An Experiment to Measure Transport Parameters in a Saturated Heterogeneous Scaled Medium

Abstract

One of the major difficulties in groundwater research is determining an appropriate scale at which to conduct an experiment. Because of a phenomenon called the scale effect, measured values of parameters in heterogeneous media can vary with the scale of measurement. The objective of this experiment was to measure the parameters of dispersivity and velocity at different length scales, to see if the measured values would converge to a limit at some scale of measurement. A good deal of research has been conducted on the scale effect in heterogeneous media, but this phenomenon is still not totally understood. The heterogeneous medium for this experiment consisted of two sands of differing hydraulic conductivity. A special structured pattern was constructed of the two sands in a flow cell in which dispersivity and velocity could be measured at several length scales. The dependence of the measurements on the scale of measurement could then be studied. An interesting result of the experiment was that values of dispersivity converged at the longest length scale while values of velocity never reached a limit. Finally, it appeared that dispersivity values measured throughout the flow cell varied depending on which type of sand the measurement was taken in.