ABSTRACT
After intensive experiments at the laboratory scale, in situ tests have been carried out in a carbonatic aquifer to estimate the linear effective velocity in uniform flow. The two-well test technique has been adopted for this purpose. Two typical tracers, NaCl (conservative) and Rhodamine WT (non conservative), were injected simultaneously for comparative evaluations. The results show different breakthrough curves of concentration at sampling well for the two tracers. The travel time for NaCl is shorter than for Rhodamine WT. This experiment confirms the necessity to know the retardation of a specific tracer used, in conjunction with the aquifer characteristics, in order to interpret correctly the results of tracer tests.
