ABSTRACT
Transverse (fl ow-dependent) dispersivity is very small — Observed transverse dispersivities are quite small and generate only minor spreading of solutes in groundwater transport.
Formation-dependent and time-dependent (diffusion) dispersivities can be large — The transverse spreading that may be observed is likely due to anastomosing or braided channel forms and temporal variations in groundwater gradient. The longitudinal spreading that is observed is probably a result of diffusive transfer of solute mass between the mobile and immobile porosities.
