Application of continuous time random walk theory to tracer test measurements in fractured and heterogeneous porous media

We examine a set of analytical solutions based on the continuous time rando m walk (CTRW) approach, which can be evaluated numerically and used to anal yze breakthrough data from tracer tests. Practical application of these sol utions, with discussion of the physical meaning of the relevant model param eters, is emphasized. The CTRW theory accounts for the often observed non-F ickian (or scale-dependent) dispersion behavior that cannot be properly qua ntified by using the advection-dispersion equation. The solutions given her e, valid for a wide range of dispersive behaviors of conservative tracers, and useful for both characterization and prediction, have been integrated i nto a library of external functions for use with the GRACE graphical displa y acid analysis package, Example applications of these solutions are presen ted. The library and graphics software are freely accessible from a Web sit e.