed tomography (CT) to estimate the bed load in sand transport. A set of current-generated sand ripple experiments were conducted in a small hydraulic flume inserted in the CT scanner. The methodology is based on the measurements of height, velocity, and density of bed forms to estimate bed load. A temporal series of bed topography is first extracted from the CT scan images. The velocity is estimated by tracking the displacement of bed forms from two successive bed topographies. The sand bed density (rho(sb)) is estimated from the CT scan measurements using a calibration technique. The method measuring rho(sb) to calculate bed load is validated comparing measurements made with sand traps. The advantages and limitations of the CT method applied to bed-load transport are discussed. (C) 2022 American Society of Civil Engineers.