Determining transport parameters for unsaturated porous media in flow-tank experiments using image analysis

摘要

Tracer experiments are carried out in water flow tank with 80cm height, 80cm length and 20cm width, which is filled homogeneously with two different types of sand materials. Brilliant Blue FCF, which makes the flow paths visible, is applied as a point source at the surface of the flow field. Dispersivity and dispersion coefficient are estimated using a time series of images of tracer transition. Experimental results show a linear dependence of dispersion coefficients on tracer velocity at a certain velocity and exhibits non-linearity in the range of higher water content. While values of dispersivity show an independency of rainfall intensity, dispersivity in unsaturated flow region is approximately one order larger than that in saturated flow region, indicating that transport parameters depend strongly on the water content where solute passes through.