Journal of Cave and Karst Studies - ISSN 1090-6924
Volume 63 Number 2: 59-66 - August 2001

A publication of the National Speleological Society

Solute transport through laboratory-scale karstic aquifers
Lee J. Florea and Carol M. Wicks

Abstract

Laboratory-scale models of branchwork and of network karstic aquifers were constructed to provide data needed for calibration of numerical models. The distribution and connectedness of the conduits and sinkholes were scaled similarly to those found in nature; however, the porosity of models (2 and 3%) and the recharge rate (80 cm/hr) could not be scaled appropriately. Pulses of 1-M NaCl were injected sequentially at ten locations on both models to determine transport parameters using QTRACER. For all experiments, the Reynolds numbers were <150, the Peclet numbers were >6, and the Froude numbers were ~0. The flow regime was laminar and subcritical and advective processes dominated transport processes. The mean tracer transit times were significantly greater in the network model (29 s and 49 s) than in the branchwork model (17 s and 35 s) for injection locations that were proximal to (<10 cm) and distal from (10-20 cm) the spring. The lag times and times to peak concentration were highly variable and no systematic variation with distance from the spring could be discerned. The results can be used in calibration of numerical models of tracer transport through karstic aquifers.

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