Real-time measurement of water profiles in a sand using neutron radiography

Digital images of water profiles in an air-water-sand system were obtained using real-time neutron radiography. This imaging technique provided measurements of moisture content at video frame rates with a spatial resolution of 0.2 mm 2 and an image area > 400 cm 2 . The experiments were conducted using aluminum chambers filled with SiO2 sand packed to a total porosity of 0.33. The velocity and water content within a flow field were obtained by measuring the intensity change of a neutron beam as it passed through the experiment chamber. The variation in matric potential within the flow field was obtained and the results were compared to the measurements of matric potential made by Selker (1992).