Estimation of α_L, Velocity, K_d and Confidence Limits from Tracer Injection Test Data

Abstract

Bromide and boron were used as tracers during an injection experiment conducted at an artificial recharge facility near Stanton, Texas. The Ogallala aquifer at the Stanton site represents a heterogeneous alluvial environment and provides the opportunity to report scale dependent dispersivities at observation distances of 2 to 15 m in this setting. Values of longitudinal dispersivities are compared with other published values. Water samples were collected at selected depths both from piezometers and from fully screened observation wells at radii of 2, 5, 10 and 15 m. An exact analytical solution is used to simulate the concentration breakthrough curves and estimate longitudinal dispersivities and velocity parameters. Greater confidence can be placed on these data because the estimated parameters are error bounded using the bootstrap method. The non‐conservative behavior of boron transport in clay rich sections of the aquifer were quantified with distribution coefficients by using bromide as a conservative reference tracer.

Evaluating the Effectiveness of a Fixed Wellhead Delineation: Regional Case Study

“…In addition, the process for deciding when to implement each prospective method often involves considerable debate. Some studies have found it necessary to delineate complex and/or karstified aquifers with tracers and/or extensive modeling (e.g., White, 1969;Quinlan, 1986;Rainwater et al, 1987;Ryan and Meiman, 1995;Broermann et al, 1997;Rayne et al, 2001), while others claim that extensive modeling is often too expensive to justify results that may be no more effective than simple radius delineations (e.g., Cleary and Cleary, 1991;Swanson, 1992;WDNR, 1999a).…”