Fig. 5. Effect of transport distance and scale of the experiment on the dispersivity (). The boxes span the 25 and 75% percentiles, the thick black line is the median, and the 0 and 90% percentiles correspond with the extremities of the vertical bars. The numbers above the boxes correspond with the number of observations in the class. (Data from experiments with ponding boundary conditions and from experiments with a flow rate >10 cm d^–1 were excluded; data from the same experiment in a travel distance class were averaged and treated as a single entry.)