Groundwater age dating
It is a well-organized, advanced, clearly written resource for all the professionals, scientists, graduate students, consultants, and water sector managers who deal with groundwater and who seek a comprehensive treatment of the subject of groundwater age.
Groundwater age dating 3 H 3 He A good tracer because 3 H is right in the water. Tritium forms 3 He by beta decay with a half-life of about 12.4 years. Tritium has been used for many years (produced by atmospheric nuclear testing).
Groundwater age is usually defined as the time between recharge at the water table to the time when groundwater was sampled.
Apparent groundwater ages based on CFC- and 3H/3He-dating techniques and model-based travel times could not be statistically differentiated, and all were strongly correlated with depth.
Confinement of 3He was high because of the rapid vertical flow velocity (of the order of 1 m/yr), resulting in clear delineation of groundwater travel times based on the 3H/3He-dating technique.
Groundwater transit time is the time between recharge and discharge from the aquifer.
So groundwater transit time is equal to groundwater age at the point of exit from the aquifer, such as the point of discharge from an irrigation well, or discharge to a stream.