Literature evaluation of induced groundwater tracers, field tracer techniques, and hydrodynamic dispersion values in porous media

Tracers have been employed to evaluate groundwater flow velocity as well as the physical characteristics of the geologic media through which they pass. A wide variety of groundwater tracers have been reported in the literature. These tracers include dyes, gases, particulate matter, thermal, and molecular and ionic substances. Well tests which include both single and multiple wells have been utilized in conjunction with these groundwater tracers. Single well evaluation includes borehole dilution and pulse technique. Multiple well tests encompass studies conducted in an unstressed well field, pumping and injection well tests, and discharging - recharging well pairs. The media's ability to disperse, or mix the tracer, which is known as the dispersivity of the specific medium, can be calculated by the use of tracers in conjunction with well tests. Dispersivities have been extracted from the literature and include values from several media types including elastics, fractured carbonates, and fractured crystalline rocks.