Experimental assessment of solute dispersion in stratified porous media

: The objective of this paper is to evaluate effects of strati‐ fied porous formation on solute dispersion using two-dimensional laboratory tracer tests. An image analysis tech‐ nique was used to analyze the solute dispersion processes and quantify the dispersivity and behaviors of forward and backward tails of solute plumes. Longitudinal dispersivity estimates for the stratified porous media increased with travel distance and are in reasonable agreement with previ‐ ous work. Moreover, in all of the stratified cases the trans‐ verse dispersivity exhibited a similar trend which decayed with travel distance. The summary of dispersivities esti‐ mated from this study and previous studies suggests that if both degree of heterogeneity and scale for stratified and randomly heterogeneous porous media are similar, the lon‐ gitudinal dispersivity is larger in stratified media than in randomly heterogeneous media. In order to quantify behav‐ iors of forward and backward tails, we defined the travel distances x 05 and x 95 corresponding to the 5th and 95th per‐ centiles, respectively, of the cumulative concentrations in the longitudinal direction, and found that the distance between x 05 and x 95 spread out linearly in the stratified cases.