QUANTIFICATION OF MACRODISPERSION IN LABORATORYSCALE HETEROGENEOUS POROUS FORMATIONS

Abstract

Solute transport in groundwater is significantly influenced by the heterogeneity associated
with spatial distribution of the hydraulic conductivity. Understanding solute transport behavior in
heterogeneous flow fields is fundamental to develop appropriate models in aquifer management. In this study,
laboratory-scale two-dimensional tracer experiments were carried out in a 1 m length, 1 m height and 0.03 m
thickness sandbox to quantify solute macrodispersion phenomena in heterogeneous porous formation. Dye
tracer of Brilliant Blue FCF mixed with NaCl was applied as a pulse type source and subsequent transport
behavior of dye was recorded with digital camera. In addition to the spatial moment approach, temporal
moment approach was also applied to estimate the longitudinal macrodispersivity by means of NaCl
concentrations at an observation point in the flow field. The experimental results indicated that longitudinal
and transverse macrodispersivity were larger than those in homogeneous formation. Moreover, it was
revealed that both macrodispersivities in longitudinal and lateral directions have a non-dependency of the
regional flow rates. Laboratory study was extended by the comparison with other studies, indicating adequate
results in a suitable quantification range.