||Advection-Dispersion Interpretation of Tracer Observations in an Aquifer.
Hoehn, Eduard ;
Roberts, Paul V. ;
||Stanford Univ., CA. Dept. of Civil Engineering.;Robert S. Kerr Environmental Research Lab., Ada, OK.
||EPA-CR-808851 ;EPA-R-804431; EPA-600/J-82-232;
Ground water recharge ;
Hydraulic models ;
Water pollution control ;
Injection wells ;
Mathematical models ;
Isotopic labeling ;
Hydraulic conductivity ;
Path of pollutants ;
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Data from field tracer experiments are interpreted to evaluate the adequacy of an advection-dispersion model for simulating field conditions. A stimulus-response approach based on chemical reactor theory was applied. Two different pulse stimuli at an injection well resulted in responses in two observation wells located at distances of 8 and 17 m, respectively, from the injection well. The wells are perforated over the entire aquifer thickness of 1-2 m. The behavior of the two conservative tracers agreed closely with each other. A two-domain model is employed to extend the simple advection-dispersion equation to account for the observed tailing. Response curves of concentrations were fitted with finite-difference simulations using the two-domain model. The responses at the more distant well were characterized by values of dispersivity equal to or slightly smaller than those at the nearer well.